Contention detection and resolution for multiple access power-line communications

Contention-detection and contention-resolution procedures are presented. This procedure is not only tailored for use over the direct-current power lines in automotive applications but is also applicable for other multiple-access networks where the users cannot simultaneously transmit and receive. Bus arbitration is accomplished by each user that is randomly switching between carrier-sense and carrier-transmission modes prior to sending data. If the bus is sensed as busy during this process, then the user switches to a packet-reception mode. Typically, contention detection and contention resolution are two separate procedures. The proposed scheme effectively combines the two while maintaining a controlled probability of collision. A detailed analysis of this scheme is given, revealing that the collision probability can be made arbitrarily small for the price of slightly increased packet overhead.