6. CONCLUSION
This study focused on the main parameters of LTE physical layer as well as the most frequent scenarios for mobile communications. Several techniques and technologies such as OFDM, OFDMA, SC-FDMA, and MIMO for the cellular systems were studied using a Link Level Simulator based on MATLAB program. A reduction of system BER and BLER can be achieved in LTE downlink transmission. The effects of different numbers of HARQ retransmissions and turbo code iterations were investigated for SISO mode. Different user speeds were simulated and analyzed in terms of BER, BLER, and throughput in SISO systems, where MMSE channel estimator has a much better consequence on transmission than the LS channel estimator. A system experiencing AWGN channel condition results in a significant BER and throughput improvement compared to systems involving with PedB, VehB or Flat Rayleigh channel types. The system involving with PedB channel results in a better performance. In MIMO systems, increasing the system bandwidth is a very effective way, but this solution obviously is significantly costly for service providers. Moreover, evaluation of physical layer throughput can be performed for next Release(s) of 3GPP, since some effective modern technologies such as bandwidth extension up to 100 MHz and supporting more antenna ports can highly impact the performance.
