User cooperation in an asynchronous cellular uplink

We present in this paper, multiuser decode-and-forward (DF) sharing scheme and a practical low-complexity adaptive pseudo-linear receiver design for cooperative diversity in an asynchronous cellular uplink. The DF schemes provide near maximum-likelihood (ML) performance, including full diversity and significant throughput improvements over no-sharing and existing schemes, under linear receiver design. The proposed linear receiver jointly separates users while suppressing the multiple-access interference (i.e., employs multiuser detection) and performs space-time decoding for diversity exploitation. We provide bit-error-probability and throughput simulations for the practical, noisy inter-user channels. The simulation results demonstrate that the three-user sharing scheme fully exploits available diversity with inter-user demodulation errors as high as 0.1% using linear joint space-time decoding and multiuser detection.