Enhanced Selection Combining by Choosing Independently the Strongest Real Component and the Strongest Imaginary Component of all Channels

Conventional selection combining (SC) selects the antenna with the largest channel envelope. In this paper, we propose to select the largest real part and largest imaginary part of the channel individually from all antennas for 2 dimensional (2-D) signals such as MPSK or MQAM. We derive the asymptotic symbol error rate (ASER) expression for this system and it is found that it has the same diversity order (DO) as does conventional SC, but has an SNR gain over conventional SC. The paper presents a closed-form expression for this gain, which monotonically increases with the DO, and is independent of the constellation size for a given modulation format. Simulation results are shown to match the theoretical analysis.