Dissertations / Theses: 'Time-Reversal Space-Time Block Coding'

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Masoud, Masoud. "Space-time block coding for wireless communications." Thesis, University of Hertfordshire, 2008. http://hdl.handle.net/2299/2548.

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Wireless designers constantly seek to improve the spectrum efficiency/capacity, coverage of wireless networks, and link reliability. Space-time wireless technology that uses multiple antennas along with appropriate signalling and receiver techniques offers a powerful tool for improving wireless performance. Some aspects of this technology have already been incorporated into various wireless network and cellular mobile standards. More advanced MIMO techniques are planned for future mobile networks, wireless local area network (LANs) and wide area network (WANs). Multiple antennas when used with appropriate space-time coding (STC) techniques can achieve huge performance gains in multipath fading wireless links. The fundamentals of space-time coding were established in the context of space-time Trellis coding by Tarokh, Seshadri and Calderbank. Alamouti then proposed a simple transmit diversity coding scheme and based on this scheme, general space-time block codes were further introduced by Tarokh, Jafarkhani and Calderbank. Since then space-time coding has soon evolved into a most vibrant research area in wireless communications. Recently, space-time block coding has been adopted in the third generation mobile communication standard which aims to deliver true multimedia capability. Space-time block codes have a most attractive feature of the linear decoding/detection algorithms and thus become the most popular among different STC techniques. The decoding of space-time block codes, however, requires knowledge of channels at the receiver and in most publications, channel parameters are assumed known, which is not practical due to the changing channel conditions in real communication systems. This thesis is mainly concerned with space-time block codes and their performances. The focus is on signal detection and channel estimation for wireless communication systems using space-time block codes. We first present the required background materials, discuss different implementations of space-time block codes using different numbers of transmit and receive antennas, and evaluate the performances of space-time block codes using binary phase-shift keying (BPSK), quadrature phase-shift keying (QPSK), and quadrature amplitude modulation (QAM). Then, we investigate Tarokh’s joint detection scheme with no channel state information thoroughly, and also propose a new general joint channel estimation and data detection scheme that works with QPSK and 16-QAM and different numbers of antennas. Next, we further study Yang’s channel estimation scheme, and expand this channel estimation scheme to work with 16-QAM modulation. After dealing with complex signal constellations, we subsequently develop the equations and algorithms of both channel estimation schemes to further test their performances when real signals are used (BPSK modulation). Then, we simulate and compare the performances of the two new channel estimation schemes when employing different number of transmit and receive antennas and when employing different modulation methods. Finally, conclusions are drawn and further research areas are discussed.

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Baker, Dirk A. "Space-time block coding with imperfect channel estimates." Morgantown, W. Va. : [West Virginia University Libraries], 2001. http://etd.wvu.edu/templates/showETD.cfm?recnum=1843.

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Thesis (M.S.)--West Virginia University, 2001. Title from document title page. Document formatted into pages; contains iv, 74 p. : ill. Includes abstract. Includes bibliographical references (p. 73-74).

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Ding, Zhiguo. "Receiver algorithm design for space time block coding systems." Thesis, Imperial College London, 2005. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.420523.

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Acharya, Om Nath, and Sabin Upadhyaya. "Space Time Coding For Wireless Communication." Thesis, Linnéuniversitetet, Institutionen för datavetenskap, fysik och matematik, DFM, 2012. http://urn.kb.se/resolve?urn=urn:nbn:se:lnu:diva-19424.

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As the demand of high data rate is increasing, a lot of research is being conducted in the field of wireless communication. A well-known channel coding technique called Space-Time Coding has been implemented in the wireless Communication systems using multiple antennas to ensure the high speed communication as well as reliability by exploiting limited spectrum and maintaining the power. In this thesis, Space-Time Coding is discussed along with other related topics with special focus on Alamouti Space-Time Block Code. The Alamouti Codes show good performance in terms of bit error rate over Rayleigh fading channel. The performance of Altamonte’s code and MIMO capacity is evaluated by using MATLAB simulation.

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Gregoratti, David. "Randomized space-time block coding for the multiple-relay channel." Doctoral thesis, Universitat Politècnica de Catalunya, 2010. http://hdl.handle.net/10803/6949.

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En la última década, la cooperación entre usuarios ha generado un gran interés por la posibilidad de mejorar la velocidad de transmisión en las redes de comunicaciones inalámbricas. El objetivo es formar un array con las antenas de todos los dispositivos y, de esta forma, aplicar técnicas de procesado espacio-temporal. El esquema de cooperación más sencillo es el canal con relays: todos los terminales que escuchen una comunicación entre dos puntos pueden ayudar a la fuente retransmitiendo lo que hayan recibido. En un sistema realista, los relays no disponen de información sobre el canal en trasmisión. En este escenario, los códigos espacio-temporales (STC, del inglés space-time coding) son la alternativa más eficiente para aprovechar la diversidad introducida por los relays. Sin embargo, los STC clásicos están diseñados para un número limitado y fijo de antenas transmisoras y no se adaptan bien a sistemas cooperativos donde el número de relays puede ser elevado y, sobretodo, puede variar en el tiempo, según los usuarios entren o salgan de la red. El problema principal es la necesidad de usar un código nuevo cada vez que cambie la configuración de la red, generando un importante tráfico de señalización. Esta tesis analiza un código espacio-temporal a bloques de dispersión lineal (LD-STBC, del inglés linear-dispersion space-time block coding), aleatorio y distribuido: a cada relay se le asigna una matriz aleatoria que aplica una transformación lineal al vector que contiene los símbolos de la fuente. Cada matriz se genera de forma independiente y sin ninguna relación con el número de usuarios involucrados. De esta manera, el número de nodos puede variar sin necesidad de modificar los códigos existentes. La forma más intuitiva de construir matrices de dispersión lineal independientes es que sus elementos sean variables aleatorias independientes e idénticamente distribuidas (i.i.d.). Por esta razón, se estudia primero la eficiencia espectral obtenida por este tipo de LD-STBC. Es importante remarcar que la eficiencia espectral es una cantidad aleatoria, ya que es una función de los códigos aleatorios anteriormente descritos. Sin embargo, cuando las dimensiones de las matrices crecen infinitamente pero manteniendo constante la tasa del código (relación entre número de símbolos de la fuente sobre el número de símbolos de los relays), la eficiencia espectral converge rápidamente hacia una cantidad determinista. Este resultado se demuestra usando la teoría de las matrices aleatorias. Por esta razón, el sistema se analiza aproximando la eficiencia espectral con su limite. Por ejemplo, la comparación con el canal directo entre fuente y destino permite definir unas condiciones suficientes en donde el sistema con relays es superior a la comunicación punto a punto. Posteriormente se debe analizar la probabilidad de outage, es decir la probabilidad de que, debido a la baja calidad del canal, la eficiencia espectral sea menor que la velocidad de transmisión solicitada por el sistema. Como ya se ha mencionado anteriormente, los relays se introducen para aumentar la diversidad del canal y, con ella, el número de caminos independientes entre la fuente y el receptor, reduciendo la probabilidad de outage. Para los LD-STBC i.i.d. las prestaciones en términos de outage dependen del tipo de relay (amplify and forward o decode and forward) y son función de la tasa del código, que debe ser cuidadosamente elegida para maximizar el orden de diversidad sin desperdiciar demasiados recursos. Finalmente, en el último capítulo de la tesis se considera otro tipo de LD-STBC, distinto del i.i.d. analizado hasta ahora. En este caso, las matrices de dispersión lineal siguen siendo independientes la una de la otra pero se añade la restricción de que cada una tenga columnas (o filas, según la tasa del código) ortogonales. Así, se consigue que el código siga siendo flexible con respecto a las variaciones en el número de usuarios, pero su estructura permite reducir la interferencia generada por cada relay, como se puede notar comparando su eficiencia espectral con la eficiencia espectral obtenida por el código i.i.d. Cabe destacar que el análisis asintótico de estos códigos (llamados isométricos) se basa en herramientas matemáticas más sofisticadas que las anteriores y, por lo tanto, es necesario un estudio más profundo para poder entender cómo se comporta en términos de outage. In the last decade, cooperation among multiple terminals has been seen as one of the more promising strategies to improve transmission speed in wireless communications networks. Basically, the idea is to mimic an antenna array and apply distributed versions of well-known space-diversity techniques. In this context, the simplest cooperative scheme is the relay channel: all the terminals (relays) that overhear a point-to-point communication between a source and a destination may decide to aid the source by forwarding (relaying) its message. In a mobile system, it is common to assume that the relays do not have any information about the channel between them and the destination. Under this hypothesis, the best solution to exploit the diversity offered by multiple transmitting antennas is to use space-time coding (STC). However, classical STC's are designed for systems with a fixed and usually low number of antennas. Thus, they are not suitable for relaying in most mobile communications systems where the number of terminals is potentially large and may vary as users join or leave the network. For each new configuration, a new code has to be chosen and notified to the relays, introducing a set-up overhead of signaling traffic. In this dissertation we will propose and analyze a randomized distributed linear-dispersion space-time block code (LD-STBC): each relay is assigned a specific matrix which linearly transforms (left-multiplies) the column vector of source symbols. Each matrix is independently generated and does not depend on the total number of transmitters, which can thus change without interrupting data transmission for a new code--relay assignment. The more intuitive way to build independent linear-dispersion matrices is to fill them with independent and identically distributed (i.i.d.) random variables. Therefore, we will first consider these i.i.d. codes and characterize the resulting spectral efficiency. In order to analyze the performance achieved by the system, we consider a large-system analysis based on random matrix theory. We will show that the random spectral efficiency (function of the random linear-dispersion matrices) converges almost surely to a deterministic quantity when the dimensions of the code grow indefinitely while keeping constant the coding rate. Since convergence is very fast, the random spectral efficiency will be approximated by the deterministic limit in the subsequent analysis. By comparison with the direct link, sufficient conditions are derived for the superiority of relaying. Next, we will analyze the outage probability of the system, that is the probability that the spectral efficiency falls below a given target rate due to channel fading. The main purpose of diversity techniques is to introduce alternative paths from the source to the destination, so that data transmission does not fail when the direct link undergoes deep fading. We will show that the diversity behavior of LD-STBC relaying mainly depends on both the coding rate and the relaying strategy (amplify and forward or decode and forward). It is then important to choose the coding rate that maximizes the diversity order without wasting too many resources. To conclude the dissertation, we will consider a different code based on independent isometric Haar-distributed random linear-dispersion matrices. The new code maintains the flexibility of the previous one with respect to variations in the number of relays. However, the more complex structure of the codes allows a noticeable reduction of the interference generated by the relays. Unfortunately, isometric codes also require more sophisticated mathematical tools for their asymptotic analysis. For this reason, we simply introduce the problem by showing that it is possible to have some spectral-efficiency gain with respect to i.i.d. codes. The outage-probability analysis requires a more thorough understanding and will be the subject of future work.

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Elazreg, A. M. "Distributed space time block coding in asynchronous cooperative relay networks." Thesis, Loughborough University, 2013. https://dspace.lboro.ac.uk/2134/12032.

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The design and analysis of various distributed space time block coding schemes for asynchronous cooperative relay networks is considered in this thesis. Rayleigh frequency flat fading channels are assumed to model the links in the networks, and interference suppression techniques together with an orthogonal frequency division multiplexing type transmission approach are employed to mitigate the synchronization errors at the destination node induced by the different delays through the relay nodes. Closed-loop space time block coding is first considered in the context of decode-and-forward (regenerative) networks. In particular, quasi orthogonal and extended orthogonal coding techniques are employed for transmission from four relay nodes and parallel interference cancellation detection is exploited to mitigate synchronization errors. Availability of a direct link between the source and destination nodes is studied, and a new Alamouti space time block coding technique with parallel interference cancellation detection which does not require such a direct link connection and employs two relay nodes is proposed. Outer coding is then added to gain further improvement in end-to-end performance and amplify-and-forward (non regenerative) type networks together with distributed space time coding are considered to reduce relay node complexity. Novel detection schemes are then proposed for decode-and-forward networks with closed-loop extended orthogonal coding which reduce the computational complexity of the parallel interference cancellation. Both sub-optimum and near-optimum detectors are presented for relay nodes with single or dual antennas. End-to-end bit error rate simulations confirm the potential of the approaches and their ability to mitigate synchronization errors. A relay selection approach is also formulated which maximizes spatial diversity gain and attains robustness to timing errors. Finally, a new closed-loop distributed extended orthogonal space time block coding solution for amplify-and-forward type networks which minimizes the number of feedback bits by using a cyclic rotation phase is presented. This approach utilizes an orthogonal frequency division multiplexing type transmission structure with a cyclic prefix to mitigate synchronization errors. End-to-end bit error performance evaluations verify the efficacy of the scheme and its success in overcoming synchronization errors.

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Lin, Rui. "Hybrid ARQ Schemes for Non-orthogonal Space-time Block Codes." Thesis, University of Canterbury. Electrical and Computer Engineering, 2007. http://hdl.handle.net/10092/1183.

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Automatic Repeat-reQuest (ARQ) schemes are extensively used in communication systems and computer networks to achieve reliable transmission. Using space-time codes (STCs) with multiple input multiple output (MIMO) or multiple input single output (MISO) systems is an effective way to combat multipath fading, which is the most severe impairment for wireless communication systems. STCs are designed to use the rich scattering multipath environment provided by using multiple transmit antennas. The work done in this thesis focuses on the use of ARQ schemes with non-orthogonal space-time block codes (NOSTBCs) based on Reed Solomon codes. The truncated-selective ARQ (TS-ARQ) scheme is considered and three novel hybrid ARQ (HARQ) schemes are proposed. Simulation results reveal that, compared to using TS-ARQ with orthogonal space-time block codes (OSTBCs), using NOSTBCs with any of the three proposed HARQ schemes can provide significant gains in terms of dropped packet rate and spectral efficiency at the cost of increased decoding complexity. The performance can be further improved by using the water filling principle to adaptively allocate transmit power among transmit antennas.

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Manna, Mustafa A. "Modified quasi-orthogonal space-time block coding in distributed wireless networks." Thesis, Loughborough University, 2015. https://dspace.lboro.ac.uk/2134/16629.

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Cooperative networks have developed as a useful technique that can achieve the same advantage as multi-input and multi-output (MIMO) wireless systems such as spatial diversity, whilst resolving the difficulties of co-located multiple antennas at individual nodes and avoiding the effect of path-loss and shadowing. Spatial diversity in cooperative networks is known as cooperative diversity, and can enhance system reliability without sacrificing the scarce bandwidth resource or consuming more transmit power. It enables single-antenna terminals in a wireless relay network to share their antennas to form a virtual antenna array on the basis of their distributed locations. However, there remain technical challenges to maximize the benefit of cooperative communications, e.g. data rate, asynchronous transmission and outage. In this thesis, therefore, firstly, a modified distributed quasi-orthogonal space-time block coding (M-D-QO-STBC) scheme with increased code gain distance (CGD) for one-way and two-way amplify-and-forward wireless relay networks is proposed. This modified code is designed from set partitioning a larger codebook formed from two quasi-orthogonal space time block codes with different signal rotations then the subcodes are combined and pruned to arrive at the modified codebook with the desired rate in order to increase the CGD. Moreover, for higher rate codes the code distance is maximized by using a genetic algorithm to search for the optimum rotation matrix. This scheme has very good performance and significant coding gain over existing codes such as the open-loop and closed-loop QO-STBC schemes. In addition, the topic of outage probability analysis in the context of multi-relay selection from $N$ available relay nodes for one-way amplify-and-forward cooperative relay networks is considered together with the best relay selection, the $N^{th}$ relay selection and best four relay selection in two-way amplify-and-forward cooperative relay networks. The relay selection is performed either on the basis of a max-min strategy or one based on maximizing exact end-to-end signal-to-noise ratio. Furthermore, in this thesis, robust schemes for cooperative relays based on the M-D-QO-STBC scheme for both one-way and two-way asynchronous cooperative relay networks are considered to overcome the issue of a synchronism in wireless cooperative relay networks. In particular, an orthogonal frequency division multiplexing (OFDM) data structure is employed with cyclic prefix (CP) insertion at the source in the one-way cooperative relay network and at the two terminal nodes in the two-way cooperative network to combat the effects of time asynchronism. As such, this technique can effectively cope with the effects of timing errors. Finally, outage probability performance of a proposed amplify-and-forward cooperative cognitive relay network is evaluated and the cognitive relays are assumed to exploit an overlay approach. A closed form expression for the outage probability for multi-relay selection cooperation over Rayleigh frequency flat fading channels is derived for perfect and imperfect spectrum acquisitions. Furthermore, the M-QO-STBC scheme is also proposed for use in wireless cognitive relay networks. MATLAB and Maple software based simulations are employed throughout the thesis to support the analytical results and assess the performance of new algorithms and methods.

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Takele, Berta. "Performance Evaluation of Simple Space-Time Block Coding on MIMO Communication System." Thesis, Växjö University, Växjö University, School of Mathematics and Systems Engineering, 2010. http://urn.kb.se/resolve?urn=urn:nbn:se:vxu:diva-6988.

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This thesis discuss on new technique called space time block coding (especially Alamouti's code) which is used to increase capacity and reliability of data transmission over time varying multi-path fading channel. The over all work of the thesis included in the following four chapters.In chapter-1 we are going to cover some theoretical part which is useful to understand thesis work and in chapter-2 we will discuss the comparison between simple space time block code (Alamouti's code) and MRRC (Maximum Ratio Receiver Combining) which is receiver diversity and then in chapter-3 we will see the channel capacity & probability error performance for 2x2 Alamouti code over Rayleigh and Rice fading channel .Finally the conclusion and further work included in chapter-4.

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Wu, Nan. "Generalized space-time block coding for co-located and cooperative MIMO systems." Thesis, University of Southampton, 2008. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.494677.

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Qaja, Walid. "Distributed space time block coding and application in cooperative cognitive relay networks." Thesis, Loughborough University, 2015. https://dspace.lboro.ac.uk/2134/18832.

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The design and analysis of various distributed space time block coding schemes for cooperative relay networks is considered in this thesis. Rayleigh frequency flat and selective fading channels are assumed to model the links in the networks, and interference suppression techniques together with an orthogonal frequency division multiplexing (OFDM) type transmission approach are employed to mitigate synchronization errors at the destination node induced by the different delays through the relay nodes. Closed-loop space time block coding is first considered in the context of decode-and-forward (regenerative) networks. In particular, quasi orthogonal and extended orthogonal coding techniques are employed for transmission from four relay nodes and parallel interference cancellation detection is exploited to mitigate synchronization errors. Availability of a direct link between the source and destination nodes is studied. Outer coding is then added to gain further improvement in end-to-end performance and amplify-and-forward (non regenerative) type networks together with distributed space time coding are considered to reduce relay node complexity. A novel detection scheme is then proposed for decode-and-forward and amplify-and-forward networks with closed-loop extended orthogonal coding and closed-loop quasi-orthogonal coding which reduce the computational complexity of the parallel interference cancellation. The near-optimum detector is presented for relay nodes with single or dual antennas. End-to-end bit error rate simulations confirm the potential of the approach and its ability to mitigate synchronization errors.

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Pau, Nicholas. "Robust High Throughput Space-Time Block Coded MIMO Systems." Thesis, University of Canterbury. Electrical and Computer Engineering, 2007. http://hdl.handle.net/10092/1167.

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In this thesis, we present a space-time coded system which achieves high through- put and good performance with low processing delay using low-complexity detection and decoding. Initially, Hamming codes are used in a simple interleaved bit-mapped coded modulation structure (BMCM). This is concatenated with Alamouti's or- thogonal space-time block codes. The good performance achieved by this system indicates that higher throughput is possible while maintaining performance. An analytical bound for the performance of this system is presented. We also develop a class of low density parity check codes which allows flexible "throughput versus performance" tradeoffs. We then focus on a Rate 2 quasi-orthogonal space-time block code structure which enables us to achieve an overall throughput of 5.6 bits/symbol period with good performance and relatively simple decoding using iterative parallel interference cancellation. We show that this can be achieved through the use of a bit-mapped coded modulation structure using parallel short low density parity check codes. The absence of interleavers here reduces processing delay significantly. The proposed system is shown to perform well on flat Rayleigh fading channels with a wide range of normalized fade rates, and to be robust to channel estimation errors. A comparison with bit-interleaved coded modulation is also provided (BICM).

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Hussin, Mohamed Nuri Ahmed. "Diversity gain enhancement for extended orthogonal space-time block coding in wireless communications." Thesis, University of Strathclyde, 2013. http://oleg.lib.strath.ac.uk:80/R/?func=dbin-jump-full&object_id=22706.

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Transmit diversity is a powerful technique for enhancing the channel capacity and reliability of multiple-input and multiple-output (MIMO) wireless systems. This thesis considers extended orthogonal space-time block coding (EO-STBC) with beamsteering angles, which have previously been shown to potentially achieve full diversity and array gain with four transmit and one receive antenna. The optimum setting of beamsteering angles applied in the transmitter, which has to be calculated based on channel state information (CSI) at the receiver side, must be quantised and feed back to the transmitter via a reverse feedback link. When operating in a fading scenario, channel coefficients vary smoothly with time. This smooth evolution of channel coefficients motivates the investigation of differential feedback, which can reduce the number of feedback bits, while potentially maintaining near optimum performance. The hypothesis that the smooth evolution of channel coefficients translates into smooth evolution of feedback angles is justified by simulations. The maximum attainable gain under optimum unquantised beamsteering angles is derived, which allows to experimentally assess the effect that quantisation in the feedback channel has on the system performance. In characterising the degradation experienced through time-variation and limited quantised feedback, we demonstrate that the new differential feedback approach offers a practical bandwidth-efficient scheme. Simulation results with Doppler spread conditions confirm that the proposed scheme achieves significant bandwidth savings over previously proposed systems. With a single feedback bit per beamsteering angle the proposed differentially encoded EO-STBC approach can achieve near optimum performance and exceed the performance of non-differential feedback schemes that employ a higher word length. We further propose combining differential encoding with channel estimation that is practically useful because the EO-S. We further propose combining differential encoding with channel estimation that is practically useful because the EO-STBC receiver requires knowledge of the channel coefficients for both detecting the transmitted symbols as well as for computing the optimum angles to be fed back to the transmitter. Channel estimation accompanied by a decision-directed (DD) tracking scheme by means of a Kalman filter has been adopted. The Kalman filter exploits the smooth evolution of the channel coefficients as a motivation for tracking as well as for differential feedback. Further we propose applying an auto-regressive (AR) predictor with order greater than one in the Kalman model. This can be shown to offer advantages in terms of temporal smoothness when addressing channels whose coefficient trajectories evolve smoothly. Simulation results show that the overall EO-STBC system achieves longer tracking periods with suitable bit error (BER) values, and that the performance of the proposed system offers a distinct advantage for lower Doppler spreads with the inclusion of second order AR model instead of the standard first order AR model. The earlier work on EO-STBC systems is for frequency-flat channels. However, in frequency-selective channel a multi-carrier approach can help to split into independent subcarriers. Therefore, the EO-STBC scheme is then applied for a dedicated chirp-based multicarrier based on a fractional Fourier transformer (FrFT) system over doubly dispersive channels, where FrFT-domain is developed to further increase robustness against channel time-variations. Applied in nearstationary channel conditions, the performance of orthogonal frequency division multiplexing (OFDM) receivers that mitigate crosstalk between individual subcarriers are evaluated for open and closed loop schemes. A higher degree of non-stationarity in mobile scenarios will destroy the orthogonality of subcarriers and result in intercarrier interference (ICI) and intersymbol interference (ISI). In this case, minimum mean square error (MMSE) of a reduced system matrix is considered for open loop EO-STBC. The equaliser complexity can be decreased even furtherby using least squares minimum residual (LSMR) iterative algorithm, equalisation are underlined by simulations, demonstrating the overall practical use if the contributions wihtin this thesis towards EO-STBC diversity schemes over both time- and frequency-dispersive channels.

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Kassim, Shakiru Kehinde. "Closed-loop space-time block coding and resource allocation in collaborative wireless networks." Thesis, Loughborough University, 2009. https://dspace.lboro.ac.uk/2134/34412.

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The focus of this thesis is to exploit closed-loop space–time block coding schemes designed for multiple antenna links composed of four transmit antennas within collaborative wireless networks. Such schemes have the potential to increase the end-to-end bit error rate performance of wireless networks as compared to established schemes which only include links composed of two transmit antennas. The two four transmit antenna closed-loop space–time block codes (STBCs) considered are the closed-loop quasi-orthogonal STBC (CL-QO-STBC) and the closed-loop extended-orthogonal STBC (CL-EO-STBC) schemes. Both techniques benefit from linear decoding complexity and symbolwise maximum likelihood decoding.

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Owojaiye, Gbenga Adetokunbo. "Design and performance analysis of distributed space time coding schemes for cooperative wireless networks." Thesis, University of Hertfordshire, 2012. http://hdl.handle.net/2299/8970.

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In this thesis, space-time block codes originally developed for multiple antenna systems are extended to cooperative multi-hop networks. The designs are applicable to any wireless network setting especially cellular, adhoc and sensor networks where space limitations preclude the use of multiple antennas. The thesis first investigates the design of distributed orthogonal and quasi-orthogonal space time block codes in cooperative networks with single and multiple antennas at the destination. Numerical and simulation results show that by employing multiple receive antennas the diversity performance of the network is further improved at the expense of slight modification of the detection scheme. The thesis then focuses on designing distributed space time block codes for cooperative networks in which the source node participates in cooperation. Based on this, a source-assisting strategy is proposed for distributed orthogonal and quasi-orthogonal space time block codes. Numerical and simulation results show that the source-assisting strategy exhibits improved diversity performance compared to the conventional distributed orthogonal and quasi-orthogonal designs.Motivated by the problem of channel state information acquisition in practical wireless network environments, the design of differential distributed space time block codes is investigated. Specifically, a co-efficient vector-based differential encoding and decoding scheme is proposed for cooperative networks. The thesis then explores the concatenation of differential strategies with several distributed space time block coding schemes namely; the Alamouti code, square-real orthogonal codes, complex-orthogonal codes, and quasiorthogonal codes, using cooperative networks with different number of relay nodes. In order to cater for high data rate transmission in non-coherent cooperative networks, differential distributed quasi-orthogonal space-time block codes which are capable of achieving full code-rate and full diversity are proposed. Simulation results demonstrate that the differential distributed quasi-orthogonal space-time block codes outperform existing distributed space time block coding schemes in terms of code rate and bit-error-rate performance. A multidifferential distributed quasi-orthogonal space-time block coding scheme is also proposed to exploit the additional diversity path provided by the source-destination link.A major challenge is how to construct full rate codes for non-coherent cooperative broadband networks with more than two relay nodes while exploiting the achievable spatial and frequency diversity. In this thesis, full rate quasi-orthogonal codes are designed for noncoherent cooperative broadband networks where channel state information is unavailable. From this, a generalized differential distributed quasi-orthogonal space-frequency coding scheme is proposed for cooperative broadband networks. The proposed scheme is able to achieve full rate and full spatial and frequency diversity in cooperative networks with any number of relays. Through pairwise error probability analysis we show that the diversity gain of the proposed scheme can be improved by appropriate code construction and sub-carrier allocation. Based on this, sufficient conditions are derived for the proposed code structure at the source node and relay nodes to achieve full spatial and frequency diversity. In order to exploit the additional diversity paths provided by the source-destination link, a novel multidifferential distributed quasi-orthogonal space-frequency coding scheme is proposed. The overall objective of the new scheme is to improve the quality of the detected signal at the destination with negligible increase in the computational complexity of the detector.Finally, a differential distributed quasi-orthogonal space-time-frequency coding scheme is proposed to cater for high data rate transmission and improve the performance of noncoherent cooperative broadband networks operating in highly mobile environments. The approach is to integrate the concept of distributed space-time-frequency coding with differential modulation, and employ rotated constellation quasi-orthogonal codes. From this, we design a scheme which is able to address the problem of performance degradation in highly selective fading environments while guaranteeing non-coherent signal recovery and full code rate in cooperative broadband networks. The coding scheme employed in this thesis relaxes the assumption of constant channel variation in the temporal and frequency dimensions over long symbol periods, thus performance degradation is reduced in frequencyselective and time-selective fading environments. Simulation results illustrate the performance of the proposed differential distributed quasi-orthogonal space-time-frequency coding scheme under different channel conditions.

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Alotaibi, Faisal T. "Distributed space-time block coding in cooperative relay networks with application in cognitive radio." Thesis, Loughborough University, 2012. https://dspace.lboro.ac.uk/2134/10965.

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Spatial diversity is an effective technique to combat the effects of severe fading in wireless environments. Recently, cooperative communications has emerged as an attractive communications paradigm that can introduce a new form of spatial diversity which is known as cooperative diversity, that can enhance system reliability without sacrificing the scarce bandwidth resource or consuming more transmit power. It enables single-antenna terminals in a wireless relay network to share their antennas to form a virtual antenna array on the basis of their distributed locations. As such, the same diversity gains as in multi-input multi-output systems can be achieved without requiring multiple-antenna terminals. In this thesis, a new approach to cooperative communications via distributed extended orthogonal space-time block coding (D-EO-STBC) based on limited partial feedback is proposed for cooperative relay networks with three and four relay nodes and then generalized for an arbitrary number of relay nodes. This scheme can achieve full cooperative diversity and full transmission rate in addition to array gain, and it has certain properties that make it alluring for practical systems such as orthogonality, flexibility, low computational complexity and decoding delay, and high robustness to node failure. Versions of the closed-loop D-EO-STBC scheme based on cooperative orthogonal frequency division multiplexing type transmission are also proposed for both flat and frequency-selective fading channels which can overcome imperfect synchronization in the network. As such, this proposed technique can effectively cope with the effects of fading and timing errors. Moreover, to increase the end-to-end data rate, this scheme is extended for two-way relay networks through a three-time slot framework. On the other hand, to substantially reduce the feedback channel overhead, limited feedback approaches based on parameter quantization are proposed. In particular, an optimal one-bit partial feedback approach is proposed for the generalized D-O-STBC scheme to maximize the array gain. To further enhance the end-to-end bit error rate performance of the cooperative relay system, a relay selection scheme based on D-EO-STBC is then proposed. Finally, to highlight the utility of the proposed D-EO-STBC scheme, an application to cognitive radio is studied.

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Steele, Andrew. "Some new classes of division algebras and potential applications to space-time block coding." Thesis, University of Nottingham, 2014. http://eprints.nottingham.ac.uk/13934/.

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In this thesis we study some new classes of nonassociative division algebras. First we introduce a generalisation of both associative cyclic algebras and of Waterhouse's nonassociative quaternions. An important aspect of these algebras is the simplicity of their construction, which is a modification of the classical definition of associative cyclic algebras. By taking the parameter used in the classical definition from a larger field, we lose the property of associativity but gain many new examples of division algebras. This idea is also applied to obtain a generalisation of the first Tits construction. We go on to study constructions of Menichetti, Knuth, and Hughes and Kleinfeld, which have previously only been considered over finite fields. We extend these definitions to infinite fields and get new examples of division algebras, including some over the real numbers. Recently, both associative and nonassociative division algebras have been applied to the theory of space-time block coding. We explore this connection and show how the algebras studied in this thesis can be used to construct space-time block codes.

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Sinnokrot, Mohanned Omar. "Space-time block codes with low maximum-likelihood decoding complexity." Diss., Atlanta, Ga. : Georgia Institute of Technology, 2009. http://hdl.handle.net/1853/31752.

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Thesis (Ph.D)--Electrical and Computer Engineering, Georgia Institute of Technology, 2010. Committee Chair: Barry, John; Committee Co-Chair: Madisetti, Vijay; Committee Member: Andrew, Alfred; Committee Member: Li, Ye; Committee Member: Ma, Xiaoli; Committee Member: Stuber, Gordon. Part of the SMARTech Electronic Thesis and Dissertation Collection.

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Koken, Erman. "A Comparison Of Time-switched Transmit Diversity And Space-time Coded Systems Over Time-varying Miso Channels." Master's thesis, METU, 2011. http://etd.lib.metu.edu.tr/upload/12613557/index.pdf.

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This thesis presents a comparison between two transmit diversity schemes, namely space-time coding and time-switched transmit diversity (TSTD) over block-fading and time-varying multi-input single-output (MISO) channels with different channel parameters. The schemes are concatenated with outer channel codes in order to achieve spatio-temporal diversity. The analytical results are derived for the error performances of the systems and the simulation results as well as outage probabilities are provided. Besides, the details of the pilot-symbol-aided modulation (PSAM) technique are investigated and the error performances of the systems are analyzed when the channel state information is estimated with PSAM. It is demonstrated using the analytical and simulation results that TSTD have a comparable error performance with the space-time coding techniques and it even outperforms the space-time codes for some channel parameters. Our results indicate that TSTD can be suggested as an alternative to space-time codes in some time-varying channels especially due to the implementation simplicity.

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Nory, Ravikiran. "Performance Analysis of Space-Time Coded Modulation Techniques using GBSB-MIMO Channel Models." Thesis, Virginia Tech, 2002. http://hdl.handle.net/10919/33449.

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Wireless systems are rapidly developing to provide high speed voice, text and multimedia messaging services which were traditionally offered by wire line networks. To support these services, channels with large capacities are required. Information theoretic investigations have shown that Multiple Input Multiple Output (MIMO) channels can achieve very high capacities. Space-Time Block Coding (STBC) and Bell Labs Layered Space-Time Architecture (BLAST) are two potential schemes which utilize the diversity offered by MIMO channels to provide reliable high date rate wireless communication. This work studies the sensitivity of these two schemes to spatial correlation in MIMO channels. The first part of the thesis studies the effect of spatial correlation on the performance of STBC by using Geometrically Based Single Bounce MIMO (GBSB-MIMO) channel models. Performance is analyzed for two scenarios: one without scatterers in the vicinity of the transmitter and other with scatterers. In the second part of the thesis, the sensitivity of BLAST to spatial correlation is analyzed. Later, schemes which use the principles of Multilayered Space-Time Coded Modulation to combine the benefits of BLAST and STBC are introduced and their performance is investigated in correlated and uncorrelated Rayleigh fading. Results indicate that schemes using orthogonal design space-time block codes are reasonably robust to spatial correlation while schemes like BLAST are very sensitive as they depend on array processing to separate signals from various transmit antennas. Master of Science

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Delestre, Fabien. "Channel estimation and performance analysis of MIMO-OFDM communications using space-time and space-frequency coding schemes." Thesis, University of Hertfordshire, 2011. http://hdl.handle.net/2299/6397.

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This thesis is concerned with channel estimation and data detection of MIMO-OFDM communication systems using Space-Time Block Coding (STBC) and Space-Frequency Block Coding (SFBC) under frequency selective channels. A new iterative joint channel estimation and signal detection technique for both STBC-OFDM and SFBC-OFDM systems is proposed. The proposed algorithm is based on a processive sequence of events for space time and space frequency coding schemes where pilot subcarriers are used for channel estimation in the first time instant, and then in the second time instant, the estimated channel is used to decode the data symbols in the adjacent data subcarriers. Once data symbols are recovered, the system recursively performs a new channel estimation using the decoded data symbols as pilots. The iterative process is repeated until all MIMO-OFDM symbols are recovered. In addition, the proposed channel estimation technique is based on the maximum likelihood (ML) approach which offers linearity and simplicity of implementation. Due to the orthogonality of STBC and SFBC, high computation efficiency is achieved since the method does not require any matrix inversion for estimation and detection at the receiver. Another major novel contribution of the thesis is the proposal of a new group decoding method that reduces the processing time significantly via the use of sub-carrier grouping for transmitted data recovery. The OFDM symbols are divided into groups to which a set of pilot subcarriers are assigned and used to initiate the channel estimation process. Designated data symbols contained within each group of the OFDM symbols are decoded simultaneously in order to improve the decoding duration. Finally, a new mixed STBC and SFBC channel estimation and data detection technique with a joint iterative scheme and a group decoding method is proposed. In this technique, STBC and SFBC are used for pilot and data subcarriers alternatively, forming the different combinations of STBC/SFBC and SFBC/STBC. All channel estimation and data detection methods for different MIMO-OFDM systems proposed in the thesis have been simulated extensively in many different scenarios and their performances have been verified fully.

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Ganji, Saichand. "Space-Time Block Coding to Achieve Spatial Diversity in a Multiple Input Multiple Output System." Ohio University / OhioLINK, 2018. http://rave.ohiolink.edu/etdc/view?acc_num=ohiou1534432423784957.

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Potter, Chris, Kurt Kosbar, and Adam Panagos. "Effects of Synchronization Error on Space Time Block Codes Equipped with FSK Waveforms." International Foundation for Telemetering, 2009. http://hdl.handle.net/10150/605966.

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ITC/USA 2009 Conference Proceedings / The Forty-Fifth Annual International Telemetering Conference and Technical Exhibition / October 26-29, 2009 / Riviera Hotel & Convention Center, Las Vegas, Nevada Space-time Coding (STC) for Multiple-Input Multiple-Output (MIMO) wireless communication systems is an effective technique for providing robust wireless link performance in telemetry systems. This paper investigates the degradation in system performance when synchronization errors between the transmitter and receiver are present. Specifically, expressions that quantify the increase in symbol-error-rate as a function of symbol synchronization error are derived for a two-transmit and single receive antenna MISO system using binary frequency shift keying waveforms. These results are then extended to the MIMO case. The analytic results are verified with simulation results that show close agreement between the theoretical expressions and Monte Carlo simulation runs.

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Wavegedara, Kapila Chandika B. "Advanced receivers for space-time block-coded single-carrier transmissions over frequency-selective fading channels." Thesis, University of British Columbia, 2008. http://hdl.handle.net/2429/620.

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In recent years, space-time block coding (STBC) has emerged as an effective transmit-diversity technique to combat the detrimental effects of channel fading. In addition to STBC, high-order modulation schemes will be used in future wireless communication systems aiming to provide ubiquitous-broadband wireless access. Hence, advanced receiver schemes are necessary to achieve high performance. In this thesis, advanced and computationally-efficient receiver schemes are investigated and developed for single-carrier space-time (ST) block-coded transmissions over frequency-selective fading (FSF) channels. First, we develop an MMSE-based turbo equalization scheme for Alamouti ST block-coded systems. A semi-analytical method to estimate the bit error rate (BER) is devised. Our results show that the proposed turbo equalization scheme offers significant performance improvements over one-pass equalization. Second, we analyze the convergence behavior of the proposed turbo equalization scheme for Alamouti ST block-coded systems using the extrinsic information transfer (EXIT)-band chart technique. Third, burst-wise (BW)-STBC is applied for uplink transmission over FSF channels in block-spread-CDMA systems with multiuser interference-free reception. The performances of different decision feedback sequence estimation (DFSE) schemes are investigated. A new scheme combining frequency-domain (FD) linear equalization and modified unwhitened-DFSE is proposed. The proposed scheme is very promising as the error-floor behavior observed in the existing unwhitened DFSE schemes is eliminated. Fourth, we develop a FD-MMSE-based turbo equalization scheme for the downlink of ST block-coded CDMA systems. We adopt BW-STBC instead of Alamouti symbol-wise (SW)-STBC considered for WCDMA systems and demonstrate its superior performance in FSF channels. Block spreading is shown to be more desirable than conventional spreading to improve performance using turbo equalization. We also devise approximate implementations (AprxImpls) that offer better trade-offs between performance and complexity. Semi-analytical upper bounds on the BER are derived. Fifth, turbo multicode detection is investigated for ST block-coded downlink transmission in DS-CDMA systems. We propose symbol-by-symbol and chip-by-chip FD-MMSE-based multicode detectors. An iterative channel estimation scheme is also proposed. The proposed turbo multicode detection scheme offers significant performance improvements compared with non-iterative multicode detection. Finally, the impact of channel estimation errors on the performance of MMSE-based turbo equalization in ST block-coded CDMA systems is investigated.

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Kim, Ngan Trieu, and Olumide Ajiboye. "PERFORMANCE ANALYSIS OF ADAPTIVE ARRAY SYSTEM AND SPACE-TIME BLOCK CODING IN MOBILE WIMAX (802.16e) SYSTEMS." Thesis, Blekinge Tekniska Högskola, Avdelningen för telekommunikationssystem, 2008. http://urn.kb.se/resolve?urn=urn:nbn:se:bth-4743.

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We live in an information hungry age, we generate and process information at a rate never before recorded in the history of mankind. Today’s computing platforms are run on Gigahertz multi-core processors churning out Gigabits streams of data that need to be transmitted as quickly as possible. Often times the source and the destination are mobile which means wired connections are not a choice. This has led to an ever increasing need to develop wireless access technologies that support high throughput regardless of the transmission environment. Till date, many proprietary solutions exist that seek to bridge this gap with little or no support for interoperability. For the sheer scale of development that is required, a standard based solution is the key. The IEEE 802.1x committee oversees the development of standards for wireless systems, it formed the 802.16 working group to develop a standards-based Wireless Metropolitan Area Network (MAN) solution. One of the fruits of this effort is the 802.16e standard fondly referred to as mobile WiMAX and it is the subject of study in this thesis. This thesis seeks to analyze the transmission characteristics of two of the antenna systems defined in the standard i.e. Adaptive Beamforming Systems and Multiple-Input Multiple-Output Systems. Multiple-Input Multiple-Output (MIMO): utilizes multiple antennas at the transmitter and receiver to provide diversity gain, multiplexing gain or both. Adaptive Antenna Systems (AAS): Adaptive array system uses an antenna array to generate in real-time radiation patterns with the main lobes and/or nulls dynamically tuned to specific directions in order to increase or suppress signal power in that direction. Worldwide Interoperability for Microwave Access (WiMAX) is the acronym for Institute of Electrical and Electronics Engineers (IEEE) 802.16 set of standards governing Air Interface for Fixed Broadband Wireless Access Systems. In the history of wireless systems, WiMAX is revolutionary technology as affords its users the Wi-Fi grade throughput and cellular system level of mobility. With WiMAX, broadband technology (traditionally ADSL and Fiber) goes wireless and WiMAX users can basically enjoy triple-play application, and split-second download and upload rates. WIMAX also offers full mobility much as traditional cellular systems do with features like seamless hand-over and roaming at vehicular speed; this is made possible because the system design covers the access network to core network. For the operator, WiMAX is a welcome development because it merges traditional cellular networks with broadband technology thus opening them to more business offerings and a larger client base and all this at a reduced cost of deployment. Base stations are comparatively cheaper and do not require extensive planning typical of other cellular systems thus WiMAX is aptly suited for emerging markets where infrastructure cost is a major issue; little wonder a lot of 3rd world countries have signified interest in the technology.

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Héliot, F. "Design and analysis of space-time block and trellis coding schemes for single-band UWB communications systems." Thesis, King's College London (University of London), 2006. http://epubs.surrey.ac.uk/2588/.

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Ultra Wide-Band (UWB) technology has recently attracted much research interest due to its appealing features in short-range mobile communications. These features include high-data rates, low power consumption, multiple-access communications and precise positioning capabilities. Space-Time Coding (STC) techniques, such as block coding and trellis coding, are known to be simple and practical ways to increase both the spectral efficiency and the capacity in wireless communications. The the- sis aims at designing robust and efficient space-time coding schemes well adapted to single-band UWB signalling. Thus, this work incorporates a fine analysis of a stan- dard Single Input Single Output (SISO) single-band UWB system, scrutinising every important aspect of this system including transceiver structure, channel modelling, multiple-access techniques and detection process. Research also leads to the deriva- tion of a novel closed-form approximation for the average probability of bit-error for single-band UWB systems. This in-depth study highlights drawbacks inherent to UWB systems such as time-jitter effects or rake-receiver complexity and proposes schemes that benefit from spatial diversity to mitigate these problems. Thus, the thesis concentrates on the design of new multiple-antenna space-time coding systems tailored for UWB communications. As a result, this work derives and generates gen- eralised full-rate space-time block codes based on orthogonal pulses to capture both spatial and multipath diversities. Space-time trellis coded modulation is then revis- ited to further improve the spectral efficiency limit and to deliver the high-data rates promised by UWB technology. A new version of space-time trellis coding is developed for the peculiar UWB signalling structure. Finally, thanks to a novel closed-form ap- proximation, a theoretical comparison is undertaken between any SISO-UWB system and the multiple antenna UWB systems proposed in this thesis. The results clearly underline the impact of STC on a single-band UWB system in terms of enhanced robustness against timing-jitter effects, higher spectral efficiency and capacity im- provement. These advantages are finally confirmed through the numerical evaluation of the error-rate performance.

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Chen, J., and K. Djouani. "A multi-user cooperative diversity for wireless local area networks." Scientific Research Publishing, 2008. http://encore.tut.ac.za/iii/cpro/DigitalItemViewPage.external?sp=1000783.

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In this paper, an idea of using space-time block coding (STBC) in multi-user cooperative diversity has been exploited to improve the performance of the transmission in wireless local area networks. The theoretical and simulation results show that, using STBC approaches can always achieve the better performance than existing techniques without introducing the space-time coding. By analyzing the throughput and frame error ratio (FER) of the two different STBC cooperative schemes, we find the trade-off between throughput and reliability. The location of the relay is crucial to the performance, which supposes a rule for future crosslayer design.

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Chi, Xuan. "The Impact of Channel Estimation Error on Space-Time Block and Trellis Codes in Flat and Frequency Selective Channels." Thesis, Virginia Tech, 2002. http://hdl.handle.net/10919/33963.

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Recently multiple antenna systems have received significant attention from researchers as a means to improve the energy and spectral efficiency of wireless systems. Among many classes of schemes, Space-Time Block codes (STBC) and Space-Time Trellis codes (STTC) have been the subject of many investigations. Both techniques provide a means for combatting the effects of multipath fading without adding much complexity to the receiver. This is especially useful in the downlink of wireless systems. In this thesis we investigate the impact of channel estimation error on the performance of both STBC and STTC. Channel estimation is especially important to consider in multiple antenna systems since (A) for coherent systems there are more channels to estimate due to multiple antennas and (B) the decoupling of data streams relies on correct channel estimation. The latter effect is due to the intentional cross-talk introduced into STBC. Master of Science

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Wen, Xin [Verfasser], Marius [Akademischer Betreuer] Pesavento, and Anthony Man-Cho [Akademischer Betreuer] So. "Higher-rank Transmit Beamforming Using Space Time Block Coding / Xin Wen. Betreuer: Marius Pesavento ; Anthony Man-Cho So." Darmstadt : Universitäts- und Landesbibliothek Darmstadt, 2016. http://d-nb.info/1112269347/34.

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Chembil, Palat Ramesh. "VT-STAR design and implementation of a test bed for differential space-time block coding and MIMO channel measurements." Thesis, Virginia Tech, 2002. http://hdl.handle.net/10919/35712.

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Next generation wireless communications require transmission of reliable high data rate services. Second generation wireless communications systems use single-input multiple-output (SIMO) channel in the reverse link, meaning one transmit antenna at the user terminal and multiple receive antennas at the base station. Recently, information theoretic research has shown an enormous potential growth in the capacity of wireless systems by using multiple antenna arrays at both ends of the link. Space-time coding exploits the spatial-temporal diversity provided by the multiple input multiple output (MIMO) channels, significantly increasing both system capacity and the reliability of the wireless link. The Virginia Tech Space-Time Advanced Radio (VT-STAR) system presents a test bed to demonstrate the capabilities of space-time coding techniques in real-time. Core algorithms are implemented on Texas Instruments TMS320C67 Evaluation Modules (EVM). The radio frequency subsystem is composed of multi-channel transmitter and receiver chains implemented in hardware for over the air transmission. The capabilities of the MIMO channel are demonstrated in a non-line of sight (NLOS) indoor environment. Also to characterize the capacity gains in an indoor environment this test bed was modified to take channel measurements. This thesis reports the system design of VT-STAR and the channel capacity gains observed in an indoor environment for MIMO channels. Master of Science

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Mannai, Usama N. "Novel transmission schemes for application in two-way cooperative relay wireless communication networks." Thesis, Loughborough University, 2014. https://dspace.lboro.ac.uk/2134/15836.

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Recently, cooperative relay networks have emerged as an attractive communications technique that can generate a new form of spatial diversity which is known as cooperative diversity, that can enhance system reliability without sacrificing the scarce bandwidth resource or consuming more transmit power. To achieve cooperative diversity single-antenna terminals in a wireless relay network typically share their antennas to form a virtual antenna array on the basis of their distributed locations. As such, the same diversity gains as in multi-input multi-output systems can be achieved without requiring multiple-antenna terminals. However, there remain technical challenges to maximize the benefit of cooperative communications, e.g. data rate, asynchronous transmission, interference and outage. Therefore, the focus of this thesis is to exploit cooperative relay networks within two-way transmission schemes. Such schemes have the potential to double the data rate as compared to one-way transmission schemes. Firstly, a new approach to two-way cooperative communications via extended distributed orthogonal space-time block coding (E-DOSTBC) based on phase rotation feedback is proposed with four relay nodes. This scheme can achieve full cooperative diversity and full transmission rate in addition to array gain. Then, distributed orthogonal space-time block coding (DOSTBC) is applied within an asynchronous two-way cooperative wireless relay network using two relay nodes. A parallel interference cancelation (PIC) detection scheme with low structural and computational complexity is applied at the terminal nodes in order to overcome the effect of imperfect synchronization among the cooperative relay nodes. Next, a DOSTBC scheme based on cooperative orthogonal frequency division multiplexing (OFDM) type transmission is proposed for flat fading channels which can overcome imperfect synchronization in the network. As such, this technique can effectively cope with the effects of fading and timing errors. Moreover, to increase the end-to-end data rate, a closed-loop EDOSTBC approach using through a three-time slot framework is proposed. A full interference cancelation scheme with OFDM and cyclic prefix type transmission is used in a two-hop cooperative four relay network with asynchronism in the both hops to achieve full data rate and completely cancel the timing error. The topic of outage probability analysis in the context of multi-relay selection for one-way cooperative amplify and forward networks is then considered. Local measurements of the instantaneous channel conditions are used to select the best single and best two relays from a number of available relays. Asymptotical conventional polices are provided to select the best single and two relays from a number of available relays. Finally, the outage probability of a two-way amplify and forward relay network with best and Mth relay selection is analyzed. The relay selection is performed either on the basis of a max-min strategy or one based on maximizing exact end-to-end signal-to-noise ratio. MATLAB and Maple software based simulations are employed throughout the thesis to support the analytical results and assess the performance of new algorithms and methods.

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Emenonye, Don-Roberts Ugochukwu. "Application of Machine Learning to Multi Antenna Transmission and Machine Type Resource Allocation." Thesis, Virginia Tech, 2020. http://hdl.handle.net/10919/99956.

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Wireless communication systems is a well-researched area in electrical engineering that has continually evolved over the past decades. This constant evolution and development have led to well-formulated theoretical baselines in terms of reliability and efficiency. However, most communication baselines are derived by splitting the baseband communications into a series of modular blocks like modulation, coding, channel estimation, and orthogonal frequency modulation. Subsequently, these blocks are independently optimized. Although this has led to a very efficient and reliable process, a theoretical verification of the optimality of this design process is not feasible due to the complexities of each individual block. In this work, we propose two modifications to these conventional wireless systems. First, with the goal of designing better space-time block codes for improved reliability, we propose to redesign the transmit and receive blocks of the physical layer. We replace a portion of the transmit chain - from modulation to antenna mapping with a neural network. Similarly, the receiver/decoder is also replaced with a neural network. In other words, the first part of this work focuses on jointly optimizing the transmit and receive blocks to produce a set of space-time codes that are resilient to Rayleigh fading channels. We compare our results to the conventional orthogonal space-time block codes for multiple antenna configurations. The second part of this work investigates the possibility of designing a distributed multiagent reinforcement learning-based multi-access algorithm for machine type communication. This work recognizes that cellular networks are being proposed as a solution for the connectivity of machine type devices (MTDs) and one of the most crucial aspects of scheduling in cellular connectivity is the random access procedure. The random access process is used by conventional cellular users to receive an allocation for the uplink transmissions. This process usually requires six resource blocks. It is efficient for cellular users to perform this process because transmission of cellular data usually requires more than six resource blocks. Hence, it is relatively efficient to perform the random access process in order to establish a connection. Moreover, as long as cellular users maintain synchronization, they do not have to undertake the random access process every time they have data to transmit. They can maintain a connection with the base station through discontinuous reception. On the other hand, the random access process is unsuitable for MTDs because MTDs usually have small-sized packets. Hence, performing the random access process to transmit such small-sized packets is highly inefficient. Also, most MTDs are power constrained, thus they turn off when they have no data to transmit. This means that they lose their connection and can't maintain any form of discontinuous reception. Hence, they perform the random process each time they have data to transmit. Due to these observations, explicit scheduling is undesirable for MTC. To overcome these challenges, we propose bypassing the entire scheduling process by using a grant free resource allocation scheme. In this scheme, MTDs pseudo-randomly transmit their data in random access slots. Note that this results in the possibility of a large number of collisions during the random access slots. To alleviate the resulting congestion, we exploit a heterogeneous network and investigate the optimal MTD-BS association which minimizes the long term congestion experienced in the overall cellular network. Our results show that we can derive the optimal MTD-BS association when the number of MTDs is less than the total number of random access slots. Master of Science Wireless communication systems is a well researched area of engineering that has continually evolved over the past decades. This constant evolution and development has led to well formulated theoretical baselines in terms of reliability and efficiency. This two part thesis investigates the possibility of improving these wireless systems with machine learning. First, with the goal of designing more resilient codes for transmission, we propose to redesign the transmit and receive blocks of the physical layer. We focus on jointly optimizing the transmit and receive blocks to produce a set of transmit codes that are resilient to channel impairments. We compare our results to the current conventional codes for various transmit and receive antenna configuration. The second part of this work investigates the possibility of designing a distributed multi-access scheme for machine type devices. In this scheme, MTDs pseudo-randomly transmit their data by randomly selecting time slots. This results in the possibility of a large number of collisions occurring in the duration of these slots. To alleviate the resulting congestion, we employ a heterogeneous network and investigate the optimal MTD-BS association which minimizes the long term congestion experienced in the overall network. Our results show that we can derive the optimal MTD-BS algorithm when the number of MTDs is less than the total number of slots.

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Sastry, Sushruth, and Kurt Kosbar. "A Modular Scheme to Detect and Combat Sinusoidal Variation in Fading Channels." International Foundation for Telemetering, 2015. http://hdl.handle.net/10150/596419.

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ITC/USA 2015 Conference Proceedings / The Fifty-First Annual International Telemetering Conference and Technical Exhibition / October 26-29, 2015 / Bally's Hotel & Convention Center, Las Vegas, NV Fading estimation in wireless communication systems depend on an expected fading model and assumptions about the channel itself. The bit error rate (BER) performance of the communication system is affected by how closely the assumptions made in de- signing the estimation technique match the deployment environment. Any unforeseen disturbances or hindrances in the environment deteriorate the BER performance of the system when the estimation system is not designed to combat the same. To combat such obstacles, estimation techniques must either be reinforced with modular systems which combat such observed types of disturbances, or be redesigned as a whole considering such observations of disturbances. In this paper a modular scheme to detect and combat sinusoidal variation in fading power is developed and tested by employing the developed scheme in a multiple-input-multiple-output (MIMO) wireless communication system which adopts Space-Time Block Coding (STBC) techniques.

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Chi, Zhanjiang. "Performance Analysis of Maximal-Ratio Combining and Space-Time Block Codes with Transmit Antenna Selection over Nakagami-m Fading Channels." School of Electrical and Information Engineering, 2007. http://hdl.handle.net/2123/2012.

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Master of Engineering (Research) The latest wireless communication techniques such as highspeed wireless internet application demand higher data rates and better quality of service (QoS). However, transmission reliability is still degraded by harsh propagation channels. Multiple-input multiple-output (MIMO) systems can increase the system capacity and improve transmission reliability. By transmitting multiple copies of data, a MIMO system can effectively combat the effects of fading. Due to the high hardware cost of a MIMO system, antenna selection techniques have been applied in MIMO system design to reduce the system complexity and cost. The Nakagami-m distribution has been considered for MIMO channel modeling since a wide range of fading channels, from severe to moderate, can be modeled by using Nakagami-m distribution. The Rayleigh distribution is a special case of the Nakagami-m distribution. In this thesis, we analyze the error performance of two MIMO schemes: maximal-ratio combining with transmit antenna selection (the TAS/MRC scheme) and space-time block codes with transmit antenna selection (the TAS/STBC scheme) over Nakagami-m fading channels. In the TAS/MRC scheme, one of multiple transmit antennas, which maximizes the total received signal-to-noise ratio (SNR), is selected for uncoded data transmission. First we use a moment generating function based (MGF-based) approach to derive the bit error rate (BER) expressions for binary phase shift keying (BPSK), the symbol error rate (SER) expressions for M-ray phase shift keying (MPSK) and M-ray quadrature amplitude modulation (MQAM) of the TAS/MRC scheme over Nakagami-m fading channels with arbitrary and integer fading parameters m. The asymptotic performance is also investigated. It is revealed that the asymptotic diversity order is equal to the product of the Nakagami fading parameter m, the number of transmit antenna Lt and the number of receive antenna Lr as if all transmit antenna were used. Then a Gaussian Q-functions approach is used to investigate the error performance of the TAS/STBC scheme over Nakagami-m fading channels. In the TAS/STBC scheme, two transmit antennas, which maximize the output SNR, are selected for transmission. The exact and asymptotic BER expressions for BPSK are obtained for the TAS/STBC schemes with three and four transmit antennas. It is shown that the TAS/STBC scheme can provide a full diversity order of mLtLr.

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Diameh, Yousef A. "The optimization of multiple antenna broadband wireless communications. A study of propagation, space-time coding and spatial envelope correlation in Multiple Input, Multiple Output radio systems." Thesis, University of Bradford, 2013. http://hdl.handle.net/10454/6361.

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This work concentrates on the application of diversity techniques and space time block coding for future mobile wireless communications. The initial system analysis employs a space-time coded OFDM transmitter over a multipath Rayleigh channel, and a receiver which uses a selection combining diversity technique. The performance of this combined scenario is characterised in terms of the bit error rate and throughput. A novel four element QOSTBC scheme is introduced, it is created by reforming the detection matrix of the original QOSTBC scheme, for which an orthogonal channel matrix is derived. This results in a computationally less complex linear decoding scheme as compared with the original QOSTBC. Space time coding schemes for three, four and eight transmitters were also derived using a Hadamard matrix. The practical optimization of multi-antenna networks is studied for realistic indoor and mixed propagation scenarios. The starting point is a detailed analysis of the throughput and field strength distributions for a commercial dual band 802.11n MIMO radio operating indoors in a variety of line of sight and non-line of sight scenarios. The physical model of the space is based on architectural schematics, and realistic propagation data for the construction materials. The modelling is then extended and generalized to a multi-storey indoor environment, and a large mixed site for indoor and outdoor channels based on the Bradford University campus. The implications for the physical layer are also explored through the specification of antenna envelope correlation coefficients. Initially this is for an antenna module configuration with two independent antennas in close proximity. An operational method is proposed using the scattering parameters of the system and which incorporates the intrinsic power losses of the radiating elements. The method is extended to estimate the envelope correlation coefficient for any two elements in a general (N,N) MIMO antenna array. Three examples are presented to validate this technique, and very close agreement is shown to exist between this method and the full electromagnetic analysis using the far field antenna radiation patterns.

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36

Dia'meh, Yousef Ali. "The optimization of multiple antenna broadband wireless communications : a study of propagation, space-time coding and spatial envelope correlation in Multiple Input, Multiple Output radio systems." Thesis, University of Bradford, 2013. http://hdl.handle.net/10454/6361.

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This work concentrates on the application of diversity techniques and space time block coding for future mobile wireless communications. The initial system analysis employs a space-time coded OFDM transmitter over a multipath Rayleigh channel, and a receiver which uses a selection combining diversity technique. The performance of this combined scenario is characterised in terms of the bit error rate and throughput. A novel four element QOSTBC scheme is introduced, it is created by reforming the detection matrix of the original QOSTBC scheme, for which an orthogonal channel matrix is derived. This results in a computationally less complex linear decoding scheme as compared with the original QOSTBC. Space time coding schemes for three, four and eight transmitters were also derived using a Hadamard matrix. The practical optimization of multi-antenna networks is studied for realistic indoor and mixed propagation scenarios. The starting point is a detailed analysis of the throughput and field strength distributions for a commercial dual band 802.11n MIMO radio operating indoors in a variety of line of sight and non-line of sight scenarios. The physical model of the space is based on architectural schematics, and realistic propagation data for the construction materials. The modelling is then extended and generalized to a multi-storey indoor environment, and a large mixed site for indoor and outdoor channels based on the Bradford University campus. The implications for the physical layer are also explored through the specification of antenna envelope correlation coefficients. Initially this is for an antenna module configuration with two independent antennas in close proximity. An operational method is proposed using the scattering parameters of the system and which incorporates the intrinsic power losses of the radiating elements. The method is extended to estimate the envelope correlation coefficient for any two elements in a general (N,N) MIMO antenna array. Three examples are presented to validate this technique, and very close agreement is shown to exist between this method and the full electromagnetic analysis using the far field antenna radiation patterns.

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Saglam, Halil Derya. "Simulation performance of multiple-input multiple-output systems employing single-carrier modulation and orthogonal frequency division multiplexing." Thesis, Monterey, Calif. : Springfield, Va. : Naval Postgraduate School ; Available from National Technical Information Service, 2004. http://library.nps.navy.mil/uhtbin/hyperion/04Dec%5FSaglam.pdf.

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Thesis (M.S. in Electrical Engineering)--Naval Postgraduate School, Dec. 2004. Thesis advisor(s): Murali Tummala, Roberto Cristi. Includes bibliographical references (p. 69-71). Also available online.

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Anoh, Kelvin Ogbonnaya Okorie. "Advanced MIMO-OFDM technique for future high speed braodband wireless communications : a study of OFDM design, using wavelet transform, fractional fourier transform, fast fourier transform, doppler effect, space-time coding for multiple input, multiple output wireless communications systems." Thesis, University of Bradford, 2015. http://hdl.handle.net/10454/14400.

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This work concentrates on the application of diversity techniques and space time block coding for future high speed mobile wireless communications on multicarrier systems. At first, alternative multicarrier kernels robust for high speed doubly-selective fading channel are sought. They include the comparisons of discrete Fourier transform (DFT), fractional Fourier transform (FrFT) and wavelet transform (WT) multicarrier kernels. Different wavelet types, including the raised-cosine spectrum wavelets are implemented, evaluated and compared. From different wavelet families, orthogonal wavelets are isolated from detailed evaluations and comparisons as suitable for multicarrier applications. The three transforms are compared over a doubly-selective channel with the WT significantly outperforming all for high speed conditions up to 300 km/hr. Then, a new wavelet is constructed from an ideal filter approximation using established wavelet design algorithms to match any signal of interest; in this case under bandlimited criteria. The new wavelet showed better performance than other traditional orthogonal wavelets. To achieve MIMO communication, orthogonal space-time block coding, OSTBC, is evaluated next. First, the OSTBC is extended to assess the performance of the scheme over extended receiver diversity order. Again, with the extended diversity conditions, the OSTBC is implemented for a multicarrier system over a doubly-selective fading channel. The MIMO-OFDM systems (implemented using DFT and WT kernels) are evaluated for different operating frequencies, typical of LTE standard, with Doppler effects. It was found that, during high mobile speed, it is better to transmit OFDM signals using lower operating frequencies. The information theory for the 2-transmit antenna OSTBC does not support higher order implementation of multi-antenna systems, which is required for the future generation wireless communications systems. Instead of the OSTBC, the QO-STBC is usually deployed to support the design of higher order multi-antenna systems other than the 2-transmit antenna scheme. The performances of traditional QO-STBC methods are diminished by some off-diagonal (interference) terms such that the resulting system does not attain full diversity. Some methods for eliminating the interference terms have earlier been discussed. This work follows the construction of cyclic matrices with Hadamard matrix to derive QO-STBC codes construction which are N-times better than interference free QO-STBC, where N is the number of transmit antenna branches.

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39

Anoh, Kelvin O. O. "Advanced MIMO-OFDM technique for future high speed braodband wireless communications. A study of OFDM design, using wavelet transform, fractional fourier transform, fast fourier transform, doppler effect, space-time coding for multiple input, multiple output wireless communications systems." Thesis, University of Bradford, 2015. http://hdl.handle.net/10454/14400.

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This work concentrates on the application of diversity techniques and space time block coding for future high speed mobile wireless communications on multicarrier systems. At first, alternative multicarrier kernels robust for high speed doubly-selective fading channel are sought. They include the comparisons of discrete Fourier transform (DFT), fractional Fourier transform (FrFT) and wavelet transform (WT) multicarrier kernels. Different wavelet types, including the raised-cosine spectrum wavelets are implemented, evaluated and compared. From different wavelet families, orthogonal wavelets are isolated from detailed evaluations and comparisons as suitable for multicarrier applications. The three transforms are compared over a doubly-selective channel with the WT significantly outperforming all for high speed conditions up to 300 km/hr. Then, a new wavelet is constructed from an ideal filter approximation using established wavelet design algorithms to match any signal of interest; in this case under bandlimited criteria. The new wavelet showed better performance than other traditional orthogonal wavelets. To achieve MIMO communication, orthogonal space-time block coding, OSTBC, is evaluated next. First, the OSTBC is extended to assess the performance of the scheme over extended receiver diversity order. Again, with the extended diversity conditions, the OSTBC is implemented for a multicarrier system over a doubly-selective fading channel. The MIMO-OFDM systems (implemented using DFT and WT kernels) are evaluated for different operating frequencies, typical of LTE standard, with Doppler effects. It was found that, during high mobile speed, it is better to transmit OFDM signals using lower operating frequencies. The information theory for the 2-transmit antenna OSTBC does not support higher order implementation of multi-antenna systems, which is required for the future generation wireless communications systems. Instead of the OSTBC, the QO-STBC is usually deployed to support the design of higher order multi-antenna systems other than the 2-transmit antenna scheme. The performances of traditional QO-STBC methods are diminished by some off-diagonal (interference) terms such that the resulting system does not attain full diversity. Some methods for eliminating the interference terms have earlier been discussed. This work follows the construction of cyclic matrices with Hadamard matrix to derive QO-STBC codes construction which are N-times better than interference free QO-STBC, where N is the number of transmit antenna branches.

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40

Vía, Rodríguez Javier. "Estima e igualación ciega de canales MIMO con y sin redundancia espacial." Doctoral thesis, Universidad de Cantabria, 2007. http://hdl.handle.net/10803/10666.

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La mayor parte de los sistemas de comunicaciones requieren el conocimiento previo del canal, el cual se suele estimar a partir de una secuencia de entrenamiento. Sin embargo, la transmisión de símbolos piloto se traduce en una reducción de la eficiencia espectral del sistema, lo que imposibilita que se alcancen los límites predichos por la Teoría de la Información. Este problema ha motivado el desarrollo de un gran número de técnicas para la estima e igualación ciega de canal, es decir, para la obtención del canal o la fuente sin necesidad de transmitir una señal de entrenamiento. Normalmente, estas técnicas se basan en el conocimiento previo de ciertas características de la señal, tales como su pertenencia a un alfabeto finito, o sus estadísticos de orden superior. Sin embargo, en el caso de sistemas de múltiples entradas y salidas (MIMO), se ha demostrado que los estadísticos de segundo orden de las observaciones proporcionan la información suficiente para resolver el problema ciego.El objetivo de esta Tesis consiste en la obtención de nuevas técnicas para la estima e igualación ciega de canales MIMO, tanto en sistemas con redundancia espacial, como en casos más generales en los que las fuentes no presentan ningún tipo particular de estructura. De manera general, los métodos propuestos se basan en los estadísticos de segundo orden de las observaciones. Sin embargo, las técnicas se presentan desde un punto de vista determinista, es decir, los algoritmos propuestos explotan directamente la estructura de las matrices de datos, lo que permite obtener resultados más precisos cuando se dispone de un número reducido de observaciones. Adicionalmente, la reformulación de los criterios propuestos como problemas clásicos del análisis estadístico de señales, ha permitido la obtención de algoritmos adaptativos eficientes para la estima e igualación de canales MIMO. En primer lugar se aborda el caso de sistemas sin redundancia. Más concretamente, se analiza el problema de igualación ciega de canales MIMO selectivos en frecuencia, el cual se reformula como un conjunto de problemas de análisis de correlaciones canónicas (CCA). La solución de los problemas CCA se puede obtener de manera directa mediante un problema de autovalores generalizado. Además, en esta Tesis se presenta un algoritmo adaptativo basado en la reformulación de CCA como un conjunto de problemas de regresión lineal acoplados. De esta manera, se obtienen nuevos algoritmos bloque y adaptativos para la igualación ciega de canales MIMO de una manera sencilla. Finalmente, el método propuesto se basa, como muchas otras técnicas ciegas, en el conocimiento a priori del orden del canal, lo que constituye un problema casi tan complicado como el de la estima o igualación ciega. Así, en el caso de canales de una entrada y varias salidas (SIMO), la combinación de la técnica propuesta con otros métodos para la estima ciega del canal permite obtener un nuevo criterio para extracción del orden de este tipo de canalesEn segundo lugar se considera el problema de estima ciega de canal en sistemas con algún tipo de redundancia o estructura espacial, con especial interés en el caso de sistemas con codificación espacio-temporal por bloques (STBC). Específicamente, se propone una nueva técnica para la estima ciega del canal, cuya complejidad se reduce a la extracción del autovector principal de una matriz de correlación modificada. El principal problema asociado a este tipo de sistemas viene dado por la existencia de ciertas ambigüedades a la hora de estimar el canal. En esta Tesis se plantea el problema de identificabilidad de una manera general, y en el caso de códigos ortogonales (OSTBCs) se presentan varios nuevos teoremas que aseguran la identificabilidad del canal en un gran número de casos. Adicionalmente, se proponen varias técnicas para la resolución de las ambigüedades, tanto en el caso OSTBC como para códigos más generales. En concreto, se introduce el concepto de diversidad de código, que consiste en la combinación de varios códigos STBC. Esta técnica permite resolver las indeterminaciones asociadas a un gran número de problemas, y en su versión más sencilla se reduce a una precodificación no redundante consistente en una simple rotación o permutación de las antenas transmisoras.En definitiva, en esta Tesis se abordan los problemas de estima e igualación ciega de canal en sistemas MIMO, y se presentan varias técnicas ciegas, cuyas prestaciones se evalúan mediante un gran número de ejemplos de simulación. The majority of communication systems need the previous knowledge of the channel, which is usually estimated by means of a training sequence. However, the transmission of pilot symbols provokes a reduction in bandwidth efficiency, which precludes the system from reaching the limits predicted by the Information Theory. This problem has motivated the development of a large number of blind channel estimation and equalization techniques, which are able to obtain the channel or the source without the need of transmitting a training signal. Usually, these techniques are based on the previous knowledge of certain properties of the signal, such as its belonging to a finite alphabet, or its higher-order statistics. However, in the case of multiple-input multiple-output (MIMO) systems, it has been proven that the second order statistics of the observations provide the sufficient information for solving the blind problem.The aim of this Thesis is the development of new blind MIMO channel estimation and equalization techniques, both in systems with spatial redundancy, and in more general cases where the sources do not have any particular spatial structure. In general, the proposed methods are based on the second order statistics of the observations. However, the techniques are presented from a deterministic point of view, i.e., the proposed algorithms directly exploit the structure of the data matrices, which allows us to obtain more accurate results when only a reduced number of observations is available. Additionally, the reformulation of the proposed criteria as classical statistical signal processing problems is exploited to obtain efficient adaptive algorithms for MIMO channel estimation and equalization.Firstly, we consider the case of systems without spatial redundancy. Specifically, we analyze the problem of blind equalization of frequency selective MIMO channels, which is reformulated as a set of canonical correlation analysis (CCA) problems. The solution of the CCA problems can be obtained by means of a generalized eigenvalue problem. In this Thesis, we present a new adaptive algorithm based on the reformulation of CCA as a set of coupled linear regression problems. Therefore, new batch and adaptive algorithms for blind MIMO channel equalization are easily obtained. Finally, the proposed method, as well as many other blind techniques, is based on the previous knowledge of the channel order, which is a problem nearly as complicated as the blind channel estimation or equalization. Thus, in the case of single-input multiple-output (SIMO) channels, the combination of the proposed technique with other blind channel estimation methods provides a new criterion for the order extraction of this class of channels.Secondly, we consider the problem of blind channel estimation in systems with some kind of redundancy or spatial structure, with special interest in space-time block coded (STBC) systems. Specifically, a new blind channel estimation technique is proposed, whose computational complexity reduces to the extraction of the principal eigenvector of a modified correlation matrix. The main problem in these cases is due to the existence of certain ambiguities associated to the blind channel estimation problem. In this Thesis the general identifiability problem is formulated and, in the case of orthogonal codes (OSTBCs), we present several new theorems which ensure the channel identifiability in a large number of cases. Additionally, several techniques for the resolution of the ambiguities are proposed, both in the OSTBC case as well as for more general codes. In particular, we introduce the concept of code diversity, which consists in the combination of several STBCs. This technique avoids the ambiguities associated to a large number of problems, and in its simplest version it reduces to a non-redundant precoding consisting of a single rotation or permutation of the transmit antennas.In summary, in this Thesis the blind MIMO channel estimation and equalization problems are analyzed, and several blind techniques are presented, whose performance is evaluated by means of a large number of simulation examples.

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Uhlemann, Elisabeth. "Hybrid ARQ Using Serially Concatenated Block Codes for Real-Time Communication : An Iterative Decoding Approach." Licentiate thesis, Halmstad University, School of Information Science, Computer and Electrical Engineering (IDE), 2001. http://urn.kb.se/resolve?urn=urn:nbn:se:hh:diva-2109.

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The ongoing wireless communication evolution offers improvements for industrial applications where traditional wireline solutions causes prohibitive problems in terms of cost and feasibility. Many of these new wireless applications are packet oriented and time-critical. The deadline dependent coding (DDC) communication protocol presented here is explicitly intended for wireless real-time applications. The objective of the work described in this thesis is therefore to develop the foundation for an efficient and reliable real-time communication protocol for critical deadline dependent communication over unreliable wireless channels.Since the communication is packet oriented, block codes are suitable for error control. Reed-Solomon codes are chosen and incorporated in a concatenated coding scheme using iterative detection with trellis based decoding algorithms. Performance bounds are given for parallel and serially concatenated Reed-Solomon codes using BPSK. The convergence behavior of the iterative decoding process for serially concatenated block codes is examined and two different stopping criteria are employed based on the log-likelihood ratio of the information bits.The stopping criteria are also used as a retransmission criterion, incorporating the serially concatenated block codes in a type-I hybrid ARQ (HARQ) protocol. Different packet combining techniques specifically adapted to the concatenated HARQ (CHARQ) scheme are used. The extrinsic information used in the iterative decoding process is saved and used when decoding after a retransmission. This technique can be seen as turbo code combining or concatenated code combining and is shown to improve performance. Saving the extrinsic information may also be seen as a doping criterion yielding faster convergence. As such, the extrinsic information can be used in conjunction with traditional diversity combining schemes. The performance in terms of bit error rate and convergence speed is improved with only negligible additional complexity.Consequently, CHARQ based on serially concatenated block codes using iterative detection creates a flexible and reliable scheme capable of meeting specified required realtime constraints.

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Chen, Chi-Chung, and 陳起忠. "Space-time Block Coding for Sensor Networks." Thesis, 2004. http://ndltd.ncl.edu.tw/handle/33724406791865358111.

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碩士 國防管理學院 國防資訊研究所 92 Space-time block coding is one of the most significant technical breakthroughs in modern communications. The technology figures prominently on the list of recent technical advances with a chance of resolving the bottleneck of traffic capacity in future Internet-intensive wireless networks. This is because it can used channel capacity, bandwidth efficiently , noise mitigation under non increase of the complexity. This paper propose in coding or increase some of the time and space dimension to provide more coding gain under the STBC design in the sensor networks, to adapted in the different fading environment. we can used different matrix in order to received signals with low BER. It also can get balance between system complexity and coded gain.

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"Distributed space-time block coding in wireless cooperative communications." 2005. http://library.cuhk.edu.hk/record=b5892631.

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Cheng Ho Ting. Thesis (M.Phil.)--Chinese University of Hong Kong, 2005. Includes bibliographical references (leaves 90-93). Abstracts in English and Chinese. Abstract --- p.i Acknowledgement --- p.iv Chapter 1 --- Introduction --- p.1 Chapter 1.1 --- Overview of Wireless Cooperative Communications --- p.1 Chapter 1.2 --- Motivation --- p.2 Chapter 1.3 --- Distributed Space-Time Block Coding --- p.4 Chapter 1.4 --- Imperfect Channel Estimation --- p.4 Chapter 1.5 --- Time-Varying Channels --- p.4 Chapter 1.6 --- Outline of the thesis --- p.5 Chapter 2 --- Background Study --- p.6 Chapter 3 --- Distributed Space-Time Block Coding --- p.13 Chapter 3.1 --- Introduction --- p.13 Chapter 3.2 --- System Model --- p.13 Chapter 3.3 --- BER Analysis by Characteristic Equations --- p.16 Chapter 3.4 --- BER Analysis by Error Terms --- p.18 Chapter 3.4.1 --- Non-fading R→D link --- p.19 Chapter 3.4.2 --- Fading R→D link --- p.19 Chapter 3.5 --- Performance --- p.20 Chapter 3.5.1 --- Accuracy of Analytical Expressions --- p.20 Chapter 3.5.2 --- Observation of Second-order Diversity --- p.21 Chapter 3.6 --- Summary --- p.22 Chapter 4 --- Distributed Space-Time Block Coding with Imperfect Channel Estimation --- p.31 Chapter 4.1 --- Introduction --- p.31 Chapter 4.2 --- System Model --- p.32 Chapter 4.3 --- BER Analysis --- p.32 Chapter 4.3.1 --- Non-fading R→D link --- p.33 Chapter 4.3.2 --- Fading R→D link --- p.34 Chapter 4.4 --- Numerical Results --- p.34 Chapter 4.5 --- Summary --- p.36 Chapter 5 --- Distributed Space-Time Block Coding with Time-Varying Channels --- p.43 Chapter 5.1 --- Introduction --- p.43 Chapter 5.2 --- System Model --- p.44 Chapter 5.3 --- Pilot Symbol Assisted Modulation (PSAM) for DSTBC --- p.45 Chapter 5.4 --- Reception Methods --- p.48 Chapter 5.4.1 --- Maximum-Likelihood Detection (ML) in [29] --- p.48 Chapter 5.4.2 --- Cooperative Maximum-Likelihood Detection (CML) --- p.50 Chapter 5.4.3 --- Alamouti's Receiver (AR) --- p.51 Chapter 5.4.4 --- Zero-forcing Linear Detection (ZF) --- p.51 Chapter 5.4.5 --- Decision-feedback Detection (DF) --- p.52 Chapter 5.5 --- BER Analysis for Time-varying Channels --- p.53 Chapter 5.5.1 --- Quasi-Static Channels (p = 1) --- p.53 Chapter 5.5.2 --- ZF: Uncorrelated Channel (p = 0) --- p.54 Chapter 5.5.3 --- ZF: General Channel --- p.55 Chapter 5.5.4 --- DF: General Channel --- p.56 Chapter 5.6 --- Numerical Results --- p.57 Chapter 5.7 --- Summary --- p.60 Chapter 6 --- Conclusion and Future Work --- p.74 Chapter 6.1 --- Conclusion --- p.74 Chapter 6.2 --- Future Work --- p.76 Chapter 6.2.1 --- Design of Code Matrix --- p.76 Chapter 6.2.2 --- Adaptive Protocols --- p.77 Chapter A --- Derivation of (3.23) --- p.79 Chapter B --- Derivation of (3.30) and (3.32) --- p.83 Chapter C --- Derivation of (4.9) and (4.13) --- p.85 Chapter D --- Derivation of (5.68) --- p.88 Bibliography --- p.90

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Wen, Xin. "Higher-rank Transmit Beamforming Using Space Time Block Coding." Phd thesis, 2016. https://tuprints.ulb.tu-darmstadt.de/5464/3/PhD_Thesis_Xin_Wen.pdf.

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With the rapid development of wireless communications, there has been a massive growth in the number of wireless communications users and progressively more new high data rate wireless services will emerge. With these developments taking place, wireless spectral resources are becoming much more scarce and precious. As a result, research on spectrally efficient transmission techniques for current and future communication networks attracts considerable interest. As a promising multi-antenna communication technique, transmit beamforming is widely recognized as being able to improve the capacity of wireless systems without requiring additional spectral resources. In conventional (rank-one) beamforming, each user is served by a single beamformer. For certain transmit beamforming applications, the beamforming performance may be poor if the degrees of freedom in the conventional beamformer design become insufficient. The scope of this thesis is to address the beamforming performance degradation problems induced by the insufficient degrees of freedom in the beamformer design in certain practical scenarios. In this thesis, a fundamentally new idea of higher-rank (>1) transmit beamforming is proposed to improve the beamforming performance. Instead of a single beamformer assigned to each user, multiple beamformers are designed and correspondingly the degrees of freedom in the beamformer design are multiplied, i.e., the increase of the degrees of freedom consists in the increase of the number of design variables. To implement higher-rank beamforming, the central idea is to combine beamforming with different space time block coding (STBC) techniques. Conventionally, STBCs are used to exploit the transmit diversity resulting from the independent fading for different transmit antennas. However, the use of STBCs in the higher-rank beamforming approaches is not for the sake of transmit diversity, but for the sake of design diversity in the sense of degrees of freedom in the beamformer design. The single-group multicast beamforming problem of broadcasting the same information to all users is firstly considered in the thesis. It is assumed that the transmitter knows the instantaneous channel state information (CSI) which describes the short-term channel conditions of a communication link and can be estimated in modern communication systems. In the conventional approach, a single beamforming weight vector is designed to steer the common information to all users. In the case of a large number of users, the performance of the conventional approach usually degrades severely due to the limited degrees of freedom offered by a single beamformer. In order to mitigate this drawback, a rank-two beamforming approach is proposed in which two independent beamforming weight vectors are designed. In the rank-two beamforming approach, single-group multicast beamforming is combined with the two dimentional Alamouti STBC, and each user is simultaneously served with two Alamouti coded symbols from two beamformers. The degrees of freedom in the beamformer design are doubled and significant performance improvement is achieved. The multi-group multicast beamforming problem of transmitting the same information to users in the same group while transmitting independent information to users in different groups, is studied next in the thesis, also assuming that instantaneous CSI is available at the transmitter. The rank-two beamforming approach, originally devised for single-group multicasting networks that are free of multiuser interference, is extended to multi-group multicasting networks, where multiuser interference represents a major challenge. By combining multi-group multicast beamforming with Alamouti STBC, two independent beamforming weight vectors are assigned to each user and the degrees of freedom in the beamformer design are doubled resulting in drastically improved beamforming performance. Then, the multiuser downlink beamforming problem of delivering independent information to different users with additional shaping constraints is investigated in the thesis, also assuming instantaneous CSI at the transmitter. Additional shaping constraints are used to incorporate a variety of requirements in diverse applications. When the number of shaping constraints is large, the degrees of freedom in the beamformer design can be rather deficient. In order to address this problem, a general rank beamforming approach is proposed in which multiuser downlink beamforming is combined with high dimensional (>2) real-valued orthogonal space time block coding (OSTBC). In the general rank beamforming approach, the number of beamforming weight vectors for each user and the associated degrees of freedom in the beamformer design are multiplied by up to eight times, which lead to significantly increased flexibility for the beamformer design. Since instantaneous CSI can be difficult to acquire in certain scenarios, the use of statistical CSI describing the long-term statistical characteristics of the channel can be more practical in these scenarios. The rank-two beamformer designs based on instantaneous CSI can be straightforwardly applied in the case of statistical CSI. However, it is impossible to extend the general rank beamforming approach for the multiuser downlink beamforming problem with additional shaping constraints based on instantaneous CSI to the case of statistical CSI straightforwardly. Therefore, multiuser downlink beamforming with additional shaping constraints using statistical CSI at the transmitter is then studied and an alternative general rank beamforming approach is proposed in the thesis. In the general rank beamforming approach using statistical CSI, multiuser downlink beamforming is combined with quasi-orthogonal space time block coding (QOSTBC). The increased number of beamforming weight vectors and the associated degrees of freedom are much beyond the limits that can be achieved by Alamouti STBC in the beamformer design. Simulation results demonstrate that the proposed higher-rank transmit beamforming approaches can achieve significantly improved performance as compared to the existing approaches.

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Chen, Chien-Yu, and 陳建宇. "Differential Unitary Space-Time Block Coding Via Orthogonal Designs." Thesis, 2006. http://ndltd.ncl.edu.tw/handle/76517693202443860135.

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碩士 國立交通大學 電機與控制工程系所 94 Based on the differential space-time coding, we use different kinds of orthogonal design to effectively improve the communication quality. Among them, especially the 4 and 8 transmit antenna designs,we are able to lower the bit-error-rate by trading off the code rate.Then, basing on those, we extend to the non-square orthogonal designs which achieve 3, 5, 6, and 7 transmit antenna applications.Finally, we propose a new method for the orthogonal design to effectively reduce the bit error rate. However, when the numbers of transmit antenna increase, the code rate will be largely lower while still let the entire system operate most properly.

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Chen, Juin-Da, and 陳俊達. "Concatenated Space-Time Block Coding With Block Coded Modulation For Noncoherent detection." Thesis, 2004. http://ndltd.ncl.edu.tw/handle/65678090342831840575.

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碩士 國立中央大學 通訊工程研究所 92 In this thesis, combing block coded modulation (BCM) and space-time block coding (STBC) with channel estimation is discussed. Taking advantage of the channel estimation using training symbols, noncoherent detection can be easily employed by STBC.The impact of STBC using training symbols concatanated with different block length of BCM is also investigate. Finally, we compare the system with unitary space-time modulation in the quasi-static flat fading channel

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Wang, Jason, and 王禎毅. "Adaptive Power Allocation for 2 × n Space-Time Block Coding." Thesis, 2008. http://ndltd.ncl.edu.tw/handle/59735888607332561354.

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碩士 國立臺灣大學 電機工程學研究所 96 In this paper, we explore the application of adaptive power allocation to 2 × nr space-time block code (STBC) systems, where nr specifies an arbitrary number of antennas at the receiver. We demonstrated how a fixed amount of transmit power allocated among the transmit antennas in different quantities can result in an improved bit error rate (BER) performance. Using a feed-back link between the transmitter and receiver, adaptive power allocation can also be used to improve the system capacity or minimize the transmit power of a system while satisfying a threshold BER equirement. Our method for allocating the transmit power is compared with the conventional power allocation method of water-filling and with a hypothetical capacity-constrained waterfilling method. The case of imperfect channel estimation at the receiver is also analyzed for its effects on the performance of adaptive power allocation.

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Wang, Jason. "Adaptive Power Allocation for 2 * n Space-Time Block Coding." 2008. http://www.cetd.com.tw/ec/thesisdetail.aspx?etdun=U0001-2807200800211700.

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Fang, Ching-Geng, and 方清庚. "Space-Time Block Coding in Orthogonal Frequency Division Multiplexing System." Thesis, 2003. http://ndltd.ncl.edu.tw/handle/48557163031437112666.

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碩士 國立臺灣科技大學 電子工程系 91 A transmitter diversity scheme for wireless communications over frequency selective fading channels is presented. Space-time block coding has emerged as a mean of attaining a significant MRC (maximal ratio combining) diversity gain. Using two transmit antennas and one receive antenna, the proposed scheme provides the same diversity order as MRC with one transmit antenna and two receiving antennas. Existing implementations of Space-time block coding are limited to flat fading environments due to the high sensitivity to delay spreads. OFDM (Orthogonal frequency division multiplexing) with a sufficiently long cyclic prefix can convert frequcncy-selective fading channels into multiple flat fading subchannels. The proposed technique utilizes OFDM to transform frequency selective fading channels into multiple flat fading subchannels on which space-time block coding and space-frequency block coding is applied. A two-branch transmitter diversity system is implemented without bandwidth expansion and with a small increase in complexity beyond that of a conventional OFDM system. Simulation results verify that in slow fading environments, the proposed space-frequency OFDM transmitter diversity technique has the same performance as a space-time OFDM transmitter diversity system. However, its shows that better performance in the fast fading environments is attained by the former schemes.

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Sithole, Sifiso, and Sifiso. "Space-time block coding with XOR coding for DL JP CoMP transmission scheme." Thesis, 2014. http://ndltd.ncl.edu.tw/handle/zb7g62.

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碩士 國立臺北科技大學 電資碩士班 102 The 3rd Generation Partnership Project (3GPP) completed a study on coordinated multi-point transmission and reception (CoMP) techniques to facilitate cooperative communications across multiple transmission and reception points (e.g., cells) for the LTE-Advanced (LTE-A) system. CoMP was initially brought forward in the study item of LTE-A to meet the requirements of the International Mobile Telecommunications Advanced (IMT-Advanced) in 2008. At their meeting (3GPP TSG RAN #50), the study item CoMP was agreed upon for Release 11 as a tool to improve the coverage of high data rates, cell-edge throughput, and also to increase the overall system throughput. In a CoMP operation, multiple points coordinate with each other in such a way that the transmitted signals from/to other points do not incur serious interference or can even be exploited as meaningful signals. Theoretical work has shown that CoMP offers considerable potential performance gains in both the uplink and the downlink. For this reasons, CoMP has been studied as a solution to increasing system throughput, especially at the cell-edge areas where inter-cell interference (ICI) is severe more so with the traditional approaches. Network coding (NC) is another technique that has been receiving much attention recently, for its ability to improve spectral efficiency and achieve throughput optimality. By using network coding on CoMP schemes, the throughput of the wireless system is improved further because network coding brings about a new perspective which utilizes the interference instead of mitigating it. Exclusive-OR (XOR) coding, is one of the simple implementation of NC, by which two bits can be sent in only one transmission (by XORing them) instead of the normal two transmissions. The XOR operation of NC at the antenna is normally dubbed Analogue Network Coding (ANC) or Physical Layer Network Coding (PNC). Through the use of XOR coding, multiple faulty packets can be rectified by the receiver at the cost of transmitting an additional coded packet. Using XOR coding with CoMP, therefore, improves the BER performance and can also yield to a significant increase in the system throughput by aggressively allocating the transmission rate is most wireless communication systems. Space-time coding (STC) in multiple-input multiple-output (MIMO) systems has also recently attracted so much interest, due to the performance gains that they can accomplish. Transmit diversity is one of the MIMO algorithms used in the LTE-A standard and it belongs to the STC class of techniques. STCs are capable of delivering a diversity order equal to the product of the number of transmit and receive antennas. Space-time block codes (STBCs), one of the simplest implementation of STCs, can be regarded as a multi-antenna modulation and mapping technique that provides full diversity and results in simple encoders and decoders. One of the simplest forms of STBC is the Alamouti code defined for 2-transmit antennas cases. Transmit diversity using STBC has been deployed in various 3GPP and WiMAX standards. Space-frequency block coding (SFBC), one technique closely related to STBC, is the transmit diversity technique used in LTE-A standard. The use of STBC in LTE-A can also yield to an improvement in the link quality and reliability of the system. One major drawback in using transmit diversity techniques like STBC or SFBC is that they do not improve the data rate or spectral efficiency of the system. In this thesis, we propose a double STBC technique (based on the Alamouti code) that can be applied on a network coded CoMP downlink (DL) transmission scheme to exploit diversity gain plus offer a tremendous improvement in the data rate of the system. The proposed double STBC technique is also known as double space-time transmit diversity (DSTTD) scheme for high rate applications with 4 transmit antennas. The proposed scheme will apply the double STBC to a network coded DL Joint Processing (JP) CoMP transmission scheme and the scheme is to be known as; Space-time block coding with XOR coding for DL JP CoMP Transmission Scheme. Performance of this scheme based on bit-error rate (BER) and system data rate, will be evaluated (through simulations), and comparisons with the conventional Space-time block coded JP CoMP scheme will be made. The proposed scheme yields better performance more especially in terms of the data rate of the system, due to the combination of the double STTD (DSTTD) and network (XOR) coding techniques and suffers little bit in terms of BER performance compared to conventional CoMP scheme. The poor performance in BER may be attributed to the fact that our scheme uses fewer decoding iterations in the turbo decoder at the receiver, yet the more the number iterations the more accurate the operation becomes. Another reason would be that we used a simple receiver structure which uses Zero Forcing (ZF) algorithm as the detection mechanism which has a poor performance and a lower computational complexity when compared to other detection methods like (Minimum Mean Square Error) MMSE or Sphere Decoding (SD).

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