In this study, the authors introduce an adaptive bit loading scheme for an amplify-and-forward orthogonal frequency division multiple cooperative system with relay selection. The proposed bit loading scheme maximises the throughput for a target error rate taking into account the quality of imperfect channel estimation. It relies on estimated channel state information (CSI) at the destination node and partial CSI (which involves the number of loaded bits) at the source node. The authors provide extensive Monte Carlo simulation results to demonstrate the throughput and the no-transmission probability performance of the proposed scheme and discuss the effect of various system and channel parameters on the performance.

In this paper, we propose an adaptive power loading algorithm for an OFDM (orthogonal frequency division multiplexing)-based multi-relay regenerative network with relay selection. The proposed scheme is based on selecting the "best" relay(s) according to different strategies and distributing the power adaptively among the subcarriers of source and selected relay(s) as to minimize an upper bound on the bit error rate (BER). Our Monte Carlo simulation results demonstrate superior performance gains through power loading with respect to conventional equal power loading schemes. The effects of imperfect channel estimation and relay location on the BER performance are further discussed.

In this paper, we investigate bit and power allocation strategies for an orthogonal frequency division multiplexing (OFDM) cooperative network over frequency-selective fading channels. We assume amplify-and-forward relaying and consider the bit error rate (BER) performance as our performance measure. Aiming to optimize the BER under total power constraint and for a given average data rate, we propose three adaptive algorithms; optimal power loading (OPL), optimal bit loading (OBL), and optimal joint bit and power loading (OBPL). Our Monte Carlo simulation results demonstrate performance gains through adaptive bit and power loading over conventional non-adaptive systems as well as currently available adaptive cooperative scheme in the literature. The impact of practical issues on the performance of proposed adaptive schemes such as imperfect channel estimation and limited feedback is further discussed.