Method and apparatus for decentralized prioritized scheduling in a CSMA/CA wireless system

• US 6,721,331 B1
• Filed: 12/15/1999
• Issued: 04/13/2004
• Est. Priority Date: 12/15/1999
• Status: Expired due to Fees

• Current Assignee: AT&T Corporation (AT&T, Inc.)
• Original Assignee: AT&T Corporation (AT&T, Inc.)
• Inventors: Agrawal, Prathima, Sreenan, Cormac John, Ramanathan, Parameswaran
• Primary Examiner(s): Nguyen, Chau
• Assistant Examiner(s): KWOH, JASPER C
• Application Number:
  US09/461,924
• Time in Patent Office: 1,581 Days
• Field of Search: 370/445, 370/446, 370/447, 370/448, 370/461, 370/462
• US Class Current: 370/448
• CPC Class Codes: H04L 12/413 with random access, e.g. carrier-sense multiple-access with collision detection [CSMA-CD]

Abstract

A method and apparatus provide decentralized prioritized scheduling of wireless access in a carrier sense multiple access with collision avoidance (CSMA/CA) wireless local area network (LAN) is presented. Prior to and during data packet transmissions, a device station in the CSMA/CA wireless LAN continuously monitors transmission traffic in the bandwidth medium of the wireless LAN to determine whether the delay associated with pre-transmission of a data packet, due to the collision avoidance protocol in the CSMA/CA wireless LAN, exceeds the time frame in which the device station necessarily must transmit the data packet. If the delay is too great for the type of data packet to be transmitted, the device station decreases the possible range of the back-off duration of the collision avoidance protocol. Thus, the station device can increase its transmission priority by decreasing the randomly selected back-off duration range of values.

Claims

1. A method of setting a priority for a plurality of streams awaiting transmission from a single station in a CSMA/CA wireless network, the method comprising:

determining a previous value change of the priority of a stream, where the stream is one of the plurality of streams awaiting transmission from the single station;

determining a previous of a utility function of the stream;

determining a current value of a utility function of the stream;

adapting the priority of the stream on a basis of the previous value change of the priority of the stream and a change between the previous value and the current value of the utility function of the stream.

2. The method of claim 1, wherein if it is determined that the previous value change of the priority of the stream was an increase, and if it is determined that the change between the previous value and the current value of the utility function of the stream is better, then the priority of the stream is increased.

3. The method of claim 1, wherein in the case where there is at least two streams awaiting transmission, selecting the stream from among the at least two streams with the highest priority.