Time domain equalization for discrete multi-tone systems
View Patent ↗A multiple carrier communication system includes a primary impulse shortening filter that receives an output signal of an analog to digital converter and accepts coefficients. A secondary impulse shortening filter receives the output signal of the analog to digital converter, outputs an output signal, and passes coefficients to the primary impulse shortening filter. A reference signal generator outputs a reference signal. A comparator compares the output signal and the reference signal and outputs a resulting error signal. An adaptive processor computes coefficients for the secondary impulse shortening filter based on the error signal.
1. A method for transmitting information comprising:
selecting a cyclic prefix length from a plurality of candidate lengths based on respective bit rates obtained for the candidate lengths; and
adding an end-portion of a block of information bits at a beginning of the block, wherein the added end-block portion has a length equal to the selected cyclic prefix length.
2. The method of claim 1 including transmitting the block of information bits with the end-portion added thereto through a communication channel.
3. The method of claim 1 wherein selecting a cyclic prefix length includes:
computing a respective maximum bit rate value for each of the candidate lengths; and
identifying a particular one of the candidate lengths having the largest maximum bit rate value of the computed maximum bit rate values.
4. The method of claim 1 including:
transmitting the computed respective bit rates; and
transmitting the block of information bits with the end-portion added thereto.
5. The method of claim 1 wherein selecting comprises determining the signal to noise ratio associated with each of the plurality of candidate lengths.
6. The method of claim 3 comprising:
transmitting the largest maximum bit rate value.
7. A method of dynamically selecting a cyclic prefix length, the method comprising:
computing a respective maximum bit rate value for each of a plurality of candidate cyclic prefix lengths;
identifying a particular one of the candidate cyclic prefix lengths having the largest maximum bit rate value of the computed maximum bit rate values; and
adding an end-portion of a block of information bits at a beginning of the block, wherein the added end-block portion has a length equal to the particular one candidate cyclic prefix length.
8. The method of claim 7 , wherein the candidate cyclic prefix lengths include at least a first length and a second length, the method including:
transmitting data having a cyclic prefix of the first length;
computing a first maximum bit rate value for the cyclic prefix of the first length;
transmitting data having a cyclic prefix of the second length; and
computing a second maximum bit rate value for the cyclic prefix of the second length.
9. The method of claim 7 wherein computing a respective maximum bit rate value comprises determining the signal to noise ratio associated with each of the plurality of candidate cyclic prefix lengths.
10. The method of claim 7 comprising:
transmitting the largest maximum bit rate value.
11. The method of claim 7 wherein:
the computing a respective maximum bit rate value is performed by a discrete multi-tone receiver; and
the identifying a particular one of the candidate cyclic prefix lengths is performed by a discrete multi-tone transmitter.
12. A discrete multi-tone communication system comprising:
a discrete multi-tone receiver comprising:
means for computing a bit rate value for each of a plurality of candidate cyclic prefix lengths;
means for transmitting the bit rate values;
a discrete multi-tone transmitter comprising:
means for receiving the bit rate values;
means for identifying a particular one of the candidate cyclic prefix lengths having the largest bit rate value of the computed bit rate values.
13. The system of claim 12 wherein the discrete multi-tone transmitter comprises:
means for adding an end-portion of a block of information bits at a beginning of the block, wherein the added end-block portion has a length equal to the particular one candidate cyclic prefix length.
14. The system of claim 12 wherein the means for computing a bit rate value determines the signal to noise ratio associated with each of the plurality of candidate cyclic prefix lengths.
15. An article comprising a machine-readable medium that stores machine-executable instructions for causing a machine to:
select a cyclic prefix length from a plurality of candidate lengths based on respective bit rates obtained for the candidate lengths; and
add an end-portion of a block of information bits at a beginning of the block, wherein the added end-block portion has a length equal to the selected cyclic prefix length.
16. The article of claim 15 , further causing a machine to:
transmit the block of information bits with the end-portion added thereto through a communication channel.
17. The article of claim 15 , further causing a machine to:
compute a respective maximum bit rate value for each of the candidate lengths; and
identify a particular one of the candidate lengths having the largest maximum bit rate value of the computed maximum bit rate values.
18. The article of claim 15 , further causing a machine to:
transmit the computed respective bit rates; and
transmit the block of information bits with the end-portion added thereto.
19. The article of claim 15 , further causing a machine to:
determine the signal to noise ratio associated with each of the plurality of candidate lengths.
20. An article comprising a machine-readable medium that stores machine-executable instructions for causing a machine to:
compute a respective maximum bit rate value for each of a plurality of candidate cyclic prefix lengths;
identify a particular one of the candidate cyclic prefix lengths having the largest maximum bit rate value of the computed maximum bit rate values; and
add an end-portion of a block of information bits at a beginning of the block, wherein the added end-block portion has a length equal to the particular one candidate cyclic prefix length.
21. The article of claim 20 , further causing a machine to:
transmit the largest maximum bit rate value.
22. The article of claim 20 , further causing a machine to:
determine the signal to noise ratio associated with each of the plurality of candidate cyclic prefix lengths.