The Mapping Between TFD and IEEE 802.11 User Priorities and Access Categories

The modern approach to the quality of service (QoS) claims that problems of assurance of the required QoS parameters may occur not only in core networks (as the classic approach assumes), but also in access networks (including local networks, or LANs), especially if the access network is of broadcast type, such as the IEEE 802.11 wireless LAN. In the case of broadcast LANs, QoS assurance in the network layer should be associated with the QoS assurance in the data link layer. The aim of this paper is to propose such an association between the 802.11 QoS assurance and the QoS assurance based on the Traffic Flow Description (TFD) option of the IP protocol. The TFD was specified by the Authors in the IETF’s working document (Internet Draft), and was intended to describe Internet traffic for the purpose of dynamic resource reservations. The TFD-based QoS assurance offers dynamic reservations for micro-flows (single data real-time streams or non-real-time flows). The proposed method associates TFD and 802.11 QoS architectures in a way similar to the association of the DiffServ architecture and the 802.11 QoS, i.e. by the mapping of corresponding signalling. This mapping was designed and then implemented by the Authors in a Linux kernel. Results of laboratory experiments carried out in a test network show that the proposed mappings sufficiently promote traffic described by the TFD option in 802.11 WLAN and protect it against degradation. The proposed method includes the mapping of static signalling. Mapping of dynamic information conveyed in the TFD option is also possible and will be a subject of further research. The mapping between TFD and IEEE 802.11 user priorities and access categories will allow a 802.11 network to preserve TFD-based QoS in wireless links.