Receiver for receiving a spectrum dispersion signal
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Accused Products
Abstract
A receiver for the CDMA system which reduces power consumption during a suspension period of intermittent receiving operation by monitoring a suspension period by a low-power timer so that a VC-TCXO, reference signal group generation and receiving units are turned off and a modem unit is set to a sleep state. Upon resumption of receiving operation, a high-accuracy timer is started to count a time period and part of a received signal is stored. A PN code phase of stored data is calculated during the time period to obtain an indication value for phase deviation. State vectors for short and long codes and a further reception time are calculated based on the indication value. When the high-accuracy timer counts the time period and produces 0V(d), demodulation operation by a rake demodulation, demultiplexing, and descrambler units is started and is continued during the reception time.
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Citations
7 Claims
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1. (canceled)
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2. A mobile communication terminal, comprising:
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a receiver which receives a spread spectrum signal transmitted by a base station;
a demodulator which generates a dispreading code for de-spreading the spread spectrum signal received by the receiver and demodulates the spread spectrum signal using the generated dispreading code;
a first oscillator which outputs a signal having a first frequency;
a second oscillator which outputs a signal having a second frequency when the receiver changes from a suspension state to a receiving state, wherein the second frequency is higher than the first frequency; and
an intermittent receiving controller which controls so that the receiver changes from the suspension state to the receiving state and the demodulator starts demodulation operation using the signal output from the second oscillator, wherein the intermittent receiving controller further controls to execute a search operation to attain synchronization of a dispreading code if an output of a signal demodulated by the demodulator is smaller than a predetermined value, and to not execute the search operation to attain synchronization of the dispreading code if the output of the signal is equal to or larger than the predetermined value, when the receiver changes from the suspension state to the receiving state, and wherein said second oscillator is a voltage controlled type temperature compensation crystal oscillator. - View Dependent Claims (3, 4)
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5. A method of communication in a mobile communication terminal, comprising the steps of:
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receiving a spread spectrum signal transmitted by a base station;
generating a dispreading code for de-spreading the received spread spectrum signal and demodulating the spread spectrum signal using the generated dispreading code;
outputting, by a first oscillator, a signal having a first frequency;
outputting, by a second oscillator, a signal having a second frequency when said mobile communication terminal changes from a suspension state to a receiving state during which said receiving step is performed, wherein the second frequency is higher than the first frequency; and
controlling so that said mobile communication terminal changes from the suspension state to the receiving state and the demodulating step is started using the signal output from the second oscillator, wherein said controlling step includes controlling execute a search operation to attain synchronization of a dispreading code if an output of a signal demodulated by the demodulating step is smaller than a predetermined value, and to not execute the search operation to attain synchronization of the dispreading code if the output of the signal is equal to or larger than the predetermined value, when said mobile communication terminal changes from the suspension state to the receiving state, and wherein said second oscillator is a voltage controlled type temperature compensation crystal oscillator. - View Dependent Claims (6, 7)
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Specification