Performance analysis of a (3, L) selection combining scheme for binary NCFSK signals on Rayleigh fading channels

A b s t r a G In a previous paper, we derived the optimum selection combining (OSC) scheme for binary noncoherent FSK (NCFSK) signak on independent (but not necessarily identically distributed) Rayleigh fading chanuels with Lautenna diversity reception. In the OSC scheme, the diversity branch having the largest magnitude of the logarithm of the ratio of the a posteriori probabilities (log-APP ratio LAPPR) of the transmitted information hit is chosen. In this paper, we derive. the bit error performance of a (3, L) selection combining scheme for binary NCFSK signak which combines the three branches whose LAPPR magnitudes are the largest among the available L branches in i.i.d Rayleigh fading. Numerical resnlb for this (3, L) selection scheme show that, for L = 5, combining the three branches with the largest LAPPR magnitudes yields almost the f d performance of the square-law combining of all the L = 5 branches. For L = 7, the performance of combining the three hrancheswith thelargest LAPPRmagnitudesis just about 0.2 dB worse from the performance of square-law combining of all the L = 7 branches. We also compare the performance of the proposed (3, L) selection scheme with the (3, L) selection combining scheme of Chyi er al.