Outage and energy efficiency tradeoff for multi-flow cooperative communication systems

The green communications, which focus on improving the energy efficiency, have attracted much attention from both academia and industry recently. In this paper, the tradeoff between outage probability and energy efficiency will be addressed for multi-flow cooperative communication systems with taking energy budget and devices energy consumption into consideration. The proposed approach will first formulate the multi-flow cooperative communication system as a weighted random bipartite graph (WRBG) model. The minimum weighted maximum matching (MWMM) method will then be proposed to select a relay for each source-destination (s-d) pair in order to minimize the outage probability and maximize the average energy efficiency simultaneously. By analyzing the properties of every sample of the WRBG model, the closed-form formulas for the outage probability and average energy efficiency will then be obtained. Therefore, based on the derived tradeoff, the outage probability and average energy efficiency can be balanced by adjusting the energy budgets and transmission rate according to the system requirement. Moreover, the proposed MWMM method also enjoys an advantage of the log-polynomial computation complexity for parallel implementations.