Apparatus and method for selecting a transmit power value from multiple calculated power levels

• US 6,697,634 B1
• Filed: 10/30/2000
• Issued: 02/24/2004
• Est. Priority Date: 03/06/1999
• Status: Expired due to Term

• Current Assignee: Optis Wireless Technology, LLC (Brevet Capital)
• Original Assignee: Matsushita Electric Industrial Company Limited (Panasonic Holdings Corporation)
• Inventors: Hayashi, Masaki
• Primary Examiner(s): Bost, Dwayne
• Assistant Examiner(s): SHARMA, SUJATHA R
• Application Number:
  US09/674,293
• Time in Patent Office: 1,212 Days
• Field of Search: 455/69, 455/522, 370/332, 370/331
• US Class Current: 455/522
• CPC Class Codes: H04W 52/06 TPC algorithms
• CPC Class Codes: H04W 52/08 Closed loop power control
• CPC Class Codes: H04W 52/10 Open loop power control
• CPC Class Codes: H04W 52/40 during macro-diversity or soft handoff
• CPC Class Codes: H04W 52/50 at the moment of starting communication in a multiple access environment

Abstract

After a channel is established, CL-TPC section 162 calculates a transmit power value based on a TPC command and carries out closed-loop transmit power control. At the same time, OL-TPC section 161 calculates a transmit power value based on a reception level and compensation value calculation section 164 calculates a compensation value based on a difference between the transmit power value output from CL-TPC section 162 and that of OL-TPC section 161. After the compensation value is confirmed, mode switching section 165 switches between switches 167 and 169 and open-loop transmit power control is performed using a value obtained by adding the compensation value to the reception-level-based transmit power value. This makes it possible to compensate a reception level measurement error without the need to maintain high reception measurement accuracy, and further handle cases where high-speed fading or intense interference emerges.

Claims

1. A transmission/reception apparatus that adaptively switches between a closed loop transmit power control and an open loop transmit power control, comprising:

a first power value calculator that calculates a first power value based on a reception level for the open loop transmit power control;

a second power value calculator that calculates a second power value based on a TPC command in a received signal for the closed loop transmit power control;

a compensation value calculator that calculates a compensation value based on a difference between the first power value and the second power value; and

a power value selector that selects one of the first power value, the second power value, and a third power value obtained by adding the compensation value to the first power value as a transmit power value.

2. The transmission/reception apparatus according to claim 1, wherein the compensation value calculator averages a value obtained by subtracting the first power value from the second power value and in the case where a variation of the average value falls below a predetermined threshold, the average value is confirmed as the compensation value.

3. The transmission/reception apparatus according to claim 2, wherein the compensation value calculator averages a value obtained by subtracting the first power value from the second power value with time weight added.

4. The transmission/reception apparatus according to claim 1, wherein the power value selector selects the first power value as the transmit power value until a channel is established, selects the second power value as the transmit power value after the channel is established until the compensation value is confirmed and selects the third power value as the transmit power value after the compensation value is confirmed.

5. The transmission/reception apparatus according to claim 1, wherein the power value selector selects the second power value as the transmit power value during handover.

6. The transmission/reception apparatus according to claim 1, wherein the power value selector selects the second power value as the transmit power value when the accuracy of the compensation value deteriorates.

7. The transmission/reception apparatus according to claim 1, wherein the power value selector divides the reception level into a number of areas and when an average reception level during a predetermined period of time moves across the divided areas, selects the second power value as the transmit power value.

8. The transmission/reception apparatus according to claim 1, wherein the power value selector sets a valid period of time for the compensation value beforehand and selects the second power value as the transmit power value when the valid period of time has elapsed after the compensation value is confirmed.

9. The transmission/reception apparatus according to claim 5, wherein the compensation value calculator recalculates the compensation value when the power value selector selects the second power value as the transmit power value.

10. A communication terminal apparatus equipped with a transmission/reception apparatus that adaptively switches between a closed loop transmit power control and an open loop transmit power control, said transmission/reception apparatus comprising:

a first power value calculator that calculates a first power value based on a reception level for the open loop power control;

A second power value calculator that calculates a second power value based on a TPC command in a received signal for the closed loop power control;

a compensation value calculator that calculates a compensation value based on a difference between the first power value and the second power value; and

a power value selector that selects one of the first power value, the second power value, and a third power value obtained by adding the compensation value to said first power value as a transmit power value.

11. A base station apparatus that stops transmission of a TPC command when the communication terminal apparatus according to claim 10 is performing transmit power control based on the reception level.

12. A base station apparatus equipped with a transmission/reception apparatus that adaptively switches between a closed loop transmit power control and an open loop transmit power control, said transmission/reception apparatus comprising:

a first power value calculator that calculates a first power value based on a reception level for the open loop transmit power control;

a second power value calculator that calculates a second power value based on a TPC command in a received signal for the closed loop transmit power control;

a compensation value calculator that calculates a compensation value based on a difference between the first power value and the second power value; and

a power value selector that selects one of the first power value, the second power value, and a third power value obtained by adding the compensation value to said first power value as a transmit power value.

13. A communication terminal apparatus that stops transmission of a TPC command when the base station apparatus according to claim 12 is performing transmit power control based on the reception level.

14. A transmit power control method that adaptively switches between a closed loop transmit power control and an open loop transmit power control, said method comprising:

controlling transmit power by an open loop using a first transmit power value calculated based on a reception level until a channel is established,

controlling the transmit power by a closed loop using a second transmit power value calculated based on a TPC command in a reception signal after the channel is established,

calculating a compensation value from a difference between the first transmit power value and the second transmit power value, and

controlling the transmit power using a third transmit power value obtained by adding said compensation value to said first transmit power value after said compensation value is confirmed.

15. The transmit power control method according to claim 14, wherein during handover, the transmit power is controlled using the second transmit power value and the compensation value is recalculated.

16. The transmit power control method according to claim 14, wherein when it is decided that the accuracy of the compensation value deteriorates, the transmit power is controlled using the second transmit power value and the compensation value is recalculated.

17. The transmit power control method according to claim 14, wherein the reception level is divided into a number of areas and when an average reception level during a predetermined period of time moves across the divided areas, the transmit power is controlled using the second transmit power value and the compensation value is recalculated.

18. The transmit power control method according to claim 14, wherein a valid period of time is set for the compensation value beforehand and when the valid period of time has elapsed after the compensation value is confirmed, the transmit power is controlled using the second transmit power value and the compensation value is recalculated.