On the Effect of Interference on the Average Degrees of Freedom in MIMO Fading Ad-Hoc Networks

We consider MIMO fading ad-hoc networks with Rayleigh co-channel interference (CCI) where, L transmitter/receiver pairs communicate independent information over the network, simultaneously. We investigate the effect of CCI on the system capacity using the concept of degrees of freedom (DOF), where DOF represents the number of valid subchannels formed by channel decomposition. We present a new definition of average degrees of freedom (ADOF). We study the impact of the number of interferers on ADOF of each user. We will show that as the number of users, L, increases the ADOF of each user decreases and as L tends to infinity, the ADOF approaches one. This supports our earlier results concerning the asymptotic optimality of beamforming in MIMO fading ad-hoc networks.