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In practice only imperfect channel state information (CSI) is available at the transmitter due to noisy and time-varying channel. In this paper, we consider optimal bit loading for orthogonal frequency division multiplexing (OFDM) with imperfect CSI subject to channel estimation. The frame length comes in as an important control parameter, while soft channel estimation and the Cramer-Rao bound are...
In this paper, we propose a low rate bandwidth efficient channel coding scheme for MC-CDMA system so that by using it, the coded system without any extra bandwidth, significantly improves the performance of an un-coded system over fading channels. Moreover, we investigate the performance of multiple antennas array aided coded MC-CDMA system by employing different smart antennas techniques at the receiver...
In this paper, we analyze the sum rate maximization problem in a two-cell wireless system under peak power and minimum service rate constraints. The optimal power allocation is found to be binary, in the sense that each base station power will have one out of only two possible discrete levels, and the result can greatly reduce the optimization and power control complexity required. A closed-form solution...
The complex sphere decoding algorithm has optimal bit error ratio performance for uncoded multiple-input multiple-output (MIMO) systems. The computational and hardware complexities of this algorithm increase significantly for detection of 64-QAM modulated signal streams. In this paper two modifications to the original sphere decoding algorithm are proposed that reduce both computational complexity...
Breadth-first search sphere decoding (SD) is considered as one of the most promising methods for multiple-input multiple-output (MIMO) detection due to its low computational complexity, capability of providing fixed throughput and pipelining features. However, the performance of the conventional breadth-first search SD is significantly degraded if the number of candidate symbols kept at each level...
Time reversal (TR) is a transmission technique that relies on pre-processing the signal at the transmitter (TX) by filtering it through a filter, the impulse response of which is a time reversed and phase conjugated version of the channel impulse response (CIR) to the target receiver (RX). TR is known to have remarkable temporal and spatial focusing properties. Specifically temporal focusing indicates...
The performance of linear filters degrade drastically when applied to mitigate intersymbol interference caused by channels with frequent nulls in their spectral characteristics like, e.g., time-dispersive radio channels. In such cases, the well-known decision feedback equalizer (DFE) is one possible nonlinear approach to improve the quality of the receiver. However, adapting the DFE filter coefficients...
A general method to develop Tanner graphs from tail-biting convolutional codes (CC) is proposed. Recursive systematic convolutional (RSC) and non-RSC codes are considered consistently and it is shown that the elimination of redundant states leads to a graph with low complexity. In addition the graphical representation is extended to derive the condition for which the tail-biting termination is valid...
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