Tiered contention multiple access (TCMA): a method for priority-based shared channel access

• US 9,270,606 B2
• Filed: 09/09/2013
• Issued: 02/23/2016
• Est. Priority Date: 11/03/2000
• Status: Expired due to Fees

• Current Assignee: AT&T Intellectual Property I LP (AT&T, Inc.), AT&T Properties, LLC (AT&T, Inc.)
• Original Assignee: AT&T Intellectual Property I LP (AT&T, Inc.)
• Inventors: Benveniste, Mathilde
• Primary Examiner(s): Lee, Jae Y
• Application Number:
  US14/022,113
• Publication Number:
  US 20140010081A1
• Time in Patent Office: 897 Days
• US Class Current: 1/1
• CPC Class Codes: H04L 47/10 Flow control; Congestion control
• CPC Class Codes: H04L 47/2416 Real-time traffic
• CPC Class Codes: H04L 47/2433 Allocation of priorities to traffic types
• CPC Class Codes: H04L 47/245 using preemption
• CPC Class Codes: H04L 47/283 in response to processing delays, e.g. caused by jitter or round trip time [RTT]
• CPC Class Codes: H04L 47/32 by discarding or delaying data units, e.g. packets or frames
• CPC Class Codes: H04L 47/6275 based on priority
• CPC Class Codes: H04W 28/02 Traffic management, e.g. flow control or congestion control
• CPC Class Codes: H04W 28/0252 per individual bearer or channel dynamic wireless traffic scheduling H04W72/12
• CPC Class Codes: H04W 56/00 Synchronisation arrangements
• CPC Class Codes: H04W 72/542 using measured or perceived quality
• CPC Class Codes: H04W 72/569 of the traffic information
• CPC Class Codes: H04W 74/02 Hybrid access
• CPC Class Codes: H04W 8/04 Registration at HLR or HSS [Home Subscriber Server]
• CPC Class Codes: H04W 84/12 WLAN [Wireless Local Area Networks]

Abstract

Quality of Service (QoS) support is provided by means of a Tiered Contention Multiple Access (TCMA) distributed medium access protocol that schedules transmission of different types of traffic based on their service quality specifications. In one embodiment, a wireless station is supplied with data from a source having a lower QoS priority QoS(A), such as file transfer data. Another wireless station is supplied with data from a source having a higher QoS priority QoS(B), such as voice and video data. Each wireless station can determine the urgency class of its pending packets according to a scheduling algorithm. For example file transfer data is assigned lower urgency class and voice and video data is assigned higher urgency class. There are several urgency classes which indicate the desired ordering. Pending packets in a given urgency class are transmitted before transmitting packets of a lower urgency class.

Claims

1. A method for transmitting a packet, the method comprising:

determining, at a node having a buffer, an urgency class for the packet according to a schedule, wherein each of a plurality of urgency classes is assigned a plurality of differentiating parameters with different values from values of other urgency classes, the plurality of differentiating parameters comprising a backoff window for drawing an initial backoff counter for the packet and a persistence factor, wherein the persistence factor is different for each urgency class of the plurality of urgency classes, wherein the persistence factor is to derive a subsequent backoff window from which a subsequent backoff counter for the packet is drawn randomly upon a transmission retrial of the packet;

using, by the node, different urgency arbitration times for different urgency classes of the plurality of urgency classes, wherein each of the different urgency arbitration times is associated with a different quality of service priority; and

transmitting, by the node, the packet in the urgency class before transmitting another packet of a lower urgency class.

2. The method of claim 1, further comprising:

remembering a number of transmission attempts by the node for a last transmission of the node;

estimating, from the number of transmission attempts, a current congestion level; and

adjusting the initial backoff counter for the packet responsive to the current congestion level.

3. The method of claim 1, further comprising:

broadcasting, with each of a plurality of transmission attempts, a number of transmission attempts by the node of the packet;

estimating, from a number of transmission attempts received from other nodes, a current congestion level experienced by the other nodes for the urgency class of the packet; and

adjusting an initial backoff counter for a pending packet of the urgency class responsive to the current congestion level experienced by the other nodes for the urgency class of the packet.

4. The method of claim 1, further comprising:

remembering a number of transmission attempts by the node for a last transmission in each urgency class of the plurality of urgency classes;

estimating, from the number of transmission attempts by the node, a current congestion level for the urgency class; and

adjusting an initial backoff counter for a pending packet of the urgency class responsive to the current congestion level.

5. The method of claim 4, further comprising:

broadcasting, with each transmission attempt, a current number of transmission attempts by the node of the packet and the urgency class of the packet;

further estimating, from a number of transmission attempts received from other nodes, the current congestion level experienced by the other nodes for the urgency class of the packet; and

further adjusting the initial backoff counter for the packet responsive to the current congestion level experienced by the other nodes for the urgency class of the packet.

6. The method of claim 1, further comprising:

broadcasting, with each of a plurality of transmission attempts, a number of transmission attempts by the node of the packet and an urgency class of the packet;

estimating, from a number of transmission attempts received from other nodes, a current congestion level experienced by the other nodes for the urgency class of the packet; and

adjusting the initial backoff counter for the packet responsive to the current congestion level experienced by the other nodes for the urgency class of the packet.

7. The method of claim 1, further comprising:

initializing the initial backoff counter and the subsequent backoff counter with a value, and then changing the value upon a transmission failure and retrial.

8. The method of claim 1, further comprising:

remembering a number of transmission attempts by the node for a last transmission of the node;

estimating, from the number of transmission attempts, a current congestion level; and

adjusting a persistence probability responsive to the current congestion level.

9. The method of claim 8, further comprising:

broadcasting, with each transmission attempt, a current number of transmission attempts by the node;

further estimating, from a number of transmission attempts received from other nodes, the current congestion level experienced by the other nodes; and

further adjusting the persistence probability responsive to the current congestion level experienced by the other nodes.

10. The method of claim 1, further comprising:

broadcasting, with each transmission attempt, a number of transmission attempts by the node of the packet;

estimating, from a number of transmission attempts received from other nodes, a current congestion level experienced by the other nodes; and

adjusting a persistence probability responsive to the current congestion level experienced by the other nodes.

11. The method of claim 1, further comprising:

remembering a number of transmission attempts by the node for a last transmission in each urgency class of the plurality of urgency classes;

estimating, from the number of transmission attempts, a current congestion level for the urgency class of the packet; and

adjusting a persistence probability for the packet responsive to the current congestion level for the urgency class of the packet.

12. The method of claim 11, further comprising:

broadcasting, with each transmission attempt, a current number of transmission attempts by the node of the packet and the urgency class of the packet;

further estimating, from a number of transmission attempts received from other nodes, the current congestion level experienced by the other nodes for the urgency class of the packet; and

further adjusting the persistence probability of the packet responsive to the current congestion level experienced by the other nodes for the urgency class of the packet.

13. The method of claim 1, further comprising:

broadcasting, with each of a plurality of transmission attempts, a number of transmission attempts by the node of the packet and the urgency class of the packet;

estimating, from a number of transmission attempts received from other nodes, a current congestion level experienced by the other nodes for the urgency class of the packet; and

adjusting a persistence probability of the packet responsive to the current congestion level experienced by the other nodes for the urgency class of the packet, in order to provide a dispersion of packet traffic bursts.

14. The method of claim 1, further comprising:

initializing a persistence probability with a value, and then increasing the value upon a transmission failure and retrial.

15. The method of claim 1, further comprising:

establishing a criterion for cancellation of transmission of the packet associated with a packet delay.

16. The method of claim 1, further comprising:

applying a backoff prior to attempting the transmitting.

17. The method of claim 1, further comprising:

checking for a permission to transmit by using a persistence probability prior to attempting the transmitting.

18. A non-transitory computer-readable medium storing a plurality of instructions which, when executed by a processor of a node having a buffer, cause the processor to perform operations for transmitting a packet, the operations comprising:

determining an urgency class for the packet according to a schedule, wherein each of a plurality of urgency classes is assigned a plurality of differentiating parameters with different values from values of other urgency classes, the plurality of differentiating parameters comprising a backoff window for drawing an initial backoff counter for the packet and a persistence factor, wherein the persistence factor is different for each urgency class of the plurality of urgency classes, wherein the persistence factor is used to derive a subsequent backoff window from which a subsequent backoff counter for the packet is drawn randomly upon a transmission retrial of the packet;

using different urgency arbitration times for different urgency classes of the plurality of urgency classes, wherein each of the different urgency arbitration times is associated with a different quality of service priority; and

transmitting the packet in the urgency class before transmitting another packet of a lower urgency class.

19. An apparatus for transmitting a packet, the apparatus comprising:

a processor of a node; and

a computer-readable medium storing a plurality of instructions which, when executed by the processor, cause the processor to perform operations, the operations comprising;

determining an urgency class for the packet according to a schedule, wherein each of a plurality of urgency classes is assigned a plurality of differentiating parameters with different values from values of other urgency classes, the plurality of differentiating parameters comprising a backoff window for drawing an initial backoff counter for the packet and a persistence factor, wherein the persistence factor is different for each urgency class of the plurality of urgency classes, wherein the persistence factor is used to derive a subsequent backoff window from which a subsequent backoff counter for the packet is drawn randomly upon a transmission retrial of the packet;

using different urgency arbitration times for different urgency classes of the plurality of urgency classes, wherein each of the different urgency arbitration times is associated with a different quality of service priority; and

transmitting the packet in the urgency class before transmitting another packet of a lower urgency class.