Effects of Nodes Geometry and Power Allocation in Space-Time Coded Cooperative Wireless Systems

Cooperative communications are effective in improving the performance and extend the coverage of wireless networks. One issue is to find proper methods to allocate cooperative nodes. In this paper we investigate the effects of relay position and power allocation strategy in cooperative communications employing space-time codes (STCs). We consider non-ideal links between source, relay, and destination enabling the analysis of relay allocation problem based on the performance of each link in realistic scenarios. The frame error rate for various channel conditions, available diversity, relay positions, and transmitted power levels is obtained. Both the situation of balanced and unbalanced transmit power levels for source, relay, and destination are compared. Cooperative pragmatic STCs in block fading channel (BFC) are considered for our analysis. The results provide insight on how to allocate relay nodes based on geometry, link quality, and transmitted power considerations. Invited paper which was presented in part at IEEE ISWCS 2009. Research supported by the FP7 European project OPTIMIX (Grant 214625). Work inspired in the context of the FP7 European Network of Excellence NEWCOM++ (contact no. 216715) WP6. L. Zuari · A. Conti (B) · V. Tralli ENDIF and CNIT, University of Ferrara, Via Saragat 1, 44100 Ferrara, Italy e-mail: [email protected] L. Zuari e-mail: [email protected] V. Tralli e-mail: [email protected]