Abstract-The performance of space-time orthogonal block (STOB) codes over slow Rayleigh fading channels and maximum-likelihood (ML) decoding is investigated. Two Bonferroni-type bounds (one upper bound and one lower bound) for the symbol error rate (SER) and bit error rate (BER) of the system are obtained. The bounds are expressed in terms of the pairwise error probabilities (PEPs) and the two-dimensional pairwise error probabilities (2-D PEPs) of the transmitted symbols. Furthermore, the bounds can be efficiently evaluated and they hold for arbitrary (nonstandard) signaling schemes and mappings. Numerical results demonstrate that the bounds are very accurate in estimating the performance of STOB codes. In particular, the upper and lower bounds often coincide even at low channel signal-to-noise ratios, large constellation sizes, and large diversity orders.Index Terms-Bit and symbol error rates, diversity, maximumlikelihood decoding, multiple antennas, pairwise error probability, slow Rayleigh fading, space-time coding, wireless communications.

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Abstract-We study the maximum a posteriori (MAP) decoding of memoryless non-uniform sources over multiple-antenna channels. Our model is general enough to include space-time coding, BLAST architectures, and single-transmit multi-receive antenna systems which employ any type of channel coding. We derive a closed-form expression for the codeword pairwise error probability (PEP) of general multi-antenna codes using moment generating function and Laplace transform arguments. We then consider space-time orthogonal block (STOB) coding and prove that, similar to the maximum likelihood (ML) decoding case, detection of symbols is decoupled in MAP decoding. We also derive the symbol PEP in closed-form for STOB codes. We apply these results in several scenarios. First, we design a binary antipodal signaling scheme which minimizes the system bit error rate (BER) under STOB coding. At a BER of 10 −6 , this constellation has a channel signal-to-noise ratio (CSNR) gain of 4.7 dB over conventional BPSK signaling for a binary nonuniform source with p0 = P (0) = 0.9. We next design space-time linear dispersion (LD) codes which are optimized for the source distribution under the criterion of minimizing the union upper bound on the frame error rate (FER). Two codes are given here: one outperforms V-BLAST by 3.5 dB and Alamouti's code by 12.3 dB at an FER of 10 −2 for a binary source with p0 = 0.9, and the other outperforms V-BLAST by 4.2 dB at an FER of 10 −3 for a uniform source. These codes also outperform the LD codes of [13] constructed under a different criteria. Finally, the problem of bit-to-signal mapping is studied. It is shown that for a binary source with p0 = 0.9, 64-QAM signaling, and SER = 10 −3 , a gain of 3.7 dB can be achieved using a better-thanGray mapping. For a system with one transmit and two receive antennas that uses trellis coding with 16-QAM signaling, a 1.8 dB gain over quasi-Gray mapping and ML decoding is observed when MAP decoding is used for binary sources with p0 = 0.9.

728[2] M. Honig and M. Tsatsanis, "Adaptive techniques for multiuser CDMA receivers: Enhanced signal processing with short spreading codes," IEEE Signal Process. Mag., vol. 17, no. 3, Image Transmission Over the Polya Channel via Channel-Optimized QuantizationFirouz Behnamfar, Fady Alajaji, and Tamás Linder Abstract-We introduce two progressive methods for image transmission over binary channels with additive bursty noise modeled by the finite-memory Polya (contagion) channel. The methods, which are based on channel-optimized scalar quantization (COSQ) of the wavelet transform coefficients, exploit channel memory to offer superior performance over a number of more complex systems designed for the fully interleaved channel.