階層式無線網路之多重註冊協定

Abstract

大多數大型的無線區域網路是用多個AP(Access Point)和透過有線實體的方式連線到網際網路上，各個區域網路的AP間以有線的形式相互通訊。也就是說，一個AP如果沒有直接以有線實體連結上網際網路或和其他已連線到網際網路的AP，則該AP及其所屬網路中的移動節點(Mobile Node, MN)就無法連上網際網路，更遑論得到網際網路上的各項服務。而假使所有無線區域網路上的MN都是直接對AP做存取，傳輸邊緣的訊號會快速衰減，影響可傳輸範圍。另外，許多的網路服務及協定在使用者提出需求時，會要求其進行註冊的程序，而在無線網路中，由於通訊節點的可移動性，這會造成了節點註冊的困難度。各個節點通常需要不只一項的服務，使用分別註冊也將使網路的負荷更為沈重。由於階層式的架構經常被應用在網路上，用來解決繞徑的效能問題，本研究以集中式(Centralized Scheme)的叢集建立方法組織無線網路中的節點，利用無線網路內的繞徑傳輸的方式來降低訊號的快速衰減，發揮階層式架構的優點，增加註冊路徑的穩定性，藉以提高繞徑的效能，整合多重協定註冊(Multiple Registration)，來減少分別註冊的網路消耗(Cost)，也能讓MN在AP間進行無縫(Seamless)換手(Handoff)。

Most large wireless local area networks (WLAN) connect to Internet via Access Points (AP) and wired devices, when APs communicates each other through wired networks. In other words, if an AP is not equipped with wired networks or connected with other APs connecting to Internet, then it and its mobile nodes do not connect to internet to gain service. In addition, many internet applications providing services and protocols will require registration procedures, when mobile users send their requests to applications. In wireless mobile network, mobile nodes set up registration procedure hardly, because of node mobility. Separate registration procedures for one node, which requires more service, will increase network overheads. In general, the hierarchical structure is applied to networks, used for improving routing performance problem. This study organizes wireless mobile nodes by a centralized cluster scheme, and reduces signal attenuation by the proposed cluster-based routing protocol. Developing hierarchical structure helps increase the stability of registration procedure and promote routing performance. This study also integrates multiple registration procedures to decrease registration cost, and achieves seamless handoff, when one node moves among different APs.