Ergodic Capacity of Two-Hop Multiple Antenna AF Systems With Co-Channel Interference

In this letter, we analyze the ergodic capacity of a two-hop multiple-antenna amplify and forward (AF) system, where the relay is subject to co-channel interference (CCI) while the destination is corrupted by additive white Gaussian noise (AWGN) only. A novel integral transform, called the complementary moment generating function transform (CMGF), is proposed as a unified tool to compute the ergodic capacity. When both the relay and destination perform maximum ratio combining (MRC), we derive a new analytical exact expression for the ergodic capacity. It is shown that the ergodic capacity is better improved by increasing the number of antennas at the relay N
_r
than that at destination N
_d
. Unfortunately, the system shows an incapability of canceling interference even if N
_r
and/or N
_d
grows large.