Joint power and backhaul bits allocation for coordinated multi-point transmission

In this paper, we study the problem of backhaul sharing in Network MIMO. In case of a backhaul of limited number of bits, we investigate how to allocate these bits jointly with the base-stations power among users in order to maximize the sum-rate under fairness constraints. Firstly, we study this problem with the assumption of one user per cell. We find that binary allocation of power is optimal. Then, the multi-user case is considered. A solution of the optimization problem is developed under high signal-to-interference and noise ratio(SINR). We prove that under these assumptions, backhaul bits allocation among the cells or among the users of each cell has no effect on the sum-rate of system. Hence, allocating these bits in order to achieve fairness conditions is possible without any loss in the sum-rate.