共查询到20条相似文献,搜索用时 15 毫秒
1.
Oggier F. 《IEEE transactions on information theory / Professional Technical Group on Information Theory》2007,53(9):3053-3065
We investigate cyclic algebras for coding over the differential noncoherent channel. Cyclic algebras are an algebraic object that became popular for coherent space-time coding, since it naturally yields linear families of matrices with full diversity. Coding for the differential noncoherent channel has a similar flavor in the sense that it asks for matrices that achieve full diversity, except that these matrices furthermore have to be unitary. In this work, we give a systematic way to find infinitely many unitary matrices inside cyclic algebras, which holds for all dimensions. We show how cyclic algebras generalize previous families of unitary matrices obtained using the representation of fixed-point-free groups. As an application of our technique, we present families of codes for three and four antennas that achieve high coding gain. 相似文献
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Bhattad K. Narayanan K.R. Caire G. 《IEEE transactions on information theory / Professional Technical Group on Information Theory》2008,54(7):2943-2958
We consider the problem of joint source-channel coding for transmitting K samples of a complex Gaussian source overT bK uses of a block-fading multiple-input multiple-output (MIMO) channel with M transmit and N receive antennas. We consider the case when we are allowed to code over L blocks. The channel gain is assumed to be constant over a block and channel gains for different blocks are assumed to be independent. The performance measure of interest is the rate of decay of the expected mean-squared error with the signal-to-noise ratio (SNR), called the distortion SNR exponent. We first show that using a broadcast strategy similar to that of Gunduz and Erkip, but with a different power and rate allocation policy, the optimal distortion SNR exponent can be achieved for 0 les b les (|N - M| + 1)/ min(M,N) and for b > MNL2. This is the first time the optimal exponent is characterized for 1/min(M, N) < b < (|N - M| + 1)/min(M, N). Then, we propose a digital layered transmission scheme that uses both time layering and superposition. The new scheme is at least as good as currently known schemes for the entire range of bandwidth expansion factors b, whereas at least for some M, N, and b, it is strictly better than the currently known schemes. 相似文献
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《IEEE transactions on information theory / Professional Technical Group on Information Theory》2009,55(2):524-530
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Berhuy G. Oggier F. 《IEEE transactions on information theory / Professional Technical Group on Information Theory》2009,55(5):2078-2082
Perfect space-time codes are codes for the coherent multiple-input multiple-output (MIMO) channel. They have been called so since they satisfy a large number of design criteria that makes their performances outmatch many other codes. In this correspondence, we discuss the existence of such codes (or more precisely, the existence of perfect codes with optimal signal complexity). 相似文献
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《Signal Processing, IEEE Transactions on》2008,56(9):4365-4376
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Kan Zheng Hang Long Ling Wang Wenbo Wang Young-Il Kim 《Vehicular Technology, IEEE Transactions on》2009,58(4):1816-1822
Multiple-input-multiple-output (MIMO) technology can efficiently increase the system capacity in rich scattering environments without increasing the bandwidth or transmission power. The precoder for MIMO transmission is a processing technique that exploits the channel state information (CSI) by operating on the signal before transmission to effectively improve link performance. A hybrid automatic repeat request (HARQ) scheme can be incorporated with the linear precoder to ensure highly reliable communication. To fully utilize the type-I HARQ diversity gain, particularly in slow-fading channels, we propose the optimal design principle of linear precoders whose column vectors are correspondingly orthogonal to each other. In addition, the practical solution based on codebook is given in this paper. Finally, simulation results demonstrate the effectiveness of the proposed precoders in reducing the detection of bit error rate (BER) and in improving normalized throughput. 相似文献
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Gresset N. Brunel L. Boutros J.J. 《IEEE transactions on information theory / Professional Technical Group on Information Theory》2008,54(5):2156-2178
The space-time bit-interleaved coded modulation (ST-BICM) is an efficient technique to obtain high diversity and coding gain on a block-fading multiple-input multiple-output (MIMO) channel. Its maximum-likelihood (ML) performance is computed under ideal interleaving conditions, which enables a global optimization taking into account channel coding. Thanks to a diversity upper bound derived from the Singleton bound, an appropriate choice of the time dimension of the space-time coding is possible, which maximizes diversity while minimizing complexity. Based on the analysis, an optimized interleaver and a set of linear precoders, called dispersive nucleo algebraic (DNA) precoders are proposed. The proposed precoders have good performance with respect to the state of the art and exist for any number of transmit antennas and any time dimension. With turbo codes, they exhibit a frame error rate which does not increase with frame length. 相似文献
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《Vehicular Technology, IEEE Transactions on》2008,57(5):2792-2803
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Ngoc-Dung ao Tellambura C. 《IEEE transactions on information theory / Professional Technical Group on Information Theory》2010,56(1):168-180
In this paper, a new class of full-diversity, rate-one space-time block codes (STBCs) called semiorthogonal algebraic space-time block codes (SAST codes) is proposed. SAST codes are delay optimal when the number of transmit antennas is even. The SAST codeword matrix has a generalized Alamouti structure where the transmitted symbols are replaced by circulant matrices and the commutativity of circulant matrices simplifies the detection of transmit symbols. SAST codes with maximal coding gain are constructed by using rate-one linear threaded algebraic space-time (LTAST) codes. Compared with LTSAT codes, SAST codes not only reduce the complexity of maximum-likelihood detection, but also provide remarkable performance gain. They also outperform other STBC with rate one or less. SAST codes also perform well with suboptimal detectors such as the vertical-Bell Laboratories layered space-time (V-BLAST) nulling and cancellation receiver. Finally, SAST codes attain nearly 100% of the Shannon capacity of open-loop multiple-input-single-output (MISO) channels. 相似文献
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Diggavi S.N. Calderbank A.R. Dusad S. Al-Dhahir N. 《IEEE transactions on information theory / Professional Technical Group on Information Theory》2008,54(1):33-50
Rate and diversity impose a fundamental tradeoff in wireless communication. High-rate space-time codes come at a cost of lower reliability (diversity), and high reliability (diversity) implies a lower rate. However, wireless networks need to support applications with very different quality-of-service (QoS) requirements, and it is natural to ask what characteristics should be built into the physical layer link in order to accommodate them. In this paper, we design high-rate space-time codes that have a high-diversity code embedded within them. This allows a form of communication where the high-rate code opportunistically takes advantage of good channel realizations while the embedded high-diversity code provides guarantees that at least part of the information is received reliably. We provide constructions of linear and nonlinear codes for a fixed transmit alphabet constraint. The nonlinear constructions are a natural generalization to wireless channels of multilevel codes developed for the additive white Gaussian noise (AWGN) channel that are matched to binary partitions of quadrature amplitude modulation (QAM) and phase-shift keying (PSK) constellations. The importance of set-partitioning to code design for the wireless channel is that it provides a mechanism for translating constraints in the binary domain into lower bounds on diversity protection in the complex domain. We investigate the systems implications of embedded diversity codes by examining value to unequal error protection, rate opportunism, and packet delay optimization. These applications demonstrate that diversity-embedded codes have the potential to outperform traditional single-layer codes in moderate signal-to-noise (SNR) regimes. 相似文献
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《IEEE transactions on information theory / Professional Technical Group on Information Theory》2009,55(2):547-556
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《IEEE transactions on information theory / Professional Technical Group on Information Theory》2008,54(11):4847-4865
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《IEEE transactions on information theory / Professional Technical Group on Information Theory》2008,54(3):1073-1085
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Via J. Santamaria I. 《IEEE transactions on information theory / Professional Technical Group on Information Theory》2008,54(2):709-722
In this paper, the conditions for blind identifiability from second-order statistics (SOS) of multiple-input multiple-output (MIMO) channels under orthogonal space-time block coded (OSTBC) transmissions are studied. The main contribution of the paper consists in the proof that, assuming more than one receive antenna, any OSTBC with a transmission rate higher than a given threshold, which is inversely proportional to the number of transmit antennas, permits the blind identification of the MIMO channel from SOS. Additionally, it has been proven that any real OSTBC with an odd number of transmit antennas is identifiable, and that any OSTBC transmitting an odd number of real symbols permits the blind identification of the MIMO channel regardless of the number of receive antennas, which extends previous identifiability results and suggests that any nonidentifiable OSTBC can be made identifiable by slightly reducing its code rate. The implications of these theoretical results include the explanation of previous simulation examples and, from a practical point of view, they show that the only nonidentifiable OSTBCs with practical interest are the Alamouti codes and the real square orthogonal design with four transmit antennas. Simulation examples and further discussion are also provided. 相似文献
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A multiuser multiple-input-multiple-output (MIMO) system with orthogonal space-time block coding (OSTBC) is analyzed for the uplink of a wireless communication system in a Rayleigh fading environment. In the first part of this paper, a simple and exact closed-form expression for the outage probability of the signal-to-interference-and-noise ratio (SINR) is derived at the input of the base station (BS) receiver by making the following two assumptions: 1) All the users transmit their data by using the same OSTBC; and 2) the users are power controlled by the same BS so that the interfering users are requested to transmit with the same power. In the second part of this contribution, the outage probability of the signal-to-interference ratio (SIR) is calculated at the output of the BS receiver, which, in our case, is a spatial matched filter. To be able to analytically solve the latter problem, the presented analysis is restricted to the case of a single interferer and a 2 2 MIMO system with Alamouti coding. Monte Carlo simulations are carried out to verify the proposed analytical expressions for the outage probability. 相似文献
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《IEEE transactions on information theory / Professional Technical Group on Information Theory》2009,55(6):2696-2704