Handover of packet-switched services in GERAN A/Gb mode

Due to strict Quality of Service requirements on low latency and packet loss, real-time packet-switched (PS) services require a minimal service interruption on the data transfer during cell change. Existing GPRS cell change mechanisms with Network Assisted Cell Change (NACC) enable a theoretical minimum service interruption of 0.7-1.2 second, while real-time PS services of conversational class do not tolerate a service gap longer than 0.15 seconds. Therefore in GERAN A/Gb mode a PS handover procedure is being designed to allow for conversational services in GPRS that would improve the network performance for any PS service. PS handover follows the GSM circuit-switched handover principle of allocating radio resources in the target cell prior to changing cell. In this paper PS handover procedure is described and its performance evaluated in terms of service interruption by means of network simulations.