Smart Handoff Scheme for Supporting Roaming between WLAN and GPRS Networks

Shiann-Tsong SHEU
Wu-Hsiao HSU
Hua-Chiang YIN
Chia-Wei LAI

Publication
IEICE TRANSACTIONS on Communications   Vol.E88-B    No.4    pp.1364-1373
Publication Date: 2005/04/01
Online ISSN: 
DOI: 10.1093/ietcom/e88-b.4.1364
Print ISSN: 0916-8516
Type of Manuscript: Special Section PAPER (Special Section on Internet Technology V)
Category: 
Keyword: 
GPRS,  handoff,  mobile IP,  WLAN,  

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Summary: 
Recent advancement in personal communication services (PCS) provides wireless multimedia services for users on the move. For establishing the convenient access environment, the evolution of IP-based integrated scheme becomes very urgent for public wireless access systems. In this paper, we clarify the well-known issues of integrating the general packet radio service (GPRS) network and IEEE 802.11 wireless local area network (WLAN). These issues include the inconsistence in transmission rate and coverage area, the difficulty in seamless handoff, the complexities of mobile IP and address translations, and so on. Based on classified cases, we propose the circular probe strategy (CPS) to solve the IP translations and measure the precise handoff latency of a mobile node roaming from one network to another. This latency information helps a mobile node and its home agent (HA) to decide the appropriate handoff timing, to maximize the data transmission rate, and to perform seamless handoff in the heterogeneous system. We also proposed the smart access point (AP) mechanism to reduce the overhead of CPS and to provide precise handoff latency information for mobile nodes (MNs) to select the most appropriate AP for association. Experiment results demonstrate that the proposed smart handoff scheme performs better than traditional algorithms in terms of handoff time in the integrated network.