Investigation of uplink admission control schemes for TDD-CDMA systems

Currently, many system load evaluations have been proposed, and some applications, such as admission control strategies, have been discussed. It is observed, however, that due to the TDD-CDMA specialization in the uplink, i.e., multiuser detection (MUD) technology is used and the transmission is discontinuous per frame, all these schemes, which are based on the FDD mode, should be carefully investigated for the TDD system. We analyze a proper uplink admission control mechanism theoretically. By estimating the increasing interference and system load by new or modified users, the proposed admission control scheme rejects or accepts the user to access the system. The proposed scheme is evaluated by an OPNET-based dynamic system simulator. The results show that the system performance improves and the proper admission control threshold is changed with the MUD factor.