An efficient algorithm for optimum joint downlink beamforming and power control

Martin Schubert, Holger Boche

Research output: Contribution to journalConference articlepeer-review

17 Scopus citations


We address the problem of joint downlink beamforming and power control in a frequency flat multi-antenna broadcast channel. In this context, a common optimization strategy is to maximize the system throughput under a certain power constraint. This, however, does not guarantee a fair sharing of throughput among the users, which is required in case that the receivers cannot cooperate. Thus, we propose a different approach, which always assumes optimally balanced data rates. If the problem is feasible, i.e., desired target rates can be reached, spare degrees of freedom can be used in order to minimize the total transmission power. This strategy can even be applied if only spatial covariance channel information is available. The authors have developed a theoretical framework based upon uplink/downlink durability, feasibility considerations, and bounds on the maximal eigenvalue of the resulting coupling matrix. In this paper an overview of the results is given and they are discussed in the context of existing literature. Finally, a theoretical benchmark is provided for the case of perfect channel knowledge. Then, beamforming can be combined with Costa pre-coding, as proposed by Caire and Shamai [1,2]. This leads to a closed-form solution of the problem.

Original languageEnglish
Pages (from-to)1911-1915
Number of pages5
JournalIEEE Vehicular Technology Conference
StatePublished - 2002
Externally publishedYes
Event55th Vehicular Technology Conference - Birmingham, AL, United States
Duration: 6 May 20029 May 2002


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