Mobile terminal, a base station, and a synchronization control method
First Claim
Patent Images
1. A mobile terminal, comprising:
- a code generator which generates a spreading code for use in a despreading operation;
a despreading unit which receives as inputs thereto a received signal as an object of the despreading and the spreading code generated by the code generator and conducting a plurality of despreading for the received signal for a plurality of timing in a concurrent fashion;
an extracting circuit which extracts highly reliable ones from a plurality of correlation values outputted from the despreading unit;
a representative value determining circuit which calculates a path location representative value using path locations of correlation values corresponding to at least two paths in the plurality of extracted correlation values;
a control circuit which controls code generation timing of the code generator according to the path location representative value determined by the representative value determining circuit; and
a demodulating unit which combines with each other the correlation values extracted by the extracting circuit and thereby demodulating data.
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Abstract
In a mobile communication system, the tracking of synchronization is conducted in a stable state even in a multipath environment. A delay profile detector calculates a delay profile a(n) using a despread signal for each processing unit n. A delay profile averaging unit averages a(n) to produce Ave(|a(n)|2). A data symbol detector conducts rake combining of the despread signal using a(n) and Ave(|a(n)|2). According to a(n) and Ave(|a(n)|2, a weighting function unit calculates a representative value representing delay waves. A loop filter generates a control signal in response to the representative value. A clock controller controls a spread code generator according to the control signal.
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Citations
25 Claims
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1. A mobile terminal, comprising:
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a code generator which generates a spreading code for use in a despreading operation;
a despreading unit which receives as inputs thereto a received signal as an object of the despreading and the spreading code generated by the code generator and conducting a plurality of despreading for the received signal for a plurality of timing in a concurrent fashion;
an extracting circuit which extracts highly reliable ones from a plurality of correlation values outputted from the despreading unit;
a representative value determining circuit which calculates a path location representative value using path locations of correlation values corresponding to at least two paths in the plurality of extracted correlation values;
a control circuit which controls code generation timing of the code generator according to the path location representative value determined by the representative value determining circuit; and
a demodulating unit which combines with each other the correlation values extracted by the extracting circuit and thereby demodulating data. - View Dependent Claims (2, 3, 4, 5)
the extracting circuit extracts correlation values of which an average value averaged for a period of observation time is equal to or more than a threshold value.
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3. A mobile terminal in accordance with claim 2, wherein an interval of the timing is 1/j (j is an integer) of a chip length of the spreading code.
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4. A mobile terminal in accordance with claim 1, wherein the representative value determining circuit determines a path location representative value through a calculation of center of gravity of the extracted correlation values.
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5. A mobile terminal in accordance with claim 1, wherein the control circuit includes a loop filter and a clock controller, wherein:
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the loop filter produces a control signal according to the representative value; and
the clock controller controls the code generator to keep synchronization between the received signal and the spreading code according to the control signal.
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6. A base station, comprising at least one receiver for conducting processing of reception of a signal from a mobile terminal, wherein the receiver includes:
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a code generator which generates a spreading code for use in a despreading operation;
a despreading unit which receives as inputs thereto a received signal as an object of the despreading and the spreading code generated by the code generator and conducting a plurality of despreading for the received signal for a plurality of timing in a concurrent fashion;
an extracting circuit which extracts, from a plurality of correlation values, correlation values of which an average value averaged for a period of observation time is equal to or more than a threshold value;
a representative value determining circuit which calculates a path location representative value using path locations of correlation values corresponding to at least two paths in the plurality of extracted correlation values;
a control circuit which controls code generation timing of the code generator according to the path location representative value determined by the representative value determining circuit; and
a demodulating unit which combines with each other the correlation values extracted by the extracting circuit and thereby demodulating data. - View Dependent Claims (7, 8, 9, 10)
the loop filter produces a control signal according to the representative value; and
the clock controller controls the code generator to keep synchronization between the received signal and the spreading code according to the control signal.
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11. A synchronization control method, comprising the steps of:
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obtaining a despread signal according to a received spectrum-spread signal and an inputted spreading code;
obtaining a delay profile for the despread signal;
conducting a rake combining for the despread signal according to the delay profile obtained and thereby producing a demodulated signal;
calculating a representative value representing spread code phases of a plurality of paths according to a plurality of correlation values and timing thereof obtained from the obtained delay profile; and
conducting a control operation for a tracking of synchronization between the inputted received signal and the spreading code according to the calculated representative value. - View Dependent Claims (12, 13, 14, 15, 16, 17, 18, 19, 20, 25)
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21. A receiver, comprising:
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an inputting circuit which produces a despread signal according to a received spectrum-spread signal and an inputted spreading code;
a delay profile measuring circuit which produces a delay profile for the despread signal from the inputting circuit;
a data symbol demodulating circuit which conducts a rake combining, according to the delay profile produced by the profile measuring circuit, for the despread signals from the inputting circuit and thereby producing a demodulated signal;
a representative value calculating circuit which calculates a representative value representing spread code phases of a plurality of paths according to a plurality of correlation values and timing thereof obtained from the delay profile produced by the profile measuring circuit; and
a clock control circuit which achieves a control operation to conduct a tracking of synchronization, according to the representative value from the representative value calculating circuit, between the received signal and the spreading code inputted to the inputting circuit. - View Dependent Claims (22, 23, 24)
the inputting circuit includes a matched filter capable of simultaneously conducting a plurality of despreading for a plurality of timing; and
the representative value calculating circuit changes, when the matched filter is receiving a signal in which a plurality of delayed waves of different timing detected in a window are combined with each other and timing of a delayed wave having other than maximum intensity changes, the representative value according to the change of the timing and thereby achieving a control operation to change timing of a correlation value outputted from the matched filter.
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23. A receiver in accordance with claim 21, wherein:
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the inputting circuit includes a matched filter capable of simultaneously conducting a plurality of despreading for a plurality of timing; and
the representative value calculating circuit changes, when the matched filter is receiving a signal in which a plurality of delayed waves of different timing detected in a window are combined with each other and intensity of delayed wave having other than maximum intensity changes within a range in which the intensity does not become the maximum intensity, the representative value according to the change of the timing and thereby changing timing of a correlation value outputted from the matched filter.
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24. A receiver in accordance with claim 23, further including a loop filter including integrating means, variable coefficient generating means, and an adding means, wherein:
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the loop filter adds, by the adding means using predetermined weights, a first value obtained by integrating by the integrating means a result attained by multiplying a representative value from the representative value calculating circuit by a square of a coefficient generated by the variable coefficient generating means to a second value obtained by multiplying the representative value by a coefficient generated by the variable coefficient generating means; and
the clock control circuit controls, using an output from the loop filter, variable frequency oscillating means or a variable frequency divider arranged therein.
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Specification