  In this paper, we propose to evaluate the performance of channel estimation
techniques for Long Term Evolution (LTE) Downlink systems based on Zero Padding
technique (ZP) instead of Cyclic Prefixing (CP). LTE Downlink system is a
multiuser system based on a MIMO-OFDMA technology. Usually, in OFDM systems, a
guard interval is inserted in order to mitigate both inter-carrier interference
(ICI) and inter-symbol interference (ISI). LTE Downlink systems are based on
CP-OFDM technique which consists of a copy a last OFDM symbols inserted at the
beginning of each transmitted OFDM symbol. Although this technique shows good
performances, the CP-LTE system suffers from a power efficiency loss.With the
number of present OFDM symbols in LTE Downlink radio frame, the bandwidth loss
becomes more important. Instead of CP, we propose to evaluate the performance
of ZP-LTE systems in order to avoid the power efficiency .In this paper, we
interest to evaluate the performance of channel estimation techniques for the
two LTE Downlink systems. Simulations results show that although ZP-LTE systems
outperform CP-LTE Downlink systems in terms of power efficiency, the CP-LTE
systems show better performance than ZP-LTE systems and especially for high SNR
values. MATLAB Monte-Carlo simulations are used to evaluate the performance of
LS, LMMSE and Lr-LMMSE estimators in terms of Mean Square Error (MSE) and Bit
Error Rate (BER) for 2x2 LTE Downlink systems.
