CDMA communication system and method

• US 7,545,777 B2
• Filed: 06/09/2003
• Issued: 06/09/2009
• Est. Priority Date: 07/09/1996
• Status: Expired due to Fees

• Current Assignee: Hitachi, Ltd.
• Original Assignee: Hitachi Denshi Kabushiki Kaisha, Hitachi Communication Technologies Limited (Hitachi, Ltd.)
• Inventors: Doi, Nobukazu, Shiga, Tesshin, Ohta, Yoshito, Ariyoshi, Masayuki
• Primary Examiner(s): Hoang; Thai D
• Application Number:
  US10/456,577
• Publication Number:
  US 20030214932A1
• Time in Patent Office: 2,192 Days
• Field of Search: 370/328, 370/335, 370/342, 370/227, 370/310, 370/441, 375/140, 375/226, 375260-264, 375/356, 375/358
• US Class Current: 370/335
• CPC Class Codes: H04B 1/707 using direct sequence modulation
• CPC Class Codes: H04B 1/7085 using a code tracking loop, e.g. a delay-locked loop
• CPC Class Codes: H04B 2201/709709 Methods of preventing interference
• CPC Class Codes: H04J 13/00 Code division multiplex systems for frequency hopping H04B1/713
• CPC Class Codes: H04W 56/0005 synchronizing of arrival of multiple uplinks
• CPC Class Codes: H04W 56/0085 detecting a given structure in the signal

Abstract

In CDMA communications, a base station detects a difference between a reference phase of a spreading code and a phase of a received signal of each terminal station, and feeds a phase jump signal PJ-i representative of the phase difference back to each terminal station. After timing acquisition, the reception operation is performed using the reference phase, and a shift amount between the phase of a received signal and the reference phase is fed back to each terminal station as phase synchronization control information PC-i. Each terminal station coarsely adjusts the phase of the spreading code in accordance with the phase jump signal PJ-i, and thereafter finely adjusts the phase of its transmitting signal in accordance with the phase synchronization control information PC-i. It is therefore possible to synchronize the phases of the signals transmitted from terminal stations and received at the base station. Accordingly, an orthogonal code is used for spreading on the reverse links.

Claims

1. A communication method in a communication system for performing communication between a base station and terminal stations, comprising the steps of:

transmitting, from each terminal station, a first signal;

performing, in the base station, a timing acquisition of the first signal from each terminal station and transmitting first difference information for coarse adjustment which indicates a phase difference between the first signal and a reference phase;

generating, in each terminal station, an orthogonal signal having a phase set in accordance with the first difference information and transmitting a second signal using the generated orthogonal signal;

performing, in the base station, a tracking of the second signal from each terminal station and transmitting a second difference information for fine adjustment between the second signal and the reference phase; and

setting, in each terminal station, a delay amount of a delay circuit in accordance with the second difference information, wherein the delay circuit is between an antenna of each terminal station and a generator means for generating the orthogonal signal,

wherein the first difference information is input to the generator means and the second difference information is input to the delay circuit.

2. The method of claim 1, wherein the second difference information is input to the delay circuit via a transmission phase controller.

3. A terminal station for performing communication with a base station, comprising:

generator means for generating an orthogonal signal assigned to the terminal station and having a phase set in accordance with first difference information transmitted from the base station, wherein the first difference information indicates a phase difference for coarse adjustment between a reference phase and a first signal which is transmitted from each terminal station and received by the base station, said reference phase being used in a timing acquisition of the first signal; and

a delay circuit, between an antenna and the generator means, having a delay set in accordance with second difference information transmitted from the base station, wherein the second difference information indicates a difference for fine adjustment during tracking between the reference phase and a second signal, transmitted from each terminal station using the orthogonal signal and received by the base station;

wherein the first difference information is input to the generator means and the second difference information is input to the delay circuit.

4. The terminal station of claim 3, wherein the generator means is adapted to slide a phase of the orthogonal signal by a predetermined amount until receiving the first difference information transmitted from the base station, wherein the first difference information indicates a completion of timing acquisition of the transmitting signal from the terminal station.

5. The terminal station of claim 4, wherein the transmitting data are fixed as consecutive symbols before the completion of the timing acquisition.

6. The terminal station of claim 5, further comprising a transmission phase controller, wherein the second difference information is input to the delay circuit via said transmission phase controller.

7. The terminal station of claim 4, further comprising a transmission phase controller, wherein the second difference information is input to the delay circuit via said transmission phase controller.

8. The terminal station of claim 3, further comprising a transmission phase controller, wherein the second difference information is input to the delay circuit via said transmission phase controller.