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 to 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. 1982-01.pdf