IEEE 802.11p/WAVE (Wireless Access in Vehicular Environments)為車載隨意網路(Vehicular Ad HocNetworks；VANETs)下新興的標準之一。於車載環境下廣播資料與控制封包變得更為重要，特別是安全性與非安全性應用下廣播資料封包與狀態交換。IEEE 1609.4標準有定義廣播封包於控制通道(Control Channel；CCH)區間內被傳送，但在車載隨意網路下車輛做通道交換(channel switch)時會經歷高於平均的通道擁塞週期。因此，本論文提出動態位移間隔(Adaptive Offset Slot；AOS)機制。此機制每輛車先利用廣播Hello訊息封包估計鄰近車輛的數目，之後計算期望的位移間隔值並預先加到初始MAC Contention Window(CWmin)之前。透過AOS機制可降低封包碰撞情況並改善傳輸的效能

IEEE 802.11p/WAVE (Wireless Access in Vehicular Environments) is an emerging family of standardsintended to support wireless access in Vehicular Ad Hoc Networks (VANETs). Broadcasting of data andcontrol packets is expected to be crucial in this environment. Both safety-related and non-safety applicationsrely on broadcasting for the exchange of data or status and advertisement messages. Most of thebroadcasting packet is designed to be delivered on a given frequency during the control channel (CCH)interval set by the IEEE 1609.4 standard. In an IEEE 802.11p VANET, vehicles that perform channel switchingmay experience a period of above-average channel congestion immediately following a channel switch.However, the AOS (Adaptive Offset Slot) mechanisms is firstly developed based on the estimation of potentialneighboring vehicles through broadcasting Hello messages, and then calculating the expected offset slots forreducing the collision situations, and thus improve transmission performance.