Capacity-Outage-Tradeoff (COT) for Cooperative Networks

We propose a novel relationship that characterizes the fundamental tradeoff between the capacity and the outage performance of a multi-user cooperative network. As far as we are aware, no such tradeoff has previously been explicitly investigated in cooperative networks that utilize realistic modulation and channel codes. We show that increased repetition cooperation maps to regions of increased transmission reliability but degrades the system capacity. Careful system design is essential to balance reliability and capacity performance and this can only be achieved through optimization with the aid of these tradeoff curves. We present both theoretical and simulation results on the tradeoffs. Furthermore, we also optimize the tradeoff relationship by employing closed-form optimized partner selection and power allocation schemes, and show that large gains can be made in both outage performance and capacity compared with blind cooperation. The proposed methodology presented in this paper can also be extended to address different system scenarios and performance metrics.