Presented at the
1997 IEEE International Conference on Acoustics, Speech,
and Signal Processing
Estimation of Optimal Weight Vectors for Spatial Broadcast Channels
Murat Torlak (1),
Guanghan Xu (1),
Brian L. Evans (1),
Hui Liu (2)
(1) Department of Electrical and Computer Engineering,
Engineering Science Building,
The University of Texas at Austin,
Austin, TX 78712-1084 USA
(2) Department of Electrical and Computer Engineering,
University of Virginia, Charlottesville, VA
In a multi-transmitter broadcast system,
the weight vector for each message signal can provide
an additional degree of freedom for signal enhancement
and interference suppression by taking advantage of the
spatial diversity among the users.
The design of optimal weight vectors that
maximize the overall channel capacity is an open problem.
Under certain power constraints, the channel capacity R
is a highly nonlinear function of the M-dimensional
weight vectors wi, where M is the number
Hence, a closed-form algebraic solution that
maximizes R over wi does not seem to be tractable.
In this paper, we decouple the weight vectors in R to simplify
the optimization problem to a search for the maxima of a smooth
Based on this decoupling, we derive and evaluate two algorithms
for computing weight vectors for the two-user and three-user cases:
orthogonal and optimal.
We also propose a near-optimum algorithm for the two-user case.
The optimal algorithm requires an iterative search.
The full paper is available in PDF format.
Last Updated 02/06/99.