Digital Cellular Systems are beginning to offer multiple bearer services that concurrently utilize a common infrastructure. Mobile stations, commonly referred to as remote units, also support multiple bearer service capabilities. For different bearer services, there can be different divisions of the hand-off functions between the mobile stations and the cellular infrastructure. As used herein, hand-off refers to the process of transitioning a remote unit from a first base station to a second base station. For example, when the mobile station is operating on an infrastructure-assigned traffic channel, such as for voice or circuit-switched data, the infrastructure will control hand-off of the remote unit. This hand-off can happen with input from the remote unit, or independent of the remote unit. In other cases, where the remote unit is using a shared channel, such as for packet-based data, control and access channels, or short message services, the remote unit may control the hand-off autonomously.
For autonomous remote unit hand-offs, as a remote unit hands off to another RF entity, such as an adjacent cell, the remote unit needs to acquire information concerning the new cell. Examples of such information include the configuration of the cell, the configuration of services at the new cell, or other configuration parameters. In some cases, the remote unit may need to acquire such information multiple times. This may occur when a cell that has more than one channel is assigned to transport packet data activity. A user that is handing-off into that cell will first obtain the overhead information from the primary channel assigned to packet data and then will determine, based on the primary channel overhead information, the specific secondary packet data channel it must use. The remote unit will then obtain the overhead information from the secondary packet data channel prior to beginning operation on the secondary channel. It is important to minimize the time required to complete the hand-off, especially for data services where any data that is lost or misdelivered during hand-off must be re-transmitted.
Consequently, a need exists for a method for handing-off a remote unit that must obtain overhead information from the target cell and minimizing the time required to perform the hand-off in order to minimize the amount of data that is delayed or lost during the hand-off.