Data processing method
View Patent ↗A suboptimal method for searching for a symbol sequence, the method comprising the steps of: determining a channel impulse response; sampling a received signal; selecting at least one of the highest and/or most reliable impulse response values; determining a reference signal using at least one impulse response value and a symbol sequence assumed as transmitted; determining differential terms corresponding to the selected impulse response values for the signal sample and the reference signal; using the determined differential terms in a transition metric for searching for a symbol sequence; forming a survivor path by adding the symbol sequence provided by the transition metric to the survivor path formed so far.
1. A suboptimal method for searching for a symbol sequence, comprising:
determining a channel impulse response;
sampling a received signal;
selecting at least one of the highest and/or most reliable impulse response values;
determining a reference signal using the at least one impulse response value and a symbol sequence assumed as transmitted;
determining differential terms corresponding to the selected impulse response values for a sample of the received signal and the reference signal;
applying the determined differential terms to a symbol sequence transition metric for searching for the symbol sequence;
forming a survivor path by adding the symbol sequence provided by the transition metric to the survivor path formed so far.
2. A method according to claim 1 , wherein at least one reference signal is determined using the selected impulse response value and at least one later impulse response value.
3. A method according to claim 1 , wherein at least one reference signal is determined using only the selected impulse response value.
4. A method according to claim 1 , wherein a number of differential terms for the transition metric is increased, when the impulse response comprises a plural number of high and/or most reliable values.
5. A method according to claim 1 , wherein a number of differential terms for the transition metric is decreased, when the impulse response contains only some high and/or most reliable values or only one high and/or reliable value.
6. A method according to claim 1 , wherein a highest possible number of differential terms for the transition metric is determined on the basis of a length of the channel memory.
7. A method according to claim 1 , wherein a magnitude of the impulse response values is emphasized in the selection of differential terms for the transition metric.
8. A method according to claim 1 , wherein the reliability of the impulse response values is emphasized in the selection of the differential terms for the transition metric.
9. A method according to claim 1 , wherein the differential term illustrates a squared Euclidean distance between the received signal sample and the symbol sequence assumed as transmitted and convoluted with the impulse response values.
10. A method according to claim 1 , wherein the differential term illustrates a squared Hamming distance between the received signal sample and the symbol sequence assumed as transmitted and convoluted with the impulse response values.
11. A method according to claim 1 , wherein the differential term illustrates a correlation between the received signal sample and the symbol sequence assumed as transmitted and convoluted with the impulse response values.
12. A method according to claim 1 , wherein the determined transition metric is added to the survivor path formed so far.
13. Computer software according to claim 1 , which comprises routines for executing the method steps.
14. A computer memory means according to claim 13 , which comprises the computer software.
15. A receiver in which a symbol sequence is searched for, the receiver comprising:
means for determining a channel impulse response,
means for sampling a received signal;
means for selecting at least one of the highest and/or most reliable impulse response values;
means for determining a reference signal using the at least one impulse response value and a symbol sequence assumed as transmitted;
means for determining differential terms corresponding to the selected impulse response values for a sample of the received signal and the reference signal;
means for using the determined differential terms in a transition metric for searching for the symbol sequence;
means for forming a survivor path by adding the symbol sequence provided by the transition metric to the survivor path formed so far.
16. A receiver according to claim 15 , wherein at least one reference signal is determined using the selected impulse response value and at least one later impulse response value.
17. A receiver according to claim 15 , wherein at least one reference signal is determined using only the selected impulse response value.
18. A receiver according to claim 15 , wherein a number of differential terms for the transition metric is increased, when the impulse response comprises a plural number of high and/or most reliable values.
19. A receiver according to claim 15 , wherein a number of differential terms for the transition metric is decreased, when the impulse response comprises only some high and/or most reliable values, or only one high and/or most reliable value.
20. A receiver according to claim 15 , wherein a maximum number of differential terms for the transition metric is determined by a length of the channel memory.
21. A receiver according to claim 15 , wherein a magnitude of the impulse response values is emphasized in the selection of differential terms for the transition metric.
22. A receiver according to claim 15 , wherein the reliability of the impulse response values is emphasized in the selection of differential terms for the transition metric.
23. A receiver according to claim 15 , wherein the differential term illustrates a squared Euclidean distance between the received signal sample and the symbol sequence assumed as transmitted and convoluted with the impulse response values.
24. A receiver according to claim 15 , wherein the differential term illustrates a Hamming distance between the received signal sample and the symbol sequence assumed as transmitted and convoluted with the impulse response values.
25. A receiver according to claim 15 , wherein the differential term illustrates a correlation between the received signal sample and the symbol sequence assumed as transmitted and convoluted with the impulse response values.
26. A receiver according to claim 15 , wherein the determined transition metric is added to the survivor path formed so far.
27. A receiver configured to:
determine a channel impulse response;
sample a received signal;
select at least one of the highest and/or most reliable impulse response values;
determine a reference signal using the at least one impulse response value and a symbol sequence assumed as transmitted;
determine differential terms corresponding to the selected impulse response values for a signal sample obtained by sampling the received signal and the reference signal;
use the determined differential terms in a transition metric for searching for a symbol sequence;
form a survivor path by adding the symbol sequence provided by the transition metric to the survivor path formed so far.
28. A receiver according to claim 27 , wherein the maximum number of differential terms for the transition metric is determined by the length of the channel memory.
29. A receiver according to claim 27 , wherein the differential term illustrates the squared Euclidean distance between the received signal sample and the symbol sequence assumed as transmitted and convoluted with the impulse response values.
30. A receiver according to claim 27 , wherein the differential term illustrates the Hamming distance between the received signal sample and the symbol sequence assumed as transmitted and convoluted with the impulse response values.
31. A receiver according to claim 27 , wherein at least one reference signal is determined using the selected impulse response value and at least one later impulse response value.
32. An apparatus configured to:
determine a channel impulse response;
sample a received signal;
select at least one of the highest and/or most reliable impulse response values;
determine a reference signal using the at least one impulse response value and a symbol sequence assumed as transmitted;
determine differential terms corresponding to the selected impulse response values for a signal sample obtained by sampling the received signal and the reference signal;
use the determined differential terms in a transition metric for searching for a symbol sequence;
form a survivor path by adding the symbol sequence provided by the transition metric to the survivor path formed so far.
33. An apparatus according to claim 32 , wherein the maximum number of differential terms for the transition metric is determined by the length of the channel memory.
34. An apparatus according to claim 32 , wherein at least one reference signal is determined using the selected impulse response value and at least one later impulse response value.