Wireless Personal Communications (2005) 33: 69–86 DOI: 10.1007/s11277-005-6326-4 C  Springer 2005 A New Technique to Expedite RSVP Path Re-establishments in 802.11 Wireless LANs NIKOS PASSAS 1 , APOSTOLIS K. SALKINTZIS 2 , GEORGIOS NIKOLAIDIS 1 and MARY KATSAMANI 1 1 Department of Informatics & Telecommunications, Communication Networks Laboratory, University of Athens, Panepistimiopolis, 15784 Athens, Greece E-mail: passas@di.uoa.gr 2 Motorola, 32 Kifissias Avenue, 15125 Athens, Greece Abstract. This paper proposes a novel scheme that exploits the Inter Access Point Protocol (IAPP), currently standardized by IEEE, in order to expedite the RSVP path re-establishment that takes place after a handover from one WLAN Access Point (AP) to another. The prime characteristic of this scheme is that a WLAN AP serves as an RSVP proxy and starts RSVP signaling on behalf of the Mobile Node much earlier compared with the standard RSVP operation in a WLAN. Therefore, a considerable handover latency reduction can be achieved, which can be as high as 20%. To evaluate the performance and the benefits of the proposed scheme, we display and discuss a series of simulation results. In addition, we present in detail its operation and we discuss the RSVP objects that should be transferred across APs through IAPP. In this context, we also explain the structure of the proposed RSVP Information Elements. Our simulation results show considerable performance improvement, especially in heavy traffic load conditions. Note that the proposed scheme can work with the standard RSVP protocol, as well as with partial path re-establishment methods and can be combined with advanced admission control algorithms in the AP. Keywords: RSVP, wireless LANs (WLANs), IAPP, handover Introduction The evolution of wireless communications in the last decade resulted in increased available bandwidth, able to support a much wider set of services besides simple data and voice com- munications. Especially Wireless Local Area Networks (WLANs) can today provide speeds in the range of hundreds of Mbps. The demand for multimedia services in wireless networks has raised several technical challenges, such as the minimization of handover latency. In this context, fast handover techniques play a key role and provide the means for eliminating the handover overhead and enabling the provision of mobile multimedia services. However, not all radio access networks support fast handover techniques. For example, the notorious IEEE 802.11 WLANs [1] feature limited handover support for real-time applications and con- sequently the use of multimedia services over such WLANs raises considerable concerns. Recently, a lot of effort has been placed on addressing these concerns and a notable example is the development of the Inter Access Point Protocol (IAPP) [2], standardized by IEEE 802.11 Task Group f as a recommended practice. The IAPP provides the means for transferring context from one Access Point (AP) to another, through a fixed distribution system (DS), in order to facilitate fast handovers across multi-vendor Access Points.