Improvement of efficiency of MIMO-OFDM system using channel adaptive subcarriers allocation algorithm with equal power

摘要

The Modern Society is becoming more and more dependable on technological inventions and gadgets which are increasing on very fast rate, hence user demands for wireless communication are increasing but existing networks are not able to fulfil the high data rate requirement for such services. As high data rate wireless access can be supported by more bandwidth but due to spectral limitations, it is very expensive to increase. Hence the available bandwidth is needed to be used efficiently. Orthogonal Frequency Division Multiplexing (OFDM) has been explored as a promising interface technology to utilize the bandwidth effectively. In order to serve multiple user demands, one of the most sophisticated techniques, resource allocation technique can be integrated into the OFDMA system. For achieving higher spectral efficiency and better Quality of Service (QoS) such as capacity and Bit Error Rate (BER) a combination of MIMO and OFDMA can be used. The present paper aims at developing a MIMO-OFDMA system for downlink transmission within one single cell. As an optimization method, subcarrier allocation is used for resource allocation. Eigen Value Decomposition (EVD) is used to decompose the MIMO channel into parallel single channels. On the basis of priority of user, subcarrier selection is done by using dominant eigen channels. By comparing the static allocation method (equal subcarrier allocation with equal power) and adaptive allocation methods (adaptive subcarrier allocation with equal power) the performance of the system is evaluated.