Multi-tier WLAN and method for propagating beacons in a multi-tier WLAN thereof

• US 8,068,467 B2
• Filed: 10/22/2004
• Issued: 11/29/2011
• Est. Priority Date: 10/22/2004
• Status: Active Grant

• Current Assignee: Motorola Solutions, Inc.
• Original Assignee: Motorola Solutions, Inc.
• Inventors: Pandey, Aparna, Ekl, Randy L., Ware, Christopher G.
• Primary Examiner(s): Edouard; Patrick N
• Assistant Examiner(s): HO, HUY C
• Application Number:
  US10/971,293
• Publication Number:
  US 20060098606A1
• Time in Patent Office: 2,594 Days
• Field of Search: 370/338, 370/503, 455/449
• US Class Current: 370/338
• CPC Class Codes: H04W 48/12 using downlink control channel
• CPC Class Codes: H04W 56/00 Synchronisation arrangements

Abstract

A method for transmitting beacons by nodes in a multi-tier wireless local area network is disclosed. First, a first beacon by a tier 1 node in the multi-tier wireless local area network is transmitted. Then, a second beacon by a tier 2 node is transmitted where the second beacon is transmitted based upon the time that the first beacon is sent by the tier 1 node.

Claims

1. A method for transmitting beacons by a coverage access point and one or more clients in a multi-tier wireless local area network, wherein the multi-tier wireless local area network comprises at least one coverage access point and a plurality of multi-tiered clients, the method comprising:

transmitting a first beacon by the coverage access point in the multi-tier wireless local area network, wherein the coverage access point provides coverage to the plurality of multi-tiered clients;

transmitting a first client beacon by at least one of the plurality of multi-tiered clients during a beacon propogation period, wherein the beacon propagation period is a protected time and

suspending transmission of traffic other than one or more client beacons during the beacon propagation period.

2. The method of claim 1 wherein the multi-tier wireless local area network comprises at least one tier 1 access point, at least one tier 2 access point, and at least one tier 3 access point, and wherein the coverage access point comprises a tier 3 access point, the method further comprising:

transmitting a second beacon by a tier 2 access point prior to transmitting the first beacon by the coverage access point,

wherein the first beacon is transmitted by the coverage access point based upon the time that the second beacon is transmitted by the tier 2 access point and a first beacon offset value, wherein the first beacon offset value is included in the second beacon transmitted by the tier 2 access point.

3. The method of claim 1 further comprising:

transmitting a second beacon by a tier 1 access point; and

transmitting a third beacon by a tier 2 access point,

wherein the third beacon is transmitted by the tier 2 access point based upon the time that the second beacon is sent by the tier 1 access point and a second beacon offset value, wherein the second beacon offset value is included in the second beacon transmitted by the tier 1 access point.

4. The method of claim 2, wherein the second beacon further comprises a quantity of coverage access points attached to it, and further wherein the step of transmitting the first beacon takes into account the quantity of coverage access points.

5. The method of claim 4 wherein the step of transmitting the first beacon further comprises waiting a time equal to TBTT_i,j+BCN_OFST_T2,Cov+(k−

1)*BCN_OFST_Cov,Cov. where;

TBTT_i,j=the times that one or more tier 2 access points transmit beacons,

BCN_OFST_T2,Cov=a predesignated number chosen to allow all the coverage access points time to receive the beacon from their respective tier 2 access points,

BCN_OFST_Cov,Cov=a predesignated number associated with the coverage access point,

i=1, 2, . . . , a number of tier 1 access points in the multi-tier WLAN,

j=1,2, . . . , a number of tier 2 access points in the multi-tier WLAN, and

k=1,2, . . . , the number of coverage access points in the multi-tier WLAN.

6. The method of claim 3, wherein the third beacon further comprises a quantity of tier 2 access points, and further wherein the step of transmitting a second beacon takes into account the quantity of tier 2 access points.

7. The method of claim 6 wherein the step of transmitting the second beacon further comprises waiting a time equal to TBTT_i+BCN_OFST_T1,T2+(j−

1)*BCN_OFST_T2,T2 where;

TBTT_i=a target beacon transmission time

BCN_OFST_T1,T2=a predesignated number chosen to allow all the tier 2 access points associated with the tier 1 access point time to receive the beacon from the tier 1 access point,

BCN_OFST_T2,T2=a predesignated number associated with one or more tier 2 access points,

i=1, 2, . . . , a number of tier 1 access points in the multi-tier WLAN,

and j=1, 2, . . . , a number of tier 2 access points in the multi-tier WLAN.

8. The method of claim 1 wherein the first beacon further comprises an information field indicating the beacon propagation period.

9. The method of claim 1 wherein the first beacon further comprises an information field comprising information about pending traffic including one or more of a destination of a pending traffic and a direction of the pending traffic, for clients associated with the coverage access point.

10. The method of claim 8 wherein the first client beacon comprises an information field including one or more information selected from a group comprising a quantity of hops to the tier 1 access point, a basic service set identification, a client identification, and a direction of pending traffic.

11. The method of claim 1 wherein the beacon propagation period is a pre-designated time corresponding to a controlled access period.

12. The method of claim 1 wherein a frequency with which the client beacon is transmitted by a client is variable, and wherein the variable frequency is based upon one or more factors selected from a group comprising a number of hops to the coverage access point, and a relative tier of the client compared to other clients served by the coverage access point.

13. The method of claim 1, further comprising:

transmitting a first client beacon by a tier 1 client in the multi-tier wireless local area network, wherein the first client beacon includes a beacon offset value; and

transmitting a second client beacon by a tier 2 client based upon the time that the first beacon is sent by the tier 1 client and the beacon offset value.

14. A multi-tier wireless local area network comprising:

a plurality of multi-tiered access points including at least one tier 1 access point, at least one tier 2 access point, and at least one tier 3 access point, wherein a tier 3 coverage access point provides coverage to a plurality of multi-tiered clients, wherein the tier 3 coverage access point transmits at first beacon; and

the plurality of multi-tiered clients, wherein at least one of the plurality of multi-tiered clients transmits a first client beacon during a beacon propogation period, wherein the beacon propagation period is a protected time in which transmission of traffic other than one or more client beacons is suspended.

15. A multi-tier wireless local area network comprising:

a single tier access point, wherein the single tier access point provides coverage to a plurality of multi-tiered clients, wherein the single tier access point transmits a first beacon; and

the plurality of multi-tiered clients, wherein at least one of the plurality of multi-tiered clients transmits a first client beacon during a beacon propogation period, wherein the beacon propagation period is a protected time in which transmission of traffic other than one or more client beacons is suspended.