Design issues for mimo-ofdm wireless communication systems

Hilal Adnan Fadhil
Dr. R. S. Fyath
Dr. K. A. Ghaidan

Abstract : In the mobile radio environment, signals are usually impaired by fading and multipath delay spread phenomenon. In such channel, severe fading of the signal amplitude and Inter-Symbol Interference (ISI) lead to unacceptable degradation of the system error performance. It is expected that Orthogonal Frequency Division Multiplexing (OFDM) is capable of providing very high data rate with strong robustness of multipath delay spread, which make that ISI is no longer a problem. In this thesis, a MATLAB-Simulink tool is used to design OFDM wireless communication systems to obtain system parameters and to test the influence of various system impairments. Simulation results are presented for both Single-Input Single-Output (SISO) and Multi-Input Multi-Output (MIMO) configurations. The performance of SISO system is examined under various modulation schemes and channel types. Simulation results are presented for QPSK, DQPSK, and 16-QAM modulation schemes and for Additive White Gaussian Noise (AWGN), Rician, and Rayleigh channel characteristics. The results indicate clearly that QPSK system gives the best performance for all channel types. For a MIMO system, two main configurations are analyzed and tested. The first configuration is based on Space Frequency-Bit Interleaved Coded Modulation (SF-BICM). The second configuration is based on Multicarrier Delay Diversity Modulation (MDDM). Both configurations are tested under various channel models and modulation schemes. The results indicate clearly that SF-BICM system gives about 2dB advantages compared with MDDM system.