Comprehensive analysis of LMS and NLMS algorithms using adaptive equalizers

The main emphasis in this paper lies on evaluation of adaptive algorithms which are predominantly used. They are LMS and NLMS algorithms respectively. Initially these algorithms are applied on adaptive equalizers. Then we further analysed and compared two types of LMS algorithms namely sign-sign LMS algorithm and sign-sign LMS algorithm. The overlap of coefficients is very high when step-size is very small. We found that LMS algorithm is simple and gives good results if proper step size is chosen and NLMS alternates step-size according to energy of input signal hence it is suitable for both stationary as well as non-stationary environment. Regarding sign-data and sign-sign LMS algorithms we found that the former is better than the latter as deviations and amplitude are very high in the latter case.

[1]  Azzedine Zerguine,et al.  Decision feedback equalisation of coded I-Q QPSK in mobile radio environments , 1999 .

[2]  Hen-Geul Yeh,et al.  The use of transform domain LMS algorithm to adaptive equalization , 1993, Proceedings of IECON '93 - 19th Annual Conference of IEEE Industrial Electronics.

[3]  A. Cole-Rhodes,et al.  Performance of an adaptive blind equalizer for QAM signals , 2005, MILCOM 2005 - 2005 IEEE Military Communications Conference.

[4]  Nikola Kasabov,et al.  CHANNEL EQUALIZATION USING ADAPTIVE FILTERING WITH AVERAGING , 2000 .

[5]  Dennis R. Morgan,et al.  On a class of computationally efficient, rapidly converging, generalized NLMS algorithms , 1996, IEEE Signal Processing Letters.

[6]  Kong-Aik Lee,et al.  Improving convergence of the NLMS algorithm using constrained subband updates , 2004, IEEE Signal Processing Letters.

[7]  Wang Junfeng,et al.  Design of Adaptive Equalizer Based on Variable Step LMS Algorithm , 2010 .

[8]  B. P. Lathi.  Modern digital and analog communication systems / B.P. Lathi , 1998 .

[9]  Tzi-Dar Chiueh,et al.  Algorithm and architecture design for a low-complexity adaptive equalizer , 2003, Proceedings of the 2003 International Symposium on Circuits and Systems, 2003. ISCAS '03..

[10]  Esam Abdel-Raheem,et al.  Computationally-efficient methods for blind adaptive equalization , 2005, 48th Midwest Symposium on Circuits and Systems, 2005..

[11]  David D. Falconer,et al.  Suppression of adjacent-channel, cochannel, and intersymbol interference by equalizers and linear combiners , 1994, IEEE Trans. Commun..