Dissertations / Theses: 'MIMO systems. Broadband communication systems. Antenna arrays'

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Chu, Min. "Phase-shifting techniques for wireless multiple-antenna transmitter applications /." Thesis, Connect to this title online; UW restricted, 2006. http://hdl.handle.net/1773/6002.

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Wennström, Mattias. "On MIMO Systems and Adaptive Arrays for Wireless Communication : Analysis and Practical Aspects." Doctoral thesis, Uppsala University, Signals and Systems Group, 2002. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-2604.

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This thesis is concerned with the use of multiple antenna elements in wireless communication over frequency non-selective radio channels. Both measurement results and theoretical analysis are presented. New transmit strategies are derived and compared to existing transmit strategies, such as beamforming and space-time block coding (STBC). It is found that the best transmission algorithm is largely dependent on the channel characteristics, such as the number of transmit and receive antennas and the existence of a line of sight component. Rayleigh fading multiple input multiple output (MIMO) channels are studied using an eigenvalue analysis and exact expressions for the bit error rates and outage capacities for beamforming and STBC is found. In general are MIMO fading channels correlated and there exists a mutual coupling between antenna elements. These findings are supported by indoor MIMO measurements. It is found that the mutual coupling can, in some scenarios, increase the outage capacity. An adaptive antenna testbed is used to obtain measurement results for the single input multiple output (SIMO) channel. The results are analyzed and design guidelines are obtained for how a beamformer implemented in hardware shall be constructed. The effects of nonlinear transmit amplifiers in array antennas are also analyzed, and it is shown that an array reduces the effective intermodulation distortion (IMD) transmitted by the array antenna by a spatial filtering of the IMD. A novel frequency allocation algorithm is proposed that reduces IMD even further. The use of a low cost antenna with switchable directional properties, the switched parasitic antenna, is studied in a MIMO context and compared to array techniques. It is found that it has comparable performance, at a fraction of the cost for an array antenna.

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Anreddy, Vikram R. "Indoor MIMO Channels with Polarization Diversity: Measurements and Performance Analysis." Thesis, Available online, Georgia Institute of Technology, 2006, 2006. http://etd.gatech.edu/theses/available/etd-04112006-093641/.

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Thesis (M. S.)--Electrical and Computer Engineering, Georgia Institute of Technology, 2006.
Ingram Mary Ann, Committee Chair ; Durgin, Gregory David, Committee Member ; Williams, Douglas B, Committee Member.

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Curry, Clifford Richard. "Multiport broadband matching and its application in the design of feed networks for array antennas /." Thesis, Connect to this title online; UW restricted, 1997. http://hdl.handle.net/1773/6105.

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Sfar, Sana. "Multiple array schemes for achieving high capacity and high diversity gains in wireless MIMO systems /." View abstract or full-text, 2005. http://library.ust.hk/cgi/db/thesis.pl?ELEC%202005%20SFAR.

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Gelal, Ece. "Cross-layer design for wireless networks using antenna arrays." Diss., [Riverside, Calif.] : University of California, Riverside, 2009. http://proquest.umi.com/pqdweb?index=0&did=1899476681&SrchMode=2&sid=1&Fmt=2&VInst=PROD&VType=PQD&RQT=309&VName=PQD&TS=1268335334&clientId=48051.

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Thesis (Ph. D.)--University of California, Riverside, 2009.
Includes abstract. Title from first page of PDF file (viewed March 11, 2010). Available via ProQuest Digital Dissertations. Includes bibliographical references (p. 149-156). Also issued in print.

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Sobhanmanesh, Fariborz School of Electrical Engineering And Telecommunications UNSW. "Hardware implementation of V-BLAST MIMO." Awarded by:University of New South Wales. School of Electrical Engineering And Telecommunications, 2006. http://handle.unsw.edu.au/1959.4/24198.

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The exploitation of the theoretically enormous capacity achieved by the multiple transmit and receive antennas systems (MIMO) in a rich scattering communication channel has been the subject of vast body of research on the field of MIMO. In particular, the Vertically-layered Bell Laboratories Layered Space-Time (V-BLAST) is a well known MIMO architecture which has demonstrated the enormous capacity of 20-40 bit/s/Hz in an indoor propagation environment with realistic SNR and error rates. However, due to the intensive computation involved, it would be difficult to implement this architecture for high data rate communication systems. Some works have been done to improve the receiver complexity and performance by coding techniques, by different detection architectures. In this thesis, we have focused on QR-based decoders for V-BLAST MIMO. For a suitable V-BLAST detection implementation, we need to carefully consider the problem from algorithmic, arithmetic and architectural aspects. At the algorithmic level, the numerical stability and robustness should be considered. At the arithmetic level, signal quantization is important, and, at the architectural level, parallelism and pipelining require attention. We have performed the above mentioned optimization on the 1-pass QR factorization with back substitution SIC (Symbol Interference Cancellation) decoder in chapter 3. At first optimizations are made on the proposed algorithm and architecture using MATLAB simulations. Then a new architecture for the QR-factorizer as the core processor of the V-BLAST decoder is developed in chapter 4. This architecture uses only two low complexity CORDIC (Coordinate rotation digital computer) processors. The parameterized feature of the controller and address generator blocks of this architecture has provided a scalable architecture for the implementation of QR factorization for square matrix of any dimension. The reduced hardware complexity of the processors and its simple parameterized controller are two outstanding features of the architecture, resulting in a more suitable alternative architecture for QR factorization than traditional triangular systolic arrays. In the next phase of the research, new hardware architectures of the back substitution SIC decoder was developed for a 4 X 4 MIMO system with 16-QAM constellation scheme in chapter 5. The division operation for back substitution needs a complex hardware, and results in the numerical instability. In the proposed hardware the elimination of division and modification of multiplier has reduced the hardware complexity and led to numerical stability. In addition the pre decoding block was designed and optimized in terms of number of the pipeline registers and CORDIC rotator processors. The developed hardware is capable of processing 20 vectors data burst and results in a throughput of 149 Mb/s. The FPGA (Field Programmable Gate Array) and ASIC (Application specific Integrated Circuit) implementations of the proposed optimized architecture are presented in Chapter 5. We found that the equivalent gates and the core area in our design is less than 30% of other designs and the maximum clock frequency and the throughput is higher (175 %) than other works. Finally the improvements of the BER performance using the branching method and parallel architectures are presented in chapter 6. In this supplementary part to back substitution OSIC decoder, the final symbol vector is selected from 2 or 8 potential candidates based on the minimum Euclidean norm, which improves the BER between 3 to 7 db and gives a very close match to the original V-BLAST performance.

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Morris, Matthew Leon. "The Impact of Antenna and RF System Characteristics on MIMO System Capacity." Diss., CLICK HERE for online access, 2005. http://contentdm.lib.byu.edu/ETD/image/etd978.pdf.

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Mayhew-Ridgers, Gordon. "Development and modelling of new wideband microstrip patch antennas with capacitive feed probes." Thesis, Pretoria : [s.n.], 2004. http://upetd.up.ac.za/thesis/available/etd-09162004-083016.

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Zajic, Alenka. "Space-time channel modeling, simulation, and coding." Diss., Atlanta, Ga. : Georgia Institute of Technology, 2008. http://hdl.handle.net/1853/26569.

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Thesis (Ph.D)--Electrical and Computer Engineering, Georgia Institute of Technology, 2009.
Committee Chair: Stuber,Gordon L.; Committee Member: Durgin, Gregory D.; Committee Member: Kim, Hyesoon; Committee Member: Li, Ye (Geoffrey); Committee Member: McLaughlin, Steven W.; Committee Member: Riley, George F.. Part of the SMARTech Electronic Thesis and Dissertation Collection.

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Chang, Yong Jun. "Design of concurrent cooperative transmission systems on software-defined radios." Diss., Georgia Institute of Technology, 2013. http://hdl.handle.net/1853/50360.

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Concurrent cooperative transmission (CCT) occurs when a collection of power-constrained single-antenna radios transmit simultaneously to form a distributed multi-input and multi-output (DMIMO) link. DMIMO can be a means for highly reliable and low-latency cooperative routing, when the MIMO channel is exploited for transmit and receive diversity; in this context, the range extension benefit is emphasized. Alternatively, DMIMO can be a means for high-throughput ad hoc networking, when the MIMO channel is used with spatial multiplexing. In both cases, concatenated DMIMO links are treated. The key contribution of this dissertation is a method of pre-synchronization of distributed single-antenna transmitters to form a virtual antenna array, in the absence of a global clock, such as a global positioning system (GPS) receiver or a network time protocol (NTP) to provide reference signals for the synchronization. Instead, the reference for synchronization comes from a packet, transmitted by the previous virtual array and simultaneously received by all the cooperative transmitters for the next hop. The method is realized for two types of modulation: narrowband non-coherent binary frequency-shift keying (NCBFSK) and wideband orthogonal frequency division multiplexing (OFDM). The pre-synchronization algorithms for transmission are designed to minimize the root-mean-square (RMS) transmit time, sampling and carrier frequency error between cooperative transmitters, with low implementation complexity. Since CCT is not supported by any existing standard or off-the-shelf radios, CT must be demonstrated by using software-defined radios (SDRs). Therefore, another contribution is a fully self-contained and real-time SDR testbed for CCT-based networking. The NCBFSK and OFDM systems have been designed and implemented in C++ and Python programming languages in the SDR testbed, providing practical performance of the CCT-based systems.

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Milliner, David Louis. "Low-complexity list detection algorithms for the multiple-input multiple-output channel." Diss., Georgia Institute of Technology, 2009. http://hdl.handle.net/1853/37248.

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Modern communication systems demand ever-increasing data rates. Meeting this increased demand is not easy due to regulation and fundamental physical constraints. The utilization of more than one antenna at both the transmitter and receiver produces a multiple-input multiple-output (MIMO) channel, thereby enabling (under certain channel conditions) increased data rates without the need for increased bandwidth or transmission power. Concurrent with this increase in bandwidth is an increase in the receiver's computational complexity which, for a brute-force detector, increases exponentially. For receivers that possess error correcting capabilities, the problem of constructing a detector with low computational complexity that allows for near-exact a posteriori detection is challenging for transmission schemes employing even a modest number of transmit antennas and modulation alphabet sizes. The focus of this dissertation is on the construction of MIMO detection algorithms with low and fixed computational complexity. Specifically, the detection algorithms in this dissertation generate a list of potential transmission vectors resulting in realizable communication receivers with low and fixed computational complexity combined with low error rate performance in both coded and uncoded systems. A key contribution in this dissertation is a breadth-first fixed-complexity algorithm known as the smart-ordered and candidate-adding algorithm that achieves a desirable performance-complexity tradeoff. This algorithm requires only a single pass of a search tree to find its list of transmission vectors. We then construct a framework within which we classify a large class of breadth-first detection algorithms. The design of receiver algorithms for MIMO systems employing space-time codes and error correction is an important area of study. In this dissertation we propose a low and fixed computational complexity algorithm for an increasingly significant algebraic space-time code known as the golden code. The notion of computational complexity is critical in the design of practical MIMO receivers. We provide an analysis of computational complexity in relation to list-based soft-output detection where, in some instances, bounds are placed on the computational complexity of MIMO detection. For this analysis we utilize a metric known as the number of branch metric computations. The value at which the log-likelihood ratio (LLR) of conditional probabilities for a transmitted bit being either a 1 or a 0 is 'clipped' has an impact on a system's error rate performance. We propose a new approach for determining LLR clipping levels that, in contrast to prior approaches which clip to a predetermined fixed LLR clipping level, exploits channel state information to improve the error rate performance of suboptimal detection algorithms. Orthogonal frequency-division (OFDM) multiplexing is an effective technique for combating frequency-selective wideband communication channels. It is common practice for MIMO-OFDM detectors to implement the same detector at each subcarrier, in which case the overall performance is dominated by the weakest subcarrier. We propose a hard-output list detection receiver strategy for MIMO-OFDM channels called nonuniform computational complexity allocation, whereby the receiver adapts the computational resources of the MIMO detector at each subcarrier to match a metric of the corresponding channel quality. The proposed nonuniform algorithm improves performance over uniform allocation.

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Chan, Francis Chun Ngai Electrical Engineering &amp Telecommunications Faculty of Engineering UNSW. "Statistical methods on detecting superpositional signals in a wireless channel." Awarded by:University of New South Wales. School of Electrical Engineering and Telecommunications, 2006. http://handle.unsw.edu.au/1959.4/30596.

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The objective of the thesis is concerned on the problem of detecting superpositional signals in a wireless channel. In many wireless systems, an observed signal is commonly represented as a linear combination of the transmitted signal with the interfering signals dispersed in space and time. These systems are generally known as the interference-limited systems. The mathematical model of these systems is generally referred as a superpositional model. A distinguished characteristic of signal transmission in a time-varying wireless channel is that the channel process is not known a priori. Reliable signal reception inherently requires exploiting the structure of the interfering signals under channel uncertainty. Our goal is to design computational efficient receivers for various interference-limited systems by using advanced statistical signal processing techniques. The thesis consists of four main parts. Firstly, we have proposed a novel Multi-Input Multi-Output (MIMO) signal detector, known as the neighbourhood exploring detector (NED). According to the maximum likelihood principle, the space time MIMO detection problem is equivalent to a NP-hard combinatorial optimization problem. The proposed detector is a sub-optimal maximum likelihood detector which eliminates exhaustive multidimensional searches. Secondly, we address the problem of signal synchronization for Global Positioning System (GPS) in a multipath environment. The problem of multipath mitigation constitutes a joint estimation of the unknown amplitudes, phases and time delays of the linearly combined signals. The complexity of the nonlinear joint estimation problem increases exponentially with the number of signals. We have proposed two robust GPS code acquisition systems with low complexities. Thirdly, we deal with the problem of multipath mitigation in the spatial domain. A GPS receiver integrated with the Inertial Navigation System (INS) and a multiple antenna array is considered. We have designed a software based GPS receiver which effectively estimates the directions of arrival and the time of arrival of the linearly combined signals. Finally, the problem of communications with unknown channel state information is investigated. Conventionally, the information theoretical communication problem and the channel estimation problem are decoupled. However the training sequence, which facilitates the estimation of the channel, reduces the throughput of the channel. We have analytically derived the optimal length of the training sequence which maximizes the mutual information in a block fading channel.

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Spencer, Quentin H. "Transmission Strategies for Wireless Multi-user, Multiple-Input, Multiple-Output Communication Channels." Diss., CLICK HERE for online access, 2004. http://contentdm.lib.byu.edu/ETD/image/etd378.pdf.

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15

Yang, Yaoqing. "An experimental investigation of wideband MIMO channels for wireless communications." Thesis, 2006. http://hdl.handle.net/2152/2673.

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Lu, Peng. "Performance evaluation and enhancement of MIMO broadcast channels." Thesis, 2010. http://hdl.handle.net/1828/3299.

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In Multiple-Input Multiple-Output (MIMO) broadcast channels, the multi-antenna basestation transmits information to multiple non-cooperative mobile users simultaneously. Among various transmission schemes, zero-forcing beamforming (ZFBF) and random unitary beamforming (RUB) are of particular interest due to their low implementation complexity and ability to explore the multiplexing gain provided by multiple transmit antennas. To investigate the effects of multiuser diversity on sum-rate performance, previous studies of beamforming schemes in multiuser MIMO systems usually employ asymptotical analysis. In this work, while assuming channel gain follows Rayleigh flat fading, we study the sum-rate performance of ZFBF and RUB through exact mathematic analysis. For this purpose, we derive the statistics of selected users's effective channel gain, which enable us to calculate the sum rate accurately and efficiently. With derived sum-rate expressions, we evaluate and compare the sum-rate performance of MIMO broadcast channels with RUB and dual-transmit-antenna ZFBF. In addition, we apply this analytical method to study strategies that mitigate multiuser interference for RUB-based multiuser MIMO systems. The strategies we consider in the thesis include • Reducing the number of served users at a time. We present a new user scheduling scheme, which imposes a threshold On user's SINR for feedback load reduction and only activates those beams that are requested by feedback users. • Exploiting receive diversity. When receivers use more than one antennas, we evaluate the sum-rate performance gain offered by selection combining (SC) and optimum combining (OC) schemes, respectively. In addition to beamforming techniques, we study the symbol error rate (SER) performance of MIMO broadcast channels with vector perturbation (VP) precoding and quantized channel feedback. Based. on the established equivalent relations in terms of minimum mean square error (MMSE) and SER between quantized and perfect channel feedback cases, we investigate the tradeoff between feedback load and achievable diversity gain.
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Lee, Jia-Han, and 李佳翰. "Optimization of antenna arrays for the channel capacity of MIMO wireless communication systems." Thesis, 2013. http://ndltd.ncl.edu.tw/handle/96734812139721863096.

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碩士
國立臺灣大學
電信工程學研究所
101
Along with the development of mobile communications, necessity and exchangeability of multimedia information of personal communication rapidly increase. Study to improve to achieve a better spectral efficiency and transmission quality within the limited bandwidth has become an important issue. In MIMO wireless communication systems, the techniques of spatial diversity and spatial multiplexing make both quality and rate ameliorate in transmission. However , the spatial correlation between the elements of antenna array significantly affects spectral efficiency and transmission quality. Miniaturization trend of mobile devices makes antenna spacing become even smaller than before, leading out the mutual coupling effect which increase channel capacity. Therefore, research of the spatial correlation, mutual coupling , and channel capacity functions under surrounding of 2-D signal arrival and 3-D signal arrival will be described first, as a valuation of efficiency. Then introduce chaotic particle swarm optimization and optimization of antenna arrays for the channel capacity. Compare the difference of using uniform antenna array and non-uniform antenna array. Present the optimal array geometry. Final,we will discuss the effect of spatial correlation and mutual coupling for channel capacity.

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Baraani, Dastjerdi Mahmood. "High-Performance Multi-Antenna Wireless for 5G and Beyond." Thesis, 2020. https://doi.org/10.7916/d8-4q2c-1y14.

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Over the next decade, multi-antenna radios, including phased array and multiple-input-multiple-output (MIMO) radios, are expected to play an essential role in the next-generation of wireless networks. Phased arrays can reject spatial interferences and provide coherent beamforming gain, and MIMO technology promises to significantly enhance the system performance in the coverage, capacity, and user data rate through the beamforming or diversity/capacity gain which can substantially increase the range in wireless links, that are challenged from the transmitter (TX) power handling, receiver (RX) noise perspectives and a multi-path environment. Furthermore, the multi-user MIMO (MU-MIMO) can simultaneously serve multiple users which is vital for femtocell base stations and access points (AP). Full-duplex (FD) wireless, namely simultaneous transmission and reception at the same frequency, is an emerging technology that has gained attention due to its potential to double the data throughput, as well as provide other benefits in the higher layers such as better spectral efficiency, reducing network and feedback signaling delays, and resolving hidden-node problems to avoid collisions. However, several challenges remain in the quest for the high-performance integrated FD radios. Transmitter power handling remains an open problem, particularly in FD radios that integrate a shared antenna interface. Secondly, FD operation must be achieved across antenna VSWR variations and a changing EM environment. Finally, FD must be extended to multi-antenna radios, including phased array and multi-input multi-output (MIMO) radios, as over the next decade, they are expected to play an essential role in the next generation of wireless networks. Multi-antenna FD operation, however, is challenged not only by the self-interference (SI) from each TX to its own RX but also cross-talk SI (CT-SI) between antennas. In this dissertation, first, a full-duplex phased array circulator-RX (circ.-RX) is proposed that achieves self-interference cancellation (SIC) through repurposing beamforming degrees of freedom (DoF) on TX and RX. Then, an FD MIMO circ.-RX is proposed that achieves SI and CT-SI cancellation (CT-SIC) through passive RF and shared-delay baseband (BB) canceller that addresses challenges associated with FD MIMO operation. Wireless radios at millimeter-wave (mm-wave) frequencies enable the high-speed link for portable devices due to the wide-band spectrum available. Large-scale arrays are required to compensate for high path loss to form an mm-wave link. Mm-wave MIMO systems with digitization enable virtual arrays for radar, digital beamforming (DBF) for high mobility scenarios and spatial multiplexing. To preserve MIMO information, the received signal from each element in MIMO RX should be transported to ADC/DSP IC for DBF, and vice versa on the TX side. A large-scale array can be formed by tiling multiple mm-wave IC front-ends, and thus, a single-wire interface is desired between DSP IC and mm-wave ICs to reduce board routing complexity. Per-element digitization poses the challenge of handling high data-rate I/O in large-scale tiled MIMO mm-wave arrays. SERializer – DESerializer (SERDES) is traditionally being used as a high-speed link in computing systems and networks. However, SERDES results in a large area and power consumption. In this dissertation, a 60~GHz 4-element MIMO TX with a single-wire interface is presented that de-multiplexes the baseband signal of all elements and LO reference that are frequency-domain multiplexed on a single-wire coax cable.

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Forenza, Antonio. "Antenna and algorithm design in MIMO communication systems: exploiting the spatial selectivity of wireless channels." Thesis, 2006. http://hdl.handle.net/2152/2457.

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Churms, Duane. "Comparison of code rate and transmit diversity in MIMO systems." Thesis, 2016. http://hdl.handle.net/10539/21155.

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A thesis submitted in ful lment of the requirements for the degree of Master of Science in the Centre of Excellence in Telecommunications and Software School of Electrical and Information Engineering, March 2016
In order to compare low rate error correcting codes to MIMO schemes with transmit diversity, two systems with the same throughput are compared. A VBLAST MIMO system with (15; 5) Reed-Solomon coding is compared to an Alamouti MIMO system with (15; 10) Reed-Solomon coding. The latter is found to perform signi cantly better, indicating that transmit diversity is a more e ective technique for minimising errors than reducing the code rate. The Guruswami-Sudan/Koetter-Vardy soft decision decoding algorithm was implemented to allow decoding beyond the conventional error correcting bound of RS codes and VBLAST was adapted to provide reliability information. Analysis is also performed to nd the optimal code rate when using various MIMO systems.
MT2016

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Dissertations / Theses on the topic 'MIMO systems. Broadband communication systems. Antenna arrays'

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