An acknowledging contention algorithm suitable for local radio networks

We present a contention transmission algorithm for local networks which is related to the p-persistent family of algorithms previously analyzed by Kleinrock and Tobagi. Our algorithm incorporates an automatic acknowledgement signal which is sent by the receiving station immediately after each packet is correctly received. The algorithm is suitable for radio environments in which transmitting stations can “capture” nearby receivers. Assuming that stations are not placed too close each other, we prove that an acknowledgement signal is received by a transmitting station only if the packet has been received correctly by the intended receiver. In a cable network where transmitters do not capture receivers, the acknowledgement signal is guaranteed (in the same sense) regardless of the distances between stations. This result depends on very weak assumptions about the type of data encoding used on the channel. We discuss the more interesting aspects of implementing this scheme, and we outline how higher-level protocols can make use of the acknowledgement signal and its properties.