Performance Analysis of Quality-of-Service Controls in a Cell-Cluster-Based Wireless ATM Network
Young-Jong Cho · Journal of Electrical Engineering and Information Science · 1997
In this paper, an efficient cell-cluster-based call control scheme with guaranteed quality-of-service (QoS) provisioning is presented for next generation wireless ATM networks and its performance is mathematically analyzed using the open queueing network. With the cell-cluster-based call control, at the time a mobile connection is admitted to the network, a virtual cell is constructed by choosing a group of neighboring base stations to which the call may probabilistically hand over and by assigning to the call a collection of virtual paths between the base stations. Within a microcell/picocell environment, it is seen that the cell-cluster-based call control can support effectively a very high rate of handovers. provides very high system capacity, and guarantees a high degree of frequency reuse over the same geographical region without requiring the intervention of the network call control processor each time a handover occurs. But since mobiles. once admitted, are free to roam within the virtual cell. congestion condition occurs in which the number of calls to be handled by one base station exceeds the cell site's capacity of radio channel and consequently a predefined QoS provision cannot be guaranteed. So, there must be a call admission control function to limit the number of calls existing in a cell-cluster such that required QoS objectives are met. As call acceptance criteria for constant-bit-rate or realtime variable-bit-rate ATM connections, we define four mobile QoS metrics: new-call blocking probability, wireless channel utilization efficiency. congestion probability and normalized average congestion duration. In addition, for QoS provisioning to available-bit-rate, unspecified-bit-rate or non-realtime variable-bit-rate connections, we further define another QoS metric. the minimum threshold breaking probability. By using the open network queueing model. we derive closed form expressions for the five QoS metrics defined above and show that they can be used as the effective acceptance criteria for call admission control of wireless ATM networks.