tailieunhanh - Expert Systems for Human Materials and Automation Part 13

Tham khảo tài liệu 'expert systems for human materials and automation part 13', kỹ thuật - công nghệ, cơ khí - chế tạo máy phục vụ nhu cầu học tập, nghiên cứu và làm việc hiệu quả | 18 Fuzzy Based Flow Management of Real-Time Traffic for Quality of Service in WLANs Tapio Frantti and Mikko Majanen VTT Technical Research Centre of Finland Finland 1. Introduction Designing heterogeneous bandwidth limited communication systems that support a wide variety of applications including file transfer web browsing interactive games audio and video calls and emerging real-time virtual world and social media applications is a challenging task because there is a shortage of resources to satisfy all traffic demands and diverse quality of service QoS requirements. For example the current Internet architecture supports only best-effort service class which is not enough especially for delay sensitive real-time multimedia applications. Therefore to improve QoS for specified traffic in the Internet the end nodes hosts should make a bandwidth reservation through all the intermediate nodes like access points and routers by using some sort of resource reservation. For the QoS guarantee the IETF has worked on the resource reservation protocol RSVP that can be used to hard resource reservation an endpoint uses RSVP to request a simplex flow through the network with specified QoS bounds and the intermediate nodes like routers along the path either agree to honor the request or deny it. It is a transport layer protocol designed to reserve resources across a network. RSVP operates over an internet protocol versions 4 or 6 IPv4 or IPv6 and provides receiver-initiated setup of resource reservations for multicast or unicast data flows. The drawback of the RSVP is that all the routers along the path must agree the resource reservation for QoS guarantee. However no any QoS system can satisfy all users demands if the network traffic exceeds network capacity. Another disadvantage is that the reserved virtual links do not necessarily use the network capacity optimally. Therefore we focus here to the cognitive flow management of delay sensitive constant bit rate real-time traffics