Adaptive medium access control
First Claim
1. A method of adaptively avoiding collisions in an ad hoc wireless network, comprising:
- synchronizing periodic epochs of time and a state of a schedule with other nodes of the network, wherein the schedule includes alternating contention periods and contention free periods within the epochs, and wherein each contention free period is allocated to one of the nodes;
initiating a transmission during a contention free period allocated to the node and completing the transmission during an immediately-subsequent contention period;
measuring busy times of contention periods and aggregating the measured busy times over durations of corresponding epochs;
maintaining an aggregate channel congestion factor, over the duration of the corresponding epochs, as a function of an elapsed time of the epoch and a corresponding aggregate of the measured busy times of contention periods within the epoch;
precluding broadcasting of a packet from the node during a contention period when the channel congestion factor is above a configurable congestion factor threshold;
maintaining a count of a number of times a unicast packet is re-transmitted from the node; and
precluding re-transmission of the unicast packet from the node during a contention period when the count reaches a first count threshold.
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Accused Products
Abstract
Bandwidth allocation configuration and fully decentralized adaptive medium access control (AMAC) systems and methods with support for time critical applications, spectrum efficiency, scalability enhancements, and fair allocation of bandwidth among nodes sharing a common channel. The methods fully integrate TDMA and CSMA/CA channel access approaches and incorporate adaptive congestion and collisions avoidance scheme to reduce bandwidth wastage and diminish adverse cross layers interactions. AMAC improves support for multi-media traffic while allowing higher transmission incidents from large number of transmitting devices sharing a common channel, with fair distribution of the available bandwidth, to enable improved multi-level-security connectivity over a common multi-hop wireless network, provide end-to-end performance enhancement for constant bit rate traffic, variable bit rate traffic, and distribute bandwidth fairly amongst competing TCP traffic flows that traverse varying length paths in multi-hop ad-hoc wireless networks.
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Citations
23 Claims
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1. A method of adaptively avoiding collisions in an ad hoc wireless network, comprising:
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synchronizing periodic epochs of time and a state of a schedule with other nodes of the network, wherein the schedule includes alternating contention periods and contention free periods within the epochs, and wherein each contention free period is allocated to one of the nodes; initiating a transmission during a contention free period allocated to the node and completing the transmission during an immediately-subsequent contention period; measuring busy times of contention periods and aggregating the measured busy times over durations of corresponding epochs; maintaining an aggregate channel congestion factor, over the duration of the corresponding epochs, as a function of an elapsed time of the epoch and a corresponding aggregate of the measured busy times of contention periods within the epoch; precluding broadcasting of a packet from the node during a contention period when the channel congestion factor is above a configurable congestion factor threshold; maintaining a count of a number of times a unicast packet is re-transmitted from the node; and precluding re-transmission of the unicast packet from the node during a contention period when the count reaches a first count threshold. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9)
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10. A non-transitory computer readable medium comprising computer program logic stored thereon, the computer program logic comprising instructions that, when executed by a processor, cause the processor to:
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synchronize periodic epochs of time and a state of a schedule amongst the nodes, wherein the schedule includes alternating contention periods and contention free periods within the epochs, and wherein each contention free period is allocated to one of the nodes; initiate a transmission during a contention free period allocated to the node, and complete the transmission during an immediately-subsequent contention period; measure busy times of contention periods, and aggregate the measured busy times over durations of corresponding epochs; maintain an aggregate channel congestion factor, over the duration of the corresponding epochs, as a function of an elapsed time of the epoch and a corresponding aggregate of the measured busy times of contention periods within the epoch; preclude broadcasting of a packet from the node during a contention period when the channel congestion factor is above a configurable congestion factor threshold; maintain a count of a number of times a unicast packet is re-transmitted from the node; and preclude re-transmission of the unicast packet from the node during a contention period when the count reaches a first count threshold. - View Dependent Claims (11, 12, 13, 14, 15, 16)
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17. An adaptive medium access control (AMAC) system to adaptively access a shared wireless channel of an ad hoc wireless network on behalf of a node of the network, comprising:
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a synchronizer to synchronize periodic epochs of time and a state of a schedule amongst the nodes, wherein the schedule includes alternating contention periods and contention free periods within the epochs, and wherein each contention free period is allocated to one of the nodes; a transmit control system to initiate a transmission during a contention free period allocated to the node, and complete the transmission during an immediately-subsequent contention period; a measurement system to measure busy times of the contention periods, and aggregate the measured busy times over durations of corresponding epochs; a congestion monitor to measure busy times of the contention periods, aggregate the measured busy times over durations of corresponding epochs, and maintain an aggregate channel congestion factor over the duration of the corresponding epochs as a function of an elapsed time of the epoch and a corresponding aggregate of the measured busy times of contention periods within the epoch; a broadcast control system to preclude broadcasting of a packet from the node during a contention period when the channel congestion factor is above a configurable congestion factor threshold; a counter to maintain a count of a number of times a unicast packet is re-transmitted from the node; and a unicast control system to preclude re-transmission of the unicast packet from the node during a contention period when the count reaches a first count threshold. - View Dependent Claims (18, 19, 20, 21, 22, 23)
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Specification