Fast Handover Scheme for Real-Time Applications in Mobile WiMAX

Abstract IEEE 802.16 WirelessMAN, which aims to provide broadband wireless access, has evolved to 4G mobile communication systems, which are defined in IEEE 802.16e standards to support mobility on existing fixed Wireless MAN systems. IEEE 802.16e (Mobile WiMAX) achieves high-speed wireless data and telephony transmission by employing high quality broadband wireless technologies including OFDM (A). 

Since handover schemes with lower delay and packet loss performances such as Soft Handover (SH) and Fast Base Station Selection (FBSS) need all base stations and sectors employ the same carrier frequency, with OFDM(A) Mobile WiMAX will basically perform hard handover, which would interrupt data transmission before new connections were setup. And this may be too slow for delay and packet loss sensitive real-time applications such as IPTV, VoIP, SatTV. 

To solve this problem while not do much changes to common 802.16e equipments, we propose an enhanced link-layer QoS aware handover scheme within the framework of 802.16e to accelerate the process of call transaction for those real-time applications. We name this handover scheme as Passport Handover, for in this scheme the connection CIDs of real-time applications assigned by the serving BS will be accepted by the handover target BS during the process of handing over until new CIDs are assigned, just as a passport used by a passenger when pass through the territory of a country. 

To assist the Passport Handover we also proposed a connection CID assignment strategy to avoid confliction of CIDs of handing over services with that of ongoing services in the target BS. Simulation work is done to evaluate the Passport Handover scheme, and the result shows that it makes real-time downlink data transmission interruption so brief that the users of real-time services may not perceive the interruption. 

And it also greatly reduces uplink data transmission delay and packet loss probability. Keywords- Mobile WiMAX, Handover, WirelessMAN , PASSPORT HANDOVER.