Receiver for receiving a spectrum dispersion signal

• US 7,269,203 B2
• Filed: 02/10/2005
• Issued: 09/11/2007
• Est. Priority Date: 03/31/1998
• Status: Expired due to Fees

• Current Assignee: Samsung Electronics Co. Ltd.
• Original Assignee: Hitachi, Ltd.
• Inventors: Eguchi, Toshiya, Hasegawa, Osamu, Sudo, Shigeyuki
• Primary Examiner(s): Ha, Dac V.
• Application Number:
  US11/054,439
• Publication Number:
  US 20050147154A1
• Time in Patent Office: 943 Days
• Field of Search: 375/140, 375/147, 375/153, 375/354, 370/311, 370/318, 370/335, 370/503, 455/425, 455/574, 455/343.2, 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, in order to reduce a power consumption during a suspension period of intermittent receiving operation, monitors a suspension period t1 by means of a low-power timer 51 so that a VC-TCXO 1, a reference signal group generation unit 2 and a receiving unit 3 are turned off and a modem unit 4 is set to a sleep state. Upon resumption of receiving operation, a high-accuracy timer 44 is supplied with a start (d) to require counting of time t3 and a part of a received signal is stored. A PN code phase of stored data is calculated in a PN code phase calculator 46 during a period t3 to obtain an indication value i for a phase deviation. State vectors for short code and long code and further a reception time t4 are calculated on the basis of the indication value i to be set. When the high-accuracy timer 44 counts t3 and produces 0V(d), demodulation operation by a rake demodulation unit 40, a demultiplexing unit 41 and a descrambler unit 42 is started in accordance with the setting and is continued during the reception time t4.

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 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.

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.