An optimum linear frequency-selective MIMO equaliser using time-domain analytic inversion

In recent years, theoretical and practical investigations have shown that it is possible to realise enormous channel capacities, far in excess of the point-to-point capacity given by the Shannon-Hartley law, if the environment is sufficient multipath. The majority of work to date on this area has assumed flat sub-channels composing the MIMO channel. As the aim of MIMO systems is often to increase the data transmission rate of a communication system, a wideband and hence highly time-dispersive model would be more appropriate. To properly exploit this environment to realise these capacity increases, the MIMO channel must be equalised so that the performance of any system attempting to harness the multipath diversity can do so while maintaining a satisfactory BER performance. Assuming that the response of the MIMO channel is known at the receiver, a method to create a suitable equaliser is to analytically invert the frequency-selective, or time-dispersive, MIMO channel using a time-domain technique described in this paper. The technique calculates the optimum equaliser coefficients in the MMSE sense.