Equalizer and method of setting initial value for same
View Patent ↗An equalizer is provided which is capable of making a filter factor to be set in the equalizer having an equalizing filter converge rapidly and a method is provided for setting an initial value for the rapid convergence of the filter factor. In the equalizer having a filter factor computing device to compute a filter factor for an equalizing filter, and a differential detecting circuit to generate a differential signal between a signal output from the equalizing filter and a common pilot diffusing code, an initial value for the filter factor computing device is generated and set by a multipath timing detecting circuit, a reverse diffusing section, and a channel estimating device being operated based on a received signal.
1. An equalizer comprising: a filter factor computing device to compute a filter factor; an equalizing filter to operate based on a filter factor computed by said filter factor computing device and to a received signal to obtain an output signal; a differential detecting circuit to detect a differential between the output signal from said equalizing filter and a common pilot diffusing code and to input the detected differential as a differential signal to said filter factor computing device; and an initial value setting circuit to set an initial value for said filter factor computing device based on said received signal;
wherein said initial value setting circuit comprises a multipath timing detecting circuit to detect multipath timing by receiving said received signal and said common pilot diffusing code, a reverse diffusing circuit to which a path timing signal is fed from said multipath timing detecting circuit, and to which said received signal and said common pilot diffusing code are input, and a channel estimating device to estimate a channel based on an output signal from said reverse diffusing circuit.
2. The equalizer according to claim 1 , wherein said filter factor computing device comprises an initial value generating circuit to generate an initial value of the filter factor by receiving a channel estimating result fed from said channel estimating device and a path timing signal fed from said multipath timing detecting circuit.
3. The equalizer according to claim 2 , wherein said filter factor computing device further comprises a renewing circuit to renew the filter factor based on the differential signal fed from said differential detecting circuit and said received signal, and a selector to select an output from said renewing circuit and said initial value generating circuit.
4. The equalizer according to claim 1 , wherein said reverse diffusing circuit has “P” pieces of correlators each operating independently (“P” is an integer being 2 or more).
5. The equalizer according to claim 1 , wherein said reverse diffusing circuit, to which a path timing signal fed from said multipath timing detecting circuit, said received signal, and said common pilot diffusing code are input, has a plurality of correlators each operating independently of one another and performs reverse diffusing operations by multiplying the received signal by the common pilot diffusing code in synchronization with the multipath timing detected by said multipath timing detecting circuit.
6. A method for setting an initial value for an equalizer having an equalizing filter to be used for a signal receiver to re-produce a signal whose quality has been degraded during signal transmission in a mobile communication device, said method comprising:
a step of setting a complex conjugate number of a fading vector obtained in synchronization with path timing of a received signal to be equalized, as a filter factor for said equalizing filter and
wherein the fading vector is obtained by multiplying a pilot signal value of the received signal with a conjugate of an ideal pilot signal value.
7. The method for setting the initial value for the equalizer according to claim 6 , wherein, after setting of said initial value, the filter factor for said equalizing filler is renewed by using a renewing signal produced based on a differential signal between an output signal from said equalizing filter and a common pilot diffusing code.
8. An equalizer comprising: a filter factor computing device to compute a filter factor; an equalizing filter to operate based on a filter factor computed by said filter factor computing device and to a received signal to obtain an output signal; a differential detecting circuit to detect a differential between the output signal from said equalizing filter and a common pilot diffusing code and to input the detected differential as a differential signal to said filler factor computing device; and an initial value setting means to set an initial value for said filter factor computing device based on said received signal,
wherein said initial value setting means comprises a multipath timing detecting circuit to detect multipath timing by receiving said received signal and said common pilot diffusing code, a reverse diffusing circuit, to which a path timing signal is fed from said multipath timing detecting circuit, and to which said received signal and said common pilot diffusing code are input, has a plurality of correlators each operating independently of one another and performs reverse diffusing operations by multiplying the received signal by the common pilot diffusing code in synchronization with the multipath timing detected by said multipath timing detecting circuit, and a channel estimating device to estimate a channel based on an output signal from said reverse diffusing circuit.