Synchronization in the presence of large initial frequency error

A method for synchronization in a user equipment, comprising:

• determining an N-symbol slice of a received signal, the N-symbol slice corresponding to a sync point hypothesis;
• dividing the N-symbol slice into one or more segments, each of the one or more segments having the same symbol length;
• determining one or more phase rotation operators for each of the one or more segments, the determined one or more phase rotation operators compensating for a phase rotation introduced by an initial frequency error, wherein determining one or more phase rotation operators for each of the one or more segments further comprises:
• determining an initial frequency error interval;
• dividing the determined initial frequency error interval into one or more frequency error hypotheses;
• determining a phase rotation for each of the one or more frequency error hypotheses;
• and
• quantizing the determined phase rotation for each of the one or more frequency error hypotheses, wherein quantizing the determined phase rotation for each of the one or more frequency error hypotheses comprises quantizing to four points on the same unit circle, the four points comprising 1, −1, j, and -j;
• performing coherent correlation within each of the one or more segments using the determined one or more phase rotation operators;
• performing differentially coherent correlation on each of the one or more segments;
• and
• determining, based on the differentially coherent correlation performed on each of the one or more segments, at least one of a time synchronization point and a frequency synchronization point for the received signal.

A network node, comprising:

• a memory;
• and
• one or more processors, the one or more processors configured to:
• determine an N-symbol slice of a received signal, the N-symbol slice corresponding to a sync point hypothesis;
• divide the N-symbol slice into one or more segments, each of the one or more segments having the same symbol length;
• determine one or more phase rotation operators for each of the one or more segments, the determined one or more phase rotation operators compensating for a phase rotation introduced by an initial frequency error, wherein the one or more processors configured to determine one or more phase rotation operators for each of the one or more segments comprises one or more processors configured to:
• determine an initial frequency error interval;
• divide the determined initial frequency error interval into one or more frequency error hypotheses;
• determine a phase rotation for each of the one or more frequency error hypotheses;
• and
• quantize the determined phase rotation for each of the one or more frequency error hypotheses, wherein the one or more processors configured to quantize the determined phase rotation for each of the one or more frequency error hypotheses comprises one or more processors configured to quantize to four points on the same unit circle, the four points comprising 1, −1, j, and -j;
• perform coherent correlation within each of the one or more segments using the determined one or more phase rotation operators;
• perform differentially coherent correlation on each of the one or more segments;
• and
• determine, based on the differentially coherent correlation performed on each of the one or more segments, at least one of a time synchronization point and a frequency synchronization point for the received signal.

A user equipment, comprising:

• a memory;
• and
• one or more processors, the one or more processors configured to:
• determine an N-symbol slice of a received signal, the N-symbol slice corresponding to a sync point hypothesis;
• divide the N-symbol slice into one or more segments, each of the one or more segments having the same symbol length;
• determine one or more phase rotation operators for each of the one or more segments, the determined one or more phase rotation operators compensating for a phase rotation introduced by an initial frequency error, wherein the one or more processors configured to determine one or more phase rotation operators for each of the one or more segments comprises one or more processors configured to:
• determine an initial frequency error interval;
• divide the determined initial frequency error interval into one or more frequency error hypotheses;
• determine a phase rotation for each of the one or more frequency error hypotheses;
• and
• quantize the determined phase rotation for each of the one or more frequency error hypotheses, wherein the one or more processors configured to quantize the determined phase rotation for each of the one or more frequency error hypotheses comprises one or more processors configured to quantize to four points on the same unit circle, the four points comprising 1, −1, j, and -j;
• perform coherent correlation within each of the one or more segments using the determined one or more phase rotation operators;
• perform differentially coherent correlation on each of the one or more segments;
• and
• determine, based on the differentially coherent correlation performed on each of the one or more segments, at least one of a time synchronization point and a frequency synchronization point for the received signal.