Inter-Substream Interference-Free Criterion for MIMO Interference-Unaware Receiver

Abstract

In this paper, we study the interference-unaware receiver (IUR), which does not need the knowledge of interference or the process for precoding at the transmitter, for the interference-limited multiple-input-multiple-output (MIMO) system. We show that if the number of receive antennas is smaller than a threshold, then the interference terms dominate the MIMO channel capacity and the achievable rates of IUR so that the achievable rates of IUR can be significantly degraded by the interferences. We further show that if the number of receive antennas is larger than the threshold, then increasing the number of receive antennas can let the interference terms be negligible so that the MIMO channel capacity and the achievable rates of IUR all can reach M times the channel capacity of 1 by N single-input-multiple-output (SIMO) channel, where M denotes the number of transmit antennas and N denotes the number of receive antennas. This implies that in addition to completely eliminating cochannel interference, increasing the number of receive antennas in IUR can also make the MIMO system transmit M parallel substreams without inter-substream interference.