In a BWA communication system, an MSS changes its connection from the serving BS to the target BS, and sends the target BS a report indicating that the MSS will change its connection upon detecting occurrence of a pingpong effect in a process of performing a network re-entry operation with the target BS. The target BS sends the serving BS a notification indicating that the MSS will change its connection. Upon receiving from the MSS a report indicating that it will change its connection to the serving BS, the serving BS allocates a contention-free-based ranging resource to the MSS so that the MSS connects a communication service with the serving BS using the contention-free-based ranging resource, minimizing a service delay.