Physical Limits to the Capacity of Wide-Band Gaussian MIMO Channels

In this letter a physical limit to the information capacity of a multiple-input multiple-output (MIMO) Gaussian channel is presented exploiting the theory of non-redundant sampling of scattered fields. For a MIMO narrow-band system of arbitrarily large spatial extension, the information capacity limit is the same as the one for a single-input single-output (SISO) ultra-wide band (UWB) system. For MIMO systems of finite size, wide band transmission, and absence of channel state information, space and frequency diversities can be optimally combined by allocating the signal power uniformly across space, and increasing linearly across frequency. (c) 2009 IEEE. Personal use of this material is permitted. Permission from IEEE must be obtained for all other users, including reprinting/ republishing this material for advertising or promotional purposes, creating new collective works for resale or redistribution to servers or lists, or reuse of any copyrighted components of this work in other works.