Random medium access methods with backoff adaptation to traffic
First Claim
1. A method for a distributed medium access protocol that schedules transmission of different types of packets on a channel based on a service quality specification for each type of packet, comprising the steps of:
- determining at a plurality of nodes in the access network, an urgency class of pending packets according to a scheduling algorithm;
transmitting pending packets in a given urgency class before transmitting packets of a lower urgency class;
remembering the number of transmission attempts by a node for the last transmission of same node;
estimating from said number of transmission attempts the current congestion experienced; and
adjusting a backoff counter to current congestion levels to provide a dispersion of packet traffic bursts.
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Accused Products
Abstract
Using low PF values in conjunction with traffic-adapted contention windows leads to substantial decreases in delay and jitter. In general, adaptation to traffic reduces contention or delay: opening up the contention window in congestion and closing it on relief. Residual backoff adaptation provides for the reduction of the already decremented backoff values of stations that interrupted the backoff countdown process due to a transmission. It is good to adapt both the contention window and the residual backoff in order to avoid jitter. Otherwise, if the contention window is reduced but residual backoffs stay unchanged, new arrivals will enjoy shorter backoff delays than older ones, resulting in greater jitter. Adjusting both preserves the relative ordering of backoff counter values, which implies also some form of age ordering. Different adjustments can be applied to different priority traffic.
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Citations
97 Claims
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1. A method for a distributed medium access protocol that schedules transmission of different types of packets on a channel based on a service quality specification for each type of packet, comprising the steps of:
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determining at a plurality of nodes in the access network, an urgency class of pending packets according to a scheduling algorithm;
transmitting pending packets in a given urgency class before transmitting packets of a lower urgency class;
remembering the number of transmission attempts by a node for the last transmission of same node;
estimating from said number of transmission attempts the current congestion experienced; and
adjusting a backoff counter to current congestion levels to provide a dispersion of packet traffic bursts. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 25, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35, 36, 37, 38, 39, 40, 41, 46, 47, 48, 49, 54, 55, 56, 57, 58, 59, 60, 61, 62, 63)
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23. A method for a distributed medium access protocol that schedules transmission of different types of packets on a channel based on a service quality specification for each type of packet, comprising the steps of:
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determining at a plurality of nodes in the access network, an urgency class of pending packets according to a scheduling algorithm;
using class-differentiated arbitration times, as idle time intervals required before transmission is attempted; and
assigning shorter arbitration times to higher urgency classes.
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24. A method for a distributed medium access protocol that schedules transmission of different types of packets on a channel based on a service quality specification for each type of packet, comprising the steps of:
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determining at a plurality of nodes in the access network, an urgency class of pending packets according to a scheduling algorithm;
using class-differentiated arbitration times, as idle time intervals required before a backoff counter is decreased; and
assigning shorter arbitration times to higher urgency classes.
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42. A method for a distributed medium access protocol, comprising:
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scheduling transmission of different types of packets on a shared channel; and
including information in the transmitted packets concerning the number of transmission attempts. - View Dependent Claims (44)
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43. A method for a distributed medium access protocol, comprising:
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scheduling transmission of different types of packets on a shared channel; and
including information in the transmitted packets concerning the time spent by the packet waiting transmission. - View Dependent Claims (45)
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50. A method for a distributed medium access protocol that schedules transmission of different types of packets on a channel based on a service quality specification for each type of packet, comprising the steps of:
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determining at a plurality of nodes in the access network, an urgency class of pending packets according to a scheduling algorithm; and
using class-differentiated retrial functions that are used to update parameters of backoff distribution used following transmission failure and subsequent transmission retrial.
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51. A method for a distributed medium access protocol that schedules transmission of different types of packets on a channel based on a service quality specification for each type of packet, comprising:
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determining in a first wireless station a first urgency class of data having a low QoS requirement;
assigning a first class-differentiated urgency arbitration time to said data having a lower requirement;
determining in a second wireless station a second urgency class of data having a high QoS requirement;
assigning a second class-differentiated urgency arbitration time shorter than said first time, to said data having a higher QoS requirement;
transmitting from said second wireless station pending packets in said second urgency class before transmitting from said first wireless station pending packets in said first urgency class; and
said urgency classes each having a correspondence urgency arbitration time that must expire before starting a random backoff interval for packets assigned to that urgency class. - View Dependent Claims (52, 53)
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64. A method for a medium access protocol that schedules transmission of packets from a plurality of nodes on a channel, comprising the steps of:
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employing a backoff countdown procedure for channel access;
monitoring traffic intensity changes continuously and providing feedback to the MAC sublayer of contending nodes;
adjusting a backoff counter of each of a plurality of contending nodes to current congestion levels in time intervals shorter than required for the completion of a transmission attempt; and
adjusting such backoff counter in a way that enables older packets to be transmitted before newer ones with high probability, thus minimizing the latency jitter. - View Dependent Claims (65, 66, 67, 68, 69, 70, 71)
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72. A method for a medium access protocol that schedules transmission of packets from a plurality of nodes on a channel, comprising the steps of:
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employing a backoff countdown procedure for random channel access;
monitoring the traffic continuously and providing feedback to the MAC sublayer of contending nodes; and
adjusting the parameters (e.g. offset and window size, or range) of a random distribution from which the backoff counter is drawn upon initiation of a transmission attempt for each of a plurality of contending nodes to reflect current congestion levels. - View Dependent Claims (73, 74, 75, 76, 77, 78, 79, 80, 81, 82, 83, 84, 86, 87, 88, 89, 90, 92, 93, 95, 96, 97)
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85. The method for a medium access protocol of 83, which further comprises:
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determining the magnitude of a fractional adjustment factor R that is larger for greater contention levels;
adjusting a backoff counter of the pending packet to increased contention levels by increasing the backoff counter values associated with each of a plurality of backlogged nodes by scaling up such counter through the multiplication of the current counter value by a term that increases with the scaling factor (1+R); and
assigning, through statistical means, an integer value to such counter with expected value equal to said multiplication product. - View Dependent Claims (91, 94)
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Specification