Sarnimi - Tarbiat.Modares University Iehran, Iran
Azmi - Tarbiat.Modares University Iehran, Iran
Hakkak Tarbiat.Modares University Iehran Iran

In this paper, we propose an approxintate analytical method for calculating symbol error probability (SEP) of hybrid selection/maximal ratio combining (H-S/MRC) diversity system in multipath fading channels. LItith using H-S/MRC technique, L out of N diversity branches are selected and their signals combined using maximal-ratio combining (MRC) method. The evaluation of SEP for such system is very complicated; since the ordered physical branches signctl used in the H-S/IIRC combining process are not independent, even though the unordered diversity branches signals are independent. This fact makes dfficult deriving the probability distribution function (PDF) of the combiner output SNII which is needed in the evaluation of SEP. In our proposed approximation melhod, ve only need the mean and the variance of the SNR of the combiner output, instead of its exact PDF. This featnre leads us to develop a closed-form simple analytical expression for approximation of SEP To presenl an application ofour proposed method and show ils reasonable accuracy, we consider coherent delectton of M-ary phase-shift keying QIIPSK) using H-S/MRC for the case of independent diversity branches signals vitlt equal signal-to-noise ratio over Rayleigh fctding channel. Comparing exact results for SEP ofthis systent with the results derived based on our approxintation method shows the good accuracy of the proposed method.

Diversity combining, Fading channel, Ceneralized Selection Combining (GSC), Maximal Ratio Cornbining (MRC), Hybrid Selection/Maximum Ratio Combining (H-S/MRC).