(AS3), Algorithm 2 also performs better than the reference
scheme by about 6 to 8 dB, and their total power performances
do not vary with the IRI level too much. The reason for this
is that the number of receive antennas of each relay (Nr = 2)
is larger than the number of interfering relays (L−1 = 1) for
(AS3), thereby providing an extra spatial degree of freedom
for the IRI suppression on the feeder links. However, when
more relays coexist, it may not be very practical for each relay
equipped with more antennas than the number of interfering
relays due to physical size limitations of relays. The simulation
results for the case of L = 3 are shown in Fig. 4, where only