Cooperative cellular networks using multi-user MIMO: trade-offs, overheads, and interference control across architectures

Multi-user multiple-input multiple-output can be viewed as an interference control technique relying on cooperative transmission and/or reception over multiple antennas. A cooperating set of antennas can be collocated at a common cell site or distributed across multiple sites. As such, MUMIMO can be applied to a wide variety of architectures ranging from traditional cellular to more elaborate intertwined cooperative designs. We consider examples of such MU-MIMO architectures, and study the impact the scheduling criterion, cell density, and coordination can have on the average and cell edge user rates across different designs. Importantly, MU-MIMO has inherent physical layer overheads, which, as the examples illustrate, depend on the degree of coordination and the architecture. Such overhead considerations are very important in assessing net rates and, depending on the scenario, can motivate designs using less cooperation.