METHOD AND PROTOCOL TO SUPPORT CONTENTION-FREE INTERVALS AND QOS IN A CSMA NETWORK

摘要

A scheme for supporting both centralized and distributed shared medium access control in a CSMA network (700). A master device (702) exchanges connection control messages with a slave device (704) using contention-oriented access to establish a connection and a session of periodic contention-free intervals. The contention-free intervals (722) alternate with contention-oriented intervals (725) according to the timing parameters specified by the connection control massages. Each of the contention-free intervals (722) is divided into slots (727), the master device (702) transmitting a downstream frame and the slave device (704) transmitting an upstream frame in a following slot if the downstream frame indicates the following: a source address matching that of the master device, a contention-free access at a highest priority and a connection number corresponding to the connection established between the master device and the slave device. Master control is passed from one device to another device during the contention-free interval using a master flag for to indicate which device has master control and a control flag to indicate the direction in which master control is being passed.