Abstract: In multi-relay cooperative communication, Optimal Relay Selection (ORS) greatly simplifies network physical layer design by eliminating the need for accurate synchronization of all nodes. Equal Gain Combining (EGC) does not need to evaluate the decline amplitude, each branch has the same unit gain, weight coefficient does not change with the strength of fading channel signal at any time, which simplifies the complexity of the system design and implementation. Therefore, we propose in this paper, the polarization antenna is configured for the communication terminal, and the polarization diversity signal is processed by EGC without increasing the terminal volume, so as to overcome channel fading and further improve the performance of Decode-and-Forward ORS cooperative communication system. The theoretical analysis and simulation results show that the outage probability index of Decode-and-Forward ORS cooperative communication system is obviously better than that of the cooperative communication system without EGC polarization diversity technology in the same SNR and channel fading. Finally, EGC is compared with other polarized diversity merging techniques.

Key words: optimal relaying selection, decode and forward, outage probability, polarization antenna