In relay-assisted cellular wireless communications the mobile terminals (MTs) near the base-station (BS) are usually preferred to being chosen as the relays for assisting the uplink transmission, for the sake of achieving the relay diversity while maintaining the system power-efficient. However, this strategy may result in the so-called 'bottleneck' problem, when each user chooses different relays. In this case a huge number of relays might be required, but the available relays around the BS are limited. In this contribution we propose a relay strategy for direct-sequence code-division multiple-access (DS-CDMA) systems, where a set of MTs in the vicinity of the BS are chosen to act as the relays for all the uplink users. Explicitly, this relay strategy can significantly mitigate the 'bottleneck' problem. In this contribution the performance of the DS-CDMA using our proposed relay strategy is investigated, when considering that there exist both multiuser and inter-relay interference. The bit error rate (BER) performance is investigated, when communicating over Nakagami- m  fading channels, where signals from the MT transmitters to the relays and that from the relays to the BS receiver may experience different fading.
['Wei Fang', 'Lie-Liang Yang', 'Lajos Hanzo']
Performance of Relay-Assisted DS-CDMA Conflicting Multiuser/Inter-Relay Interference in Nakagami-m Fading Channels