When do cooperative networks profit from CSI feedback? - An outage capacity perspective

Letting nodes cooperate improves the performance of wireless networks. To organize this cooperation, many cooperative transmitters employ channel knowledge that they obtain from the destination. Such Channel State Information (CSI) feedback introduces errors and overhead whose degrading effect on the overall performance has not been consistently studied so far. Capturing this degradation, we provide a new framework to analyze cooperation's outage capacity with limited feedback. Our framework holds for selection relaying and can be easily applied to arbitrary network graphs. Applying it to a simple example shows that selection relaying profits from CSI feedback when the acceptable error rate is high. Surprisingly, no effort for feedback needs to be spend at a strict target error rate.