In this thesis, the performances of Least Square (LS) and Minimum Mean Square Error (MMSE) techniques for Long Term Evolution-Advanced (LTE-A) physical layer are evaluated using different transmission schemes and different detectors. Transmission schemes include Transmit Diversity (TxD) and Open Loop Spatial Multiplexing (OLSM). Different detectors consist of the use of Zero Forcing (ZF) and Soft Sphere decoder (SSD) detectors. The evaluation is conducted using different number of transmit-receive antennas (Multiple Input Multiple Output MIMO). The performance is measured in terms of throughput and Bit Error Rate (BER) for different wireless channel models where the simulation is carried out using link level simulator from "Vienna University of Technology" and a developed model using Matlab. The obtained results show that MMSE perform better than LS under different environments in minimizing the occurrence of BER using TxD scheme with both detectors, while MMSE achieve high system's throughput using OLSM especially when SSD detectors are employed. The estimation techniques in 4x4 achieve better BER than 4x2 when using TxD as a transmission scheme while LS and MMSE in 4x4 doubles the throughput compared with 4x2 when applying OLSM transmission scheme. This is due to the fact that in TxD, diversity gain is obtained and lead to diversity order. As a diversity order increase, which depends on the number of transmit-receive antennas, the BER decrease. In OLSM, 4 data streams are detected at the receiver side in 4x4 MIMO system that make the throughput to increase and doubles than that in 4x2 MIMO system. Furthermore, channel estimation for LTE-A system is implemented with (8x1) transmit-receive antennas. The result obtained shows a decrease in the BER and achieve Transmit Diversity (TxD) between Base Station (BS) and User Equipment (UE) that makes the system provides better performance in term of BER.