Methods and Apparatus for Determining an Offset for Time Synchronization in a Communication Network

A method of determining an offset between a first time reference and a second time reference in a communication network, the method comprising:

• obtaining information relating to the following:
• a first detection time, at a first node, of a first photon of a first pair of photons generated at the first node, and
• a second detection time, at a second node, of a second photon of the first pair of photons;
• obtaining information relating to the following:
• a third detection time, at the first node, of a first photon of a second pair of photons generated at the first node, and
• a fourth detection time, at the first node, of a third photon received from the second node in response to sending a second photon of the second pair of photons to the second node;
• and
• determining an offset between a first time reference at the first node and a second time reference at the second node based on the obtained information relating to the first, second, third, and fourth detection times.

A method performed in a first node configured for operation in a communication network, the method comprising:

• generating a first pair of photons;
• obtaining information relating to a first detection time, at the first node, of a first photon of the first pair of photons;
• sending a second photon of the first pair of photons to a second node;
• obtaining information relating to a second detection time, at the second node, of the second photon of the first pair of photons;
• generating a second pair of photons;
• obtaining information relating to a third detection time, at the first node, of a first photon of the second pair of photons;
• sending a second photon of the second pair of photons to a second node;
• obtaining information relating to a fourth detection time, at the first node, of a third photon received from the second node in response to sending the second photon of the second pair of photons;
• and
• determining an offset between a first time reference at the first node and a second time reference at the second node based on the obtained information relating to the first, second, third, and fourth detection times.

An apparatus configured to determine an offset between a first time reference and a second time reference in a communication network, the apparatus comprising:

• processing circuitry;
• and
• memory operably coupled to the processing circuitry and storing executable instructions that, when executed by the processing circuitry, cause the apparatus to:
• obtain information relating to the following:
• a first detection time, at a first node, of a first photon of a first pair of photons generated at the first node, and
• a second detection time, at a second node, of a second photon of the first pair of photons;
• obtain information relating to the following:
• a third detection time, at the first node, of a first photon of a second pair of photons generated at the first node, and
• a fourth detection time, at the first node, of a third photon received from the second node in response to sending a second photon of the second pair of photons to the second node;
• and
• determine an offset between a first time reference at the first node and a second time reference at the second node based on the obtained information relating to the first, second, third, and fourth detection times.

A first node configured for operation in a communication network, the first node comprising:

• processing circuitry;
• and
• memory operably coupled to the processing circuitry and storing executable instructions that, when executed by the processing circuitry, cause the first node to:
• generate a first pair of photons;
• obtain information relating to a first detection time, at the first node, of a first photon of the first pair of photons;
• send a second photon of the first pair of photons to a second node;
• obtain information relating to a second detection time, at the second node, of the second photon of the first pair of photons;
• generate a second pair of photons;
• obtain information relating to a third detection time, at the first node, of a first photon of the second pair of photons;
• send a second photon of the second pair of photons to a second node;
• obtain information relating to a fourth detection time, at the first node, of a third photon received from the second node in response to sending the second photon of the second pair of photons;
• and
• determine an offset between a first time reference at the first node and a second time reference at the second node based on the obtained information relating to the first, second, third, and fourth detection times.