Frequency offset estimation apparatus for intersymbol interference channels
AssigneeMediatek Inc.
InventorHung-Kun Chen
Life of this patent
Estimating the term…
Abstract
A frequency offset estimation apparatus for intersymbol interference channels. A storage area having M elements is provided to shift a received sample sequence by M samples to generate a lagged sample sequence. A sequence of preliminary values is calculated by differential operation between the received sample sequence and the lagged sample sequence. Next, a summation of the power of the preliminary value sequence over M′ samples is taken to obtain an accumulative sum. Finally, the angle of the accumulative sum is derived and then scaled by a factor. A frequency offset estimate for the received sample sequence is thus obtained.
Claims20
A frequency offset estimation apparatus for intersymbol interference channels, comprising:
- a storage area having M elements to take a received sample sequence serially, for shifting the received sample sequence by M samples to generate a lagged sample sequence, where M is a first positive integer;
- a differential unit for performing a differential operation between the received sample sequence and the lagged sample sequence to obtain a sequence of preliminary values as intermediate data;
- a power operator coupled after the differential unit, for calculating a pth power of each preliminary value from the differential unit, wherein p denotes the power to raise the sequence of preliminary values and is an integer greater than one;
- an argument extractor for obtaining an angle of the intermediate data;
- and
- a scale unit coupled after the argument extractor, for scaling the angle of the intermediate data by a factor of 1/p to output as a frequency offset.
A frequency offset estimation apparatus for intersymbol interference channels, comprising:
- a state indicator receiving a sequence of data symbols, for generating a state signal indicative of a symbol state defined by a current data symbol and L most recently received data symbols, where L is a first positive integer;
- a state bank having a first input to take a received sample sequence, a second input to receive a current index associated with the current data symbol and a third input to receive the state signal, in accordance with the state signal, for storing the current index from the second input and M currently received samples of the current data symbol from the first input, and retrieving M previously received samples of the same symbol state and an associated previous index, where M is a second positive integer;
- a differential unit for performing a differential operation between the M currently received samples in the received sample sequence and the M previously received samples of the same symbol state from the state bank to obtain a sequence of preliminary values as intermediate data;
- a plurality of computation units each of which is allowed to take the preliminary value sequence in accordance with an index difference between the current index associated with the M currently received samples and the previous index associated with the M previously received samples of the same symbol state, each computation unit comprising:
- an argument extractor for obtaining an angle of the intermediate data as a raw frequency offset;
- whereby the computation units generate a plurality of raw frequency offsets;
- and
- a weighting calculator for performing a weighted average operation over the raw frequency offsets to generate a frequency offset estimate.
A frequency offset estimation apparatus for intersymbol interference channels, comprising:
- a storage area having M elements to take a received sample sequence serially, for shifting the received sample sequence by M samples to generate a lagged sample sequence, where M is a first positive integer;
- means for performing a differential operation between the received sample sequence and the lagged sample sequence to obtain a sequence of preliminary values;
- means for calculating a pth power of the preliminary value sequence, where p denotes the power to raise the sequence of preliminary values and is an integer greater than one;
- means for taking a summation of the power of the preliminary value sequence over M′ samples with respect to the received sample sequence to acquire an accumulative sum, where the accumulative sum is a complex number and M′ is a second positive integer;
- means for obtaining an angle of the accumulative sum;
- and
- means for scaling the angle of the accumulative sum by a factor of 1/p and yielding a frequency offset estimate.
Dependencies are inferred from the claim text.