tailieunhanh - Nhiều giao thức truy cập đối với truyền thông di động P9

MD PRMA WITH PRIORITISED BAYESIAN BROADCAST This last of the three chapters dealing exclusively with MD PRMA-related research results finally treats scenarios that are not limited to voice traffic only. To assess the performance of the prioritised Bayesian broadcast algorithm proposed in the following, a simulation study for different mixtures of voice and data traffic is conducted, where the latter consists either of Web traffic, email traffic, or a combination of the two. | Multiple Access Protocols for Mobile Communications GPRS UMTS and Beyond Alex Brand Hamid Aghvami Copyright 2002 John Wiley Sons Ltd ISBNs 0-471-49877-7 Hardback 0-470-84622-4 Electronic 9 MD PRMA WITH PRIORITISED BAYESIAN BROADCAST This last of the three chapters dealing exclusively with MD PRMA-related research results finally treats scenarios that are not limited to voice traffic only. To assess the performance of the prioritised Bayesian broadcast algorithm proposed in the following a simulation study for different mixtures of voice and data traffic is conducted where the latter consists either of Web traffic email traffic or a combination of the two. Preceding the discussion of the simulation results possible approaches to prioritisation at the random access stage are evaluated and a number of different algorithms which combine Bayesian broadcast with prioritisation are presented. Prioritisation at the Random Access Stage The reader questioning the motivation for introducing prioritisation at the random access stage is referred to Section where this topic was treated in considerable detail and to the priority-class specific access control feature of GPRS described in Section . UMTS provides also random access prioritisation see Chapter 10. For a mobile terminal to successfully send a channel request message in a given timeslot three events must occur simultaneously 1 there must be a random access slot or C-slot in the terminology used so far in this time-slot 2 the terminal must gain permission to access this slot and 3 the request packet transmitted in this slot must be successfully received by the base station. If the capture effect and transmission failures due to bad channel conditions are ignored the last event essentially means that the packet must not collide with another packet transmitted in the same slot. Since the collision probability depends on how access to C-slots is controlled events 2 and 3 cannot be de-coupled. On the other hand .