Multiple access communication

摘要

The application concerns interference mitigation in a CSMA/CA system (e.g. WLAN/WIFI); a distinction is made between two kinds of interference, namely “noise” and “congestion/collision”; a measure of congestion is determined as follows: if packets are queued waiting for transmission, a timer is started and the clear channel assessment (CCA) function is initiated. Periodically a check is made to determine whether a channel is available and when a channel becomes available the first queued packet is transmitted and the timer is stopped. The value recorded by the timer is used to indicate a measure of congestion.

主权项

1. A method of operating a communications node in a carrier sense multiple access communications system with collision avoidance the method comprising:
the node measuring properties of a communications channel indicative of noise on the channel, if noise is detected above a predetermined threshold, the node implementing a channel management process to attempt to reduce the noise level, and only if the channel management process is successful in reducing the noise level below a predetermined threshold, when the node has a queue of data to transmit, the node measuring the time that it takes to gain access to a channel for transmission of the data, and deriving therefrom a measure of availability of capacity in the network, and operating a data management process to reduce the number of bits in the transmission to a level where collisions are minimised.