A Novel Method to Estimate the End to Multi-End Capacity Bounds in MU-MIMO-Relay Broadcast Channel

We characterize the capacity of broadcast channel in MU-MIMO system with fixed relays. By analyzing the similarities between the model of MU-MIMO with relays and the circuit with multiple capacitors, we give a method to estimate the end to multi-end broadcast capacity. In our method, we first partition the relay system into simple point to point components and calculate the capacity of each point to point link; then, we get the sum capacity of the broadcast channel, by calculating the point to point capacities in "parallel" or "cascade" way. Due to the difficulty of finding close-form solution to the non-convex problem, we estimate the upper and lower bounds of the broadcast capacity.