Performance Evaluation of LMS and VSS-LMS Channel Estimation Techniques for LTE Uplink

Abstract

One of the essential goal of Long Term Evolution (LTE) is increasing speed and capacity without consuming high power especially in uplink, in order to save battery life of user equipment as long as possible. Since Single Carrier Frequency Division Multiple Access (SC-FDMA)achieves this, it has been utilized in the uplink of 3GPP LTE. However the high capacity and speed will affect the received data since it will cause increasing in Doppler shift. This leads to the need of using channel estimation technique in the receiver (eNodeB) to recover the received signal. In this thesis SC-FDMA is modeled using MATLAB and then Least Mean Square (LMS) and Variable Step Size Least Mean Square (VSS-LMS) channel estimation techniques are applied in order to evaluate their performance in terms of Bit Error Rate (BER), Mean Square Error (MSE) and algorithm complexity. The evaluation of the algorithms was done under different modulation techniques (Binary Phase Shift Keying (BPSK) and Quaternary Phase Shift Keying (QPSK)) and different channel models (Additive White Gaussian Noise (AWGN) and Rayleigh fading channel with fading shift 5, 50 and 500 Hz). The simulation results shown that the modulation type affects the performance on BER and MSE; however, channel environment has an obvious effect. VSS-LMS algorithm has better performance than LMS in all cases; however it requires more multiplication and addition operations.