由於頻譜短缺的問題日益嚴重，無線感知網路 (Cognitive Radio Net-works ) 便被發展來解決這個問題。在無線感知網路中用來解決頻譜短缺的方法主要分為兩個大方向，一個是共同的控制用頻道 (Common Control Channel) ，另一個則是無線跳頻 (Channel Hopping)。然而，在共同的控制頻道的方法中，控制用頻道容易被主要使用者 (Primary User) 長時間占用而造成無法進行通訊問題 (CR long-time blocking problem)，因此，本篇論文主要在探討後者―無線跳頻的演篹法。在現存的方法中，為了要避免干擾主要使用者，網路中的節點必須相遇在一個目前沒有被主要使用者所使用到的頻道。為了避免通訊失敗，兩節點必須及早相遇在可用的頻道上 (也就是 maximum conditional time to rendezvous (MCTTR) 越小越好)。在本篇論文中，我們提出了一個無線跳頻演算法―ID-CH ，這個演算法無需要時間同步，也不需要事先定義節點的角色 (發訊者及接收者)。ID-CH 的 MCTTR 為( lambda + 1) × (N^2 + N)，其中，N 為可用頻道的數目，還有 lambda 為節點所使用的 ID 字串的長度。;Due to the shortage of Spectra, Cognitive Radio Network (CRN) become a key technique to utilize the licence spectrum. There are two solutions in the CRN, common control channel and channel hopping methods. However, there is a serious problems (i.e., CR long time block-ing problem) in the common control channel method. Thus, this paper foucs on channel hopping method. In order not to interference with the existed network in the channel hopping method, two nodes should rendezvous on an available channel (a channel not used by the user in the existed network) . For avoiding communication failure, two nodes in the CRN should rendezvous on all the available licensed channels and rendezvous on available channel as soon as possible (i,e., minimizing the maximum conditional time to rendezvous (MCTTR)). In this paper, we proposed an channel hopping approach, ID-CH, which is without time synchronization and don’t need to pre-assign roles (sender or receiver) of nodes. ID-CH has MCTTR = (lambda + 1) × (N^2 + N), where N is the number of licensed channels and lambda is the length of binary ID string of a SU.
