Showing papers by "Mohammad Patwary published in 2004"
26 Sep 2004
TL;DR: The performance of an adaptively-modulated and adaptive-rate hybrid automatic-repeat-request (hybrid-ARQ) scheme is proposed for wideband communications based on orthogonal frequency division multiplexing and it is found that the proposed adaptive approach achieves near capacity rates for wide band transmission.
Abstract: The performance of an adaptively-modulated and adaptive-rate hybrid automatic-repeat-request (hybrid-ARQ) scheme is proposed for wideband communications based on orthogonal frequency division multiplexing (OFDM). The adaptation scheme presents the optimal code rate and signal constellation in order to maximize the spectral efficiency per sub-carrier. By employing type-III turbo hybrid-ARQ with OFDM, utilization of a complete set of sub-carriers is achieved. The adaptation scheme is presented for both Gaussian and fading channels. It is found that the proposed adaptive approach achieves near capacity rates for wideband transmission.
5 citations
30 Aug 2004
TL;DR: In this paper, a reduced complexity decision feedback maximum likelihood sequence estimation (DF-MLSE) for MIMO frequency selective fading channels has been proposed, which takes advantage of the a priori knowledge hidden in the received signal structure to produce receivers with the same BER performance as the standard MLSE detector.
Abstract: A reduced complexity decision feedback maximum likelihood sequence estimation (DF-MLSE) for MIMO frequency selective fading channels has been proposed. The BER performance of the proposed algorithm is the same as for the standard MLSE, yet computational complexity is significantly reduced. For a typical MIMO system with 4 transmitter antennas and 4 receiver antennas the computational complexity reduction is 20-fold. The complexity reduction in previously proposed receivers is even higher at the cost of 2 dB SNR loss for the same BER performance as for the standard MLSE. Unlike previous approaches we are taking advantage of the a priori knowledge hidden in the time domain received signal structure to produce receivers with the same BER performance as the standard MLSE detector and significantly lower computational cost.
1 citations
24 Oct 2004
TL;DR: It has been found that the SNR loss due to the blind nature of the detection technique is less than 1 dB compared to the detection with perfect knowledge of the channel at the receiver.
Abstract: In this paper an improved blind sequence detection scheme has been proposed. Both uncoded and coded systems have been analyzed. It has been found that the SNR loss due to the blind nature of the detection technique is less than 1 dB compared to the detection with perfect knowledge of the channel at the receiver. The proposed blind algorithm is highly scalable with the cost of computational complexity decided with the length of the processing window.