Capacity scaling in dual-antenna-array wireless systems

Wireless systems using multi-element antenna arrays simultaneously at the both transmitter and receiver promise a much higher capacity than conventional systems. Previous studies have shown that single-user systems employing n-element transmit and receive arrays can achieve a capacity proportional to n, assuming independent Rayleigh fading between pairs of antenna elements. We explore the capacity of dual-antenna-array systems via theoretical analysis and simulation experiments. We present expressions for the asymptotic growth rate of capacity with n for both independent and correlated fading cases; the latter is derived under some assumptions about the fading correlation structure. We show that the capacity growth is linear in n in both the independent and correlated cases, but the growth rate is smaller in the latter case. We compare the predictions of our asymptotic theory to the capacities of channels simulated using ray tracing, and find good agreement even for moderate n, i.e., 1⩽n⩽16. Our results address both the cases when the transmitter does and does not know the channel realization