Phase-based distance determination for wireless networks

Method for determining a distance and/or a frequency offset between a first node and an second node in a wireless network, the method comprising:

• the first node transmitting request messages based on carrier signals at different carrier frequencies to the second node and receiving for each of the request signals, a time series of response messages from the second node, wherein for each of the request messages the time series of response messages being transmitted based on one of reference carrier signals, each one of the reference carrier signals being transmitted at one of reference carrier frequencies by the second node to the first node, wherein the carrier frequencies and the reference carrier frequencies form frequency channels between the first node and the second node;
• the first node receiving first phase differences from the second node, each of the first phase differences defining a difference between a phase of one the carrier signals and a phase of one of the reference carrier signals at a predetermined time instance associated with one of first request messages, the frequency of the one of the carrier signals and the frequency of the one of the reference carrier signals being in the same frequency channel;
• the first node determining second phase differences based on the request signals and the response messages, the determining of the second phase differences including computing for each one of the carrier signals phase differences, each of the phase differences defining a difference between a phase of one of the reference carrier signals and a phase of one of the carrier signals at a predetermined time instance associated with one of the time series of response messages;
• and,
• the first node and/or the second node or a further node determining a distance and/or a frequency offset between the first node and the second node based on the first phase differences and the second phase differences.

A wireless node comprising a transceiver, an oscillator coupled to a frequency synthesizer for generating carrier signals at different carrier frequencies, a phase detector configured to determine a phase difference between a phase of a response signal received by the node from a further node and a phase of a carrier signal selected from the different carrier signals, a computer readable storage medium having at least part of a program embodied therewith;

• and, a processor, preferably a microprocessor, coupled to the computer readable storage medium and the transceiver, wherein responsive to executing the computer readable program code, the processor is configured to perform executable operations comprising:
• transmitting a first request message based on a first carrier signal to the further node and receiving a plurality of first response messages from the further node, the plurality of first response messages being transmitted based on a first reference carrier signal by the further node to the node;
• transmitting a second request message based on a second carrier signal to the further node and receiving a plurality of second response messages from the further node, the plurality of second response messages being transmitted based on a second reference carrier signal by the further node to the node;
• receiving a first phase difference and second phase difference from the further node, the first phase difference defining a difference between a phase of the first carrier signal and a phase of the first reference carrier signal at a predetermined time instance associated with the first request message and the second phase defining a difference between a phase of the second carrier signal and a phase of the second reference carrier signal at a predetermined time instance associated with the second request message;
• determining a set of third phase differences and a set of fourth phase differences based on the plurality of first response messages and the plurality of second response messages respectively, each of the set of third phase differences defining a difference between a phase of the first reference carrier signal and a phase of the first carrier signal at a predetermined time instance associated with one of the plurality of first response messages;
• and, each of the set of fourth phase differences defining a difference between a phase of the second reference carrier signal and a phase of the second carrier signal at a predetermined time instance associated with one of the plurality of second response messages;
• and, optionally,
• determining a distance and/or a frequency offset between the node and the further node based on the first and second phase difference and the set of third and fourth phase differences.

A wireless node comprising a transceiver, an oscillator coupled to a frequency synthesizer for generating carrier signals of different carrier frequencies, a phase detector configured to determine a phase difference between a phase of a response signal received by the node from an further node and a phase of a carrier signal selected from the N carrier signals, a computer readable storage medium having at least part of a program embodied therewith;

• and, a processor, preferably a microprocessor, coupled to the computer readable storage medium and the transceiver, wherein responsive to executing the computer readable program code, the processor is configured to perform executable operations comprising:
• transmitting request messages based on carrier signals at carrier frequencies to the further node and receiving for each of the request signals, a time series of response messages from the further node, wherein for each of the request messages the time series of response messages being transmitted based on one of reference carrier signals, each one of the reference carrier signals being transmitted at one of reference carrier frequencies by the further node to the node, wherein the carrier frequencies and the reference carrier frequencies form frequency channels between the node and the further node;
• receiving first phase differences from the further node, each of the first phase differences defining a difference between a phase of one the carrier signals and a phase of one of the reference carrier signals at a predetermined time instance associated with one of first request messages, the frequency of the one of the carrier signals and the frequency of the one of the references carrier signals being in the same frequency channel;
• determining second phase differences based on the request signals and the response messages, the determining of the second phase differences including computing for each one of the carrier signals phase differences, each of the phase differences defining a difference between a phase of one of the reference carrier signals and a phase of one of the carrier signals at a predetermined time instance associated with one of the time series of response messages;
• and, optionally,
• determining a distance and/or a frequency offset between the node and the further node based on the first phase differences and the second phase differences.