Sum rate maximization for uplink distributed massive MIMO systems with limited backhaul capacity

We investigated the uplink sum rate maximization for Distributed Massive MIMO (DM-MIMO) system with limited backhaul capacity. In this system, a number of single antenna autonomous terminals simultaneously transmit data streams to a group of distributed Remote Radio Heads (RRH). These RRHs are connected to a Central Unit (CU) via links with limited capacity. Each RRH quantizes the signal received by each of its antennas and forwards the bits to the backhaul. In this paper we first derive uplink achievable sum rate of the DM-MIMO system under limited backhaul capacity. Due to the complexity of the derived sum rate, an estimation is presented considering the massive MIMO context. This estimated sum rate is verified numerically. Then we show that even if backhaul capacity is limited, DM-MIMO can outperform the centralized case. Finally the sum rate maximization problem for DM-MIMO is formulated and simplified version of the problem is solved.