In WCDMA systems the downlink power is the limiting radio resource.
Admission control is used to control that new links are setup only
if there is sufficient power available. Even if admission control
strategies work sufficiently well, overload situations may still occur.
To be able to maintain system stability, a mechanism for preventing
such events must be included. This can be done by adjusting the users’
bit rates to changing load levels and traffic requirements.
This study considers admission control and rate adaptation for packet
data in WCDMA systems with adaptive antennas. The rate adaptation
scheme is based on the power load and the users’ data traffic requirements.
The advantage of using adaptive antennas instead of ordinary sector
antennas is also evaluated.
It is shown that the adaptive antenna system offers significant capacity
gain compared to the sector case. The rate adaptation scheme provides
exibility to traffic variations and ensures system stability during
high load levels. Compared to fixed bit rate schemes, there is however
no significant overall system capacity improvement achieved.
