Mobility is the most important feature of a wireless cellular communication system. Usually, continuous service is achieved by supporting handoff (or handover) from one cell to another. Handoff is the process of changing the channel (frequency, time slot, spreading code, or combination of them) associated with the current connection while a call is in progress. It is often initiated either by crossing a cell boundary or by a deterioration in quality of the signal in the current channel. | Handbook of Wireless Networks and Mobile Computing Edited by Ivan Stojmenovic Copyright 2002 John Wiley Sons Inc. ISBNs 0-471-41902-8 Paper 0-471-22456-1 Electronic CHAPTER 1 Handoff in Wireless Mobile Networks QING-AN ZENG and DHARMA RAGRAWAL Department of Electrical Engineering and Computer Science University of Cincinnati INTRODUCTION MobiHtyisthemost important featmeof awireless cellular communication system. Usually cortviLOus sersiceisacluevedVASLpyortmg handoff or handover from one cell to m thtsr. Handvffivlhe process of changing the channel frequency time slot spreading code or combination of them associated with the current connection while a call is in progress. It is often initiated either by crossing a cell boundary or by a deterioration in quality of the signal in the current channel. Handoff is divided into two broad categories hard and soft handoffs. They are also characterized by break before make and make before bredd Inhcd handoffs current resources are released before new resources are used in soft handoffs both existing and new resources are used during the handoff geneimeveryheavy signaling traffic and de crease in ciaolttyol servioe QoS .CInthiv ctiapti vgrlein Voifis aevuinedtoocnii oniyattVvcod lOoundaryjTho reacoe vliyhandod s arecTiticalincdlu-lainstiviminicmionsgrloiniistrad vviahbowngcxytstyvtil vvvunsingn. tijicnt tubsel of frequency baodo so negotiatlonitmist tnVo place Vetvcevutlte mobila etntion VMSV thu cnrrenS voryingboce ttaliotiBSf and tUe neetnvlenllni tits oreStCedissttes sncllas Oecoton mokOcgand priotity ctcaleglnsdvtungovcdoading. icevto iidloencuthntwerail pvnOonnonce . In the next oentivn wc 00 06 different types vi pocsibte hcndrVic tn Ooction dp wedesccibediffvrentOvndofftnitivtiodprosucces .TOo types afhandold 00X0100 001 d vflydost irrdr dcgaep ic t oid se cloC. repcesentatlvdtondofCycheniesoten ei cn iitedinSev tlon .
