Analytic quantification of outage probability and radiated power of cooperative base stations

Cooperative transmissions allow fast and reliable communication between user equipment (UE) and base stations (BSs) in radio access networks. Selecting which base stations cooperate is important to keep both effective radiated power (ERP) and outage probability low. In this paper, we quantify how knowledge about the instantaneous channel conditions can be used to select which BSs cooperate. We analytically derive the outage probability and ERP when instantaneous channel knowledge is used for BS selection, power control, both, or not at all. In particular, we quantify the added benefit of instantaneous over average channel knowledge, depending on the differences in average channel gains of the BSs. We determine that the greatest reduction (both in terms of outage probability and ERP) from using instantaneous channel knowledge is achieved when the average channel gains of all possibly cooperating BSs are the same. Additionally, we show that when using instantaneous channel knowledge to select the cooperating BSs, adding power control only makes a difference at a single BS.