Some Results on the Asymptotic Downlink Capacity of MIMO Multi-user Networks

In this contribution , some results on the downlink capacity of MIMO multi-user networks are provided when only the scattering environment (and not the channel realization) is known at the transmitter. Considering a multi-user system where each terminal employs multiple antennas (including the base station), asymptotic (in the number of antennas) analytical expressions of the system capacity are presented and studied in three different cases: equal time sharing, equal power sharing and optimum time-power scheduling. Interestingly, based only on the knowledge at the base station of the number of scatterers at each receiver link and not the full instantaneous channel realization (which can be fed back with limited overhead), one is able to derive optimal power and time scheduling policies which enhance the performance with respect to uniform time and power allocation. Simulations provided in the case of a small number of antennas confirm the asymptotic claims.