SYSTEM AND METHOD FOR SELECTING A ROUTE BASED ON LINK METRICS INCORPORATING CHANNEL BANDWIDTH, SPATIAL STREAMS AND/OR GUARD INTERVAL IN A MULTIPLE-INPUT MULTIPLE-OUTPUT (MIMO) NETWORK

• US 20100246480A1
• Filed: 03/31/2009
• Published: 09/30/2010
• Est. Priority Date: 03/31/2009
• Status: Active Grant

• Current Assignee: Extreme Networks, Inc.
• Original Assignee: Motorola, Inc. (Motorola Solutions, Inc.)
• Inventors: Shukla, Manish, Joshi, Avinash, Gossain, Hrishikesh, Aggarwal, Pankaj
• Granted Patent: US 8,798,034 B2
• Time in Patent Office: Days
• US Class Current: 370/328
• CPC Class Codes: H04L 45/123 Evaluation of link metrics techniques for monitoring network metrics H04L43/08
• CPC Class Codes: H04L 45/124 using a combination of metrics
• CPC Class Codes: H04W 40/02 Communication route or path selection, e.g. power-based or shortest path routing

Abstract

Systems and methods are provided for determining a link metric for a communication link along a path between a source node to a destination node is provided. A node can generate a link metric (LM) for the communication link between the particular node and next-hop node towards the destination node in the path based on a plurality of variables. The node can determine the LM for the communication link based on a plurality of variables including: bandwidth on the communication link, a number of spatial streams used to transmit over the communication link, and a guard interval used used to transmit over the communication link.

Claims

1. A method for selecting one of a plurality of paths between a source node and a destination node in an ad-hoc multi-hopping peer-to-peer wireless communications network with MIMO capability based on link metrics (LMs) for each of the paths, the method comprising:

(a) selecting, at a source node, a first path from the plurality of possible paths to the destination node, wherein the first path comprises one or more communication links that wirelessly connect the source node to the destination node;

(b) determining, at each node along the first path, a corresponding link metric (LM) for the communication link between each particular node and next-hop node towards the destination node in the first path based on a plurality of variables including at least one of;

a number of spatial streams used to transmit over the communication link, and a guard interval used to transmit over the communication link; and

(c) summing, at the source node, the link metrics (LMs) for each communication link along the path to generate a path metric for the first path.

2. A method according to claim 1, further comprising the steps of:

repeating steps (a) through (c) for each of the plurality of paths from the source node to the destination node; and

determining, at the source node after performing steps (a) through (c) for each path of the plurality of paths from the source node to the destination node, which particular one of the plurality of paths from the source node to the destination node has a best path metric;

selecting, at the source node, the particular one of the plurality of paths from the source node to the destination node that is determined to have the best path metric as the route for transmitting packet(s) to the destination node.

3. A method according to claim 1, wherein step (b) comprises the step of:

(b) determining, at each node along the first path, a link metric (LM) for each of the communication links in the first path based on a plurality of variables including;

bandwidth on the communication link, a number of spatial streams used to transmit over the communication link, and a guard interval used used to transmit over the communication link.

4. A method according to claim 1, wherein step (b) comprises the steps of:

(b1) determining, at each node along the path after each transmission on that communication link towards the next-hop node, the number of spatial streams used to transmit over that communication link, the guard interval used to transmit over that communication link, and the bandwidth used to transmit over that communication link;

(b2) determining, at each node along the path after each transmission on that communication link towards the next-hop node, scaling factors for the communication link, wherein the scaling factors comprise at least one of;

a scaling factor for a number of spatial streams used to transmit over that communication link, a scaling factor for a guard interval used used to transmit over that communication link, and a scaling factor for bandwidth used to transmit over that link;

(b2) determining, at each node an average value for each of the scaling factors.

5. A method according to claim 4, wherein steps (b1) through (b3) comprises the step of:

(b) determining, at each node along the first path after each transmission on that communication link towards the next-hop node, a corresponding link metric (LM) for each of the communication links in the first path, wherein each link methric (LM) is determined using an equation;

6. A method according to claim 5, wherein the exponentially weighted moving average of the scaling factor (Ps(t)) for the number of streams is determined based on an equation:

Ps(t)=λ

·

Pss(t₀)+(1−

λ

)·

Ps(t<sub>−

1</sub>), where

7. A method according to claim 5, wherein the exponentially weighted moving average of the scaling factor (Pb(t)) for the bandwidth is determined based on an equation:

Pb(t)=λ

·

Pbs(t₀)+(1−

λ

)·

Pb(t<sub>−

1</sub>), where

8. A method according to claim 5, wherein the exponentially weighted moving average of the scaling factor (Pg(t)) for the guard interval is determined based on an equation:

Pg(t)=λ

·

Pgs(t₀)+(1−

λ

)·

Pg(t<sub>−

1</sub>), where

9. A method according to claim 1, wherein each link metric represents an estimated transmission time associated with communicating information over a particular communication link, and wherein the best path metric is the one of the plurality of path metrics for a particular path that is determined to have a lowest estimated transmission time associated with communicating information to the destination node.

10. A method for determining a link metric for a communication link, the method comprising:

determining, at a particular node, a link metric (LM) for the communication link between the particular node and a next-hop node towards a destination node based on a plurality of variables including at least one of;

bandwidth on the communication link, a number of spatial streams used to transmit over the communication link, and a guard interval used to transmit over the communication link.

11. A method according to claim 10, wherein the step of determining comprises the steps of:

determining the number of spatial streams used to transmit over the communication link, the guard interval used to transmit over the communication link, and the bandwidth used to transmit over the communication link;

determining scaling factors for the communication link, wherein the scaling factors comprise at least one of;

a scaling factor for a number of spatial streams used to transmit over the communication link, a scaling factor for a guard interval used used to transmit over the communication link, and a scaling factor for bandwidth used to transmit over the link; and

determining an average value for each of the scaling factors.

12. A method according to claim 11, wherein the determining step comprises the step of:

determining a link metric (LM) for the communication link, wherein the link methric (LM) is determined using an equation;

13. A method according to claim 12, wherein the exponentially weighted moving average of the scaling factor (Ps(t)) for the number of streams is determined based on an equation:

Ps(t)=λ

·

Pss(t₀)+(1−

λ

)·

Ps(t<sub>−

1</sub>), where

14. A method according to claim 12, wherein the exponentially weighted moving average of the scaling factor (Pb(t)) for the bandwidth is determined based on an equation:

Pb(t)=λ

·

Pbs(t₀)+(1−

λ

)·

Pb(t<sub>−

1</sub>), where

15. A method according to claim 12, wherein the exponentially weighted moving average of the scaling factor (Pg(t)) for the guard interval is determined based on an equation:

Pg(t)=λ

·

Pgs(t₀)+(1−

λ

)·

Pg(t<sub>−

1</sub>) where

16. A method according to claim 10, wherein each link metric represents an estimated transmission time associated with communicating information over a particular communication link.

17. A node, comprising:

a processor designed to determine a link metric for a communication link between the node to and a next-hop node towards a destination node based on a plurality of variables including at least one of;

bandwidth on the communication link,

a number of spatial streams used to transmit over the communication link, and

a guard interval used to transmit over the communication link.

18. A node according to claim 17, wherein the processor is designed to determine the link metric for the communication link based on the number of spatial streams used to transmit over the communication link, the guard interval used to transmit over the communication link, the bandwidth used to transmit over the communication link, a scaling factor for a number of spatial streams used to transmit over the communication link, a scaling factor for a guard interval used used to transmit over the communication link, and a scaling factor for bandwidth used to transmit over the link.

19. A node according to claim 17, wherein the link methric (LM) is determined using an equation:

20. A method according to claim 17, wherein each link metric represents an estimated transmission time associated with communicating information over a particular communication link.