Method and apparatus for determining position and trajectory of gateways to optimize performance in hybrid non-terrestrial-terrestrial multi-hop mobile networks

• US 20030053424A1
• Filed: 08/07/2001
• Published: 03/20/2003
• Est. Priority Date: 08/07/2001
• Status: Active Grant

• Current Assignee: HRL Laboratories LLC A Limited Liability Company of Delaware
• Original Assignee: HRL Laboratories LLC A Limited Liability Company of Delaware
• Inventors: Ahmed, Mohin, Krishnamurthy, Srikanth, Kondylis, George D.
• Granted Patent: US 6,807,158 B2
• Time in Patent Office: Days
• US Class Current: 370/316
• CPC Class Codes: H04B 7/185 Space-based or airborne stations; Stations for satellite systemsH04B7/204 takes precedence
• CPC Class Codes: H04B 7/18563 Arrangements for interconnecting multiple systems data switching networks H04L12/00
• CPC Class Codes: H04W 24/02 Arrangements for optimising operational condition
• CPC Class Codes: H04W 64/00 Locating users or terminals or network equipment for network management purposes, e.g. mobility management
• CPC Class Codes: H04W 76/10 Connection setup
• CPC Class Codes: H04W 84/06 Airborne or Satellite Networks space-based or airborne stations H04B7/185
• CPC Class Codes: H04W 84/18 Self-organising networks, e.g. ad-hoc networks or sensor networks
• CPC Class Codes: H04W 88/16 Gateway arrangements

Abstract

A wireless hybrid network consisting at least one satellite 118 and a plurality mobile ad hoc nodes 104. The nodes 104 are assumed to be clustered into mobile groups 102 within the footprint of the satellite 118, and the objective is to enable reliable communications between the various nodes 104. At least one relatively powerful gateway 110, also mobile, is deployed for each cluster 102 of nodes to facilitate communication with a LEO or GEO satellite 118. The environment is characterized by the presence of terrestrial barriers 100 or other severe channel impairments. One of the goals of the invention is to provide a mechanism by which a mobile gateway 112 can change its position or define its trajectory based on the position and loading of the nodes 104 in an ad hoc network, so as to optimize certain pre-defined performance criterion, such as power, overhead, throughput.

Claims

1. A method for optimizing performance in a hybrid mobile wireless ad-hoc network comprising the steps of:

providing a first wireless cluster comprising the following elements;

i. a first plurality of mobile nodes, and

ii. a first gateway node

where the first plurality of mobile nodes are communicatively linked to the first gateway node;

providing a second wireless cluster including the following elements;

i. a second plurality of mobile nodes, and

ii. a second gateway node

where the second plurality of mobile nodes are communicatively linked to the second gateway node;

establishing a communications link between the first wireless cluster and the second wireless cluster by directing data sequentially through;

i. the first gateway node;

ii. a satellite; and

iii. the second gateway node

2. The method as set forth in claim 1 wherein the first gateway node'"'"'s and the second gateway node'"'"'s positions are dynamically selected to optimize at least one of the following:

i. data throughput;

ii. data transmission reliability including at least one of the following;

a) maximizing bandwidth utilization;

b) minimizing bit error rate; and

c) minimizing message delay;

iii. total power consumption;

iv. wireless node-level power consumption;

V. gateway level power consumption;

vi. periodicity of updates and resulting signaling overhead; and

vii. complexity of updates and resulting signaling overhead.

3. The method as set forth in claim 1 wherein each mobile node in the wireless ad-hoc network performs a local computation comprising the steps of:

i. estimating its position and transmitting its position to the gateway node at every time interval T;

ii. computing and transmitting its data load information at time interval t, where t<

T.

4. The method as set forth in claim 1 where the first and second gateway nodes perform the following computational steps during a time interval:

i. receive control information from each mobile node in the cluster;

ii. compute optimal gateway node position;

iii. assign gateway node to new optimal position and;

iv. transmit updated routing information.

5. The method as set forth in claim 1 wherein the wireless ad-hoc network is sub-divided into a cluster of smaller wireless ad-hoc networks and additional gateways are introduced to reduce the computational complexity of the optimization calculation.

6. The method as set forth in claim 1 wherein the satellite is selected from a list comprising at least one of the following:

i. a low earth orbit satellite;

ii. a geosynchronous earth orbit satellite.

7. The method as set forth in claim 1 wherein the gateway node ignores at least one node for the purposes of an optimization calculation, based on at least one of the following criterion:

i. degree of node load;

ii. node remoteness;

iii. unacceptable complexity in the optimization calculation; and

directs said at least one node to communicate through a neighboring node.

8. The method as set forth in claim 7 wherein a decision to force said at least one node to form a link via its neighbor can be ordered by at least one of the following:

i. the gateway node with a centralized protocol;

ii. a distributed protocol wherein said at least one node itself may query its neighbors and elect to use a relay node rather than to contact the gateway directly.

9. An apparatus for increasing performance in a hybrid, non-terrestrial to terrestrial multi-hop mobile wireless network comprising:

a first wireless cluster including the following elements;

i. a first plurality of mobile nodes; and

ii. a first gateway node;

where the first plurality of mobile nodes are communicatively linked to the first gateway node;

a second wireless cluster including the following elements;

i. a second plurality of mobile nodes; and

ii. a second gateway node;

where the second plurality of mobile nodes are communicatively linked to the second gateway node;

a communications link between the nodes in the first wireless cluster and the nodes in the second wireless cluster that sequentially directs data through;

i. the first gateway node;

ii. a satellite; and

iii. the second gateway node.

10. The apparatus as set forth in claim 9 wherein the first gateway node and the second gateway node comprise elements that are configured to receive data from at least one mobile node in the relevant gateway node'"'"'s cluster and based on this data to dynamically select the gateways position relative to the mobile nodes to optimize one or more of the following:

i. data throughput;

ii. data transmission reliability including at least one of the following;

a) maximizing bandwidth utilization;

b) minimizing bit error rate; and

c) minimizing message delay;

iii. total power consumption;

iv. wireless node-level power consumption;

v. gateway level power consumption;

vi. periodicity of updates and resulting signaling overhead; and

vii. complexity of updates and resulting signaling overhead.

11. The apparatus as set forth in claim 9 wherein each mobile node in the wireless ad-hoc network comprises elements configured to perform a local computation comprising the steps of:

i. estimating the mobile nodes'"'"' positions and transmitting these position to the gateway node at time interval T;

ii. computing and transmitting the mobile nodes'"'"' data load information at time interval t where t<

T.

12. The apparatus as set forth in claim 9 wherein the mobile nodes positions are estimated with the aid of at least one of the following:

i. a global positioning system;

ii. a terrestrially based triangulation system; and

iii. a generic positioning system.

13. The apparatus as set forth in claim 9 where the gateway nodes comprise an element configured to perform the following computations during a time interval:

i. receive control information from each node in each cluster;

ii. compute the optimal position;

iii. assign the gateway node to a new optimal position and;

iv. transmit updated routing information;

14. The apparatus as set forth in claim 9 wherein the wireless ad-hoc network is sub-divided into a cluster of smaller wireless ad-hoc networks and additional gateways are introduced to reduce the computational complexity of the optimization calculation.

15. The apparatus as set forth in claim 9 wherein the non-terrestrial relay is selected from a list comprising at least one of the following:

i. a low earth orbit satellite;

ii. a geosynchronous earth orbit satellite.

16. The apparatus as set forth in claim 9 wherein the gateway node is configured to ignore at least one node for the purposes of the optimization calculation, based on at least one of the following criterion:

i. a lightly loaded node;

ii. a relatively remote node;

iii. a node that introduces an unacceptable complexity into the optimization calculation; and

directs said at least one node to communicate through a neighboring node.

17. The apparatus as set forth in claim 16 wherein the decision to force said at least one node to form a link via its neighbor can be ordered by at least one of the following:

i. the gateway node with a centralized protocol

ii. a distributed protocol wherein said at least one node itself may query its neighbors and elect to use a relay node rather than to contact the gateway directly.

iii.

18. The apparatus as set forth in claim 9 wherein the gateway nodes comprise separate processors which are solely dedicated to the optimization calculations.

19. The apparatus as set forth in claim 9 wherein the gateway node comprises a separate processor which is solely dedicated to the optimization calculations.