Delay management for heterogeneous traffic in vehicular sensor networks using packet fragmentation of low priority data

Vehicular sensor networks (VSNs) are expected to revolutionize the transportation systems through automated decision-making. These networks function on the communication between vehicles, traffic infrastructure, and people. One of the major challenges of VSNs is to deal with heterogeneous traffic due to the diverse nature of information and data generated by different types of sensors and devices within the vehicular environment. To ensure an effective operation of the network, it is crucial to offer a differentiated quality of service to each traffic class. Media access control (MAC) protocols offer an opportunity to provide differentiated channel access to the traffic of different priorities. This work is focused on offering comparison of recent MAC schemes in terms of their performance for heterogeneous traffic generated by VSNs. Two protocols FROG-MAC and UrgMAC have been selected: FROG-MAC is developed using a simple concept of packet fragmentation, where the packets of lower priority are fragmented to offer an early transmission opportunity to urgent traffic; on the other hand, urgMAC is designed using advanced cross-layer techniques of two-tiered service differentiation mechanism, adaptive data rate adjustment mechanism, urgency-based contention window size adaptation, traffic type adaptive duty cycle, and multimedia message passing. It has been found that the FROG-MAC outperforms urgMAC in terms of delay, energy consumption and packet delivery ratio.