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US 6,438,173 B1Granted
Multicarrier transmission system for irregular transmission of data blocks
AssigneeInfineon Technologies AG
InventorBranimir Stantchev
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Abstract
The invention relates to a method for receiving a multicarrier signal, in particular for a single transmission of a data block. In which case a multicarrier test signal having a cyclic time layout is transmitted together with the data block, and the multicarrier test signal is used for combined measurement of a start of a first data symbol of a data block and of any carrier-frequency shift between a transmitter and a digital receiver. The digital receiver evaluates the multicarrier test signal by performing a sequence of test steps.
Claims10
A method for receiving a multicarrier signal, including a single transmission of a data block, in which case a cyclic multicarrier test signal having a cyclic time layout is transmitted together with the datablock, and the cyclic multicarrier test signal being used for a combined measurement of a start of a first data symbol of the data block and of any carrier-frequency shift between a transmitter and a digital receiver, the cyclic multicarrier test signal being evaluated in the digital receiver performing the steps which comprises:
- performing a coarse measurement of the start of the data block by evaluating the cyclic multicarrier test signal without any fast fourier transformation (FFT) being calculated in the step;
- determining a fine carrier-frequency shift, present between the transmitter and the digital receiver, by isolation and evaluation of a part of the cyclic multicarrier test signal without any FFT being calculated in the step;
- performing isolation and digital frequency correction of NFFT sample values from the cyclic multicarrier test signal and
- calculation of an FFT of length NFFT from the sample values resulting in calculated FFT values;
- performing isolation and phase correction of a test vector d1 of length M<NFFT from the calculated FFT values resulting in a phase-corrected test vector d1;
- calculating a further test vector z1 of length M−1 by differential decoding of the phase-corrected test vector d1;
- measuring any integer carrier-frequency shift present between the transmitter and the digital receiver with a maximum value of θ subcarrier intervals, in terms of magnitude, by isolation of at least L+2θ values from the further test vector z1 and by carrying out 2θ+1 correlations using a basic, known training sequence Qk of length L;
- performing a fine measurement of the start of the data block at least by correlation of the further test vector z1 with a basic, known training sequence of maximum length M−1, which contains the known training sequence Qk as a subsequence;
- deriving an exact determination of the start of the first data symbol in the data block by addition of the start of the data block from the coarse measurement and a corrected value for the start of the data block from the fine measurement;
- and
- deriving an exact determination of a total carrier-frequency shift between the transmitter and the digital receiver by adding the integer carrier-frequency shift and the fine carrier-frequency shift.
8 more elements
A configuration for determining a start of a first data symbol of a data block of a multicarrier signal, comprising:
- at least one first-in-first-out (FIFO) memory having an input and a negated output;
- a multiplier receiving two complex samples of a received signal and connected to said at least one FIFO memory;
- a first memory;
- an accumulator receiving input values from said input and said negated output of said at least one FIFO memory and writing calculated results to said first memory;
- a first apparatus for root calculation and calculation of a square of a magnitude being connected to said accumulator;
- a metric memory;
- a computation unit for calculating metrics for time synchronization and receives input values from at least said first apparatus and writes calculated metrics to said metric memory;
- a second apparatus for calculating a tan−1 of a value and connected to said first memory;
- a third apparatus for searching for a maximum and a minimum value and connected to said metric memory, said third apparatus providing addressing data to said first memory and controls said second apparatus;
- a first isolator connected to said third apparatus and receiving a test signal;
- a fourth apparatus performing digital frequency synthesis functions and receiving values from said second apparatus, said fourth apparatus generating and outputting values;
- a fifth apparatus for vector multiplication of the test signal from said first isolator and the values output by said fourth apparatus;
- a FFT apparatus receiving input values from said fifth apparatus and outputting FFT values;
- a second memory receiving the FFT values;
- a second isolator connected to said second memory and generating a test vector;
- a first read only memory generating an output;
- a sixth apparatus for vector multiplication of the test vector of said second isolator by the output of said first read only memory;
- a seventh apparatus for differential decoding connected to said sixth apparatus and outputting results;
- a third memory receiving the results from said seventh apparatus;
- a third isolator connected to said third memory and having an output outputting results, said third isolator preparing test vectors for correlations with a training sequence Qk;
- a second read only memory outputting a training sequence conj Zk and the training vector Qk containing values conj Qk;
- an eighth apparatus performing vector multiplication and connected to said output of said third isolator, said eighth apparatus vector multiplying the training vector containing the values conj Qk by the results outputted by said third isolator and generating calculated values;
- a ninth apparatus for performing magnitude formations receiving said calculated values and generating norm values from the calculated values;
- a fourth memory storing said norm values from said ninth apparatus;
- a tenth apparatus for searching for a maximum value and connected to said fourth memory;
- a first computation unit for calculating an exact carrier-frequency shift ε connected to said tenth apparatus, said first computation unit contains at least one real multiplier with a constant and one real adder;
- a fifth memory connected to said first computation unit for storing the exact carrier-frequency shift ε;
- a fourth isolator connected to said third memory and outputting a test vector;
- an eleventh apparatus, controlled by a calculated integer carrier-frequency shift for vector multiplication, being connected to said fourth isolator and to said second read only memory supplying the training sequence conj Zk, said eleventh apparatus generating a calculated vector being added up element-by-element;
- a twelfth apparatus for calculating a tan−1 connected to said eleventh apparatus and receiving the calculated vector from said eleventh apparatus and having an output;
- and
- a second computation unit for calculating an exact position of the first data symbol of the data block, said second computation unit connected to said twelfth apparatus and to said fifth memory, said second computation unit containing at least one real multiplier with a constant and one real adder.
29 more elements
Dependencies are inferred from the claim text.