Method of equalization in digital mobile communication with improved tracking ability
First Claim
1. A method of equalization, comprising the steps of:
- obtaining a signal sequence from received signals by applying frequency transformation and sampling;
carrying out a forward equalization of the signal sequence to obtain a forward equalization output in which the signal sequence is equalized in an order in which the received signals are received;
calculating a forward evaluation function indicating a reliability of the forward equalization by using the signal sequence;
carrying out a backward equalization of the signal sequence to obtain a backward equalization output in which the signal sequence is equalized in an order opposite to that in which the received signals are received;
calculating a backward evaluation function indicating a reliability of the backward equalization by using the signal sequence; and
obtaining a final equalization output by selecting for each bit of the signal sequence one of the forward equalization output and the backward equalization output for which the reliability indicated by a corresponding one of the forward evaluation function and the backward evaluation function is higher as the final equalization output for each bit, such that the final equalization output is given as a composition of those parts of the forward equalization output for which the reliability indicated by the forward evaluation function is higher than the reliability of the backward equalization output indicated by the backward evaluation function and those parts of the backward equalization output for which the reliability indicated by the backward evaluation function is higher than the reliability of the forward equalization output indicated by the forward evaluation function.
3 Assignments
0 Petitions
Accused Products
Abstract
A method of equalization in a digital mobile communication capable of realizing an improved tracking of the variations of the transmission path characteristics, such that it becomes possible to achieve the good error rate characteristic. In the method, the forward and backward equalizations are carried out, while the forward and backward evaluation functions indicating reliabilites of the forward and backward equalizations are calculated by using the signal sequence, and a final equalization output is obtained by selecting for each bit of the signal sequence one of the forward and backward equalization outputs for which the reliability indicated by corresponding one of the forward and backward evaluation functions is higher as final equalization output for each bit. The detection of an abnormal state such as a sudden drop of a signal strength of the signal sequence or a limit cycle state of an equalizer may be used instead of the evaluation functions.
-
Citations
16 Claims
-
1. A method of equalization, comprising the steps of:
-
obtaining a signal sequence from received signals by applying frequency transformation and sampling; carrying out a forward equalization of the signal sequence to obtain a forward equalization output in which the signal sequence is equalized in an order in which the received signals are received; calculating a forward evaluation function indicating a reliability of the forward equalization by using the signal sequence; carrying out a backward equalization of the signal sequence to obtain a backward equalization output in which the signal sequence is equalized in an order opposite to that in which the received signals are received; calculating a backward evaluation function indicating a reliability of the backward equalization by using the signal sequence; and obtaining a final equalization output by selecting for each bit of the signal sequence one of the forward equalization output and the backward equalization output for which the reliability indicated by a corresponding one of the forward evaluation function and the backward evaluation function is higher as the final equalization output for each bit, such that the final equalization output is given as a composition of those parts of the forward equalization output for which the reliability indicated by the forward evaluation function is higher than the reliability of the backward equalization output indicated by the backward evaluation function and those parts of the backward equalization output for which the reliability indicated by the backward evaluation function is higher than the reliability of the forward equalization output indicated by the forward evaluation function. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12)
-
-
13. A method of equalization, comprising the steps of:
-
obtaining a signal sequence from received signals by applying frequency transformation and sampling; carrying out a forward equalization of the signal sequence to obtain a forward equalization output in which the signal sequence is equalized in an order in which the received signals are received; carrying out a backward equalization of the signal sequence to obtain a backward equalization output in which the signal sequence is equalized in an order opposite to that in which the received signals are received; detecting an abnormal state in one of the forward equalization and the backward equalization; and obtaining a final equalization output by making a selection of one of the forward equalization output and the backward equalization output as the final equalization output until the abnormal state of said one of the forward equalization and the backward equalization is detected, and switching the selection for the final equalization output to another one of the forward equalization output and the backward equalization output after the abnormal state of said one of the forward equalization and the backward equalization is detected. - View Dependent Claims (14, 15)
-
-
16. A method of equalization, comprising the steps of:
-
obtaining a signal sequence from received signals by applying frequency transformation and sampling, where the signal sequence comprises data to be equalized, and first and second training sequences which sandwich the data to be equalized; carrying out a forward equalization of the signal sequence to obtain a forward equalization output in which the signal sequence is equalized in an order in which the received signals are received, from a top of the first training sequence to an end of the second training sequence; detecting a presence of errors in the forward equalization output for the second training sequence; in a case the presence of the errors in the forward equalization output for the second training sequence is not detected, obtaining a final equalization output as the forward equalization output for the data to be equalized; and in a case the presence of the errors in the forward equalization output for the second training sequence is detected, calculating a forward evaluation function indicating a reliability of the forward equalization by using the signal sequence; carrying out a backward equalization of the signal sequence to obtain a backward equalization output in which the signal sequence is equalized in an order opposite to that in which the received signals are received, from an end of the second training sequence to a top of the data to be equalized; calculating a backward evaluation function indicating a reliability of the backward equalization by using the signal sequence; and obtaining a final equalization output by selecting for each bit of the data to be equalized of the signal sequence one of the forward equalization output for the data to be equalized and the backward equalization output for the data to be equalized for which the reliability indicated by a corresponding one of the forward evaluation function and the backward evaluation function is higher as the final equalization output for each bit, such that the final equalization output is given as a composition of those parts of the forward equalization output for the data to be equalized for which the reliability indicated by the forward evaluation function is higher than the reliability of the backward equalization output for the data to be equalized indicated by the backward evaluation function and those parts of the backward equalization output for the data to be equalized for which the reliability indicated by the backward evaluation function is higher than the reliability of the forward equalization output for the data to be equalized indicated by the forward evaluation function.
-
Specification