Iterative, Rate-Constrained Capacity of MIMO Broadcast Channels


M. Airy, B. Mondal, Robert W. Heath Jr. and S. Shakkottai


In Proc. 38th Annual Conference on Information Sciences and Systems (CISS), 2004.


A transmitter antenna array has the ability to simultaneously transmit to multiple receivers within a wireless network. While the general capacity region of such multiple antenna broadcast channels remains unknown, the sum capacity point is well characterized and is the point most distant from the origin in the “dirty paper” rate region of the multiple antenna broadcast channel. The primary contribution of this paper is to present a method that achieves a specified point, i.e. a given rate vector, within the “dirty paper” rate region of the multiple antenna Gaussian broadcast channel. Using a combination of linear precoding (known interference precoding) and spatial filtering (beamforming), an iterative algorithm using unitary eigenspace rotations and waterfilling is presented that converges to the given rate vector.