GCQCP Based Vertical Handoff Scheme for Heterogeneous Hierarchical Wireless Networks

A handoff scheme based on guard channel, queuing and channel preemption (GCQCP) is proposed to guarantee the QoS of handoff traffic in the heterogeneous hierarchical wireless networks. On the basis of bidirectional call-overflow between different networks, guard channels are set for real-time traffic handoffs and buffer queues are set for nonreal-time traffic handoffs. In order to further decrease the call dropping probability of real-time traffic handoffs, channel preemption is also used, which principle is that real time traffic handoff calls can preempt the channel resources occupied by the nonreal-time traffic. Simulation results show that the proposed handoff control scheme can remarkably decrease the dropping probability of real-time traffic handoffs, the channel utilization of overall heterogeneous system is slightly increased simultaneously.