Coordination limits in MIMO networks

Communication quality in interference-limited wireless networks depends heavily on the collective coordination among the users for mitigating the interference. Coordinating the users, viable through information exchange across the network, consumes communication resources and, therefore, is desired to be free of redundancy. This paper focuses on dense multi-cell multi-antenna networks and assesses the minimum coordination level that ensures achieving the optimal scaling law of the downlink sum-capacity of the network. It is demonstrated that exchanging a finite number of bits across the network, in the form of feedback and cooperation, suffices to achieve the optimal capacity scaling. This coordination level is considerably less than those required by the existing coordination strategies which necessitate exchanging infinitely many bits across the network. A constructive proof is provided.