Method and system for multipath reduction for wireless synchronization and/or locating

A location anchor network, comprising:

• a plurality of location anchors including:
• a first location anchor having a first self-reception transmitting and receiving antenna configured to communicate via a broadcast transmission medium, the first location anchor configured to broadcast a first broadcast message at least twice and self-receive each first broadcast message and determine a self-reception time, and
• a second location anchor having a second self-reception transmitting and receiving antenna configured to communicate via the broadcast transmission medium, the second location anchor configured to broadcast a second broadcast message at least twice and self-receive each second broadcast message and determine a self-reception time;
• and
• wherein the second location anchor receives the first broadcast messages, and the first location anchor receives the second broadcast messages, and the first and second location anchors generate time-or-arrival (TOA) stamps indicative of respective times of reception of the first broadcast messages and the second broadcast messages;
• and
• a location server;
• wherein the first and second location anchors are configured to send the TOA stamps to the location server;
• wherein the location server is configured to receive the TOA stamps and identify the first location anchor of the plurality of location anchors broadcasting a broadcast message corresponding to a first TOA stamp based on a first identifier of the first location anchor sent to the location server with the first TOA stamp, the first location anchor being connected to the location server, and identify the second location anchor of the plurality of location anchors broadcasting a broadcast message corresponding to a second TOA stamp based on an second identifier of the second location anchor sent to the location server with the second TOA stamp, the second location anchor being connected to the location server;
• wherein the location server is configured to calculate time-difference-of-arrival (TDOA) values from the received TOA stamps corresponding to the first broadcast messages and the second broadcast messages;
• and
• wherein the location server is further configured to calculate a phase difference between time bases of the first location anchor and the second location anchor to correct the TDOA values with steps for calculating a phase difference.

A method for determining a phase difference between time bases of at least two location anchors for a point in time, each of the location anchors having a self-reception transmitting and receiving antenna device connected to a broadcast transmission medium, the method comprising:

• broadcasting a first broadcast message at least twice from a first location anchor, wherein the first location anchor determines a self-reception time, and at least a second location anchor receives, the first broadcast messages;
• broadcasting a second broadcast message at least twice from the second location anchor wherein the second location anchor determines a self-reception time, and at least the first location anchor receives, the second broadcast messages;
• generating time-of-arrival (TOA) stamps indicative of respective first and second times of reception of the first broadcast messages and the second broadcast messages;
• delivering the generated TOA stamps to a location server, the location server identifying the location anchor broadcasting each broadcast message having a TOA stamp;
• calculating time-difference-of-arrival (TDOA) values with the location server from the delivered TOA stamps corresponding to the first broadcast messages and second broadcast messages, wherein calculating comprises steps for calculating TDOA values;
• and
• calculating an instantaneous phase difference between time bases of different location anchors with the location server with steps for calculating a phase difference and using the instantaneous phase difference to correct at least one of the TDOA value for a message received at two location anchors.