Figure 2From: Network-coded primary-secondary cooperation in OFDM-based cognitive multicast networksLocation-based necessary condition sketch for tripartite cooperation.(a) Node SS is not located within the intersection transmission range of PT 1 and PT 2. (b) One primary receiver is not located within the transmission range of its cooperative primary member. (c) Both conditions are satisfied and necessary condition of 1S2P cooperation for further progress is guaranteed.Back to article page