Performance evaluation of MIMO system using LTE downlink physical layer

Orthogonal Frequency Division Multiplexing (OFDM) is the transmission scheme adopted for downlink of the popular Long Term Evolution (LTE) technology. It is a multi-carrier technique which divides a large system bandwidth into multiple narrowband sub-carriers and treat the frequency selective fading as flat fading. LTE employ Multiple Input Multiple Output transmission in conjunction with OFDM (MIMO-OFDM) to improve the data rates and system performance. In this paper, the Physical Downlink Shared Channel (PDSCH) performance of MIMO system based on LTE specification, is evaluated using linear and non-linear receiver's decoder in ITU defined channel models with different modulations. The result are presented for Transmit Diversity (TD) scheme using different antenna configurations, and Spatial Multiplexing (SM) scheme using optimum performance configuration with the said receiver structure. The result shows the needs of equipping wireless system with multiple antennas for system Bit Error Rate (BER) and the overall system capacity. Significant improvement in BER is achieve with Sphere Decoding (SD) receiver as compared with Minimum Mean Square Error (MMSE) receiver and improved system capacity with the increase in the Base Station (BS) transmitting antennas.