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Advanced wireless networks 4g technologies phần 5

bộ nhớ so với các hệ thống MsCAC memoryless. rằng lưu lượng truy cập được cung cấp loại 1 là Erlangs 7λ, lớp 2 là Erlangs 2λ và loại 3 là Erlangs λ. Như vậy, tổng lưu lượng được cung cấp là 10 Erlangs nếu λ = 1. Hình 12,11 trình bày mới chặn cuộc gọi cũng như xác suất thất bại bàn giao của từng loại dịch vụ ở MdCAC và MsCAC hệ thống vs phổ biến | CELLULAR SYSTEMS WITH PRIORITIZED HANDOFF 331 The complementary distribution function FcrH r is Fc7 h i 1 FrH í FrH r _ 1 - e M - e M Fr f XcFrh 0 for r 0 11-5 0C 0 elsewhere By differentiating Equation 11.4 we get the probability function PDF of rH as 0 Z -mZ LLkaQ ZZ-mZ fĩH í I vC p fTn f yefTb t - . If í rcFrh i 1 Xc 1 Xc 11.6 To simplify the analysis the distribution of rH is approximated in References 75 76 by a negative exponentia 1 dietribution evlih mean 7jj 1 az-h - From the family of negative exponential distribution functions a function which best tits the distribution of Th by comparing F nt and a i 11 fs ahosen which is defined as oo ao 4b yie Dep ob MH di 11.7 Z H J 0 Because a negftive ex oneetidisirilibtion functi0n is determined by its mean value we choose 7h 1 mh which satisfies the above condition. The goodness of fit forOlit approximation is measured by roo y Irhtí -eO ge S2 l tsd _ eei8 yffi Jo __ . In the sequel the following dgSnitiosswill be ured 1 The probability that a new call does not enter service because of unavailability of abannels is calledthe blocking probabiitty de. 2 The probgbititythet a cahis ultimalety foredcl mSdterminatiddCthougli notbldckedi .sPfj.Tlris rapipsactbtiie average fraction of new calls which are not blocked but which are eventually uncompleted. . . . . 3 Pfl is the probability that a given hens 0ff attempt fails. It represents the average fraction of handoff attempts that are eesuccessful. _ 2 Il s 4 The probability Pn that a new call that is not blocked will require at least one handoff before completion because of the mobile crossing the cell boundary is P8gFM l ll-.hi1 t n i í iss 8 epp i l í l í t .dl Jo Jo 332 MOBILITY MANAGEMENT 5 The probability Ph that a call that has already been handed off successfully will require another handoff before completion is P 1T 7 rh ị 1 PrM í rh í dí I e- fTh t át 11.10 0 0 Let the integer random variable K be the number of times that a nonblocked