Receiver for receiving a spectrum dispersion signal

• US 7,400,667 B2
• Filed: 06/12/2007
• Issued: 07/15/2008
• Est. Priority Date: 03/31/1998
• Status: Expired due to Fees

• Current Assignee: Samsung Electronics Co. Ltd.
• Original Assignee: Hitachi, Ltd.
• Inventors: Hasegawa, Osamu, Sudo, Shigeyuki, Eguchi, Toshiya
• Primary Examiner(s): Ha, Dac V.
• Application Number:
  US11/808,607
• Publication Number:
  US 20070242632A1
• Time in Patent Office: 399 Days
• Field of Search: 375/140, 375/147, 375/153, 375/354, 375/375, 375/376, 375/344, 370/311, 370/318, 370/355, 370/503, 455/425, 455/574, 455/434.2, 713/320, 713/324, 713/500, 713/502
• US Class Current: 375/147
• CPC Class Codes: H04B 1/707 using direct sequence modulation
• CPC Class Codes: H04B 1/7075 with code phase acquisition
• CPC Class Codes: H04B 1/70756 Jumping within the code, i.e. masking or slewing H04B1/70758 takes precedence
• CPC Class Codes: H04B 2201/70709 with discontinuous detection
• CPC Class Codes: H04W 52/029 reducing the clock frequency of the controller
• CPC Class Codes: Y02D 30/70 in wireless communication networks

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.

Claims

1. A mobile communication terminal, comprising:

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 first timer which executes a counting operation when the receiver is in a suspension state, the first timer being driven by the first oscillator;

a second oscillator which starts to output a signal having a second frequency when the receiver changes from the suspension state to a receiving state,

wherein the second frequency is higher than the first frequency;

a second timer which executes a counting operation when the receiver is in the receiving state, the second timer being driven by the second oscillator; and

a controller which controls the receiving state and the suspension state based on the count by the first timer and the second timer,

wherein the controller further controls so that the receiver changes from the suspension state to the receiving state and the demodulator starts demodulation operation, and 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.

2. The mobile communication terminal according to claim 1, wherein the second frequency is higher than a chip rate of the spread spectrum signal.

3. The mobile communication terminal according to claim 2, further comprising:

a frequency controller which adjusts the second frequency.

4. The mobile communication terminal according to claim 1, wherein the second oscillator is suspended when the receiver is in the suspension state.

5. The mobile communication terminal according to claim 1, wherein said second oscillator is a voltage controlled type temperature compensation crystal oscillator.