Method for rapid carrier frequency estimation in a communication system
First Claim
1. A method for estimating a frequency offset of at least one frame, containing at least one synchronization field being divided into at least two subsections, the at least two subsections being composed of substantially equivalent pseudorandom symbols, the frame being received by a receiver from a transmitter, the receiver including at least an analog-to-digital processing unit, the steps of the method being performed by a data processor, the steps of the method comprising:
- (a) determining an initial frequency offset, finitial;
(b) calculating a first phase in radians for at least a portion of a first subsection according to an equation;
wherein i denotes time in symbols;
Ts is a symbol period;
n and m are integers, in≧
im;
a length of said at least portion of said first subsection is in−
im+1;
Yi is an output of the analog-to-digital processing unit;
ai* is the complex conjugate of the ith training symbol ai;
(c) calculating a second phase in radians for at least a portion of a second subsection according to an equation;
wherein q and p are integers, iq≧
ip;
a length of said at least a portion of said second subsection is iq−
ip+1;
(d) calculating a phase difference of said first phase and said second phase angle according to an equation;
5 Assignments
0 Petitions
Accused Products
Abstract
A modem for more efficiently processing a received analog signal into a digital output. The modem preferably estimates the carrier frequency offset in at least one stage, by receiving a synchronization field divided into at least two portions, calculating a difference of the phase between the portions, and then calculating the frequency offset from the phase difference. More preferably, the modem estimates the carrier frequency offset in two stages, with a first stage being a initial frequency estimate of the offset.
22 Citations
1 Claim
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1. A method for estimating a frequency offset of at least one frame, containing at least one synchronization field being divided into at least two subsections, the at least two subsections being composed of substantially equivalent pseudorandom symbols, the frame being received by a receiver from a transmitter, the receiver including at least an analog-to-digital processing unit, the steps of the method being performed by a data processor, the steps of the method comprising:
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(a) determining an initial frequency offset, finitial;
(b) calculating a first phase in radians for at least a portion of a first subsection according to an equation;
wherein i denotes time in symbols;
Ts is a symbol period;
n and m are integers, in≧
im;
a length of said at least portion of said first subsection is in−
im+1;
Yi is an output of the analog-to-digital processing unit;
ai* is the complex conjugate of the ith training symbol ai;(c) calculating a second phase in radians for at least a portion of a second subsection according to an equation;
wherein q and p are integers, iq≧
ip;
a length of said at least a portion of said second subsection is iq−
ip+1;(d) calculating a phase difference of said first phase and said second phase angle according to an equation;
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Specification