We consider MlMO schemes with N/sub t/ transmit and N/sub r/ receive antennas using BPSK modulation in quasi-static fading. We show that space-time (ST) bit-interleaving coded-modulation (BICM) approaches mapping binary codes to BPSK ST codes show a loss over coded-modulation (CM) MIMO capacity. This is despite the use of an optimal inner detector and is illustrated using capacity CDFs for the CM and ST-BICM cases. The CDFs are translated to plots of outage probabilities as functions of SNR. For capacity-achieving schemes, these indicate that SNR losses of ST-BICM over CM approaches decrease with N/sub r/ and increase with N/sub t/. Finally, we amend our method for where the outer binary code is only capacity-approaching - we find this provides accurate predictions of FERs for ST-BICM using an outer turbo code.

A pilot symbol assisted modulation (PSAM) based iterative channel estimation method - applied in conjunction with turbo equalization - over time and frequency selective fading channels is proposed. Initial channel estimates are derived from periodic optimal pilot sequences by maximum likelihood (ML) acquisition and Wiener filtering. In the iterative channel estimator, soft decisions from the decoder are used to cancel inter-symbol-interference (ISI) and thus the frequency selective channel is decoupled into multiple flat fading sub-channels. Refined channel estimates of individual multipath taps are obtained independently from each sub-channel which is treated as a flat fading channel. Simulation results using a continuously time-variant channel model show bit error ratio (BER) performance gains and normalized mean squared error (MSE) improvements achieved by the iterative channel estimation scheme over those of the non-iterative scheme for normalized fade rates f/sub d/T/sub s/ = 0.01 and f/sub d/T/sub s/ = 0.005.

Up to now most research on the capacity of MIMO systems has been carried out on a point-to-point link. However the capacity and BER performance of such systems in a cellular environment have not been much investigated. In this paper, we investigate the BER performance of a space-time block coded MIMO system in the presence of an interferer, which is treated as unknown, and interferers in a cellular system. The concept of a spatially pre-whitened matched filter is used to improve the BER performance of the system in which interference will not in general be spatially white.

This work investigates the up-link capacity of a multiple-input multiple-output (MlMO) wireless channel subject to finite multipath scattering in the presence of co-channel interference (CCI). We first consider single interferers with fixed position and then extend to cellular systems. We observe that the average capacity of MlMO system in the presence of interference is significantly greater than that of a single-input single-output (SISO) system and a single-output multiple-output (SIMO) system at moderate SNRs. It is presented that the link capacity of a MIMO system could be maximised by means of a spatially-whitened matched filter, which converts the interference uncorrelated between receive antennas. It is shown that the capacity of the finite scatterers channel can be even larger than that of the independent Rayleigh channel through the use of spatial pre-whitening filter.

For the quasi-static Rayleigh fading multiple-input/multiple output (MIMO) channel, we consider BPSK space-time (ST) codes with rates /spl ges/ 1 and diversity /spl les/ L derived from linear binary codes where L is the number of transmit antennas. For L = 2,3 and 4, we derive conditions on both the generator matrix G and the parity-check matrix H for a code to achieve diversities 2, ..., L. we then introduce the concept of duals of linear binary-based ST codes, since a particular relationship between the conditions on G and on H shows that rate 1, diversity L and rate L - 1, diversity 2 codes are duals. Thus, a matrix G (or a matrix H) of a rate 1, diversity L BPSK ST code may also be used as the matrix H (or matrix G) of a rate L-1, diversity 2 code. Example codes for 3 and 4 antennas are given along with decoding results from simulations.

In this paper we consider a multiple-input multiple-output (MIMO) downlink multi-cell CDMA system employing BLAST space-time turbo codes (STTuC) over the frequency-selective fading channel. The system performance is measured in terms of system spectral efficiency (bits/s/Hz/cell). A space-time RAKE receiver and a space-time turbo receiver are proposed. The turbo receiver is based on space-time parallel interference cancellation (ST-PIC), which can reconstruct and subtract all the types of interference in the multipath MIMO CDMA channel at the same time. In each iteration, the soft output of the space-time turbo decoder is fed back to improve the PIC's performance. The simulation shows that the turbo PIC receiver enhances the STTuC CDMA system spectral efficiency by 50% over the RAKE receiver. This result suggests that, with the turbo reception technique, the MIMO CDMA system can serve much more users in a cell or provide much higher rate downlink packed data service to one user.

Turbo product codes (TPCs) provide an attractive alternative to recursive systematic convolutional (RSC)-based turbo systems. Rather than employ trellis-based decoders, an algebraic decoder may be repeatedly employed in a low-complexity, soft-input/soft-output errors-and-erasures decoder such as the Chase algorithm. Taking motivation from efficient forced erasure decoders, this implementation re-orders the Chase algorithm's repeated decodings such that the inherent computational redundancy is greatly reduced without degrading performance. The result is a highly efficient fast Chase implementation. The algorithm presented here is principally applicable to single error-correcting codes although consideration is also given to the more general case. The new decoder's value in practical turbo schemes is demonstrated via application to decoding of the (64,57,4) extended Hamming TPC.