近年來對於像視訊傳輸以及網路電話等講求高品質的網路傳輸需求與日俱增，為因應這樣的環境需求，IEEE 802.16就是針對都會型區域網路所提出的無線寬頻網路傳輸摽準。在IEEE 802.16的MAC標準中，網路傳輸的效能會被一個傳輸幀(frame)中競爭時槽的長度所影響，如果競爭時槽的時間太長，將會影響到一個傳輸幀中的資料傳輸時間，造成傳輸空間的浪費。為了減少這個問題的發生，我們根據一個傳輸幀中所能傳輸資料的空間，動態的調整每個傳輸幀中競爭時槽的長短，同時為了讓這個動態競爭時槽的機制能配合802.16網路穩定運作，我們使用了p-persistence的競爭機制，然而這個機制在短競爭時槽的環境下，很容易發生浪費傳輸幀中資料傳輸空間的情形，所以我們提出了一個平滑的p-persistence競爭機制來改善這個問題，並透過網路模擬的實驗，證明我們的方法在動態變動時槽的環境下擁有比原先的機制更佳更穩定的網路效能。 Demands for a mobile communication and a high quality service such as video steaming or VoIP have been increasing in recent years. According to these social environments, IEEE 802.16 standard for BWA (Broadband Wireless Access) systems was proposed to supports a metropolitan area network architecture. In IEEE 802.16 MAC protocol, the performance of the system is affected by the size of the contention period, a long contention period would be a waste of transmission space. To reduce this problem, we dynamic change the length of the contention period according to the transmission space. In order to let our dynamic contention period mechanism work more stably. We choose the p-persistence scheme to be our contention mechanism. Unfortunately, even if the p-persistence scheme is stable enough, BS may receive no requests during a frame and result in the waste of transmission space under short contention period situation. To solve this problem, we propose a smooth p-persistence contention scheme. The experiment results show that our scheme unrolls better performance than original algorithm under dynamic contention period situation.
