MULTIPLE ACCESS COMMUNICATION
First Claim
1. A method of operating a communications node (3) in a carrier sense multiple access communications system with collision avoidance (CSMA/CA), in which, the node measures properties of a communications channel indicative of noise on the channel (36),and if noise is detected above a predetermined threshold, the node implements a channel management process (37) to attempt to reduce the noise level,and, only if the channel management techniques (37) are successful in reducing the noise level below a redetermined threshold, when the node has a queue of data to transmit, the node measures the time that it takes to gain access to a channel for transmission of the data (38), and derives therefrom a measure of availability of capacity in the network, and operates a data management process (39) to reduce the number of bits in the transmission to a level where collisions are minimised.
1 Assignment
0 Petitions
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.
19 Citations
28 Claims
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1. A method of operating a communications node (3) in a carrier sense multiple access communications system with collision avoidance (CSMA/CA), in which, the node measures properties of a communications channel indicative of noise on the channel (36),
and if noise is detected above a predetermined threshold, the node implements a channel management process (37) to attempt to reduce the noise level, and, only if the channel management techniques (37) are successful in reducing the noise level below a redetermined threshold, when the node has a queue of data to transmit, the node measures the time that it takes to gain access to a channel for transmission of the data (38), and derives therefrom a measure of availability of capacity in the network, and operates a data management process (39) to reduce the number of bits in the transmission to a level where collisions are minimised.
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4. (canceled)
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6. (canceled)
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7. (canceled)
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15. A carrier sense multiple access communications system node (3) with collision avoidance (CSMA/CA) having a transmitter (30) for transmitting data over a communications channel, a frame transmission queuing system (31) for maintaining a queue of data for transmission, and having a congestion detection processor (38) 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 (39) responsive to the congestion detection processor (38) to reduce the number of bits in the queued data to a level where collisions are minimised, and further comprising channel monitoring means (36) for measuring properties indicative of noise on the communications channel, and channel management means (37) 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 (35) being arranged to transmit data only if the channel management means (37) successful in reducing the noise level below a predetermined threshold.
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18. (canceled)
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20. (canceled)
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21. (canceled)
Specification