Approximately 3 dB signal-to-noise ratio (SNR) loss is always paid with conventional differential space-time block codes (STBCs), compared with coherent STBCs. In this paper, a multiple-symbol differential detection (MSDD) technique is proposed for M-ary phase-shift keying (PSK) STBCs. The new scheme can greatly narrow the 3-dB performance gap by extending the observation interval for differential decoding. The technique uses maximum-likelihood sequence detection instead of traditional symbol-by-symbol detection, and is carried out on the slow, flat Rayleigh fading channel. A generalized decision metric is derived for an observation interval of arbitrary length. It is shown that for a moderate number of symbols, MSDD provides approximately 1.5 dB performance improvement over conventional differential detection. In addition, a closed-form pairwise error probability and approximate bit-error probability (BEP) are derived for multiple-symbol differential binary PSK STBC. Results show that the theoretical BEP matches simulation results well. The BEP is shown to converge asymptotically with the number of symbols in the observation interval to that of the differential scheme with coherent detection.

New expressions are derived for the exact symbol error probability and bit-error probability for optimum combining with multiple phase-shift keying. The expressions are for any numbers of equal-power cochannel interferers and receive branches. It is assumed that the aggregate interference and noise is Gaussian and that both the desired signal and interference are subject to flat Rayleigh fading. The new expressions have low computational complexity, as they contain only a single integral form with finite limits and finite integrand.

In this paper we evaluate the average throughput of two types of W-CDMA systems with Multiple-input-multiple-output and adaptive modulation and coding by numerical simulation and theoretic analysis. One system employs space-time transmit diversity, another implements per antenna rate control. In both systems the modulation levels and turbo coding rates are dynamically adjusted depending on the channel conditions. The channels are assumed to be Rayleigh fading channels. Closed-form expressions are derived for the average throughput of both systems. The simulation results prove the accuracy of the analysis.

A multiple-symbol differential detector is formulated for M-ary differential phase-shift keying modulation where the channel state information is unknown to the receiver. The maximum-likelihood decision statistic is derived for the detector, and its performance is demonstrated by analysis and simulation. Under the Gaussian assumption for the aggregate interference plus noise, an exact expression for the symbol pairwise error probability is developed for M-ary differential phase-shift keying modulation over a diversity, slow-fading Rayleigh channel in the presence of an interference source. A simpler expression of the pairwise error probability is developed for the asymptotic case of large signal-to-noise ratio and small signal-to-interference ratio. It is shown that with an increasing observation interval, the performance of the differential detector over an unknown channel approaches that of optimum combining with known channel.

A new closed-form expression is derived for the exact bit-error probability (BEP) for optimum combining with binary phase-shift keying. The exact BEP expression is for multiple, equal power, cochannel interferers and multiple reception branches. It is assumed that the aggregate interference and noise is Gaussian and that both the desired signal and interference are subject to Rayleigh fading. The derivation starts by expressing the optimum combining decision statistic as a sum of quadratic forms of Gaussian random variables and it proceeds to average over the fading interference. The new BEP expression has low complexity as it contains only finite sums and products.

The performance of multiple symbol differential detection (MSDD) over Rayleigh diversity channels and in the presence of cochannel interference is compared with that of optimum combining (OC). For this purpose, we derive the asymptotic expressions for the approximate upper bound of the bit error probability of MSDD for multiple phase shift keying modulation. Similar asymptotic expressions are derived for OC. These relatively simple expressions provide a clear insight into the performance of MSDD and OC. Through analysis and simulation results, we show that as the observation interval increases, the performance of MSDD approaches that of OC (with differential encoding).