The ultimate capacity of MIMO channels and its realization

It has been shown recently that the point-to-point capacity can be significantly increased if multiple transmitting and receiving (MIMO) antennas are used [1], [2], [3] and [4]. Since the MIMO channel depends on the relative positions and the relative beam directions of their antennas, it may be interesting to find the limitation of the capacities of MIMO channels, i.e., the ultimate capacity. In this presentation, the explicit solution of ultimate capacity is derived. The criterion for the channel that realizes the ultimate capacity is presented. It is shown that when the ultimate capacity is realized, this ultimate channel can both block all interferences and raise the capacity to the ultimate capacity, which can not be achieved by either the commonly used coding/decoding technique or the signal processing technique. Simulation shows that the ultimate capacity is about 50% higher than the average capacity with strong interferences and 19% higher than the average capacity without interferences.