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Seamless handoff is critical to providing highquality services for mobile users. Before handoff, a mobile terminal (MT) must be aware of the impending handoff and determine what other wireless networks are available in time. In the network discovery stage, an MT must activate its interfaces for base station search, association, AAA (Authentication, Authorization, Accounting), address acquisition, and so on. Therefore, if insufficient time is available for the MT to perform these procedures, then the connection will be disrupted. However, frequent interface activation can cause considerable battery drain. This paper presents a Network Discovery algorithm with Motion Detection, NDMD, to solve these problems. NDMD can simply use the received signal strength (RSS) to predict a user's motion without the assistance of a positioning system. Based on the predicted moving behavior, an MT can perform network discovery in time to reduce handoff dropping rate and prevent unnecessary activation of its interfaces to save the battery power. Simulation results show that NDMD can effectively detect user behavior, reduce power consumption in network discovery, and improve handoff quality.

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This paper presents a novel motion detection scheme by using the Momentum of Received Signal Strength (MRSS) to improve the quality of handoff in a general wireless network. MRSS can detect the motion state of a mobile node (MN) without assistance of any positioning service. Although MRSS is sensitive in detecting user's motion, it is static and fails to detect quickly the motion changes of users. Thus, a novel motion state dependent MRSS scheme called Dynamic MRSS (DMRSS) algorithm is proposed to address this issue. Extensive simulation experiments were conducted to study performance of our presented algorithms. The simulation results show that MRSS and DMRSS can be used to assist a handoff algorithm in substantially reducing unnecessary handoff and saving power.