The impact of cooperation on diversity-exploiting protocols

Cooperative relaying is a recently developed concept that allows for providing single-antenna devices with gains from spatial diversity. So far, the performance of those schemes has mainly been investigated in comparison to conventional multiple-antenna systems and conventional relaying techniques. Yet, the cooperation of mobile terminals offers another important enhancement. Whenever other sources of diversity are scarce, the transmission over a statistically independent relay path can provide a significant amount of spatial diversity then to be exploited by error correction techniques to effectively combat fading effects. We therefore examine the performance of cooperative relaying protocols in slow and fast fading regimes, in comparison to approaches that exploit temporal diversity. Our results imply that user cooperation is a powerful means of enhancing link level performance in environments where temporal diversity is limited and delay constraints preclude the use of larger interleavers.