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

• US 7,864,674 B2
• Filed: 08/21/2006
• Issued: 01/04/2011
• Est. Priority Date: 11/03/2000
• Status: Active Grant

• Current Assignee: AT&T Intellectual Property II LP (AT&T, Inc.), AT&T Properties, LLC (AT&T, Inc.)
• Original Assignee: AT&T Intellectual Property II LP (AT&T, Inc.)
• Inventors: Benveniste, Mathilde
• Primary Examiner(s): Phan, Tri H
• Application Number:
  US11/507,241
• Publication Number:
  US 20070041398A1
• Time in Patent Office: 1,597 Days
• Field of Search: 370/437, 370442-465, 370229-2381
• US Class Current: 370/230
• 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, such as file transfer data. Another wireless station is supplied with data from a source having a higher QoS priority, such as voice and video data. Each wireless station can determine the urgency class of its pending packets according to a scheduling algorithm. Pending packets in a given urgency class are transmitted before transmitting packets of a lower urgency class by relying on class-differentiated urgency arbitration times, which are the idle time intervals required before the random backoff counter is decreased.

Claims

1. A method for a distributed medium access protocol, comprising:

scheduling, via a node in an access network, a transmission of different types of packets on a shared channel; and

including information in the transmitted packets concerning a number of transmission attempts via a header field in a reservation message compatible with a tiered contention multiple access protocol.

2. The method for a distributed medium access protocol of claim 1, which further comprises:

differentiating the packets into different urgency classes based on different backoff distributions for different packets that are assigned a same urgency arbitration time.

3. The method of claim 1, wherein the reservation message is a request to send message.

4. The method of claim 1, wherein the reservation message is a clear to send message.

5. The method of claim 1, further comprising:

calculating congestion estimates for each urgency class based upon the information in the transmitted packets.

6. A method for a distributed medium access protocol, comprising:

scheduling, via a node in an access network, a transmission of different types of packets on a shared channel; and

including information in the transmitted packets concerning a time spent by a packet waiting for transmission via a header field in a reservation message compatible with a tiered contention multiple access protocol.

7. The method of claim 6, wherein the reservation message is a request to send message.

8. The method of claim 6, wherein the reservation message is a clear to send message.

9. The method of claim 6, further comprising:

calculating congestion estimates for each urgency class based upon the information in the transmitted packets.

10. A method for a distributed medium access protocol that schedules a transmission of different types of packets on a channel based on a service quality specification for each type of packet, comprising:

determining at a plurality of nodes in an access network, an urgency class of pending packets according to a scheduling algorithm; and

using a class-differentiated time limit that leads to a packet being dropped once a time spent by a packet waiting for transmission has exceeded the class-differentiated time limit, wherein each urgency class of a plurality of urgency classes has a different class-differentiated time limit.

11. The method of claim 10, wherein the reservation message is a request to send message.

12. The method of claim 10, wherein the reservation message is a clear to send message.

13. The method of claim 10, further comprising:

calculating congestion estimates for each urgency class based upon the information in the transmitted packets.

14. A method for a distributed medium access protocol that schedules a transmission of different types of packets on a channel based on a service quality specification for each type of packet, comprising:

determining at a plurality of nodes in an 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 a backoff distribution used following a transmission failure and a subsequent transmission retrial, wherein the parameters are found in a header field in a reservation message compatible with a tiered contention multiple access protocol and the parameters comprise a lower value and an upper value of a contention window range which are functions of the urgency class.

15. The method of claim 14, wherein the reservation message is a request to send message.

16. The method of claim 14, wherein the reservation message is a clear to send message.

17. The method of claim 14, further comprising:

calculating congestion estimates for each urgency class based upon the information in the transmitted packets.