Real-time massage differentiation with priority data service flows in VANET

摘要

The IEEE 802.11e standard was designed to support Quality of Service (QoS) at the MAC layer to support incapability of real-time traffic. The real-time safety messages in critical VANETs environment are guaranteed high priority transmission as a requirement of DSRC. Due to the intermittent connection in VANETs, the transmission of real-time traffic data frame needs to obtain a higher priority of channel access to the best-effort data. Data frame of higher priority is based on the intensity of message (urgency) which is consorted with different QoS in terms of delay and throughput. Classifying data packets of the same priority, the physical layer from the IEEE 802.11p which is the recommended VANETs MAC protocol suffers a huge amount of packet losses. More so, when messages are placed with the same queue, data packet loss and variable delay are much likely to occur. To overcome these difficulties, in this paper, our scheme adheres to the DSRC seven channels bandplan to set the priority queues over separate. To achieve the level of QoS in our scheme, messages of the same priority would be sent using strict priority queue (SPQ) priority traffic differentiation techniques to improve Packet Delivery Ratio for real-time traffic based on IEEE 802.11e MAC protocol. The results were obtained through NCTUns simulator which is used for the analysis to improve the packet delivery ratio of the real-time messages.