Handover and Channel Assjanment J in Mobile Cellular Networks Quick and timely handover has a crucial effect on how users perceive quality of service, however, handover strategies should not be too complicated.

rhe Ph. D. degree at Georg~ Mason Unharsirys School qf lnfornlation Technology and Engineering In Farfar, Virgmia hc rapid growth in the demand for mobile communications has led the industry into intense research and development efforts toward\ a new generation of cellular systems. One of theimportant objectives in the developmentofthenewgenerationisimprovingthequalityofcellularservice,with handoversnearlyinvisiblc to the Mobile Subscriber (MS). In general, the handover function isamost frequentlyencountered network function and has direct impact on the perceived quality of servicc. It provides continuation of calls as the MS travels across cell boundaries, where new channels are assigned by thc new Base Station (BS) and the Mobile Switching Center (MSC). The system performancc characteristics include probability of blocking of new traffic, probability of forced termination of ongoing calls, delay in channel assignment, and total carried traffic. There is a tradeoff between the quality of service and implementation complcxity of the channel allocation algorithms, number of database lookups and spectrum utilization. In selecting a channcl assignment strategy, the objective is to achieve a high degree of spectrum utilization for a given quality of service with thc least possible number of database lookups and simplest possible algori thms employed at the RS and/or the MSC. Handover prioritizationschemesarechannel assignment stratcgics that allocate channels to handover requests more readily than originating calls. Prioritization schemes provide improved pcrformance at the expense of reduction in the total admitted traffic. Inthisarticle,weprovideataxonomyofthechanne1 assignmcnt strategies along with the complexity in each cellular component. Next, we consider various handover scenarios and the roles of the BS and MSC. We then discuss the prioritization schemes and define the required intelligence distribution among the network components.