Design of Beamformaing in the Satellite Downlink with Static and Mobile Users

We consider the downlink (DL) of a satellite communication system, where a satellite equipped with a large number of antenna elements conveys information to single-antenna mobile receivers and static users on the earth's surface, i.e., the DL is modeled as a vector broadcast channel (BC). While for the static users, perfect channel state information is a valid assumption, only the statistics of the channels to mobile users are known to the satellite due to the large round-trip time. As especialty of satellite communications, the channel covariance matrices of the statistical CSI users are rank-one. In this scenario, we design beamforming techniques that are able to deal with full CSI users and statistical CSI users at the same time. Unfortunately, we cannot resort to efficient strategies that are known for the purely complete CSI vector BC due to the lack of a general BC to multiple access channel (MAC) rate duality for statistical transmitter CSI. However, a sufficiently large number of transmit antennas enables us to employ zero-forcing (ZF) techniques with regard to the mobile users. for the remaining static users, a duality w.r.t. the signal-to-interference-and-noise-ratio (SINR) between the resulting vector BC and an appropriately constructed vector MAC is established. Based on the observation that an interference function can be defined in the dual vector MAC that is standard, an iterative solution for the quality-of-service power minimization and the rate balancing problem can be found.     «

We consider the downlink (DL) of a satellite communication system, where a satellite equipped with a large number of antenna elements conveys information to single-antenna mobile receivers and static users on the earth's surface, i.e., the DL is modeled as a vector broadcast channel (BC). While for the static users, perfect channel state information is a valid assumption, only the statistics of the channels to mobile users are known to the satellite due to the large round-trip time. As especialt...     »