Title :
Adaptive WHT Aided QAM for Fading Channels Subjected to Impulsive Noise
Author :
Byoungjo Choi ; Hanzo, Lajos
Author_Institution :
Dept. of Embedded Syst. Eng., Univ. of Incheon, Incheon, South Korea
Abstract :
The Bit Error Rate (BER) expressions of Walsh-Hadamard Transform (WHT) aided Quadrature Amplitude Modulation (QAM) transmitted in impulsive noise environments are derived. It is found that there is a crossover point between the conventional and WHT-aided schemes´ BER curves, above which WHT is beneficial in terms of the corresponding BER performance. The exact crossover SNR is analysed and its approximate closed-form expression is derived for a QPSK scheme based on the Chernoff bound. An adaptive WHT scheme is proposed for QAM systems, where the transmitter activates the WHT only when the instantaneous SNR at the receiver is higher than the crossover SNR. The theoretical BER of our adaptive WHT scheme is derived for QAM systems operating over Nakagami-m fading channels. It is found that our adaptive WHT scheme is effective in terms of mitigating the detrimental effects of impulsive noise over the entire SNR range.
Keywords :
Hadamard transforms; Nakagami channels; Walsh functions; approximation theory; error statistics; impulse noise; quadrature amplitude modulation; quadrature phase shift keying; radio transmitters; Chernoff bound; Nakagami-m fading channels; QPSK scheme; SNR; WHT-aided scheme BER curve; Walsh-Hadamard transform; adaptive WHT aided QAM; bit error rate; closed-form expression approximation; impulsive noise environments; quadrature amplitude modulation; transmitter; Bit error rate; Fading; Lead; Phase shift keying; Quadrature amplitude modulation; Signal to noise ratio; QAM; WHT; adaptive; impulsive noise;
Journal_Title :
Communications Letters, IEEE
DOI :
10.1109/LCOMM.2013.052413.130690