Effect of mobility on the performance of Amplify-and-Forward cooperation in SC-FDMA systems

Cooperative relay communication is a promising technique in the future wireless communication systems. The cooperation techniques allow mobiles to increase their uplink diversity by relaying the data of other users. In this paper, we analyze the impact of the cooperative region of a mobile terminal on the system performance of the Single-Carrier Frequency Division Multiple Access (SC-FDMA) in dynamic cooperation transmission scenarios. This cooperative region is defined as the area where a mobile terminal has at least 1-connected neighbor. Using the Random Way Point (RWP) mobility model and the Effective Exponential SNR Mapping (EESM), we give an analytical expression of the Bit Error Rate (BER) at the destination in terms of the radius of cooperative region and of the users density. Using two different assumptions for users´ distributions, we show that for a cell radius normalized to one unit, and with the RWP model, the optimal cooperative region radius depends on the users density in the network. Compared to the non-cooperative scenario, and depending on the spreading length, the SNR gain obtained through dynamic cooperation can reach few dBs. Our results are validated through simulations.