http://idl-bnc.idrc.ca:80/dspace/handle/10625/49273 Sat, 25 May 2013 02:37:42 GMT 2013-05-25T02:37:42Z http://idl-bnc.idrc.ca:80/dspace/handle/10625/49763 Title: Asymptotic Performance of Lp-Norm MIMO Detection Authors: Ahmed, I; Schober, R; Mallik, R K Abstract: Full search L1-norm (FS-L1) and sphere decoding L∞-norm (SD-L∞) detectors have been previously proposed for multiple-input multiple-output (MIMO) systems as they entail a lower receiver complexity than the optimal L2-norm detector. However, the performance loss caused by application of these suboptimal detectors in additive white Gaussian noise (AWGN) has not been well investigated yet. In this paper, we analyze the asymptotic bit error rate of general FS-Lp and SD-Lp detectors in independent identically distributed Rayleigh fading channels. Our results are valid for all types of noise with finite moments including AWGN. We show that both FS-Lp and SD-Lp detectors achieve a diversity gain equal to the number of receive antennas independent of the metric parameter p and the type of noise. However, except for the conventional L2 case, the performances of FS-Lp and SD-Lp detectors are not identical and the performance differences may be several dB for large numbers of receive antennas. Also, our results show that p=2 is not optimal in non-Gaussian noise and L1 and L∞ detectors may result in large performance gains or degradations compared to L2 detectors depending on the type of noise. Fri, 01 Jan 2010 00:00:00 GMT http://idl-bnc.idrc.ca:80/dspace/handle/10625/49763 2010-01-01T00:00:00Z http://idl-bnc.idrc.ca:80/dspace/handle/10625/49760 Title: Cooperative BICM-OFDM: Sub-carrier and power allocation Authors: Islam, T; Schober, R; Mallik, R K; Bhargava, V K Abstract: In this paper, we consider amplify-and-forward cooperative diversity for wireless systems employing bit-interleaved coded modulation (BICM) and orthogonal frequency division multiplexing (OFDM). In the second hop, multiple relays transmit concurrently over disjoint sets of sub-carriers. We propose uniform and non-uniform sub-carrier allocation schemes, which guarantee full diversity if all involved channels have identical lengths. The non-uniform allocation scheme also guarantees full diversity if the involved channels have different lengths. In addition, we formulate a power allocation problem for minimization of an upper bound on the worst-case pairwise error probability of the considered cooperative diversity scheme and provide an efficient solution using geometric programming. Simulation results confirm the effectiveness of the proposed sub- carrier and power allocation schemes. Fri, 01 Jan 2010 00:00:00 GMT http://idl-bnc.idrc.ca:80/dspace/handle/10625/49760 2010-01-01T00:00:00Z http://idl-bnc.idrc.ca:80/dspace/handle/10625/49759 Title: Network Coded Cooperative BICM-OFDM Authors: Islam, T; Nasri, A; Schober, R; Mallik, R K; Bhargava, V K Abstract: In this paper, we study a cooperative diversity scheme for wireless systems employing network coding and the combination of bit-interleaved coded modulation (BICM) and orthogonal frequency division multiplexing (OFDM). The considered system comprises multiple sources, one relay, and one destination. The relay decodes the signal received from all sources and performs network coding before forwarding the signal to the destination. We propose a simple cooperative maximum-ratio combining scheme for decoding at the destination which can successfully exploit the full spatial and frequency diversity offered by the channel for arbitrary number of sources and arbitrary modulation schemes. We derive a closed-form upper bound for the asymptotic worst-case pairwise error probability and the diversity gain of the considered network coded cooperative BICM-OFDM scheme. Simulation results corroborate the derived diversity gain and show the effectiveness of a low complexity decoding scheme. Sat, 01 Jan 2011 00:00:00 GMT http://idl-bnc.idrc.ca:80/dspace/handle/10625/49759 2011-01-01T00:00:00Z http://idl-bnc.idrc.ca:80/dspace/handle/10625/49757 Title: Analysis and relay placement for DF cooperative BICM-OFDM systems Authors: Islam, T; Nasri, A; Schober, R; Mallik, R K Abstract: In this paper, we study a decode-and-forward cooperative diversity scheme for wireless systems using the combination of bit-interleaved coded modulation (BICM) and orthogonal frequency division multiplexing (OFDM). We propose a simple cooperative maximum-ratio combining scheme for the destination which can successfully exploit the full spatial and frequency diversity offered by the channel. Taking possible decision errors at the relay into account, we develop a closed- form upper bound on the asymptotic worst-case pairwise error probability (PEP) of the considered cooperative diversity system which provides insight into the influence of various code and channel parameters on performance. The PEP expression is then exploited for optimal relay placement. Simulation results corroborate the derived analytical results regarding the diversity gain of the system and confirm the effectiveness of the proposed relay placement scheme. Sat, 01 Jan 2011 00:00:00 GMT http://idl-bnc.idrc.ca:80/dspace/handle/10625/49757 2011-01-01T00:00:00Z http://idl-bnc.idrc.ca:80/dspace/handle/10625/49756 Title: Amplify-and-Forward Cooperative Diversity for BICM-OFDM Systems Authors: Islam, T; Schober, R; Mallik, R K; Bhargava, V K Abstract: In this paper, we propose a novel amplify-and- forward cooperative diversity scheme for wireless systems using the combination of bit-interleaved coded modulation (BICM) and orthogonal frequency division multiplexing (OFDM). In the proposed scheme, multiple relays transmit concurrently over disjoint sets of sub-carriers. A careful joint design of the sub- carrier allocation at the relays and the interleaver at the source ensures that the proposed scheme can exploit the maximum spatial and frequency diversity offered by the wireless channel. An upper bound on the asymptotic worst-case pairwise error probability of the proposed cooperative diversity scheme is developed which provides insight into to the influence of various code and channel parameters on performance. Simulation results corroborate the analytical results regarding the diversity gain of the system and confirm the effectiveness of a newly developed relay selection criterion. Fri, 01 Jan 2010 00:00:00 GMT http://idl-bnc.idrc.ca:80/dspace/handle/10625/49756 2010-01-01T00:00:00Z