Space-division repetition-based broadcasting protocol for reliable beaconing in VANETs

In vehicular ad hoc networks (VANETs), beaconing (i.e. periodic transmissions of beacons) is one of the most challenging issues, which is mainly used to advertise the presence of a car to its neighbor cars. Based on the proximity awareness achieved through the beaconing, safety applications can quickly detect dangerous road situations and help drivers avoid them. Recently, repetition-based protocols have been proposed to meet the requirements of timeliness and reliability for the beaconing. However, since most of existing protocols employ CSMA as their underlying medium access control strategy, they are vulnerable to interference from hidden nodes. In this paper, we propose a new broadcasting protocol called Space-Division Repetition-based Broadcasting protocol (SDRB) in order to reduce interference caused by hidden nodes. In SDRB, the geographical area where vehicles are located is divided into smaller space divisions. Vehicles within difference space divisions are allowed to transmit their beacons at different points of time in order to cope with interference from hidden nodes. From the ns-2 simulation results, we verified that SDRB provides more reliable broadcasting service due to its capability of removing such interference as compared to CSMA.