Analysis of SIP-based mobility management in 4G wireless networks
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wireless networks. Because of the transparency to the lower layer characteristics, application-layer mobility management protocol like the Session Initiation Protocol (SIP) has been considered as the right candidate for handling mobility in the heterogeneous 4G wireless networks. SIP is capable of providing support for not only terminal mobility but also for session mobility, personal mobility and service mobility. However, the performance of SIP, operating at the highest layer of the protocol stack, is only as good as the performance of the underlying transport layers in such a heterogeneous environment. In this paper we analyze the handoff performance of SIP in a IP-based 4G network with Universal Mobile Telecommunication System (UMTS) and Wireless LAN (WLAN) access networks. Analytical results show that the handoff to a UMTS access network introduces a minimum delay of 1.4048 s for 128 kbps channel, while for handoff to a WLAN access network the minimum delay is 0.2 ms. In the former case the minimum delay is unacceptable for streaming multimedia trafﬁc and requires the deployment of soft-handoff techniques in order to reduce the handoff delay to a desirable maximum limit of 100 ms.
Fuelled by the advancement of wireless technologies and the emergence of multimedia data services, cellular wireless networks have evolved to their third generation (3G) in just two decades. However, comprehensive 3G wireless networks are yet to be available due to the costly deployment and upgrade of already deployed system equipment. It may also be possible that 3G technology will never be fully deployed. Other predictions foresee a ‘generation jump’ directly to 4G wireless networks [18,24]. The major task towards 4G architecture is system integration [19,22], where a uniﬁed wireless access system is to be established through the integration of the services offered by current access technologies such as General Packet Radio Service (GPRS), CDMA2000 or Wireless LAN (WLAN) as well as future wireless access technologies such as Universal Mobile Telecommunication System (UMTS). The trend towards packet switched technologies and increasingly general use and acceptance of the Internet Protocol (IP) indicate that different wireless access networks are to be connected to an IP-based core network, namely the Internet. Conceptually, a 4G wireless network architecture can be viewed as many overlapping wireless Internet access domains as shown in Fig. 1. In this heterogeneous environment, a mobile host (MH) is equipped with multiple (often called multi-mode) wireless interfaces to connect to any or all wireless access networks anytime anywhere. Therefore, providing seamless mobility support is one of the most challenging problems for the system integration in 4G wireless networks