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Mitigation of Impairments due to Noise and Rayleigh Fading in an MIMO-OFDM System

R. Bijukumar, Bijan B.Das

Abstract



The chance of impairment in broadband communication is mainly due to multipath delay spread. Since the signal duration is very short compared to the coherence time of the channel, the loss due to this multipath delay spread, so called as fading will be very high. And it is found that the nature of this fading is frequency selective. Other impairments are inter symbol interference (ISI) and noise. In this paper a method is proposed, to mitigate the error due to channel impairments in wide band communication systems. This is achieved by effectively employing Multi Input Multi Output-Orthogonal Frequency Division Multiplexing (MIMO-OFDM) system. Since this system divides a broadband channel into narrow band sub channels the frequency selective fading may change into flat fading which can be easily mitigated by OFDM technique. Interference can also be reduced by OFDM by the insertion of cyclic prefix. MIMO ensures spatial diversity and increase in throughput. Then combining Forward Error Correction (FEC) codes and the interleaver, the error due to noise can also be minimized.

Keywords


Orthogonal frequency division multiplexing (OFDM), Convolutional code, Multi Input Multi Output (MIMO), Minimum Mean Square Error (MMSE) estimate.

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