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US 9,071,327 B2Granted
Efficient frequency estimation
AssigneeGilat Satellite Networks Ltd.
InventorsUzi Ram, Oded Bialer
Life of this patent
Estimating the term…
Abstract
Methods are presented herein for estimating at least a frequency (offset) for a block of received symbols using two or more estimation stages. These methods may allow reducing the computational complexity of a frequency estimator while maintaining large frequency offset coverage and high frequency estimation accuracy. Also presented herein are satellite communication systems employing a burst transmission or continuous transmission, and configured to estimate at least a frequency (offset) for a received burst or a block of received symbols using two or more estimation stages. In some embodiments, a received burst or a received block of symbols may include a Unique Word located at or about the center of the received burst or the block of symbols.
Claims20
A method, comprising:
- receiving a block of symbols;
- determining a first group of samples, the first group of samples corresponding to a first group of symbols included in the block of symbols, the first group of samples corresponding to a first interval determined in accordance with a maximum frequency offset;
- determining, in accordance with the first group of samples, a first frequency offset estimation associated with the block of symbols;
- back-rotating one or more symbols in the block of symbols in accordance with at least the first frequency offset estimation;
- producing a second group of samples, the second group of samples corresponding to a second group of symbols that are based at least in part on symbols that are back-rotated according to the first frequency offset estimation, wherein the second group of samples correspond to a second interval that is longer than the first interval determined in accordance with the maximum frequency offset;
- and
- determining, in accordance with the second group of samples, a second frequency offset estimation associated with the block of symbols.
4 more elements
A satellite communication system, comprising:
- at least one terminal configured to transmit at least one transmission burst that includes at least one block of symbols;
- and
- a hub configured to:
- receive the at least one transmission burst from the at least one terminal and to utilize two or more estimation stages to determine at least one of a frequency or a frequency offset of the at least one transmission burst;
- back-rotate a plurality of symbols included in the at least one transmission burst in accordance with a frequency offset estimation determined in a previous estimation stage of the two or more estimation stages to produce a plurality of back-rotated symbols;
- remove a modulation property from each of the plurality of back-rotated symbols,
- sum one or more groups of consecutive back-rotated symbols from amongst the plurality of back-rotated symbols to produce a set of samples;
- and
- calculate, for each frequency hypothesis in a set of frequency hypotheses, a value of a target function associated with at least one estimation stage using the set of samples.
6 more elements
A satellite communication system, comprising:
- at least one terminal configured to transmit at least one transmission burst that includes at least one block of symbols, the at least one block of symbols includes a unique word comprising a group of consecutive pilot symbols;
- and
- a hub configured to receive the at least one transmission burst from the at least one terminal, the hub is further configured to:
- determine, in accordance with a first group of samples corresponding to the unique word, a first frequency offset estimation associated with the at least one block of symbols;
- back-rotate symbols in the at least one block of symbols in accordance with the first frequency offset estimation associated with the at least one block of symbols to produce a second group of samples associated with a second interval longer than a first interval between adjacent symbols in the unique word;
- determine, in accordance with the second group of samples associated with the second interval longer than an the first interval between adjacent symbols in the unique word, a second frequency offset estimation associated with the at least one block of symbols;
- calculate, in accordance with the second frequency offset estimation associated with the block of symbols, at least one of a phase or a phase offset;
- and
- correct each symbol in the at least one block of symbols in accordance with the second frequency offset estimation associated with the at least one block of symbols and the at least one of the phase or the phase offset.
6 more elements
A satellite communication system, comprising:
- at least one terminal configured to transmit a continuous signal;
- and
- at least one receiving station configured to:
- receive the continuous signal;
- break the continuous signal into one or more successive symbol blocks;
- determine a first group of samples, the first group of samples corresponding to a first group of symbols included in at least one block of symbols of the one or more successive symbol blocks, the first group of samples corresponding to a first interval determined in accordance with a maximum frequency offset;
- determine, in accordance with the first group of samples, a first frequency offset estimation associated with the at least one block of symbols;
- back-rotate one or more symbols in the at least one block of symbols in accordance with at least the first frequency offset estimation;
- produce a second group of samples, the second group of samples corresponding to a second group of symbols that are based at least in part on symbols that are back-rotated according to the first frequency offset estimation, wherein the second group of samples correspond to a second interval that is longer than the first interval determined in accordance with the maximum frequency offset;
- and
- determine, in accordance with the second group of samples, a second frequency offset estimation associated with the at least one block of symbols.
8 more elements
Dependencies are inferred from the claim text.