Error Rate Probability for Coded MQAM with MRC Diversity in the Presence of Cochannel Interferers over Nakagami-Fading Channels

Exact expressions for bit-error probability (BEP) for coherent square detection of uncoded and coded M-ary quadrature amplitude modulation (MQAM) using an array of antennas with maximal ratio combining (MRC) in a flat fading channel interference limited system in a Nakagami-m fading environment is derived. The analysis assumes an arbitrary number of independent and identically distributed Nakagami interferers. The results for coded MQAM are computed numerically for the case of (24,12) extended Golay code and compared with uncoded MQAM by plotting error probabilities versus average signal-to-interference ratio (SIR) for various values of order of diversity N, number of distinct symbols M, in order to examine the effect of cochannel interferers on the performance of the digital communication system. The diversity gains and net gains are also presented in tabular form in order to examine the performance of digital communication system in the presence of interferers, as the order of diversity increases. The analytical results presented in this paper are expected to provide useful information needed for design and analysis of digital communication systems with space diversity in wireless fading channels.

Authors:

• J.S. Ubhi
• M.S. Patterh
• T.S. Kamal

Keywords:

• Cochannel interference
• maximal ratio combining
• Nakagami-m fading
• wireless digital communications.

References:

[1] J. H. Winters, "Optimum combining in digital mobile radio with
cochannel interference," IEEE J. Select. Areas Commun., vol. SAC-2,
pp. 528-539, July 1984.
[2] J. Cui and A. U. H. Sheikh, "Outage probability of cellular radio systems
using maximal ratio combining in the presence of multiple interferers,"
IEEE Trans. Commun., vol. 47, pp. 1121-1124, Aug. 1999.
[3] J. Cui, D. Falconer, and A. Sheikh, "Performance evaluation of optimum
combining and maximal ratio combining in the presence of co-channel
interference and channel correlation for wireless communication
systems," Mobile Networks Applicat., vol. 2, pp. 315-324, 1997.
[4] Y. Yao and A. U. H. Sheikh, "Investigation into cochannel interference
in microcellular mobile radio systems," IEEE Trans. Veh. Technol., vol.
41, pp. 114-123, May 1992.
[5] N. Nakagami, "The m-distribution, a general formula for intensity
distribution of rapid fading," in Statistical Methods in Radio Wave
Propagation, N. G. Hoffman, Ed. Oxford, U.K.: Pergamon, 1960.
[6] A. Abu-Dayya and N. C. Beaulieu, "Outage probabilities of cellular
mobile radio systems with multiple Nakagami interferers," IEEE
Trans.Veh. Technol., vol. 40, pp. 757-768, Nov. 1991.
[7] V. A. Aalo and J. Zhang, "Performance analysis of maximal ratio
combining in the presence of multiple equal-power cochannel interferers
in a Nakagami fading channel," IEEE Trans. Veh. Technol., vol. 50, pp.
497-503, Mar. 2001.
[8] Simon, M. K., Hinedi, S. M., and Lindsey, W. C., Digital
Communication Techniques-Signal Design and Detection. Englewood
Cliffs, NJ: PTR Prentice Hall, 1995.
[9] T. T. Tjhung and C. C. Chai, "Distribution of SIR and performance of
DS-CDMA systems in lognormally shadowed Rician channels," IEEE
Trans. Veh. Technol., vol. 49, June 2000.
[10] A. Shah and A. M. Haimovich, "Performance analysis of optimum
combining in wireless communications with Rayleigh fading and
cochannel interference," IEEE Trans. Commun., vol. 46, pp. 473-479,
Apr. 1998.
[11] J. G. Proakis, Digital Communication. New York: McGraw-Hill, 1995.
[12] D. Yoon, K. Cho, J. Lee, "Bit error probability of M-ary quadrature
amplitude modulation," Proc. IEEE Veh. Technol. Conf. VTC-2000 Fall,
Sept. 2000; Boston, MA USA; 2000.
[13] M. Abramowitz and I. A. Stegun, Handbook of Mathematical Functions.
New York: Dover, 1970.