  The Society of Automotive Engineers (SAE) has specified a wireless channel
congestion control algorithm for cellular vehicle-to-everything (C-V2X)
communication in J3161/1. A notable aspect of J3161/1 standard is that it
addresses persistent packet collisions between neighboring vehicles. Although
the chances are slim, the persistent collisions can cause so called the
wireless blind spot once the event takes place. Then the involved vehicles
cannot inform their presence to neighboring vehicles, an extremely dangerous
condition for driving safety. J3161's solution to the problem is stochastic
one-shot transmission, where the transmission occasionally occurs in a resource
that is not originally reserved. Through the one-shot transmission, the
worst-case packet inter-reception time (PIR) is bounded and the wireless blind
spot problem can be effectively mitigated. Interestingly, the standard one-shot
transmission scheme does not resolve the persistent collision relation itself.
This paper shows that by breaking out of the relation as soon as the persistent
collision condition is identified, vehicles can improve the worst-case PIR by
approximately 500 ms, the number of packet collisions per persistent collision
event by 10%, and the number of total collisions by 15% to 57% over the
standard one-shot transmission.
