  The design of linear precoders or decoders for multiuser (MU) multiple-input
multiple-output (MIMO) filterbank multicarrier (FBMC) modulations in the case
of strong channel frequency selectivity is presented. The users and the base
station (BS) communicate using space division multiple access (SDMA). The low
complexity proposed solution is based on a single tap per-subcarrier
precoding/decoding matrix at the base station (BS) in the downlink/uplink. As
opposed to classical approaches that assume flat channel frequency selectivity
at the subcarrier level, the BS does not make this assumption and takes into
account the distortion caused by channel frequency selectivity. The expression
of the FBMC asymptotic mean squared error (MSE) in the case of strong channel
selectivity derived in earlier works is developed and extended. The linear
precoders and decoders are found by optimizing the MSE formula under two design
criteria, namely zero forcing (ZF) or minimum mean squared error (MMSE).
Finally, simulation results demonstrate the performance of the optimized
design. As long as the number of BS antennas is larger than the number of
users, it is shown that those extra degrees of freedom can be used to
compensate for the channel frequency selectivity.
