Abstract
In single-user MIMO communication, the first-order
throughput scaling is determined by the smallest of the number of
transmit and receive antennas. This typically renders terminals
the constraining bottleneck. In a multiuser downlink, this
bottleneck can be bypassed by having the base station communicate
with multiple terminals simultaneously, in which case the receive
antennas at those terminals are effectively pooled in terms of the
capacity scaling. This, however, requires that the base have
instantaneous channel information. Without such information, the
structure and statistics of the channel can be exploited to form
multiple simultaneous beams towards the various users, but these
beams are in general mutually interfering. This paper proposes the
use of multiuser detection to discriminate the signals conveyed
over interfering beams. This approach is formulated and
experimentally evaluated on an HSDPA MIMO testbed that involves a
commercial base station, multiantenna terminals, and custom ASICs.