This paper addresses the problem of designing optimum full-symbol-rate linear space-time block codes (STBC) for a multi-input multi-output (MIMO) communication system with M transmitter and N ≥ M receiver antennas and a linear minimum mean square error (MMSE) receiver. By analyzing the detection error probability expression for the optimized STBC, it is shown that for QAM signaling, the maximum diversity gain for such a system is N - M + 1. The minimum probability of error STBC design is then extended to systems in which the transmission spans L independent realizations from a block fading channel model, and a (multiblock) linear MMSE receiver is employed. Necessary and sufficient conditions for the optimality of the code are obtained, and a systematic design method for generating codes that satisfy these conditions is presented. The detection error probability and diversity gain of this optimized linear multiblock transceiver are analyzed. It is proved that the error probability decreases with L, and it is shown numerically that the diversity gain increases with L. Thus, if the corresponding latency can be accommodated, for sufficiently large L an optimally designed multiblock system with a linear receiver can exploit the temporal diversity provided by the block-fading channel and achieve higher diversity gain than that of any single-block system of the same symbol rate with a maximum likelihood (ML) receiver. The optimized multiblock linear system achieves this diversity at a substantially lower computational cost. In fact, the structure of the optimal codes can be exploited to significantly reduce the cost of the multiblock linear receiver.

We proposed a new signal transmission scheme for a multi-input multi-output (MIMO) communication system, in which the signals are encoded to span multi-block channel realizations and received by a linear equalizer followed by a maximum likelihood (ML) detector. The proposed system achieves a diversity gain proportional to the number of blocks of channels over which the signals span. The detection complexity is comparable to that of a linear receiver, with additional complexity independent of the number of antennas. A general criterion for designing the optimal precoder is presented. A design example is provided. Simulation results verify the effectiveness of such a combination.

We consider the problem of space-time block code (STBC) design for Ricean fading channels in a multiple-input multiple-output (MIMO) communication system equipped with a linear minimum mean square error (MMSE) receiver. Two criteria, i.e., ergodic channel capacity and mean square error (MSE) are used for the design. Due to the complexity of the mathematics involved, no general solution has yet been proposed for a Ricean channel with arbitrary mean. In this paper, we present the necessary and sufficient conditions for the design of the optimal precoder applicable to any channel condition and any range of signal-to-noise ratio (SNR). Simulations verify that the performance of the MIMO system using the optimum precoder is indeed superior in performance.

In this paper, a general criterion for space-time block codes (STBC) to achieve full diversity with a linear receiver is proposed for a wireless communication system having multiple transmitter and single receiver antennas [multiple-input-single-output (MISO)]. Particularly, the STBC with Toeplitz structure satisfies this criterion, and therefore, enables full diversity. Further examination of this Toeplitz STBC reveals the following important properties: (1) the symbol transmission rate can be made to approach unity; (2) applying the Toeplitz code to any signalling scheme having nonzero distance between the nearest constellation points results in a nonvanishing determinant. In addition, if quadratic-amplitude modulation (QAM) is used as the signalling scheme, then for independent MISO flat-fading channels, the Toeplitz codes is proved to approach the optimal diversity-versus-multiplexing tradeoff with a zero-forcing (ZF) receiver when the number of channel uses is large. This is, so far, the first nonorthogonal STBC shown to achieve the optimal tradeoff for such a receiver. On the other hand, when maximum-likelihood (ML) detection is employed in a MISO system, the Toeplitz STBC achieves the maximum coding gain for independent channels. When the channel fading coefficients are correlated, the inherent transmission matrix in the Toeplitz STBC can be designed to minimize the average worst case pairwise error probability.

We consider a multi-input multi-output (MIMO) communication system equipped with a linear minimum mean-square error (MMSE) receiver. We design a full-rate linear space-time block code (STBC) for blocks of data that span several realizations of a block-static fading channel to achieve high diversity gain. The proposed code structures are necessary and sufficient to minimize the detection error probability. They also enable the detection computations to be partitioned into separate blocks such that the normalized complexity is reduced to little more than that for a single block. The additional complexity grows only linearly with L, the number of blocks for which the code design covers. Analysis shows that the diversity gain achieved by the code also grows linearly with L. This is confirmed by simulation results

In this paper we consider coherent flat fading wireless communication systems with multiple transmitter antennas and single receiver antenna (MISO). We propose a Toeplitz linear space time block code (STBC) that converts an original MISO flat fading channel into a Toeplitz virtual multiple inputs multiple outputs (MIMO) channel. We show that our proposed code has the following main features: (a) The symbol transmission rate is (T-M + 1)/T, where M is the number of transmitter antenna and T is the number of channel uses (T > M). (b) Linear receivers (zero-forcing and minimum mean square error) can extract full diversity. Moreover, when the channel coefficients are independent and the maximum likelihood (ML) detector is employed, our Toeplitz STBC minimizes the exact worst case average pair-wise error probability, (c) When channels are correlated, we design our Toeplitz STBC that minimizes the exact average worst case pair-wise error probability. By transforming this non-convex optimization problem into a convex one, the problem can be solved efficiently by employing an interior point method. In particular, when the design criterion in question is approximated by the Chernoff bound, we obtain a closed form solution, (d) Finally, for the independent MISO flat fading system, we prove that our proposed codes can approach the optimal diversity-vs-multiplexing tradeoff developed by Zheng and Tse with a linear zero-forcing receiver when the number of channel uses is large

In this paper, we present a design of linear codes which improves the bit error rate (BER) performance for multiple-input multiple-output (MIMO) communication systems, under a flat-fading environment, in which the channel information is unknown for the transmitter but known at the receiver. Recently, space-time codes have been designed to achieve capacity and/or minimize the overall mean square error. Our codes here simultaneously achieve the lower bound of BER, the upper bound of the overall signal to interference plus noise ratio (SINR) and the lower bound of substream minimum mean square error. Our code structure is orthogonal in both overall and individual senses.

In this paper we propose a trace-orthonormal linear dispersion code that is an extension of the generalized complex orthogonal space-time block codes and present a method to systematically design such code family. We prove that our proposed codes can minimize the average bit error probability for the QPSK modulation when the minimum mean square error (MMSE) detector is employed. Furthermore, we establish a unified framework to systematically and efficiently construct trace-orthonormal full diversity cyclotomic linear dispersion codes with any integer symbol transmission rate which is less than or equals to the number of transmitter antennas. This result generalizes the currently available linear space-time block code designs into a full diversity linear dispersion code design

A new approach to adaptive beamforming with sidelobe control is developed. The proposed beamformer represents a modification of the popular minimum variance distortionless response (MVDR) beamformer. It minimizes the array output power while maintaining the distortionless response in the direction of the desired signal and a sidelobe level that is strictly guaranteed to be lower than some given (prescribed) threshold value. The resulting modified MVDR problem is shown to be convex, and its second-order cone (SOC) formulation is obtained that facilitates a computationally efficient way to implement our beamformer using the interior point method.