Methods and devices for managing a shared transmission medium

• US 20050122935A1
• Filed: 10/20/2004
• Published: 06/09/2005
• Est. Priority Date: 11/06/2003
• Status: Abandoned Application

• Current Assignee: Mitsubishi Denki Kabushiki Kaisha (Mitsubishi Electric Corporation)
• Original Assignee: Mitsubishi Denki Kabushiki Kaisha (Mitsubishi Electric Corporation)
• Inventors: Rollet, Romain, Mangin, Christophe
• Application Number:
  US10/968,326
• Publication Number:
  US 20050122935A1
• Time in Patent Office: Days
• US Class Current: 370/329
• CPC Class Codes: H04W 48/12 using downlink control channel
• CPC Class Codes: H04W 74/02 Hybrid access
• CPC Class Codes: H04W 84/12 WLAN [Wireless Local Area Networks]

Abstract

There is disclosed a method and a device for managing a shared transmission medium, between a plurality of stations in a wireless local area network having an Access Point (AP). The AP transmits to all stations substantially periodic management frames, a SuperFrame being defined as the time period between two consecutives management frames. This SuperFrame is divided into a plurality of time periods and these time periods correspond to respective access schemes. This time division is performed according to a management information comprised in the periodic management frame. There is a first time period corresponding to a contention free access scheme which includes a Time Frame (TF) having at least one synchronous Frame Time Interval (FTI), and a second time period corresponding to a contention access scheme.

Claims

1. A method for managing a shared transmission medium between a plurality of stations in a wireless local area network having an Access Point (AP), the method comprising the steps of:

said AP transmitting to all stations substantially periodic management frames, a SuperFrame being defined as the time period between two consecutives management frames,

splitting said SuperFrame into a plurality of time periods, which time periods correspond to respective access schemes, according to a management information comprised in said management frame, said SuperFrame comprising;

a first time period corresponding to a contention free access scheme,

a second time period corresponding to a contention access scheme,

wherein said first time period comprises a Time Frame (TF) having at least one synchronous Frame Time Interval (FTI).

2. The method of claim 1, wherein the TF comprises a set of a given number N of consecutive FTIs, each FTI having a same duration D.

3. The method of claim 2, wherein N and D are fixed on a per SuperFrame basis.

4. The method of claim 2 or 3, wherein N and D of each synchronous FTI of the SuperFrame are comprised in the management information, transmitted by the AP to the stations.

5. The method of claim 4, wherein N and/or D of FTIs are determined by the AP for each SuperFrame, each according to a respective algorithm running in the AP.

6. The method of claim 5, wherein the algorithm of the AP takes into account transmission requirements received from the respective stations, in order to determine D and/or N.

7. The method of any one of the preceding claims, wherein the TF is located at the beginning of the Superframe, directly after the management frame transmission.

8. The method of any one of the preceding claims, wherein a protocol A is used during the SuperFrame, except during the TF for which a protocol B is used, protocol A and protocol B being different.

9. The method of claim 8, wherein the plurality of stations includes IEEE Standard 802.11 compliant stations and wherein the protocol A and the protocol B are different versions of said IEEE Standard 802.11.

10. The method of claim 9, wherein the FTI information element included in the management frame comprises a specific element identifier, which is different from these defined by 802.11 standard.

11. The method of claim 9 or 10, wherein the first time period includes a time period managed by a Point Coordination Function (PCF) access mechanism as defined by the IEEE Standard 802.11.

12. The method of claim 9, 10 or 11, wherein the first time period includes a time period managed by a Hybrid Coordination Function (HCF) access mechanism as defined by the 802.11 standard.

13. The method of claim 10, wherein stations do not manage any message received through the shared transmission medium during the TF when they do not recognise the specific element identifier and/or do not support the protocol version corresponding to said message.

14. The method of any one of claims 4 through 13, wherein the AP distributes dynamically transmission resource between the different supported access schemes according to the characteristics of the different transmission requirements.

15. A device for managing a shared transmission medium between a plurality of stations in a wireless local area network, the device comprising:

means to transmit to all stations substantially periodic management frames, a SuperFrame being defined as the time period between two consecutives management frames,

means to split said SuperFrame into a plurality of time periods, which time periods correspond to respective access schemes, according to a management information comprised in said management frame, said SuperFrame comprising;

a first time period corresponding to a contention free access scheme,

a second time period corresponding to a contention access scheme,

wherein said first time period comprises a Time Frame (TF) having at least one synchronous Frame Time Interval (FTI).