Partially Coherent EGC Reception of Uncoded and LDPC-Coded Signals over Generalized Fading Channels

This paper studies the bit-error rate (BER) performance of partially coherent equal-gain combining reception of uncoded and low-density parity-check (LDPC)-coded binary and quaternary phase-shift keying signals over generalized α − μ fading channels. For the uncoded signal detection case the obtained numerical and simulation results illustrate the BER performance degradation due to the imperfect reference signal recovery, receiver unbalancing and fading. It is demonstrated that imperfect cophasing causes an irreducible BER performance. Furthermore, we design large girth quasi-cyclic LDPC code with high code rate, suitable for use in communications over generalized fading channels. The proposed LDPC code does not exhibit the error floor phenomena, in the region of interest, even in the presence of imperfect cophasing and receiver unbalances, and outperforms standard convolutional code of lower code rate in the observed impairments. The effects of number of iterations in decoding algorithm and codeword length on BER performance are also investigated. A part of this paper was presented at IEEE WCNC 2009. G. T. Djordjevic (B) Department of Telecommunications, Faculty of Electronic Engineering, University of Nis, Aleksandra Medvedeva 14, 18000 Nis, Serbia e-mail: [email protected] I. B. Djordjevic Department of Electrical and Computer Engineering, University of Arizona, 1230 E. Speedway Blvd., Tucson, AZ 85721, USA e-mail: [email protected] G. K. Karagiannidis Department of Electrical and Computer Engineering, Aristotle University of Thessaloniki, Thessaloniki 54 124, Greece e-mail: [email protected]