Method and system for target positioning and tracking in cooperative relay networks

1. A method for locating a position of a transceiver, in a cooperative relay network of nodes, comprising:

broadcasting, by a primary node in the cooperative relay network, a range request (RREQ) message;

broadcasting, by a target node in the cooperative relay network in response to receiving the RREQ message, a range reply (RREP) message, wherein the RREP message includes a time difference between receiving the RREQ message and broadcasting the RREP message;

broadcasting, by a secondary node in the cooperative relay network in response to receiving the RREQ message and the RREP message, a range data (RDAT) message, wherein the RDAT message includes a time difference between receiving the RREQ message and the RREP message; and

determining, in a position solver of the cooperative relay network, a location of the target node based on the time differences in the RREP message and the RDAT message.

2. The method of claim 1 , further comprising:

implementing the position solver in the target node.

3. The method of claim 1 , further comprising:

implementing the position solver in a coordinator node in the cooperative relay network.

4. The method of claim 1 , wherein the target node is mobile.

5. The method of claim 1 , wherein each message includes a messageType field identifying the message as the RREQ, RREP or RDAT message, a localID field for storing a network address of the primary reference node, a sourceID field for identifying the primary reference node, a targetID for identifying the target node, a sequenceNo field for counting a number of position update requests, and a time difference field for storing the time difference.

6. The method of claim 1 , wherein a range estimate z between the primary node and the secondary node is based on a round trip time for the RREQ message and RREP.

7. The method of claim 6 , wherein the range estimate is

z

=

r

+

n

T

2

-

n

P

2

,

⁢

where

⁢

⁢

r

=

(

x

P

-

x

T

)

2

+

(

y

P

-

y

T

)

2

(

1

)

a range r is between the primary node P and the target node T, n T is a timing error at the target node, and n p is a timing error at the primary node.

8. The method of claim 1 , wherein the network has multi-path channels, and further comprising:

searching for a first copy of the RREQ message at the target node and a first copy of the RREP message at the primary node.

9. The method Of claim 1 , wherein a statistical approach uses a maximum likelihood estimator, which estimates the target coordinates that maximize p θ ( z )=∫ p θ ( z|n T )ƒ θ ( n T ) dn T ,

where ƒ θ (n T ) is the probability density function of noise components due to the measurements at the target node.

10. The method of claim 1 , further comprising:

broadcasting a plurality of RREQ, RREP and RDAT messages over time to track the target node.

11. A system for locating a position of a transceiver, in a cooperative relay network of nodes, comprising:

a primary node in the cooperative relay network is configured to broadcast, a range request (RREQ) message;

a target node in the cooperative relay network is configured to broadcast, in response to receiving the RREQ message, a range reply (RREP) message, wherein the RREP message includes a time difference between receiving the RREQ message and broadcasting the RREP message;

a secondary node in the cooperative relay network is configured to broadcast, in response to receiving the RREQ message and the RREP message, a range data (RDAT) message, wherein the RDAT message includes a time difference between receiving the RREQ message and the RREP message; and

a position solver of the cooperative relay network determines a location of the target node based on the time differences in the RREP message and the RDAT message.