Spread spectrum communication system and transmission power control method therefor

• US 7,376,107 B2
• Filed: 07/09/2003
• Issued: 05/20/2008
• Est. Priority Date: 07/23/1993
• Status: Expired due to Fees

• Current Assignee: FIPA Frohwitter Intellectual Property AG
• Original Assignee: FIPA Frohwitter Intellectual Property AG
• Inventors: Doi, Nobukazu, Yano, Takashi
• Primary Examiner(s): Patel; Ajit
• Application Number:
  US10/614,796
• Publication Number:
  US 20050128984A1
• Time in Patent Office: 1,777 Days
• Field of Search: 370/203, 370/208, 370/209, 370/332, 370/335, 370/328, 370/342, 370/441, 370/318, 455/517, 455/522, 455/69, 375/130
• US Class Current: 370/335
• CPC Class Codes: H04B 1/707 using direct sequence modulation
• CPC Class Codes: H04B 1/7097 Interference-related aspects
• CPC Class Codes: H04W 52/08 Closed loop power control
• CPC Class Codes: H04W 52/24 using SIR [Signal to Interference Ratio] or other wireless path parameters
• CPC Class Codes: H04W 52/58 Format of the TPC bits

Abstract

In a spread spectrum communication system, one (W_n) of a series of orthogonal codes for spectrum spreading is assigned to signal-to-noise ratio measurement in a terminal. On the basis of a noise signal detected by de-spreading a signal received from an antenna with the above described orthogonal code (W_n) and a pilot signal, each terminal derives a signal-to-noise ratio. Each terminal transmits the signal-to-noise ratio to the base station as a power control signal. On the basis of signal-to-noise information received from each terminal as the power control signal, the base station controls signal transmission power for each terminal.

Claims

1. A transmission control method for a base station in a spread spectrum communication system, comprising the steps of:

transmitting, from said base station, a first signal via a first channel;

receiving, at a mobile terminal in said spread spectrum communication system, said first signal and measuring said received first signal;

transmitting, from said mobile terminal, a second signal to said base station generated according to a result of said measuring of said first signal; and

receiving, at said base station, said second signal, and controlling, based on said second signal, a third signal which is to be transmitted to said mobile terminal from said base station via a second channel which is different from said first channel.

2. A transmission control method according to claim 1, wherein said first signal is spread using a first spreading code, and said third signal is spread using a second spreading code.

3. A transmission control method according to claim 1, wherein said measuring of said first signal by said mobile station evaluates reception condition of said first signal.

4. A transmission control method according to claim 3, wherein said base station transmits said first signal with a constant transmission power.

5. A transmission control method according to claim 1, wherein said base station controls transmission power of said third signal based on said second signal.

6. A transmission control method according to claim 1, wherein said first signal is a pilot signal.

7. A transmission control method according to claim 1, wherein said second channel is transmitted together with said first channel.

8. A base station for communicating with a mobile station in a wireless communication system, comprising:

a transmitting circuit for transmitting a first signal over a first channel, and a second signal over a second channel which is different from said first channel;

a reception circuit for receiving a third signal transmitted from said mobile station; and

a transmission controller for controlling transmission of a signal,

wherein said third signal received from said mobile station is generated by the mobile station according to a measurement of said first signal received at said mobile station, and

wherein said transmission controller controls transmission of said second signal to said mobile station based on said third signal.

9. A base station according to claim 8, wherein said first signal is spread with a first spreading code, and said second signal is spread with a second spreading code.

10. A base station according to claim 8, wherein said first signal is transmitted with a constant transmission power, and said mobile station evaluates reception condition of said first signal to generate said third signal.

11. A base station according to claim 8, wherein said transmission controller controls transmission power of said second signal based on said third signal.

12. A base station according to claim 8, wherein said first signal is a pilot signal.

13. A base station according to claim 8, wherein said second channel is transmitted together with said first channel.

14. A mobile station for communicating with a base station in a wireless communication system, comprising:

a reception unit for receiving, from said base station, a first signal via a first channel and a second signal via a second channel which is different from said first channel, and measuring said first signal;

a signal generator for generating a third signal according to first signal; and

a transmission unit for transmitting said third signal to said base station,

wherein said third signal is used for controlling transmission of said second signal.

15. A mobile station according to claim 14, wherein said reception unit comprises:

a first despreader for dispreading said first signal using a first spreading code; and

a second despreader for dispreading said second signal unit a second spreading code.

16. A mobile station according to claim 14, wherein said reception unit evaluates reception condition of said first signal.

17. A mobile station according to claim 16, wherein said first signal has a constant transmission power.

18. A mobile station according to claim 14, wherein transmission power of said second signal is controlled based on said third signal.

19. A mobile station according to claim 14, wherein said first signal is a pilot signal.

20. A mobile station according to claim 14, wherein said second channel is transmitted together with said first channel.