An Effective Multi-Hop Broadcast Control for Alert Message in VANET

[[abstract]]在最近幾年，有越來越多的車輛會利用安全行車輔助系統來提升行車時的安全。當有車輛遭遇或是發現有事故發生時，通常此系統會利用multi-hop的廣播方式來發送緊急訊息給附近的所有車輛。而使用廣播的方式會造成很嚴重的封包碰撞問題，使得緊急訊息的傳遞效率會大大的降低。在本篇論文中，我們提出了一個控制廣播封包的單元，稱為緊急訊息廣播控制單元(Broadcast Control Unite, BCU)，此單元利用減少傳送廣播封包的節點來降低緊急封包的碰撞率，進而提升緊急封包傳遞的效率。此單元不用和其他網路分層架構作協調，也沒有使用額外的控制訊號，因此可以很簡單的加入到任何一種WAVE/802.11p裝置。最後我們將此單元加到NS2網路模擬器來進行模擬，證明出我們所提的方法是可以有效地提高廣播訊息傳輸的效率。[[abstract]]In recent years, vehicle safety application has been introduced to improve the traffic safety. And safety applications are widely using multi-hop broadcast method to propagate emergent messages to the surrounding vehicles. However, with increasing the broadcast messages, the probability of the collision will Increase significantly, leading to higher delivery loss and latency. We propose a position-base broadcast module, named Broad Control Unit (BCU), in order to reducing the re-broadcast nodes and then minimizing emergent message conflict. This module can be easily implemented in WAVE/DSRC devices and doesn’t need any additional signaling overhead or explicit coordination among vehicles. We implemented this module and WAVE/802.11p communication into NS2. The simulation’s results show that this module’s superiority in multi-hop delay.[[note]]碩