Apparatus, and associated method for selecting a size of a contention window for a packet of data system

• US 6,285,662 B1
• Filed: 05/14/1999
• Issued: 09/04/2001
• Est. Priority Date: 05/14/1999
• Status: Active Grant

• Current Assignee: Nokia Solutions and Networks US LLC (Nokia Corporation)
• Original Assignee: Nokia Mobile Phones UK Limited (Nokia Corporation)
• Inventors: Watanabe, Fujio, Jokela, Jari, Buot, Theodore, Kuntze, Roland
• Primary Examiner(s): Chin, Wellington
• Assistant Examiner(s): JONES, PRENELL P
• Application Number:
  US09/312,579
• Time in Patent Office: 844 Days
• Field of Search: 370/280, 370/447, 370/461, 370/462, 370/347, 370/470-476, 375/347, 375/219, 375/233, 375/260, 375/222, 455/133, 455/518
• US Class Current: 370/280
• CPC Class Codes: H04W 28/06 Optimizing the usage of the radio link, e.g. header compression, information sizing , discarding information system modifying transmission characteristic according to link quality by modifying frame length H04L1/0007; dynamic adaptation of the packet size for flow control or congestion control H04L47/365
• CPC Class Codes: H04W 74/0841 with collision treatment
• CPC Class Codes: H04W 84/12 WLAN [Wireless Local Area Networks]
• CPC Class Codes: Y02D 30/70 in wireless communication networks

Abstract

Apparatus, and an associated method, by which to select the size of a contention window within which to transmit a packet of data upon a random access channel in a multi-user scheme. The number of time slots allocated to form random access channels in a frame is selectably variable in a dynamic manner. Advantage is made of the dynamic allocation of random access channels to select the size of the contention window. Operation is advantageously implemented in a mobile terminal operable in a wireless LAN (local area network), such as that set forth in the BRAN (broadband access network) promulgated by the ETSI.

Claims

1. Apparatus for selecting a contention window within which to transmit a packet of data at a sending terminal to a receiving station, the packet of data transmittable upon a random access channel defined in a time-division communication system in which frames, each formed of a plurality of time slots, are defined, the frames having a dynamically-allocable number of time slots forming random access channels, said apparatus comprising:

a detector coupled to receive indications of the number of time slots allocated to form the random access channels of the frames, said detector for detecting the number of time slots allocated to form the random access channels of at least a selected frame;

a contention window selector coupled to receive indications of detection by said detector of the number of time slots allocated to form the random access channels of the selected frame, said contention window selector selectably operable to select a size of the contention window responsive, at least in part, to the number of time slots detected by said detector.

2. The apparatus of claim 1 wherein said contention window selector selects the size of the contention window to correspond to the number of time slots detected by said detector to be allocated to the selected frame to form random access channels.

3. The apparatus of claim 2 wherein said contention window selector selects the size of the contention window to correspond to the number of time slots detected to be allocated to the selected frame if the number of time slots is greater than a selected value, otherwise said contention window selector selects the size of the contention window to correspond to the selected value.

4. The apparatus of claim 3 wherein the selected value is related to an average number of time slots allocated to form random access channel in a plurality of frames.

5. The apparatus of claim 4 further comprising an average calculator also coupled to receive the indications of detection by said detector of the number of time slots allocated to form the random access channels of the selected frame, said average calculator for calculating the average value of time slots which forms the selected value.

6. The apparatus of claim 3 wherein said contention window selects the size of the contention window within which to attempt an initial transmission of the packet of data.

7. The apparatus of claim 1 wherein the time-division communication system comprises a time-division-duplex communication system, and wherein the indications of the number of time slots allocated to form the random access channel to which said detector is coupled to receive are broadcast at a front portion of a frame.

8. The apparatus of claim 1 wherein said detector is further coupled to receive an indication of a number of attempts by which the sending terminal has attempted to transmit the packet of data to the receiving station, wherein said contention window selector is further coupled to receive indications of detection by said detector of the number of attempts by which the sending terminal has attempted to transmit the packet of data, and wherein the size of the contention window selected by said contention window selector is further responsive to the number of attempts detected by said detector.

9. The apparatus of claim 8 wherein said contention window selector selects the size of the contention window to be of a number of time slots defined to be random access channels related to the number of attempts detected by said detector.

10. The apparatus of claim 9 wherein the size of the contention window is selected to be of a number of time slots exponentially related to the number of attempts detected by said detector.

11. The apparatus of claim 8 wherein said contention window selector selects the size of the contention window to be of a number of frames related to the number of attempts detected by said detector.

12. The apparatus of claim 11 wherein the size of the contention window is selected to be of a number of frames exponentially related to the number of attempts detected by said detector.

13. The apparatus of claim 11 wherein said contention window selector alternately selects the size of the contention window to be of a number of time slots defined to be random access channels related to the number of attempts detected by said detector when the number of attempts detected by said detector is within a selected value, and, if the number of attempts detected by said detector is beyond the selected number, said contention window selector selects the size of the contention window to be of the number of frames related to the number of attempts detected by said detector.

14. The apparatus of claim 13 wherein the selected value comprises a traffic-load parameter.

15. The apparatus of claim 13 wherein the selected value comprises a time-related value.

16. The apparatus of claim 8 further comprising a counter coupled to receive an indication of each attempt by the sending terminal to transmit the packet of data, said counter for counting the attempts, a count value formed by said counter forming the indication of the number of attempts to which said detector is coupled to receive.

17. The apparatus of claim 1 wherein said detector is further coupled to receive an indication of a success indicia representative of a number of successful prior transmissions of packet data in a prior frame, wherein said contention window selector is further coupled to receive indications of detection by said detector of the success indicia, and wherein the size of the contention window selected by said contention window is further responsive to the number of successful prior transmissions.

18. The apparatus of claim 17 wherein the time-division communication system comprises a time-division-duplex (TDD) communication system, and wherein the indication of the success indicia to which said detector is coupled to receive are broadcast at a front portion of a frame.

19. The apparatus of claim 17 wherein said detector is further coupled to receive an indication of a number of attempts by which the sending terminal has attempted to transmit the packet of data to the receiving station, wherein said contention window selector is further coupled to receive indications of detection by said detector of the number of attempts by which the sending terminal has attempted to transmit the packet of data, and wherein the size of the contention window selected by said contention window selector is further responsive to the number of attempts detected by said detector.

20. A method for selecting a contention window within which to transmit a packet of data at a sending terminal to a receiving station, the packet of data transmittable upon a random access channel defined in a time-division communication system in which frames, each formed of a plurality of time slots, are defined, the frames having a dynamically-allocable number of time slots forming random access channels, said method comprising:

detecting a number of time slots allocated to form the random access channels of at least a selected frame; and

selecting a size of the contention window responsive, at east in part, to the number of time slots detected during said operation of detecting.

21. The method of claim 20 wherein said operation of detecting further comprises detecting an indication of a number of attempts by which the ending terminal has attempted to transmit the packet of data and wherein said operation of selecting is further responsive to the number of attempts detected during said operation of detecting.

22. The method of claim 20 wherein said operation of detecting further comprises detecting an indication of a success indicia representative of a number of successful prior transmissions of packet data in a prior frame, and wherein said operation of selecting is further responsive to the indication of the success indicia detected during said operation of detecting.

23. In a mobile terminal having a receiver portion and a transmitter portion, the mobile terminal operable in a time-division radio communication system at least to communicate a packet of data to a remote station upon a random access channel in which frames, each formed of a plurality of time slots, are defined, the frames having a dynamically-allocable number of time slots forming random access channels, the number of time slots allocated to form random access channels of a selected frame broadcast to the mobile terminal, an improvement of apparatus for selecting a contention window within which to transmit the packet of data from the mobile terminal, said apparatus comprising:

a detector coupled to the receiver portion of the mobile terminal, said detector for detecting an indication of the number of time slots allocated to form the random access channel of the selected frame broadcast to the mobile terminal and received at the receiver portion thereof, and

a contention window selector coupled to receive indications of detection by said detector of the number of time slots allocated to form the random access channels of the selected frame, said contention window selector selectably operable to select a size of the contention window responsive, at least in part, to the number of time slots detected by said detector.