Fair rate allocation on an ieee 802.11e communication medium

• US 20070019591A1
• Filed: 08/23/2004
• Published: 01/25/2007
• Est. Priority Date: 09/03/2003
• Status: Active Grant

• Current Assignee: Koninklijke Philips Electronics N.V. (Koninklijke Philips N.V.)
• Original Assignee: Koninklijke Philips N.V.
• Inventors: Del Prado Pavon, Javier, Nandagopalan, Sai, Chou, Chun
• Granted Patent: US 7,756,089 B2
• Time in Patent Office: Days
• US Class Current: 370/337
• CPC Class Codes: H04W 28/10 Flow control between communication endpoints
• CPC Class Codes: H04W 74/08 Non-scheduled access, e.g. ALOHA hybrid access H04W74/02
• CPC Class Codes: H04W 74/0816 with collision avoidance
• CPC Class Codes: H04W 84/12 WLAN [Wireless Local Area Networks]

Abstract

Wireless stations (108-1-108-N) contending for exclusive access for a predetermined period of time (S232) to transmit on a communication medium (112) are regulated by a common external controller (104) using a single timing parameter (S204). Attempts at transmission access are preceded by respective delays that are expired simultaneously and at a common rate by the stations at times when the stations sense the medium to be idle (S224). The delays are pseudo-randomly selected to avoid collisions among stations in their respective access attempts (S208). Default, initial values of the respective delays (S204) applied to the stations, when multiplied by the respective expected number of transmission attempts by the stations over the long term over periods of time when no transmission attempt is unsuccessful, yield respective products equal to a constant value common to all stations (S312). The default values therefore serve as a knob by which the controller regulates air time opportunity.

Claims

1. A method for regulating transmission of traffic on a communication medium (112), said method comprising the steps of:

providing a plurality of stations able to successfully transmit on the medium not more than one at a time (108-1-108-N), the plural stations expiring simultaneously and at a common rate respective actual delays applied before re-attempting to transmit on said medium (S224, S228, S232); and

using a single timing parameter (S204), by specifying as its values respective default quantities based upon which values corresponding ones of said delays are selected, to regulate, for any given one or more of the plural stations, the number of attempts to gain, for a predefined period (S232), exclusive transmission-access, the values being updated responsive to outcomes of respective ones of said attempts (S204, S244), the products of said default quantities and expected rates of respective ones of said attempts, for long-term periods when none of said attempts is unsuccessful and during which the stations are continuously backlogged, respectively approaching a predefined constant (S312).

2. The method of claim 1, wherein said default quantities represent respective upper limits on ranges from which said corresponding ones of said delays are selected (S208).

3. The method of claim 1, wherein the updating increments said values being updated upon respective unsuccessful ones of said attempts and resets said values being updated to their corresponding default values upon respective successful ones of said attempts (S204, S244).

4. The method of claim 1, wherein the stations are configured to wirelessly transmit the traffic by means of the medium (112).

5. The method of claim 1, wherein said default values are the same for respective ones of said attempts at the same quality-of-service (QoS) priority regardless of respective rates of data transmission (S204).

6. The method of claim 1, wherein the portion of the traffic transmitted by any of the plural stations is divided into sessions of respective priority, said expected rates and said default quantities varying by priority according to the respective priorities (S204).

7. The method of claim 1, wherein a portion of the traffic is transmitted to the stations by a controller, said portion being divided into sessions (S420), the session being divided into frames (S416), the controller according, based on an unsuccessful attempt at transmission for a frame of the frames, extra transmission opportunity to a frame of another session (S420).

8. The method of claim 1, wherein said specifying as its values involves observing bandwidth actually utilized by different priority classes of the traffic and setting respective ones of the default values in inverse proportion to the observed bandwidths (S304, S308), and further involves, to meet any given, targeted, proportional increase or decrease in respective ones of said expected rates, a single instance of re-specification (S312).

9. The method of claim 1, wherein said stations sense that the medium is idle for a predetermined period before applying said respective actual delays (S216, S220), said predetermined period not varying by quality-of-service (QoS) priority, said expected rates and said default quantities varying by said priority (S204).

10. A system for regulating transmission of traffic on a communication medium, said system comprising:

a plurality of stations able to successfully transmit on the medium not more than one at a time(108-1-108-N), the plural stations being configured to expire simultaneously and at a common rate respective actual delays applied before re-attempting to transmit on said medium (S224, S228, S232); and

a controller configured to use a single timing parameter (104, S204), by specifying as its values respective default quantities based upon which values corresponding ones of said delays are selected, to regulate, for any given one or more of the plural stations, the number of attempts to gain, for a predefined period (S232), exclusive transmission-access, the values being updated responsive to outcomes of respective ones of said attempts (S204, S244), the products of said default quantities and expected rates of respective ones of said attempts, for long-term periods when none of said attempts is unsuccessful and during which the stations are continuously backlogged, respectively approaching a predefined constant (S312).

11. The system of claim 10, wherein said default quantities represent respective upper limits on ranges from which said corresponding ones of said delays are selected (S208).

12. The system of claim 10, wherein the updating increments said values being updated upon respective unsuccessful ones of said attempts and resets said values being updated to their corresponding default values upon respective successful ones of said attempts (S204, S244).

13. The system of claim 10, wherein said controller comprises an access point, the stations being configured to wirelessly transmit the traffic by means of the medium (112).

14. The system of claim 10, wherein said default values are the same for respective ones of said attempts at the same quality-of-service (QoS) priority regardless of respective rates of data transmission (S204).

15. The system of claim 10, wherein the portion of the traffic transmitted by any of the plural stations is divided into sessions of respective priority, said expected rates and said default quantities varying by priority according to the respective priorities (S204).

16. The system of claim 10, wherein a portion of the traffic is transmitted to the stations by said controller, said portion being divided into sessions (S420), the session being divided into frames (S416), the controller according, based on an unsuccessful attempt at transmission for a frame of the frames, extra transmission opportunity to a frame of another session (S420).

17. The system of claim 10, wherein said specifying as its values involves observing bandwidth actually utilized by different priority classes of the traffic and setting respective ones of the default values in inverse proportion to the observed bandwidths (S304, S308), and further involves, to meet any given, targeted, proportional increase or decrease in respective ones of said expected rates, a single instance of re-specification (S312).

18. The system of claim 10, wherein said stations sense that the medium is idle for a predetermined period before applying said respective actual delays (S216, S220), said predetermined period not varying by quality-of-service (QoS) priority, said expected rates and said default quantities varying by said priority (S204).

19. A communication program stored in a computer-readable medium to cause a computer regulating transmission on a communication medium to execute the steps of:

communicating with a plurality of stations able to successfully transmit on the medium not more than one at a time (108-1-108-N), the plural stations expiring simultaneously and at a common rate respective actual delays applied before re-attempting to transmit on the medium (S224, S228, S232); and

using a single timing parameter (S204), by specifying as its values respective default quantities based upon which values corresponding ones of said delays are selected, to regulate, for any given one or more of the plural stations, the number of attempts to gain, for a predefined period (S232), exclusive transmission-access, the values being updated responsive to outcomes of respective ones of said attempts, the products of said default quantities and expected rates of respective ones of said attempts (S204, S244), for long -term periods when none of said attempts is unsuccessful and during which the stations are continuously backlogged, respectively approaching a predefined constant (S312).

20. An integrated circuit comprising the program and computer-readable medium of claim 19 (S312).