A Channel Coordination Scheme for High Density Vehicular Ad-Hoc Networks Based on Time Division Multiplexing

IEEE 802.11p Vehicular Ad-Hoc Network (VANET) applies one control channel (CCH) and six service channels (SCHs). CCH is dedicated for broadcasting traffic safety messages, SCHs are dedicated for transmission of varying application messages. In IEEE 802.11p standard, Coordinated Universal Time (UTC) scheme is recommended for coordinating channel access on CCH and multiple SCHs, Enhanced Distributor Channel Access (EDCA) algorithm is used for wireless channel assignment and priority support. However, both the static methods of synchronization interval partition in UTC or priority queue management in EDCA and contention-based channel competition mechanism in EDCA may have great influence on transmission efficiency in high density VANETs. In this paper, we present a time division multiplexing channel coordination (TDMCC) scheme, which can assign synchronization interval and CCH priority queues dynamically according to estimated real-time VANET conditions. Besides, instead of traditional contention-based channel competition mechanism, a contention-free mechanism is provided for service channel assignment. The analysis results show that our scheme can improve performance of VANETs efficiently in high density scenario.