WIRELESS ROUTING SELECTION SYSTEM AND METHOD

• US 20110158122A1
• Filed: 03/07/2011
• Published: 06/30/2011
• Est. Priority Date: 06/09/2006
• Status: Abandoned Application

• Current Assignee: Trapeze Networks Incorporated (Juniper Networks Incorporated)
• Original Assignee: Trapeze Networks Incorporated (Juniper Networks Incorporated)
• Inventors: Murphy, James, Morain, Gary
• Application Number:
  US13/042,080
• Publication Number:
  US 20110158122A1
• Time in Patent Office: Days
• US Class Current: 370/252
• CPC Class Codes: H04L 45/121 by minimising delays
• CPC Class Codes: H04W 40/14 based on stability

Abstract

A technique involves untethered access points (UAPs) that can broadcast estimated transmission time (ETT) that represents an estimated time it would take for a packet to be transmitted from the first UAP to an AP that is wire coupled to a network. The proposed system can offer, among other advantages, accurate ETT values for use by UAPs of a wireless network.

Claims

1. A method comprising:

receiving, at a first wireless node, an estimated transmission time (ETT) from each wireless node from a plurality of wireless nodes that are within a range of the first wireless node, the ETT for each wireless node from the plurality of wireless nodes is a next-hop-to-destination-path ETT (ETTp) associated with one remaining wireless node from the plurality of wireless nodes;

at the first wireless node, adding for each wireless node from the plurality of wireless nodes a link ETT (ETT1) to a corresponding ETTp to determine a node-specific path metric for that wireless node; and

at the first wireless node, selecting a next hop based on the determined node-specific path metrics.

2. The method of claim 1, wherein each ETTp is a function of an ETT1, another ETTp, and a node transmission time of a second wireless node from the plurality of wireless nodes.

3. The method of claim 1, further including, at the first wireless node, calculating an advertised ETTp for the first wireless node, the advertised ETTp based on at least one ETT1, the ETTp of the first wireless node, and a node transmission time of the first wireless node.

4. The method of claim 1, further including broadcasting an advertised ETTp from the first wireless node to a second wireless node from the plurality of wireless nodes.

5. The method of claim 1, further including measuring an ETT1 from the first wireless node to each wireless node from the plurality of wireless nodes.

6. The method of claim 1, further including:

placing a packet on an egress queue of the first wireless node at a first time;

receiving an acknowledgement that the packet was received by a second wireless node from the plurality of wireless nodes at a second time; and

measuring an ETT1 between the first wireless node and the second wireless node based on the first time and the second time.

7. The method of claim 1, further including:

receiving a packet on an ingress interface of a wireless node from the plurality of wireless nodes at a first time;

placing the packet on an egress interface of that wireless node at a second time; and

calculating the ETTp of that wireless node based on the first time and the second time.

8. An apparatus comprising:

a first access point configured to be wirelessly coupled to a second access point;

the first access point is configured to broadcast an estimated transmission time (ETT) for a packet to be transmitted from the first access point to the second access point, the ETT including an estimated node transition time (NTT) at the first access point and an ETT over a link to the next hop that is based on current load.

9. The apparatus of claim 8, the first access point configured to transmit the packet to a network via a station.

10. The apparatus of claim 8, the first access point is configured to compare a next-hop-to-destination-path ETT (ETTp) of the second access point to an ETTp advertised by a third access point, and to send the first packet to the third access point when the advertised ETTp of the third access point is lower than the ETT of the second access point.

11. The apparatus of claim 8, the first access point is configured to calculate an ETT between the first access point and the second access point by queuing the first packet to be sent to the second access point and by measuring the amount of time the first packet is queued.

12. The apparatus of claims 8, the first access point is configured to calculate the ETT between the first access point and the second access point by sending the first packet to the second access point, receiving an acknowledgment of receipt from the second access point, and measuring the amount of time between sending the packet and receiving the acknowledgment.

13. The apparatus of claim 8, wherein the first access point is untethered.

14. The apparatus of claim 8, wherein the first access point is untethered and the second access point is tethered.

15. An apparatus, comprising:

an estimated transmission time (ETT) engine configured to receive an estimated path transmission time (ETTp) advertised for each wireless node from a plurality of wireless nodes linked to an access point (AP), the ETTp for each wireless node from the plurality of wireless nodes being a function of a link ETT (ETT1), the ETTp for a remaining wireless node from the plurality of wireless nodes, and a node transition time (NTT) of that wireless node;

the ETT engine configured to measure, for each wireless node from the plurality of wireless nodes, the ETT1 between the AP and that wireless node; and

the ETT engine configured to determine a node-specific path metric for each wireless node from the plurality of wireless nodes, based on the measured ETT1 and the ETTp for that wireless node; and

a next hop selector coupled to the ETT engine and configured to select a transmission path for a message received at the AP, based on the node-specific path metrics.

16. The apparatus of claim 15, wherein the ETT engine is configured to calculate an advertised ETTp for the AP, based on the measured ETT1s and the received advertised ETTps.

17. The apparatus of claim 15, wherein the ETT engine is configured toe to calculate the advertised ETTp for the AP as a function of one of (1) the measured ETT1'"'"'s, (2) a received advertised ETTps or (3) a computed NTT of the AP.

18. The apparatus of claim 15, wherein the AP computes an NTT as a function of an amount of time to be enqueue the message within the AP for transmission to another node.

19. The apparatus of claim 15, wherein the ETT engine is configured to calculate each ETT1 as an indication of an amount of time between a packet being enqueued at an egress interface of the AP and an acknowledgement of the packet being received by the AP.

20. The apparatus of claim 15, further including:

an ETTp broadcast engine coupled to the ETT engine and configured to broadcast the advertised ETTp for the access point, from the access point to a wireless node from the plurality of wireless nodes.