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1
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.
2
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.
3
Potter, Chris, Kurt Kosbar, and Adam Panagos. "Hardware Discussion of a MIMO Wireless Communication System Using Orthogonal Space Time Block Codes." International Foundation for Telemetering, 2008. http://hdl.handle.net/10150/606194.
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ITC/USA 2008 Conference Proceedings / The Forty-Fourth Annual International Telemetering Conference and Technical Exhibition / October 27-30, 2008 / Town and Country Resort & Convention Center, San Diego, California<br>Although multiple-input multiple-output (MIMO) systems have become increasingly popular, the existence of real time results to compare with those predicted by theory is still surprisingly limited. In this work the hardware description of a MIMO wireless communication system using orthogonal space time block codes (OSTBC) is discussed for two antennas at both the transmitter and receiver. A numerical example for a frequency flat time correlated channel is given to show the impact of channel estimation.
4
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.<br>Thesis advisor(s): Murali Tummala, Roberto Cristi. Includes bibliographical references (p. 69-71). Also available online.
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Abaza, Mohamed. "Cooperative MIMO techniques for outdoor optical wireless communication systems." Thesis, Brest, 2015. http://www.theses.fr/2015BRES0073/document.
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Au cours de la dernière décennie, les communications optiques en espace libre (FSO) ont pris de l’ampleur dans les deux domaines académiques et industriels. L’importance de FSO s’appuie sur la possibilité de faire un système de transmission économique et écologique avec un débit élevé et sans licence à l’opposition des systèmes de transmission radiofréquences (RF). Dans la plupart des travaux antécédents sur les systèmes multi-émetteurs, seulement les canaux décorrélés ont été considérés. Un canal décorrélé nécessite un espace suffisant entre les émetteurs. Cette condition devient difficile et non-réalisable dans certaines applications. Pour cette raison, nos études se focalisent sur les performances des codes à répétition RC (Repitition Codes) et les codes OSTBC (Orthogonal Space-Time Block Codes) dans des canaux log-normaux corrélés en utilisant une modulation d’intensité et une détection directe (IM/DD). En addition, les effets des différentes conditions météorologiques sur le taux d’erreur moyen (ABER) sont étudiés. Les systèmes FSO à multi-entrées/ multi-sorties MIMO (Multiple-Input Multiple-Output) avec une modulation SSK (Space Shift Keying) ont été abordés. Les résultats obtenus montrent que la SSK est supérieure aux RC avec une modulation d’impulsion (Multiple Pulse Amplitude Modulation) pour toute efficacité spectrale égale ou supérieure à 4 bit/s/Hz. Nous avons aussi analysé les performances d’un système à sauts multiples (Multi-Hop) et des relais à transmission directe (forward relays). Nos simulations montrent que le système ainsi considéré est efficace pour atténuer les effets météorologiques et les pertes géométriques dans les systèmes de communication FSO. Nous avons montré qu’un tel système avec plusieurs entrées et une sortie (MISO, i.e. multiple-input single-output) à sauts multiples est supérieur à un système MISO avec un lien direct (direct link) avec une forte atténuation. Pour satisfaire la demande croissante des réseaux de communication à débits élevés, la communauté scientifique s'intéresse de plus en plus aux systèmes FSO avec des relais full-duplex (FD). Pour ces derniers systèmes, nous avons étudié la probabilité d'erreur moyenne (ABER) et nous avons analysé leurs performances. En considérant des différentes conditions de transmission, les performances de relais FD ont été comparées à celles d'un système avec un lien direct ou des relais half-duplex. Les résultats obtenus montrent que les relais FD ont le minimum ABER. En conséquence, les résultats obtenus dans cette thèse sont très prometteurs pour la prochaine génération de FSO<br>Free-space optical (FSO) communication has been the subject of ongoing research activities and commercial attention in the past few years. Such attention is driven by the promise of high data rate, license-free operation, and cheap and ecological friendly means of communications alternative to congested radio frequency communications. In most previous work considering multiple transmitters, uncorrelated channel conditions have been considered. An uncorrelated channel requires sufficient spacing between transmitters. However, this can be difficult and may not be always feasible in some applications. Thereby, this thesis studies repetition codes (RCs) and orthogonal space-time block codes performance in correlated log-normal FSO channels using intensity modulation and direct detection (IM/DD). Furthermore, the effect of different weather conditions on the average bit error rate (ABER) performance of the FSO links is studied. Multiple-input multiple-output (MIMO) FSO communication systems using space shift keying (SSK) modulation have been also analyzed. Obtained results show that SSK is a potential technique for spectral efficiencies equal or greater than 4 bits/s/Hz as compared to RCs with multiple pulse amplitude modulations. The performance analysis of a multi-hop decode and forward relays for FSO communication system using IM/DD is also considered in this thesis. It is shown that multi-hop is an efficient technique to mitigate atmospheric turbulence and different weather attenuation effects and geometric losses in FSO communication systems. Our simulation results show that multiple-input single-output (MISO) multi-hop FSO systems are superior to direct link and MISO systems over links exhibiting high attenuation. Meeting the growing demand for higher data rates communication networks, a system with full-duplex (FD) relays is considered. For such a system, the outage probability and the ABER performance are analyzed under different turbulence conditions, misalignment error and path loss effects. FD relays are compared with the direct link and half-duplex relays. Obtained results show that FD relays have the lowest ABER and the outage probability as compared to the two other systems. Finally, the obtained results in this thesis are very promising towards the next generation of FSO systems
6
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.
7
Hassan, Mohamed Abdulla S. "Channel Estimation and Equalisation for Multicarrier Systems Employing Orthogonal Space-Time Block Code." Thesis, University of Newcastle Upon Tyne, 2006. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.519490.
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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.
9
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.
Full textAbstract:
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.
10
Anoh, Kelvin O. O., Raed A. Abd-Alhameed, G. N. Okorafor, James M. Noras, Jonathan Rodriguez, and Steven M. R. Jones. "Performance Evaluation of Spatial Modulation and QOSTBC for MIMO Systems." 2015. http://hdl.handle.net/10454/7623.
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Yes<br>Multiple-input multiple-output (MIMO) systems require simplified architectures that can maximize design parameters without sacrificing system performance. Such architectures may be used in a transmitter or a receiver. The most recent example with possible low cost architecture in the transmitter is spatial modulation (SM). In this study, we evaluate the SM and quasi-orthogonal space time block codes (QOSTBC) schemes for MIMO systems over a Rayleigh fading channel. QOSTBC enables STBC to be used in a four antenna design, for example. Standard QO-STBC techniques are limited in performance due to self-interference terms; here a QOSTBC scheme that eliminates these terms in its decoding matrix is explored. In addition, while most QOSTBC studies mainly explore performance improvements with different code structures, here we have implemented receiver diversity using maximal ratio combining (MRC). Results show that QOSTBC delivers better performance, at spectral efficiency comparable with SM.
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"Expanded Super-Orthogonal Space-Time Block Codes with Systematic Construction." 2006. http://www.cetd.com.tw/ec/thesisdetail.aspx?etdun=U0016-1303200709274168.
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丁元玟. "Expanded Super-Orthogonal Space-Time Block Codes with Systematic Construction." Thesis, 2006. http://ndltd.ncl.edu.tw/handle/92681399502022704182.
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碩士<br>國立清華大學<br>通訊工程研究所<br>94<br>Space-time codes in both spatial and temporal domains have been proposed and become very
popular for use in multi-input multi output systems. This thesis introduces a more general
structure for super-orthogonal space-time codes called expanded super-orthogonal space time
codes, which can retain the property that the maximum-likelihood decoding complexity is
linear in the number of transmit antennas. Its codebook can be obtained by expanding
the original space-time block code via both sides of unitary transformations. Besides, with
a systematic parameterization, we can show a systematic procedure to obtain codebooks
with optimal diversity gain. The results demonstrate better performance compared with
super-orthogonal space-time block codes in terms of bit error rate.
13
Fan, Sheng-Po, and 范盛博. "Power Allocation for Minimum BER in Quasi-Orthogonal Space-Time Block Coded Systems." Thesis, 2006. http://ndltd.ncl.edu.tw/handle/56520837139961863219.
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碩士<br>國立交通大學<br>電信工程系所<br>94<br>It is well known that transmit diversity is a popular technique in modern wireless communication. In this thesis, we focus on one of quasi-orthogonal space-time block codes with full rate (the so-called ABBA code). By exploiting a distinctive channel matrix structure induced by the ABBA code, we derive an explicit formula of the associated QR-decomposition. We propose a minimal BER power allocation scheme for the ABBA code over i.i.d. Rayleigh fading channels under the QR-based successive detection framework. Under a fixed channel realization, we propose optimal power allocation schemes depending on whether or not inter-layer error propagation is taken into account first. Instead of relying on BER under a fixed channel realization, the design criterion adopted by us is the overall mean BER averaged with respect to the channel distribution. Without inter-layer error propagation, we derive an upper bound of the average BER. The closed-form formula is obtained by averaging the upper bound of mean BER with respect to the channel distribution. We then minimize the closed-form formula and an optimal power allocation scheme is obtained. Numerical simulation shows that the resultant performance is almost identical to that of the joint maximum-likelihood decoding in the medium-high SNR region.
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Chen, Yu-Ching, and 陳郁青. "Comparison and Performance Analysis of Different Quasi-Orthogonal Space Time Block Code Decoders." Thesis, 2010. http://ndltd.ncl.edu.tw/handle/91516737870554401811.
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碩士<br>國立臺灣海洋大學<br>通訊與導航工程系<br>98<br>In the conventional STBC scheme, system cannot achieve full diversity and full rate for more than two transmitting antennas. Quasi-Orthogonal Space-Time Block Code has been proposed to improve the diversity and full rate for the STBC. This paper surveys several QOSTBC decoding methods. Through the theoretic analyses and computer simulations, a
simple QOSTBC decode with low computational complexity and
satisfactory bit error rate (BER) performance is proposed in this paper.
15
Zu, Bing-Syuan, and 祖秉瑄. "Super-Orthogonal Space-Time Trellis Codes for MIMO Block Fading Channels." Thesis, 2005. http://ndltd.ncl.edu.tw/handle/64837900099860652567.
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碩士<br>國立清華大學<br>通訊工程研究所<br>93<br>In the thesis, we consider communication systems over the multi-input multi-output (MIMO)
block fading channels. We try to design super-orthogonal space-time trellis codes (SOSTTC),
which can provide great error performance in slow fading channels, for MIMO block fading
channels. The concept of constellation partition and (quasi-) regular property are used to
analyze the code construction. Then, the practical encoder construction and line connection
principle are proposed. We start from simple cases of 2-by-2 SOSTTC and then generalize
our design to di®erent constellations and antennas while full-rate transmission is still main-
tained. A systematic methodology to design powerful coding schemes for MIMO block fading
channels is thus introduced. Compared with the space-time block code (STBC) only system,
our codes can provide much better error performance because of large coding and diversity
gains. We also compare our codes with STBC-bit interleaved coded modulation (BICM)
schemes, which can provide extremely high diversity orders with large time delay. Although
our codes cannot achieve higher diversity orders, we find that the error performance will be
almost the same as those of STBC-BICM schemes at high signal-to-noise ratios and even
better at low signal-to-noise ratios when the numbers of antennas and states increase.
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Wang, Shih-Han, and 汪師韓. "Distributed Quasi-Orthogonal Space Time Block Code for Cooperative Communication with Information Exchange Errors." Thesis, 2011. http://ndltd.ncl.edu.tw/handle/w49gq6.
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碩士<br>國立臺北科技大學<br>電腦與通訊研究所<br>99<br>In the cooperative communication systems, the users exchange information symbols from the other users and transmit to the destination in the form of Distributed Space Time Block Code (DSTBC). Orthogonal Space Time Block Code (OSTBC) with two transmit antennas considering the information exchange error have been proposed, but OSTBC with full rate does not exist for more than two transmit antennas. In this paper, we design full rate quasi orthogonal space time block code (QOSTBC) matrix for four transmit antennas and still consider information exchange errors. In the simulation results, the proposed rate 1 DQOSTBC scheme with parallel interference cancellation (PIC) obtains 5.5~6.5 dB gains over rate 1/2 DOSTBC scheme at 10-4 bit error rate at the same transmission rate of 2 bits/s/Hz. For the DQOSTBC without PIC case, the gain is about 3.5~4.5dB. The performance analysis result also confirms that the proposed rate 1 DQOSTBC scheme without PIC outperforms rate 1/2 DOSTBC scheme at the same transmission rate.
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Jithamithra, G. R. "Space-Time Block Codes With Low Sphere-Decoding Complexity." Thesis, 2013. http://etd.iisc.ernet.in/handle/2005/2612.
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One of the most popular ways to exploit the advantages of a multiple-input multiple-output (MIMO) system is using space time block coding. A space time block code (STBC) is a finite set of complex matrices whose entries consist of the information symbols to be transmitted. A linear STBC is one in which the information symbols are linearly combined to form a two-dimensional code matrix. A well known method of maximum-likelihood (ML) decoding of such STBCs is using the sphere decoder (SD).
In this thesis, new constructions of STBCs with low sphere decoding complexity are presented and various ways of characterizing and reducing the sphere decoding complexity of an STBC are addressed. The construction of low sphere decoding complexity STBCs is tackled using irreducible matrix representations of Clifford algebras, cyclic division algebras and crossed-product algebras. The complexity reduction algorithms for the STBCs constructed are explored using tree based search algorithms. Considering an STBC as a vector space over the set of weight matrices, the problem of characterizing the sphere decoding complexity is addressed using quadratic form representations. The main results are as follows.
A sub-class of fast decodable STBCs known as Block Orthogonal STBCs (BOSTBCs) are explored. A set of sufficient conditions to obtain BOSTBCs are explained. How the block orthogonal structure of these codes can be exploited to reduce the SD complexity of the STBC is then explained using a depth first tree search algorithm. Bounds on the SD complexity reduction and its relationship with the block orthogonal structure are then addressed. A set of constructions to obtain BOSTBCs are presented next using Clifford unitary weight designs (CUWDs), Coordinate-interleaved orthogonal designs (CIODs), cyclic division algebras and crossed product algebras which show that a lot of codes existing in literature exhibit the block orthogonal property.
Next, the dependency of the ordering of information symbols on the SD complexity is discussed following which a quadratic form representation known as the Hurwitz-Radon quadratic form (HRQF) of an STBC is presented which is solely dependent on the weight matrices of the STBC and their ordering. It is then shown that the SD complexity is only a function of the weight matrices defining the code and their ordering, and not of the channel realization (even though the equivalent channel when SD is used depends on the channel realization). It is also shown that the SD complexity is completely captured into a single matrix obtained from the HRQF.
Also, for a given set of weight matrices, an algorithm to obtain a best ordering of them leading to the least SD complexity is presented using the HRQF matrix.
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Shashidhar, V. "High-Rate And Information-Lossless Space-Time Block Codes From Crossed-Product Algebras." Thesis, 2004. http://hdl.handle.net/2005/314.
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It is well known that communication systems employing multiple transmit and multiple receive antennas provide high data rates along with increased reliability. It has been shown that coding across both spatial and temporal domains together, called Space-Time Coding (STC), achieves, a diversity order equal to the product of the number of transmit and receive antennas. Space-Time Block Codes (STBC) achieving the maximum diversity is called full-diversity STBCs. An STBC is called information-lossless, if the structure of it is such that the maximum mutual information of the resulting equivalent channel is equal to the capacity of the channel.
This thesis deals with high-rate and information-lossless STBCs obtained from certain matrix algebras called Crossed-Product Algebras. First we give constructions of high-rate STBCs using both commutative and non-commutative matrix algebras obtained from appropriate representations of extensions of the field of rational numbers. In the case of commutative algebras, we restrict ourselves to fields and call the STBCs obtained from them as STBCs from field extensions. In the case of non-commutative algebras, we consider only the class of crossed-product algebras.
For the case of field extensions, we first construct high-rate; full-diversity STBCs for arbitrary number of transmit antennas, over arbitrary apriori specified signal sets. Then we obtain a closed form expression for the coding gain of these STBCs and give a tight lower bound on the coding gain of some of these STBCs. This lower bound in certain cases indicates that some of the STBCs from field extensions are optimal m the sense of coding gain. We then show that the STBCs from field extensions are information-lossy. However, we also show that the finite-signal-set capacity of the STBCs from field extensions can be improved by increasing the symbol rate of the STBCs. The simulation results presented show that our high-rate STBCs perform better than the rate-1 STBCs in terms of the bit error rate performance.
Then we proceed to present a construction of high-rate STBCs from crossed-product algebras. After giving a sufficient condition on the crossed-product algebras under which the resulting STBCs are information-lossless, we identify few classes of crossed-product algebras that satisfy this sufficient condition and also some classes of crossed-product algebras which are division algebras which lead to full-diversity STBCs. We present simulation results to show that the STBCs from crossed-product algebras perform better than the well-known codes m terms of the bit error rate.
Finally, we introduce the notion of asymptotic-information-lossless (AILL) designs and give a necessary and sufficient condition under which a linear design is an AILL design. Analogous to the condition that a design has to be a full-rank design to achieve the point corresponding to the maximum diversity of the optimal diversity-multiplexing tradeoff, we show that a design has to be AILL to achieve the point corresponding to the maximum multiplexing gain of the optimal diversity-multiplexing tradeoff. Using the notion of AILL designs, we give a lower bound on the diversity-multiplexing tradeoff achieved by the STBCs from both field extensions and division algebras. The lower bound for STBCs obtained from division algebras indicates that they achieve the two extreme points, 1 e, zero multiplexing gain and zero diversity gain, of the optimal diversity-multiplexing tradeoff. Also, we show by simulation results that STBCs from division algebras achieves all the points on the optimal diversity-multiplexing tradeoff for n transmit and n receive antennas, where n = 2, 3, 4.
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Beres, Elzbieta. "Blind channel estimation for orthogonal space-time block codes in MISO systems." 2004. http://link.library.utoronto.ca/eir/EIRdetail.cfm?Resources__ID=81080&T=F.
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Hsin, Chien-Wei, and 辛建威. "Blind Detection of Orthogonal Space-Time Block Codes for 16-QAM Constellations." Thesis, 2008. http://ndltd.ncl.edu.tw/handle/49745512689626408911.
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Das, Smarajit. "Low-PAPR, Low-delay, High-Rate Space-Time Block Codes From Orthogonal Designs." Thesis, 2009. http://hdl.handle.net/2005/1046.
Full textAbstract:
It is well known that communication systems employing multiple transmit and multiple receive antennas provide high data rates along with increased reliability. Some of the design criteria of the space-time block codes (STBCs) for multiple input multiple output (MIMO)communication system are that these codes should attain large transmit diversity, high data-rate, low decoding-complexity, low decoding –delay and low peak-to-average power ratio (PAPR). STBCs based on real orthogonal designs (RODs) and complex orthogonal designs (CODs) achieve full transmit diversity and in addition, these codes are single-symbol maximum-likelihood (ML) decodable. It has been observed that the data-rate (in number of information symbols per channel use) of the square CODs falls exponentially with increase in number of antennas and it has led to the construction of rectangular CODs with high rate.
We have constructed a class of maximal-rate CODs for n transmit antennas with rate if n is even and if n is odd. The novelty of the above construction is that they 2n+1 are constructed from square CODs. Though these codes have a high rate, this is achieved at the expense of large decoding delay especially when the number of antennas is 5or more. Moreover the rate also converges to half as the number of transmit antennas increases. We give a construction of rate-1/2 CODs with a substantial reduction in decoding delay when compared with the maximal- rate codes.
Though there is a significant improvement in the rate of the codes mentioned above when compared with square CODs for the same number of antennas, the decoding delay of these codes is still considerably high. For certain applications, it is desirable to construct codes which are balanced with respect to both rate and decoding delay. To this end, we have constructed high rate and low decoding-delay RODs and CODs from Cayley-Dickson Algebra.
Apart from the rate and decoding delay of orthogonal designs, peak-to-average power ratio (PAPR) of STBC is very important from implementation point of view. The standard constructions of square complex orthogonal designs contain a large number of zeros in the matrix result in gin high PAPR. We have given a construction for square complex orthogonal designs with lesser number of zero entries than the known constructions. When a + 1 is a power of 2, we get codes with no zero entries. Further more, we get complex orthogonal designs with no zero entry for any power of 2 antennas by introducing co- ordinate interleaved variables in the design matrix. These codes have significant advantage over the existing codes in term of PAPR. The only sacrifice that is made in the construction of these codes is that the signaling complexity (of these codes) is marginally greater than the existing codes (with zero entries) for some of the entries in the matrix consist of co-ordinate interleaved variables. Also a class of maximal-rate CODs
(For mathematical equations pl see the pdf file)
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hsieh, Chi-Hsuan, and 謝其軒. "Source-Assisting Distributed Quasi-Orthogonal Space-Time Block Codes with Embedded Adaptive AAF/DAF Elements in Cooperative Wireless Relay Networks." Thesis, 2013. http://ndltd.ncl.edu.tw/handle/z5h7hs.
Full textAbstract:
碩士<br>國立臺北科技大學<br>電腦與通訊研究所<br>101<br>Source-assisting strategy distributed quasi-orthogonal space-time block codes (SA-DQOSTBC) to present involved source is actively in cooperation. The scheme also reduces the number of relay node. In order to improve error probability, in this paper proposed embedded adaptive element of the DQOSTBC to be decoded and forward (DAF) or amplify and forward (AAF) types. When the channel coefficient is above the threshold, the corresponding elements are the DAF type. On the other hand, when the channel coefficient is below the threshold the corresponding elements are the (AAF) type. In addition, we consider path loss influence with direct link. The simulation results show that the scheme can enhance 4 dB at 10-3 bit error rate (BER)
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Cheng, Kai-lung, and 鄭凱隆. "Diagonal and Orthogonal Design of Space Time Block Codes with Group Interference Cancellation." Thesis, 2015. http://ndltd.ncl.edu.tw/handle/44688451844263972409.
Full textAbstract:
碩士<br>國立中山大學<br>通訊工程研究所<br>103<br>In this paper, we propose a design of space-time block codes (STBC) for multiple-input multiple-output (MIMO) system. Leveraging high coding rate of diagonal space-time block code (DSTBC) and low decoding complexity of orthogonal block space-time coding (OSTBC). The proposed design employs the concepts of DSTBC and OSTBC to inherit both benefits. Furthermore, to achieve full diversity, encoded symbols and partitioned into a few groups with respect to different phase relations on the signal constellations. Constructing the codeword with the proposed diagonal and orthogonal structure, the proposed STBC has coding rate 2 spcu and attain full diversity. To reduce decoding complexity, the receiver adopts partial interference cancellation (PIC), group interference cancellation, successive interference cancellation (SIC) sequentially to eliminate inter-group and intra-group interference. Specifically, group interference cancellation eliminates interference through orthogonal projection of signal space based on the diagonal structure and zero padding of the proposed design. Moreover, orthogonal structure if the proposed design effectively reduces computational complexity at decoder. Through computer simulations, it shows that the proposed design outperform OSTBC in terms of BER given the same transmission rate. Moreover, the proposed decoding algorithm demand with DSTBC scheme.
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Liao, Che-Ying, and 廖哲瑩. "Distributed Orthogonal and Quasi-Orthogonal Space Time Block Code with Embedded AAF/DAF Matrix Elements in Wireless Relay Networks with Four Relays." Thesis, 2012. http://ndltd.ncl.edu.tw/handle/r5p7u7.
Full textAbstract:
碩士<br>國立臺北科技大學<br>電腦與通訊研究所<br>100<br>We consider the cooperative networks of one source, four relays, and one destination. Each of them has single antenna. The four relays use a proposed full rate distributed quasi orthogonal space time block code (DQOSTBC) scheme.
If the channel state between the source and a relay is above a threshold, we select the elements of the DQOSTBC matrix to be the decoded and forward (DAF) type. If below the threshold, the corresponding elements are the amplify and forward (AAF) type. Thus the proposed scheme is a DQOSTBC matrix with embedded adaptive DAF/AAF elements.
The bit error rate (BER) simulation results show that the proposed DQOSTBC is approximately 7dB better than the traditional DQOSTBC (all matrix elements are fixed to DAF type) at 10-3 BER because traditional DQOSTBC loses full diversity due to information received errors. The proposed DQOSTBC is about 2dB better than the rate 1/2 DOSTBC also proposed with adaptive DAF/AAF matrix elements at 10-3 BER at the same spectrum efficiency 2 bits/sec/Hz.
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Rajan, G. Susinder. "Low Decoding Complexity Space-Time Block Codes For Point To Point MIMO Systems And Relay Networks." Thesis, 2008. http://hdl.handle.net/2005/742.
Full textAbstract:
It is well known that communication using multiple antennas provides high data rate and reliability. Coding across space and time is necessary to fully exploit the gains offered by multiple input multiple output (MIMO) systems. One such popular method of coding for MIMO systems is space-time block coding. In applications where the terminals do not have enough physical space to mount multiple antennas, relaying or cooperation between multiple single antenna terminals can help achieve spatial diversity in such scenarios as well. Relaying techniques can also help improve the range and reliability of communication. Recently it has been shown that certain space-time block codes (STBCs) can be employed in a distributed fashion in single antenna relay networks to extract the same benefits as in point to point MIMO systems. Such STBCs are called distributed STBCs. However an important practical issue with STBCs and DSTBCs is its associated high maximum likelihood (ML) decoding complexity. The central theme of this thesis is to systematically construct STBCs and DSTBCs applicable for various scenarios such that are amenable for low decoding complexity.
The first part of this thesis provides constructions of high rate STBCs from crossed product algebras that are minimum mean squared error (MMSE) optimal, i.e., achieves the least symbol error rate under MMSE reception. Moreover several previous constructions of MMSE optimal STBCs are found to be special cases of the constructions in this thesis.
It is well known that STBCs from orthogonal designs offer single symbol ML decoding along with full diversity but the rate of orthogonal designs fall exponentially with the number of transmit antennas. Thus it is evident that there exists a tradeoff between rate and ML decoding complexity of full diversity STBCs. In the second part of the thesis, a definition of rate of a STBC is proposed and the problem of optimal tradeoff between rate and ML decoding complexity is posed. An algebraic framework based on extended Clifford algebras is introduced to study the optimal tradeoff for a class of multi-symbol ML decodable STBCs called ‘Clifford unitary weight (CUW) STBCs’ which include orthogonal designs as a special case. Code constructions optimally meeting this tradeoff are also obtained using extended Clifford algebras. All CUW-STBCs achieve full diversity as well.
The third part of this thesis focusses on constructing DSTBCs with low ML decoding complexity for two hop, amplify and forward based relay networks under various scenarios. The symbol synchronous, coherent case is first considered and conditions for a DSTBC to be multi-group ML decodable are first obtained. Then three new classes of four-group ML decodable full diversity DSTBCs are systematically constructed for arbitrary number of relays. Next the symbol synchronous non-coherent case is considered and full diversity, four group decodable distributed differential STBCs (DDSTBCs) are constructed for power of two number of relays. These DDSTBCs have the best error performance compared to all previous works along with low ML decoding complexity. For the symbol asynchronous, coherent case, a transmission scheme based on orthogonal frequency division multiplexing (OFDM) is proposed to mitigate the effects of timing errors at the relay nodes and sufficient conditions for a DSTBC to be applicable in this new transmission scheme are given. Many of the existing DSTBCs including the ones in this thesis are found to satisfy these sufficient conditions. As a further extension, differential encoding is combined with the proposed transmission scheme to arrive at a new transmission scheme that can achieve full diversity in symbol asynchronous, non-coherent relay networks with no knowledge of the timing errors at the relay nodes. The DDSTBCs in this thesis are proposed for application in the proposed transmission scheme for symbol asynchronous, non-coherent relay networks. As a parallel to the non-coherent schemes based on differential encoding, we also propose non-coherent schemes for symbol synchronous and symbol asynchronous relay networks that are based on training. This training based transmission scheme leverages existing coherent DSTBCs for non-coherent communication in relay networks. Simulations show that this training scheme when used along with the coherent DSTBCs in this thesis outperform the best known DDSTBCs in the literature.
Finally, in the last part of the thesis, connections between multi-group ML decodable unitary weight (UW) STBCs and groups with real elements are established for the first time. Using this connection, we translate the necessary and sufficient conditions for multi-group ML decoding of UW-STBCs entirely in group theoretic terms. We discuss various examples of multi-group decodable UW-STBCs together with their associated groups and list the real elements involved. These examples include orthogonal designs, quasi-orthogonal designs among many others.
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Dama, Yousef A. S., Hassan S. O. Migdadi, Wafa S. A. Shuaieb, et al. "A new approach for implementing QO-STBC over OFDM." 2015. http://hdl.handle.net/10454/9138.
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No<br>A new approach for implementing QO-STBC and DHSTBC over OFDM for four, eight and sixteen transmitter antennas is presented, which eliminates interference from the detection matrix and improves performance by increasing the diversity order on the transmitter side. The proposed code promotes diversity gain in comparison with the STBC scheme, and also reduces Inter Symbol Interference.
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Paul, Prabal. "On The Peak-To-Average-Power-Ratio Of Affine Linear Codes." Thesis, 2006. http://hdl.handle.net/2005/350.
Full textAbstract:
Employing an error control code is one of the techniques to reduce the Peak-to-Average Power Ratio (PAPR) in an Orthogonal Frequency Division Multiplexing system; a well known class of such codes being the cosets of Reed-Muller codes. In this thesis, classes of such coset-codes of arbitrary linear codes are considered. It has been proved that the size of such a code can be doubled with marginal/no increase in the PAPR. Conditions for employing this method iteratively have been enunciated. In fact this method has enabled to get the optimal coset-codes. The PAPR of the coset-codes of the extended codes is obtained from the PAPR of the corresponding coset-codes of the parent code. Utility of a special type of lengthening is established in PAPR studies
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Sreedhar, Dheeraj. "Interference Cancelling Detectors In OFDMA/MIMO/Cooperative Communications." Thesis, 2007. http://hdl.handle.net/2005/604.
Full textAbstract:
In this thesis, we focus on interference cancelling (IC) detectors for advanced communication systems. The contents of this thesis is divided into the following four parts:
1. Multiuser interference (MUI) cancellation in uplink orthogonal frequency division multiple access (OFDMA).
2. Inter-carrier interference (ICI) and inter-symbol interference (ISI) cancellation in space-frequency block coded OFDM (SFBC-OFDM).
3. Single-symbol decodability (SSD) of distributed space-time block codes (DSTBC) in partially-coherent cooperative networks with amplify-and-forward protocol at the relays
4. Interference cancellation in cooperative SFBC-OFDM networks with amplify-and-forward (AF) and decode-and-forward (DF) protocols at the relays.
In uplink OFDMA systems, MUI occurs due to different carrier frequency offsets of different users at the receiver. In the first part of the thesis, we present a weighted multistage linear parallel interference cancellation approach to mitigate the effect of this MUI in uplink OFDMA. We also present a minimum mean square error (MMSE) based approach to MUI cancellation in uplink OFDMA. We present a recursion to approach the MMSE solution and show structure-wise and performance-wise comparison with other detectors in the literature.
Use of SFBC-OFDM signals is advantageous in high-mobility broadband wireless access, where the channel is highly time- as well as frequency-selective because of which the receiver experiences both ISI as well as ICI. In the second part of the thesis, we are concerned with the detection of SFBC-OFDM signals on time- and frequency-selective MIMO channels. Specifically, we propose and evaluate the performance of an interference cancelling receiver for SFBC-OFDM, which alleviates the effects of ISI and ICI in highly time- and frequency-selective channels
The benefits of MIMO techniques can be made possible to user nodes having a single transmit antenna through cooperation among different nodes. In the third part of the thesis, we derive a new set of conditions for a distributed DSTBC to be SSD for a partially-coherent relay channel (PCRC), where the relays have only the phase information of the source-to-relay channels. We also establish several properties of SSD codes for PCRC.
In the last part of the thesis, we consider cooperative SFBC-OFDM networks with AF and DF protocols at the relays. In cooperative SFBC-OFDM networks that employ DF protocol, i) ISI occurs at the destination due to violation of the `quasi-static' assumption because of the frequency selectivity of the relay-to-destination channels, and ii) ICI occurs due to imperfect carrier synchronization between the relay nodes and the destination, both of which result in error-floors in the bit error performance at the destination. We propose an interference cancellation algorithm for this system at the destination node, and show that the proposed algorithm effectively mitigates the ISI and ICI effects.
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Sezgin, Aydin [Verfasser]. "Space time codes for MIMO systems: quasi-orthogonal design and concatenation / von Aydin Sezgin." 2005. http://d-nb.info/975479385/34.
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CHANG, CHIA-JUI, and 張家睿. "Semi-blind Equalization for TWIN-QPSK Orthogonal Space Time Block Code." Thesis, 2008. http://ndltd.ncl.edu.tw/handle/03380377386767067358.
Full textAbstract:
碩士<br>中原大學<br>電子工程研究所<br>96<br>To solve multi-path propagation is an important problem in wireless communication. It induces an intersymbol interference(ISI), the channel estimation combined with the equalizer in the receiver is the way to reduce the ISI. In the early time, it needs a training sequence to identify the channel coefficient; the drawback is to decrease the channel bandwidth efficient. Blind equalization method doesn’t need any training sequence instead to know the statistic of transmit signal. Space-time block code is combine time diversity and space diversity technology. It is not only bandwidth efficient but also the outperformance in the decoding. Under the condition of unknown channel, the blind and semi-blind zero-forcing equalizer was proposed by Swindlehurst, to solve the generalized space-time block code. A TWIN-QPSK orthogonal space time block code with four transmit antennas was presented, by Lin-Yi Su[5]. We can solve the TWIN-QPSK orthogonal space time block code, by semi-blind equalization technology. The result known that the performance by TWIN-QPSK space time blocks code has better performance than other space time block code.
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Jiang, Jian-Da, and 江建達. "Blind Channel Estimation for Orthogonal Space-Time Block Coded MIMO-OFDM systems." Thesis, 2013. http://ndltd.ncl.edu.tw/handle/35148916014750976449.
Full textAbstract:
碩士<br>國立臺灣大學<br>電信工程學研究所<br>101<br>Orthogonal frequency division multiplexing (OFDM) has recently received con-
siderable interest for its advantages in high-bit-rate transmissions over frequency-
selective fading channels. Space-time block coding (STBC) has emerged as a powerful
approach to exploit spatial diversity and to combat fading in multiple-input multiple-
output (MIMO) wireless communication systems This thesis studies the blind channel
estimation for OFDM systems with multiple transmit antennas. The thesis consists
of three parts. In the rst part, we review an existing channel estimation method us-
ing subspace. This method though gives good performance but for many orthogonal
STBCs (OSTBCs), it cannot uniquely identify the channels when only one receive
antenna is available. In order to solve this issue, we propose an improved method.
In the second part, we propose a new subspace-based method for blind channel esti-
mation. The proposed method exploits the null space induced by the OSTBCs with
rare < 1. The identi ability is also studied. In the third part, we introduce a modi-
cation of the proposed method so that fewer received blocks are needed. Moreover
the modi ed method has low computational complexity. We also provide numerical
simulation to verify the performance of the proposed methods.
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Chang, Tsung-Hui, and 張縱輝. "Maximum-Likelihood Detection of Orthogonal Space-Time Block Coded OFDM in Unknown Block Fading Channels." Thesis, 2008. http://ndltd.ncl.edu.tw/handle/68990826625155438466.
Full textAbstract:
博士<br>國立清華大學<br>通訊工程研究所<br>96<br>現存大多數針對正交空時區塊碼正交分頻多工(orthogonal space-time block coded orthogonal frequency division multiplexing, OSTBC-OFDM)系統的盲蔽檢測與通道估測技術皆基於一根本假設，通道(channel)在多個OSTBC-OFDM區塊區間內為靜止不變的。本論文考量只需使用一個OSTBC-OFDM區塊信號之盲蔽最大勢然檢測(maximum-likelihood (ML) detection)技術。此技術的優點在於其更適合應用於具有較短同調時間(coherence time)的通道環境。基於BPSK/QPSK符碼調變，我們探討包括接收機實現(receiver implementation)及盲蔽唯一資料鑑別(blind unique data identifiability)的問題。對於接收機實現問題，我們提出降底複雜度的子通道群組(subchannel grouping)檢測機制。對於盲蔽唯一資料鑑別，我們證明所提出的檢偵機制在獨立瑞立衰減通道(Rayleigh fading channels)中只需使用非常少量的前導資料(pilot data)就能保證資料鑑別的唯一性。
本論文的第二部分更進一步針對任意非全零的通道環境，發展能夠在盲蔽接收機唯一鑑別通道的傳輸機制，我們證之為「完美之通道鑑別」(perfect channel identifiability, PCI)機制。我們證明只要使用所謂的子空間無交集碼(nonintersecting subspace codes)就能達到所期望的完美通道鑑別。此外，我們分析證明在獨立瑞立衰減通道中，此完美之通道鑑別傳輸機制能夠保證盲蔽最大勢然檢測器獲得最大之空間分集增益(spatial diversity gain)。最後，我們將所提出的完美之通道鑑別傳輸機制以及所提出之盲蔽最大勢然檢測器延伸到分散式空時編碼(distributed space time coding)系統。
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Tsung-Yen, Tsai, and 蔡宗延. "Channel Estimation Technique for Space-Time Block Coded Orthogonal Frequency Division Multiplexing System." Thesis, 2003. http://ndltd.ncl.edu.tw/handle/35634526574522357090.
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碩士<br>國立交通大學<br>電子工程系<br>91<br>Bandwidth is a very important resource in the wireless communication system. Improving the reliability of the wireless communication system without bandwidth expansion is always an interesting research topic. In 1998, space-time block code (STBC) is proposed to solve this problem. The basic concept of STBC is equipping multiple transmit antennas and/or receive antennas in the system to improve the performance. For simplicity, we only consider the system equipped with one receive antenna and two transmit antennas in this thesis.
The performance of STBC employed in conventional single-carrier system is usually poor in the frequency-selective fading channel. Therefore, we apply STBC to the orthogonal frequency division multiplexing (OFDM) system to form the space-time block coded orthogonal frequency division multiplexing (STBC-OFDM) system. OFDM can transform frequency-selective fading channel to multiple flat fading subchannels. Aided by OFDM, STBC-OFDM system can work quite well over the frequency-selective fading channel.
Multi-channel estimation plays an important role in the STBC-OFDM system. In this thesis, we present two simple channel estimation methods by using pilot signals. The first method (method Ⅰ) is the comb-type pilot subcarrier arrangement, and the second method (method Ⅱ) is the block-type pilot subcarrier arrangement. We also show the simulation results of comparison between method Ⅰ and method Ⅱ. Finally, we consider the IEEE standard 802.16 WirelessMAN with STBC. Equipping one receive antenna and two transmit antennas to the IEEE 802.16 system without channel coding, we apply our two channel estimation methods to improve the performance. Simulations show that the performance of our channel estimation methods is 2~3 dB loss compared with the ideal channel estimation in the IEEE 802.16 environment.
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Su, Lin-Yi, and 蘇林逸. "A New Orthogonal Space-Time Block Code for Four Transmit Antennas by Using Twin-QPSK." Thesis, 2008. http://ndltd.ncl.edu.tw/handle/75326294933851758975.
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碩士<br>中原大學<br>電子工程研究所<br>96<br>More than two antennas complex orthogonal space-time block code with full diversity and full code rate has been shown does not exist. Here, combining Twin-QPSK modulation with quasi-orthogonal space-time block code which was presented by Jafarkhani, we encode a new four antennas orthogonal space-time block code. This orthogonal code achieves full diversity and full code rate. There are twelve transmitting bits in this new code, ten of them are information bits and rests are the redundancy. According to the characteristic of the orthogonal space-time block code by using Twin-QPSK, the receiver has to decode the transmitted signals in pairs.
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LI, ZHONG-WEI, and 李仲偉. "Study of Applying Orthogonal Space-Time Block Code for UEP with SCM System for Multimedia Transmission." Thesis, 2016. http://ndltd.ncl.edu.tw/handle/63165284293434737623.
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碩士<br>國立雲林科技大學<br>電機工程系<br>104<br>Application of wireless transmissions such as mobile communications, Wi-Fi, internet of things(IoT), and internet of vehicles(IoV) etc. are blooming in recent years. We can expect more and more diversified traffics with different demand of bandwidth and transmission quality. How to improve the transmission quality such as the error rate under limited spectrum is an interesting research topic. This thesis is to study the performance of using the Unequal Error Protection (UEP) transmission scheme for H.264 video transmission compared to that of traditional equal error protection(EEP). In this study, we combine the Orthogonal Space-Time Block Code (OSTBC) and Superposition Coded Modulation(SCM) scheme to the multiple input multiple output(MIMO) system under the UEP scheme. Simulation shows that by assigning different power levels to different protection need of the data layers, the overall video quality can be improved.
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Huang, Zhi-Ting, and 黃誌廷. "Estimation of I/Q Imbalance and Carrier Frequency Offset for Orthogonal Space-Time Block Coded OFDM Systems." Thesis, 2012. http://ndltd.ncl.edu.tw/handle/77124536409315874202.
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碩士<br>國立臺灣大學<br>電信工程學研究所<br>100<br>Nowadays, direct-conversion radio frequency (RF) receivers become
more appealing due to its cost advantage. However, orthogonal frequency division multiplexing (OFDM) systems with direct-conversion RF receivers are very sensitive to non-idealities at the front-end of receiver, such as I/Q imbalance and carrier frequency offset (CFO). These non-idealities at the receiver result in inter-carrier interference (ICI). Accurate estimates of the non-idealities and
channel response are required in OFDM systems.
This thesis studies the CFO estimation for OFDM systems with multiple transmit antennas. The thesis consists mainly of two parts. In the first part, we consider OFDM systems with 2 transmit antennas. The Alamouti code is employed at the transmitter and both ST-OFDM and SF-OFDM systems are considered. For these systems with 2 transmit antennas, we extend two known blind CFO estimation algorithms (which were derived for OFDM systems with one transmit antenna) to solve the CFO estimation problem in ST and SF-OFDM systems. IN the second part, we consider OFDM systems with 3 transmit antennas. Orthogonal space time block codes (OSTBC) codes are used to encode the single at the transmitter. For this system, we derive a new blind CFO estimation algorithm. The idea is to exploit the fact that the rate of OSTBC is only 3/4. We show how to exploit the redundant information in OSTBC for blind CFO estimation. Moreover, the problem of I/Q imbalance is also consider in the second part. At the end, we also provide numerical simulation to verify the performance of the proposed methods.
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Chi, Kung-Hong, and 紀坤宏. "Semi-Blind Channel Estimation of Space Time Block Code Orthogonal frequency-division multiplexing System by Using Subspace Algorithm." Thesis, 2008. http://ndltd.ncl.edu.tw/handle/98482072879547258119.
Full textAbstract:
碩士<br>中原大學<br>電子工程研究所<br>96<br>In this paper，a space time block code OFDM system was proposed that can increased the channel capacity。we analyzed a complex Alamouti code in OFDM，Multiple input multiple output system, base on this derivative, ，the Alamouti code can be encoded in real or complex form in OFDM system。The semi-blind channel estimation can improve the accuracy of the channel coefficients。
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Hu, Hsu-Chia, and 胡煦佳. "Joint Blind Estimation of I/Q Imbalance and Carrier Frequency Offset for Orthogonal Space-Time Block Coded OFDM Systems." Thesis, 2014. http://ndltd.ncl.edu.tw/handle/14940244071805934972.
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碩士<br>國立臺灣大學<br>電信工程學研究所<br>102<br>Orthogonal frequency division multiplexing (OFDM) has recently received considerable interest for its advantages in high-bit-rate transmissions over frequency-selective fading channels. Space-time block coding (STBC) has emerged as a powerful approach to exploit spatial diversity and to combat fading in multiple-input multiple-output (MIMO) wireless communication systems. However, OFDM systems with direct-conversion RF receivers are very sensitive to non-idealities at the front-end of receiver, such as I/Q imbalance and carrier frequency o&;#8629;set (CFO). These non-idealities at the receiver result in intercarrier interference (ICI). Accurate estimates of the non-idealities and channel response are required in OFDM systems. This thesis studies the blind CFO and I/Q imbalance estimation for OFDM systems with multiple transmit antennas. The thesis consists of three parts. In the first part, we review an existing CFO and I/Q imbalance estimation method based on rank criterion. This method though gives good performance but not for joint estimation, it cannot estimate the I/Q imbalance in the presense of CFO. In order to solve this issue, we propose an improved method. In the second part, we propose a new rank criteron and group method for joint CFO and independent I/Q imbalance estimation. The proposed method exploits the redundant information in OSTBC for joint blind CFO and I/Q imbalance estimation. In the third part, we extend the proposed method to the estimation of frequency dependent I/Q imbalance in the presence of CFO. We also provide numerical simulation to verify the performance of the proposed methods.
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Hong-Yu, Liu. "Exact Error Probability for Orthogonal Space-Time Block Coded MIMO Systems Using Arbitrary Rectangular QAM Transmission over Rayleigh Fading Channels." 2006. http://www.cetd.com.tw/ec/thesisdetail.aspx?etdun=U0002-0401200617063300.
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Liu, Hong-Yu, and 劉鴻裕. "Exact Error Probability for Orthogonal Space-Time Block Coded MIMO Systems Using Arbitrary Rectangular QAM Transmission over Rayleigh Fading Channels." Thesis, 2006. http://ndltd.ncl.edu.tw/handle/53242298647191807024.
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博士<br>淡江大學<br>電機工程學系博士班<br>94<br>In this work, a pre-averaging method is proposed for deriving theoretical symbol error probability (SEP) expressions for orthogonal space-time block code (OSTBC) diversity systems employing arbitrary rectangular M-QAM transmission over flat Rayleigh fading channels. Independent fading between diversity channels are assumed for simplicity as the technique of channel decorrelation has been proposed in the literature. Channel average powers may be distinctive, identical, or mixed with both. The rectangular M-QAM results are extended to square M-QAM, M-PAM, and binary antipodal signaling. All derived expressions are in elementary forms without complicated high order transcendental functions and/or unevaluated integrals and hence are strictly exact and can be readily simulated by the computer with good accuracy. We delve into the error probability performance by proposing a new derivation method, from which many new equations and properties are shown and proved. Moreover, we show that mixed Rayleigh fading results can be readily extended to various Nakagami-m fading results. We use a four transmit antenna system with a half-rate OSTBC for 16-QAM signaling as the example to demonstrate that our theoretical results are in excellent agreements with the Monte Carlo simulated results. From simulation curves, we show that, under the independent channel fading condition, channels with identical powers have better error rate performance than channels with distinctive powers. Moreover, we discuss the performance of OSTBC with generalized complex orthogonal design (GCOD) in a rather general scope, which has not been explored in depth in the literature. Thus far, the SEP expressions for OSTBC found in the literature are only restricted to complex orthogonal design (COD) or some special GCOD cases. An important discovery is that OSTBC can produce different SEP performances for different information symbols. Although our derivation is presented based on the assumption of independent fading channels, we also provide an outline for the derivation for correlative fading channels.
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Yang, Chieh-Chih, and 楊傑智. "On Frequency-Domain Equalization with Training-Based Channel Estimation for Orthogonal Space-Time Block Coded System via MIMO Frequency-Selective Fading Channels." Thesis, 2007. http://ndltd.ncl.edu.tw/handle/02950626224237711536.
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碩士<br>國立交通大學<br>電機與控制工程系所<br>95<br>We propose an instructive derivation for the generalized block-level orthogonal space-time block encoder, capable of achieving full spatial diversity via frequency- selective fading environment provided that channel order is known. Instead of dealing with special case and then extending the results intuitively, we provide an alternative by starting with the general signal model with multiple transmit and multiple receive antennas, from which a general form of block-level orthogonality is established. In particular, transmit diversity with more than two transmit antennas can be achieved without compromise by means of frequency-domain equalization, in contrast to the QO-STBC-based approach. Pairwise error probability analysis is derived, under certain assumption which is numerically supported by simulation results, for analytical verifications of our claim on full diversity, inclusive of transmit-receive diversity and the multipath one. Moreover, the encoder structure enables us to generalize a training-based channel estimation technique, originally proposed for flat-fading scenario, to the frequency-selective fading scenario. Surprisingly we even obtain similar optimality criteria for optimal training block design which in our case, the signal block are fixed as OSTBC-based and the design derivation reduces to derive optimal power constraint over the training blocks. The optimality criteria for the training blocks are easy to satisfy when randomness of signal constellation is not a concern. Simulation results validate our discussion of the behaviors of the least-squares and linear MMSE channel estimates.
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Ροπόκης, Γεώργιος. "Επίδοση συστημάτων διαφορισμού MIMO σε γενικευμένα κανάλια διαλείψεων". Thesis, 2010. http://nemertes.lis.upatras.gr/jspui/handle/10889/4197.
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Στο πλαίσιο αυτής της διατριβής μελετάται η επίδοση συστημάτων διαφορισμού MIMO σε γενικευμένα κανάλια διαλείψεων. Αρχικά, εξετάζεται η επίδοση των OSTBC σε περιβάλλοντα διαλείψεων Hoyt. Αποδεικνύεται ότι, στην περίπτωση τέτοιων συστημάτων, ο σηματοθορυβικός λόγος (signal to noise ratio, SNR) εκφράζεται ως μία τετραγωνική μορφή κανονικών τυχαίων μεταβλητών και γίνεται χρήση της συνάρτησης πυκνότητας πιθανότητας και της αθροιστικής συνάρτησης κατανομής αυτής της μορφής για τον υπολογισμό των μετρικών επίδοσης. Επιπλέον, μελετάται η σύγκλιση των σειρών που χρησιμοποιούνται για τον υπολογισμό των δύο αυτών συναρτήσεων και κατασκευάζονται νέα άνω φράγματα για το σφάλμα αποκοπής των σειρών. Τα φράγματα αυτά είναι σαφώς πιο αυστηρά από τα ήδη γνωστά από τη βιβλιογραφία. Στη συνέχεια, εισάγεται ένα γενικευμένο μοντέλο διαλείψεων για την ανάλυση επίδοσης των OSTBC και των δεκτών MRC και υπολογίζονται όλες οι μετρικές επίδοσης των δύο συστημάτων για το συγκεκριμένο μοντέλο διαλείψεων. Το μοντέλο αυτό περιλαμβάνει ως ειδικές περιπτώσεις τα πλέον διαδεδομένα μοντέλα καναλιών διαλείψεων, ενώ επιπλέον, επιτρέπει την ανάλυση επίδοσης σε μικτά περιβάλλοντα διαλείψεων όπου τα πολλαπλά κανάλια μπορούν να ακολουθούν διαφορετικές κατανομές. Στη συνέχεια, μελετάται η επίδοση συστημάτων συνεργατικού διαφορισμού με χρήση αναμεταδοτών ανίχνευσης και προώθησης (Detect and Forward, DaF) σε περιβάλλοντα διαλείψεων Rayleigh. Εξετάζονται τρεις διαφορετικοί δέκτες και υπολογίζεται η πιθανότητα σφάλματος ανά bit γι' αυτούς. Τέλος προτείνεται ένας νέος δέκτης για συνεργατικά συστήματα DaF και αποδεικνύεται η ανωτερότητά του σε σύγκριση με τους υπόλοιπους μελετώμενους δέκτες. Όλα τα θεωρητικά αποτελέσματα που παρουσιάζονται στο πλαίσιο της διατριβής συγκρίνονται με αποτελέσματα προσομοιώσεων Monte Carlo που αποδεικνύουν την ορθότητα της ανάλυσης.<br>This thesis studies the performance of MIMO diversity systems in generalized fading channels. First, we examine the performance of OSTBC in Hoyt fading channels. It is proven that, for this fading model, and when an OSTBC is employed, the signal-to-noise ratio (SNR) of the OSTBC can be expressed as a quadratic form in normal random variables. Therefore, the performance analysis for OSTBC over Hoyt fading channels is performed using the PDF and the CDF of such quadratic forms. In the statistical literature, these functions are expressed in terms of infinite series. The convergence of the series is thoroughly studied and new expressions for the truncation error bound of these series are proposed. The proposed bounds are much tighter than the bounds that can be found in the literature. The expressions for the PDF and the CDF are then used for the performance analysis of OSTBC over Hoyt fading and several performance metrics are calculated. Then, a generalized fading model for the performance analysis of OSTBC and MRC is proposed and the theoretical performance analysis of both MRC and OSTBC is carried out. The main advantage of this model is the fact that it includes as special cases most of the widely used fading models. Furthermore, the performance of cooperative diversity systems employing Detect and Forward (DaF) relays is studied for Rayleigh fading channels. More specifically, three low complexity detection algorithms for these channels are examined and closed-form expressions of the bit error probability (BEP) for these receivers are derived. Finally, a new low complexity receiver for cooperative systems with DaF relays is proposed. Using Monte Carlo Simulations it is shown that this receiver outperforms the three receivers that have been studied. For the systems studied in the thesis, the performance analysis results that have been derived theoretically are compared with Monte Carlo simulations that prove the validity of the analysis.
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Maasdorp, Francois De Villiers. "Design and performance evaluation of a full rate, full diversity space-time-spreading code for an arbitrary number of Tx antennas." Diss., 2008. http://hdl.handle.net/2263/28015.
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Since the mid 1990’s, the wireless communications industry has witnessed explosive growth. The worldwide cellular and personal communication subscriber base surpassed 600 million users by late 2001, and the number of individual subscribers surpassed 2 billion at the end of 2006 [1, 2]. In order to attract and accommodate these subscribers, modern communication systems, like the Third Generation (3G) and Fourth Generation (4G) cellular networks, will have to provide attractive new features such as increased data throughput rates, greater system capacity, and better speech quality. These modern communication systems promise to have advantages such as wireless access in ways that have never been possible before, providing, amongst others services such as live television (TV) broadcasting to Mobile Stations (MS)s, multi-megabit Internet access, communication using Voice over Internet Protocol (VoIP), unparalleled network capacity, seamless accessibility and many more. With specific, but not exclusive reference to the cellular environment, there are numerous ways to increase the data throughput rate and system capacity. From an economical perspective, it would be more efficient to add equipment to the Base Station (BS) rather than the MSs. To achieve these improvements the motivation to utilise transmit diversity’s capabilities have been identified as a key research issue in this study. Alamouti [3] proposed a transmit diversity technique using two transmit antennas and one receive antenna, providing the same diversity order than using one transmit antenna and two receive antennas. Since Alamouti’s publication in 1998, many papers in the field of Space-Time (ST) coding have been published. Current research in the field of ST coding consists of finding methods to extend the number of transmit antennas to more than four, while still achieving full rate, as well as full diversity which is the main motivation for this study. This study proposes a novel idea of breaching the limitations with ST coding theory by combining ST coding with Spread Spectrum (SS) modulation techniques in order to extend the number of transmit antennas to more than four and still achieve full rate as well as full diversity. An advantage of the proposed scheme, called Direct Sequence Space-Time Spreading (DSSTS) has over current Space-Time Spreading (STS) techniques is that it uses 50% less spreading codes. A performance evaluation platform for the DSSTS scheme was developed to simulate the performance of the scheme in a realistic mobile communication environment. A mobile communication channel that has the ability to simulate time-varying multipath fading was developed and used to evaluate the performance of the DSSTS scheme. From the simulation results obtained, it is evident that Walsh sequences that exhibit particularly good cross-correlation characteristics, cannot overcome the effect of the antenna self-noise in order to exploit the diversity gain by adding extra antennas, i.e. diversity extension. The research also showed that an optimal trade-off exists between antenna diversity and antenna created self-noise. Performance results of the DSSTS scheme in slow and fast fading channels for a different number of transmit antennas are also presented in this study. With the capacity analysis of the DSSTS scheme, it was shown that the addition of extra transmit antennas to the system indeed increased the system capacity. A further addition to this study is the investigation into the assumption that the channel should be quasi-static over the frame length of the ST code. A Space Sequence Transmit Diversity (SSTD) technique is consequently proposed that allows the transmission of the Alamouti symbols during one time interval instead of two. This relieves the ST code from the assumption that the channel should be quasi-static, allowing it to be used in a more realistic multi-user environment. A performance evaluation platform for the SSTD scheme was developed and used to obtain simulation results in a multipath fading channel. It was also shown that the proposed SSTD scheme is successful in combating the effects of multipath fading for small Code Division Multiple Access (CDMA) user loads. However, as a rule of thumb, the square root of the spreading sequence length divided by two depicts the user load at which the SSTD scheme was not capable of overcoming the combined effects of Multi-User Interference (MUI) and multipath fading.<br>Dissertation (MEng)--University of Pretoria, 2008.<br>Electrical, Electronic and Computer Engineering<br>unrestricted