Joint Optimization of Transmit Power and Codebook Size for Multiuser MISO Systems

Transmit power and feedback bandwidth are two limited and interrelated resources which are crucial to system performance in wireless channel with feedback, so it is necessary to maximize their utilization efficiencies in the joint sense. In this paper, we investigate the inherent relationship between transmit power and codebook size in multiuser limited feedback MISO system by making use of Grassmann line packing theory, as an effort to provide an insight on how to jointly distribute the two resources to fulfill the diverse requirements. Then, the impact of feedback delay on the tradeoff relation is characterized in detail, and we find that even with relatively small delay, there is considerable performance loss with respect to the ideal case. Thereby, much more transmit power or feedback bandwidth should be consumed to achieve the same performance target. Finally, the theoretical claims are validated by numerical results.