On the Value of Cooperation in Interference Relay Networks ∗

We study fading interference relay networks where M single-antenna sourcedestination terminal pairs communicate concurrently through a set of K relays, each of which is equipped with N (cooperating) transmit/receive antennas, using half-duplex two-hop relaying under the two protocols introduced in [1] and [2], respectively. The main contributions of this paper are: • For fixed N and M, K → ∞, we establish the impact of cooperation at the relay level on network capacity scaling. More specifically, it is shown that asymptotically in M and K cooperation in groups of N relay antenna elements leads to an N-fold reduction in the total number of relays needed to achieve a given per source-destination terminal pair capacity. • We characterize the rate at which the network “crystallizes”, i.e., the individual single-input single-output source-destination terminal pair links decouple and the corresponding random (fading) channel gains converge to a deterministic limit.