Method and system for controlling transmission power

• US 7,486,935 B2
• Filed: 03/09/2004
• Issued: 02/03/2009
• Est. Priority Date: 06/16/2003
• Status: Expired due to Fees

• Current Assignee: Oki Semiconductor Company Limited (ROHM Co., Ltd.)
• Original Assignee: Oki Semiconductor Company Limited (ROHM Co., Ltd.)
• Inventors: Akahori, Hiroji
• Primary Examiner(s): Maung; Nay
• Assistant Examiner(s): Young; Janelle N.
• Application Number:
  US10/795,416
• Publication Number:
  US 20040253929A1
• Time in Patent Office: 1,792 Days
• Field of Search: 455/12, 455/13, 455/68, 455/69, 455/517, 455/522, 370/17, 370/318
• US Class Current: 455/68
• CPC Class Codes: H04W 52/04 TPC
• CPC Class Codes: H04W 52/08 Closed loop power control
• CPC Class Codes: H04W 52/228 using past power values or information
• CPC Class Codes: H04W 52/241 taking into account channel quality metrics, e.g. SIR, SNR, CIR, Eb/lo

Abstract

A transmission power control system includes a control and a controlled station. In the control station, an SIR (Signal-to-interference Ratio) estimator calculates two different kinds of estimated SIRs having a long and a short mean processing time, respectively. A subtractor subtracts a target SIR from the estimated SIR with the long mean processing time while an error decider compares the resulting difference with a threshold to thereby output a result of decision. A comparison value updater updates, based on the result of decision, a comparison SIR held in a comparison value holder. Another subtractor subtracts the comparison SIR from the estimated SIR with the short mean processing time. A control information converter generates power control information in accordance with the output of the another subtractor. The controlled station selectively increases or decreases transmission power in accordance with the power control information received from the control station.

Claims

1. A method of controlling a transmission power of a transmission-power controlled station from a transmission-power control station such that an SIR (Signal-to-Interference Ratio) value of received power of the transmission-power control station converges to a desired target SIR, said method comprising:

a first step of calculating a first estimated SIR having a short mean processing time on a basis of a signal received by said transmission-power control station and a second estimated SIR having a longer mean processing time than the mean processing time to calculate the first estimated SIR, the first step includes a first sub-step of calculating mean powers of said received signals, a second sub-step of calculating a mean value of the mean powers obtained in the first sub-step, a third sub-step of calculating mean powers of desired signal wave components of the received signals, a fourth sub-step of calculating a mean value of said mean powers obtained in the third sub-step, a fifth sub-step of calculating said first estimated SIR on the basis of the mean powers obtained in the first and the third sub-steps, and a sixth sub-step of calculating said second estimated SIR on the basis of the mean values obtained in the second and fourth sub-steps;

a second step of generating power control information for setting said first estimated SIR in a comparison SIR and storing the comparison SIR to thereby control said transmission power such that the first estimated SIR converges to the comparison SIR;

a third step of updating said comparison SIR such that said second estimated SIR converges to a desired target SIR; and

a fourth step of controlling the transmission power of the transmission-power controlled station in accordance with said power control information.