在這篇論文中，我們針對多頻道環境下的無線行動隨建即連網路提出一個具有動態頻道分配的 MAC ( Medium Access Control )協定，此協定有下列數個特性: (i) 此協定中以On-Demand的方式分配頻道給行動主機，(ii) 系統提供給網路所需的頻道個數與網路的拓樸是無關的，(iii) 此協定只需要交換少數的控制訊息就可以完成頻道分配與媒介存取兩個功能，(iv)在此協定中行動主機不需要任何型式的同步(Synchronization)。相較於其他的協定，以往有些協定是使用靜態的方式分配頻道，如此可能造成一個行動即使沒有資料欲傳送仍會佔用頻道，而造成浪費的情況。而有些協定其頻道的數目是最大允許的鄰居數的函數，而最大允許鄰居數在具移動性的隨建即連網路中是不易掌握的。另外有些協定則需要行動主機之間做同步，這在隨建即連網路上也是不易達成的。因此前述的四個特性使得此篇論文中所提出的MAC協定非常適用於無線行動隨建即連網路上。最後我們利用實驗來展現其效能。 The wireless mobile ad hoc network (MANET) architecture has received a lot of attention recently. This thesis considers the access of multiple channels in a MANET with multi-hop communication behavior. We point out several interesting issues that should be paid attention of when using multiple channels. We then propose a new multi-channel MAC protocol, which is characterized by the following features: (i) it follows an 'on-demand' style to assign channels to mobile hosts, (ii) the number of channels required is independent of the network topology and degree, (iii) it flexibly adapts to host mobility and only exchanges few control messages to achieve channel assignment and medium access, and (iv) no form of clock synchronization is required. Compared to existing protocols, some assign channels to hosts statically (thus a host will occupy a channel even when it has no intention to transmit), some require a number of channels which is a function of the maximum connectivity, and some necessitate a clock synchronization among all hosts in the MANET. Extensive simulations are conducted to evaluate the proposed protocol.
