由於傳輸速率的增加，讓使用者可在行動中使用大傳輸量的及時性服務，但因為會議起始協定本身的特性，會讓換手完成的時間拉長，造成通訊中部分資料的遺失。本論文針對SIP的特性，提出了一個改良以原有SIP為基礎的換手策略，目的在減少換手過程中資料的遺失，提供給使用者一個更好的通訊品質。 As a result of a great deal of demands in multimedia and mobility communication services from users, 2.5G and 3G mobile communication system services are available nowadays. This advanced technology provides users being able to having high transmission rate service, such as video conference. With the popularity of portable personal electronics, e.g. notebook, PDA and smart phone, the integration of mobile communication system and WLAN has been proceeding actively and aims for building the network with mobility and high transmission rate . Therefore, there are now two major solutions available for mobility management, one is Mobile IP witch works on network layer while another is Session Initiation Protocol that works on application layer. With the increasing of transfer rate, users already have mass transfer and real-time services today, however, the characteristics of SIP would enlarge the time of handoff that usually cause apparent data losing problem during the communication. This paper presents a new handoff strategy based on SIP that reducing the losing of data during handoff, and hoping to provide a better quality of the communication services for users.
