On the Design of Highly Efficient Traffic Information Forwarding and Video Broadcasting Solutions for Inter-Vehicle Communication

• Main Authors: Chu, Yung-Cheng, 朱永正
• Other Authors: 黃能富
• Format: Others
• Language: en_US
• Published: 2012
• Online Access: http://ndltd.ncl.edu.tw/handle/82687636267981049269

博士 === 國立清華大學 === 通訊工程研究所 === 100 === For inter-vehicle communication (IVC), efficiently propagating adequate and effective traffic information to drivers helps increase driving safety and reduces traffic jams on highways. In addition, by high performance and real-time video broadcasting, the enhanced vision assistance further increases the driving safety and traveling fun for drivers. However, it is hard to structure vehicles into permanent network topologies and schedules to propagate multi-source traffic information and broadcast video streaming real-time in IVC in a high-mobility vehicular environment. To achieve this, firstly we have designed an overlay traffic information solution which considers the challenges of propagating multi-source information caused by vehicle mobility and multi-hop forwarding. The overlay solution is composed of a mobility-adaptive information reduction scheme (IR scheme) and a vehicle-adaptive cluster-to-cluster multi-hop forwarding method (VAC method). The IR scheme creates a mobility-adaptive cluster to represent local traffic information. The purpose of the scheme is to simplify individual high-speed movements and reduce large amounts of information broadcasts. Based on the results of the IR scheme, the VAC method selects the optimal relay node of the inter-cluster forwarding pair to increase the efficiency of multi-hop propagation. In simulation, we compared network performance with two other protocols by defining three objective metrics of driving-perceived quality under different traffic scenarios, and analyzed the results. Furthermore, we explored the protocol overhead, the broadcasting reduction ratio, and technological deviations to verify the advantages and efficiencies of our solution. The simulation proves that our solution is an efficient multi-source and multi-hop forwarding framework that allows well-connected vehicular networks to disseminate a higher degree of correct traffic information, especial for highway safety-related information. Secondly, we have developed a burst effort broadcast (BEB) approach, which considers the features of MPEG-4 video streams to adapt to highway scenarios and overcome the challenges of high mobility and multi-hop broadcast. The BEB approach is distributed real-time without protocol overheads, and comprises a queuing procedure and scheduling scheme. The queuing procedure is of the pre-process of video transmission including the video shaping of groups of pictures (GOPs) and sequentially re-ordering video frames. Based on the queuing procedure, a mobility-adaptive scheduler is applied to process the broadcast and re-broadcast of the video stream. The concept of macroscopic broadcast is for MPEG-4 specific and utilized to increase the broadcast performance and video perceived quality of service (PQoS) as well as to reduce the number of unnecessary redundant broadcasts. As an evaluation, the real MPEG-4 video was conducted in simulation and the broadcast performance was compared with another protocol by the metrics of peak signal to noise ratio (PSNR) and loss of video frames in different broadcasting scenarios, and the results were analyzed. The simulation proved that this approach is an efficient multi-hop broadcast solution that does indeed provide a realistic solution to promote a higher degree of MPEG-4 video PQoS on highways. Both the proposed solutions are highly adaptive to high mobility and capable of effective and efficient multi-hop transmission on traffic information and video streams on highways for the safety-related and infotainment IVC applications, and therefore, the practice of the proposed solutions will be beneficial for increasing the driving safety and comfort in the future.