This work is inspired by the large capacity increase that may be
achieved by using multi-element antenna arrays (MEA) at both
transmitting and receiving sites. We present a numerical study of the
information-theoretic capacity of indoor wireless systems that employ
MEAs, based on realistic ray-tracing modeling of propagation in an
office building. The Shannon capacity, C(n), for multi-antenna
systems assuming that the transmitter knows the channel is computed,
and is compared to the mutual information, M(n), achieved with
equal power allocation when the transmitter does not know the
channel. Results show that for a fixed average received SNR, the gap
between C(n) and M(n) grows as the number of antennas is
increased. We also investiage the effect of the received SNR on
C(n) and M(n). We derive expressions for the asymptotic
growth of capacity as the number of antennas grows large and compare
these asymptotic results with the capacities computed using simulated
channel responses. The results reported in this paper serve as a
preliminary exploration of MEA systems, and we anticipate obtaining
different capacity estimates for different environments or when actual
measurements are made.