ABSTRACT
Scaling Laws of Multiple
Antenna Group-Broadcast Channels
Broadcast (or point to multipoint)
communication has attracted a lot of research
recently. In this talk, we consider the
multiple antenna group broadcast channel
where a base station is to transmit to a
group of users and where the users' pool
is divided into K groups, each group of
which is interested in common information.
Such a situation occurs for example in digital
audio and video broadcast where the users
are divided into various groups according
to the shows they are interested in. When
each group consists of exactly one user,
group broadcast simplifies to the familiar
broadcast problem. When there is exactly
one group of users (interested in common
information), the scenario simplifies to
the unicast problem.
Finding the sum-rate capacity
for the group broadcast is very challenging.
As such, we study the scaling laws of the
sum-rate in the large number of users and/or
large number of antennas regimes. In the
talk, we quantify the effect of spatial
correlation on the system capacity and the
sum-rate achieved by various scheduling
schemes. Intuitively, the group broadcast
capacity should decrease with the number
of users. The talk thus shows that in order
to achieve a constant rate per user, the
number of transmit antennas should scale
at least logarithmically with the number
of users.
This is a joint work with
Amir Dana (Qualcomm Corporation) and Babak
Hassibi (California Institute of Technology)