Vertical Handover Efficient Transport for Mobile IPTV Salah S. Al-Majeed and Martin Fleury University of Essex, Colchester, United Kingdom {ssaleha,fleum}@essex.ac.uk Abstract. The success of IPTV suggests that an expansion to mobile devices is likely. A key difference between IPTV delivery to mobile devices and broadband access is the possibility of vertical handovers, which can cause disruption to real-time video streaming. This paper proposes a lightweight form of IPTV transport based on negative acknowledgments. The performance of the scheme is analyzed in comparison to an industry standard congestion controller and baseline UDP transport. A selective acknowledgment variation of the scheme is also examined. The paper shows both proposed schemes result in better mean video quality (by as much as 4 dB) but that the non-selective scheme is better in the presence of vertical handovers. The paper presents a case study which emulates an IPTV streaming architecture with handovers between IEEE 802.16e (WiMAX) broadband wireless and an 802.11 network. Keywords: IEEE 802.16e, IEEE 802.21, media transport, mobile IPTV, vertical handover, WiMAX 1 Introduction Next Generation Mobile Networks (NGMN) [1] will consist of a number of overlapped heterogeneous networks, allowing the user to seamless pass between them through the process of vertical handover (VHO). VHO can be accomplished with the Media Independent Handover (MIH) part of the IEEE 802.21 standard [2] or through all-IP framing as integrated within the IP Multimedia Subsystem (IMS) initiative [3]. MIH is a looser way of approaching the goal of NGMN through optimized signaling between access points (APs) and/or base stations (BSs). This paper considers the MIH approach, which appears now to be gaining ground in the marketplace relative to IMS. The scenario considered is a mobile device crossing between an IEEE 802.16e (mobile WiMAX) [4] network to an IEEE 802.11 WLAN and vice versa, representing movement from indoors to outdoors reception. However, the general principles of efficient transport extend to transitions between other types of network. In this scenario, even though IEEE 802.21 attempts to harmonize signaling, the extent of signally differs between the two network types because of the relative complexity of WiMAX, which adds quality-of-service management to the underlying transmission system. The contribution of the paper is a transport method tuned to the needs of