This top-selling vocabulary book is now available with a CD-ROM offering hundreds of completely new exercises. Vocabulary is clearly presented and contextualized on left-hand pages with practice activities on facing right-hand pages. Students can listen to audio recordings, create their own tests and make personal notes within the dictionary. The second in the family of best-selling vocabulary reference and practice books from elementary to advanced level. The CD-ROM has a built-in dictionary with full definitions and example sentences of key vocabulary.
English Vocabulary in Use Pre-Intermediate/Intermediate Pack (+ CD-ROM)
|Формат:|| Страниц 263 Размер 27x20x1 см Вес 0,703 кг |
Cambridge University Press
Evaluating the GPRS Radio Interface for Different Quality of Service...
Figure 8 i ves iga es he impac of he maximum umber of GPRS user per cell o he performa ce of GPRS for he dy amic cha el alloca io scheme wi h 1 PDCH reserved. Of course, he expec ed umber of GPRS users should be less ha he maximum umber i order o avoid he rejec io of ew GPRS sessio s. O he o her ha d, he maximum umber of ac ive GPRS sessio s mus be limi ed for guara eei g quali y of service for every ac ive GPRS sessio eve u der high raffic. he radeoff be wee i creasi g performa ce for allowi g more ac ive GPRS sessio s a d he i creasi g blocki g probabili y for GPRS users is illus ra ed by he curves of Figure 8. Co clusio s his paper prese ed a discre e-eve simula or o he IP level for he Ge eral Packe Radio Service (GPRS). Wi h he simula or, we provided a comprehe sive performa ce s udy of he radio resource shari g by circui swi ched GSM co ec io s a d packe swi ched GPRS sessio s u der a s a ic a d a dy amic cha el alloca io scheme. I he dy amic scheme we assumed a reserved umber of physical cha els perma e ly alloca ed o GPRS a d he remai i g cha els o be o -dema d cha els ha ca be used by GSM voice service a d GPRS packe s.