Multiple access communication
First Claim
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, andonly 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.
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Accused Products
Abstract
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.
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Citations
27 Claims
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1. A method of operating a communications node in a carrier sense multiple access communications system with collision avoidance the method comprising:
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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. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11)
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12. A carrier sense multiple access communications system node with collision avoidance having a transmitter for transmitting data over a communications channel, a frame transmission queuing system for maintaining a queue of data for transmission, and having a congestion detection processor for measuring the time that it takes for the transmitter to access a channel when the node has a queue of data to transmit, and to determine therefrom the availability of capacity in the network for the transmission of the remaining data in the queue,
wherein the frame transmission queuing system is arranged to operate a data management process responsive to the congestion detection processor to reduce the number of bits in the queued data to a level where collisions are minimised, and further comprising channel monitoring means for measuring properties indicative of noise on the communications channel, and channel management means for modifying transmissions in response to the noise properties, the channel management means being arranged to attempt to reduce the noise level if the noise detected is initially above a predetermined threshold, and the frame transmission queuing system being arranged to transmit data only if the channel management means is successful in reducing the noise level below a predetermined threshold.
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23. A communications node comprising a computer processor, the communications node being configured at least to:
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operate in a carrier sense multiple access communications system with collision avoidance; measure properties of a communications channel indicative of noise on the channel; implement a channel management process to attempt to reduce the noise level if detected noise is above a threshold; and only if the channel management process is successful in reducing the noise level below the threshold, and the node has a queue of data to transmit; measure the time that it takes to gain access to a channel for transmission of the data; derive therefrom a measure of availability of capacity in the network; and operate a data management process to reduce the number of bits in the transmission to a level where collisions are minimized. - View Dependent Claims (24, 25, 26, 27)
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Specification