By most predictions, fourth-generation wireless systems will be composed of heterogeneous networks. Two important constituent networks will be wireless LAN (WLAN) and cellular mobile radio systems (e.g., UMTS). WLAN is designed for low-range, high/medium data rate access and can be used as a complement to larger cellular mobile radio systems. In this paper, we consider a heterogeneous system in which WLANs are built on the boundaries of the UMTS cells with hot spots to provide additional bandwidth and to support handover between cellular cells. The cellular bandwidth reservation for handover and the new call queueing are considered. We show that such an integrated system can be modeled by a discrete 3-D Markov chain. Using this analytical model, the handover and new call blocking probabilities, queueing probability and mean queueing delay are found under various system parameters. These results then allow us not only to quantify the performance gain of integrated systems but also to optimize system parameters
['Danyan Chen', 'Xiaofeng Wang', 'Ahmed K. Elhakeem']
Performance analysis of UMTS handover with the help of WLAN