# Maximizing Spectral Efficiency in Multiple-Input Multiple-Output Antenna Systems

### Authors:

Robert W. Heath Jr, David Gesbert, and A.J. Paulraj

### Reference:

Proc. of XXVIth International Union of Radio Science (URSI '99), Toronto, Canada, August 13-21, 1999.

### Abstract:

There has been significant recent interest in communication in Rayleigh fading environments with {\it both} transmit and receive antennas. This is no surprise since it has been shown that the so-called M x N multivariate Raleigh fading channel has the potential to have a capacity which grows asymptotically in proportion to min(M,N). Both transmit diversity and spatial multiplexing schemes have been proposed to approach this capacity, each with different diversity and rate tradeoffs. In this paper we study space-time block coding, delay diversity, and simple spatial multiplexing in the 2 x 2 and the 10 x 10 multivariate Rayleigh fading channels. Through analytical results and simulations we examine some relative tradeoffs in terms of power, rate, and spectral efficiency among the systems. For the smaller number of antennas we find that diversity plays a key role while for the larger number of antennas the potential rate offered by spatial multiplexing becomes more significant.

### Keywords:

MIMO, spatial multiplexing, space-time coding.

Only a summary appeared in the conference proceedings.