Abstract: In this paper, we investigate the user selection algorithm in MIMO BC systems with many users. Consider frequency division duplex (FDD) systems, where channel state information (CSI) at the base station is obtained via feedback mechanisms from the users. An algorithm aiming to optimize the average signal-to-noise ratio (SNR) is presented. After setting a threshold value, only users whose channel gains are above the set threshold are considered. Among these candidate users, the transmitter selects a set of users whose minimum eigenvalue is maximal among the possible user sets. The proposed algorithm can achieve the full multiplex gain and get a desirable sum capacity and BER performance. Meanwhile, compared with the exhaustive search scheme, the system overheads, such as the amount of feedback and number of selections in the base station, decrease evidently.

Key words:

user selection, MIMO BC systems, sum capacity, amount of the feedback