Broadcast reception rates and effects of priority access in 802.11-based vehicular ad-hoc networks
Proceedings of the 1st ACM international workshop on Vehicular ad hoc networks
An overlay MAC layer for 802.11 networks
Proceedings of the 3rd international conference on Mobile systems, applications, and services
Overhaul of ieee 802.11 modeling and simulation in ns-2
Proceedings of the 10th ACM Symposium on Modeling, analysis, and simulation of wireless and mobile systems
How much of dsrc is available for non-safety use?
Proceedings of the fifth ACM international workshop on VehiculAr Inter-NETworking
TDM MAC protocol design and implementation for wireless mesh networks
CoNEXT '08 Proceedings of the 2008 ACM CoNEXT Conference
EURASIP Journal on Wireless Communications and Networking - Special issue on wireless access in vehicular environments
Coloring spatial point processes with applications to peer discovery in large wireless networks
Proceedings of the ACM SIGMETRICS international conference on Measurement and modeling of computer systems
LIMERIC: a linear message rate control algorithm for vehicular DSRC systems
VANET '11 Proceedings of the Eighth ACM international workshop on Vehicular inter-networking
A tutorial survey on vehicular ad hoc networks
IEEE Communications Magazine
Intervehicle Transmission Rate Control for Cooperative Active Safety System
IEEE Transactions on Intelligent Transportation Systems
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The IEEE 802.11p standard specifies the PHY and MAC layer operations for transmitting and receiving periodic broadcast messages for vehicular safety. Many studies have identified issues with the CSMA based IEEE 802.11p MAC at high densities of devices, mainly reflected by low packet reception rate. In this paper, we make an interesting observation that with increasing density, the IEEE 802.11p MAC tends towards an ALOHA-type behavior where concurrent transmissions by close-by devices are not prevented. This behavior can lead to poor packet reception rate even for vehicles in close neighborhood. Many efforts have been made to address the IEEE 802.11p MAC issues to provide better performance for DSRC safety applications, including the introduction of Decentralized Congestion Control (DCC) algorithm to ETSI standards in Europe. In this paper, we evaluate the performance of the proposed DCC algorithm and observe that the nominal parameters in DCC are unsuitable in many scenarios. Using transmit power control as an example, we develop a simple rule within the DCC framework that can significantly improve the safety packet reception performance with increasing densities. The DCC algorithms are fully compatible with the IEEE 802.11p standards and asynchronous in nature. A parallel approach to handle high device densities is a slotted synchronous MAC, where time is slotted based on GPS synchronization and each transmitter contends for a set of recurring time slots (or channels) with periodicity matching the required safety message periodicity. As compared to the per-packet based contention scheme as in CSMA defined in IEEE 802.11, such a scheme is much better suited for periodic safety broadcast. In this paper, we design a standard compliant TDM overlay on top of the MAC layer that can significantly improve the packet reception performance. Combined with a distributed resource selection protocol, the synchronous MAC can discover even more neighboring devices than the improved asynchronous approach, making DSRC safety applications more reliable.