Tham khảo tài liệu 'the_handbook_of_ad_hoc_wireless_networks_10', công nghệ thông tin, quản trị mạng phục vụ nhu cầu học tập, nghiên cứu và làm việc hiệu quả | Simpo PDF Merge and Split Unregistered Version - http of packet loss lo ss rate and so on. The QoS forum defines QoS as the ability of a network element . an application a host or a router to provide some level of assurance for consistent network data delivery 13 . The IETF RFC 2386 10 characterizes QoS as a set of service requirements to be met by the network while transporting a packet stream from source to destination. Different applications require different levels of assurance or more exactly QoS requirements from the network. Real-time applications such as voice and video transmission need a packet by a certain time otherwise the packet is essentially worthless non-real-time applications such as file transfer and e-mail emphasize reliability instead. QoS support has been widely discussed in various networks. The Asynchronous Transfer Mode ATM network for instance has made a great emphasis on the support of QoS for traffic of different classes. Tremendous efforts have been made by the IETF to enhance the current Internet to support multimedia services. QoS mechanisms are applied to wisely manage network resources bandwidth buffer to meet the various QoS requirements of applications. With the rising popularity of multimedia applications among end users in various networks and the widened scope of applications for ad hoc wireless networks which are also called Mobile Ad hoc NETworks MANETs QoS support of distributed non-real-time and real-time applications in MANETs has emerged as a major area of research. This issue however as Corson stated in 8 is really a challenging task faced by researchers. A network s ability to provide a specific QoS depends upon the inherent properties of the network itself 25 which span over all the elements in the network. For the transmission link the properties include link delay throughput loss rate and error rate. For the nodes the properties include hardware capability such as processing speed and memory size.
