Combined open and closed loop power control with differential measurement

• US 20030176202A1
• Filed: 03/07/2002
• Published: 09/18/2003
• Est. Priority Date: 03/07/2002
• Status: Active Grant

• Current Assignee: Siemens AG
• Original Assignee: Siemens Information And Communication Mobile LLC (Siemens AG)
• Inventors: Malaugh, John, Bartl, Thomas
• Granted Patent: US 6,985,751 B2
• Time in Patent Office: Days
• US Class Current: 455/522
• CPC Class Codes: H03G 3/3042 in modulators, frequency-changers, transmitters or power amplifiers transmission power control in bidirectional transmission systems H04W52/04
• CPC Class Codes: H03G 3/3047 for intermittent signals, e.g. burst signals
• CPC Class Codes: H04W 52/08 Closed loop power control
• CPC Class Codes: H04W 52/10 Open loop power control
• CPC Class Codes: H04W 52/36 with a discrete range or set of values, e.g. step size, ramping or offsets
• CPC Class Codes: H04W 52/52 using AGC [Automatic Gain Control] circuits or amplifiers

Abstract

A power control system and method for a wireless telephone employs an open loop technique for relatively low power levels and a closed loop technique at higher power levels. In the open loop technique, a wireless telephone (104, 106, 108) stores a phasing table of automatic power control (APC) values for the power levels (which are used to control upconverter gain levels measured at different channels. In operation, a power controller (322) reads the power level and reads the APC value in the table. Another table stores the APC value for one power level as the channel and temperature are varied. This value is interpolated, as needed, during operation. The APC value for the open loop approach is determined by reading the input channel; finding the closest higher and closest lower channels in the temperature-channel table; interpolating between APC values for the temperature column of the closest lower temperature, to get the actual value. The difference between this value and the APC value for the actual power level in the phasing table is then obtained.

Claims

1. A telecommunications device, comprising:

an open loop power controller adapted to maintain a first phasing table and a channel-temperature table;

a closed loop power controller adapted to maintain a second phasing table and receive a power detector output;

wherein said open loop power controller is adapted to provide a power set (APC) value in a first mode and said closed loop power controller is adapted to provide said power set value in a second mode, and in said second mode, said closed loop power controller receives said power detector output during a transmit burst and after a transmit burst.

2. A telecommunications device in accordance with claim 1, said first phasing table comprising pre-initialized power level and power set values.

3. A telecommunications device in accordance with claim 2, said second phasing table comprising pre-initialized power detector and power level values.

4. A telecommunications device in accordance with claim 2, said channel temperature table comprising a two-dimensional table of power set values with temperature and channel.

5. A telecommunications method for controlling transmit power in a wireless telecommunications device, comprising:

initializing first and second phasing tables, the first phasing table comprising pre-initialized power level and power set values, said second phasing table comprising pre-initialized power detector and power level values;

initializing a channel-temperature table, said channel temperature table comprising a two-dimensional table of power set values with temperature and channel;

generating a power set value using said first phasing table and said channel-temperature table in an open loop mode; and

generating a power set value by reading a power detector and accessing said second phasing table in a closed loop mode, wherein in said second mode said power detector is read while a transmitter is on and while a transmitter is off.

6. A method in accordance with claim 5, said initializing a first phasing table comprising adjusting the APC value until the nominal power for each power level is output from the telecommunications device and storing that value is stored in the first phasing table.

7. A method in accordance with claim 6, wherein said initializing said channel-temperature table comprising setting a number of telecommunications devices to a specific channel and temperature;

adjusting the APC values of the telecommunications devices until the telecommunications devices output the nominal power for power level zero; and

averaging the results for each telecommunications device.

8. A method in accordance with claim 5, said generating a power set value in an open loop mode comprising determining a nominal APC value for the channel used to phase the telecommunications device by finding the closest higher channel and closest lower channel in the table, and interpolating between the room temperature APC values in the table.

9. A method in accordance with claim 5, said initializing said second phasing table comprising adjusting the APC value until the nominal power for each power level is output from the telecommunications device and storing the output of the power detector in the table.

10. A method in accordance with claim 9, said generating a power set value in a closed loop mode comprising:

reading the power detector to get an actual RF power value;

looking up the desired RF power value in the second phasing table;

obtaining an RF error; and

running a servo control loop calculation to find the APC value needed to correct for the RF error.

11. A telecommunications method, comprising:

providing an open loop power controller adapted to maintain a first phasing table and a channel-temperature table;

providing a closed loop power controller adapted to maintain a second phasing table and receive a power detector output;

wherein said open loop power controller is adapted to provide a power set (APC) value in a first mode and said closed loop power controller is adapted to provide said power set value in a second mode, said closed loop power controller receives said power detector output during a transmit burst and after a transmit burst.

12. A telecommunications method in accordance with claim 11, said first phasing table comprising pre-initialized power level and power set values.

13. A telecommunications method in accordance with claim 12, said second phasing table comprising pre-initialized power detector and power level values.

14. A telecommunications method in accordance with claim 12, said channel temperature table comprising a two-dimensional table of power set values with temperature and channel

15. A telecommunications device, comprising:

an open loop power controller adapted to provide a automatic power control (APC) value in a low power mode;

a closed loop power controller adapted to provide an APC value in a high power mode;

wherein in said high power mode, said closed loop power controller receives a power detector output during a transmit burst and after a transmit burst.