Inter-System Handover for Packet Switched Services

Inter-system handover is used when a UE moves out of 3G coverage or into an area of high interference. It may also be used if the load on the 3G system becomes high. This paper describes the signalling and measurements associated with inter-system handover for packet switched data services. RNC databuild parameters are identified and discussed. A set of measurements are used to illustrate the dominant phases of inter-system handover. The dominant phases are discussed in terms of minimising the impact upon end-user experience. The paper concludes by suggesting ways in which inter-system handover delays can be refined.