Transmitter for transmitting signals over radio channels and mehtod for transmitting signals over radio channels

• US 20030156657A1
• Filed: 02/24/2003
• Published: 08/21/2003
• Est. Priority Date: 12/23/1999
• Status: Active Grant

• Current Assignee: Robert Bosch GmbH
• Original Assignee: Robert Bosch GmbH
• Inventors: Hentati, Nabil, Lochau, Mirko, Schrader, Marc, Harms, Lars
• Granted Patent: US 7,423,958 B2
• Time in Patent Office: Days
• US Class Current: 375/295
• CPC Class Codes: H04L 27/2602 Signal structure
• CPC Class Codes: H04L 27/2626 Arrangements specific to the transmitter only
• CPC Class Codes: H04L 27/368 adaptive predistortion

Abstract

A transmitter for sending signals over wireless channels and a method of sending signals over wireless channels are described. The transmitter and the method are used to determine a transfer characteristic of an amplifier (8) in the transmitter. Symbols in the OFDM signals to be transmitted are multiplied by test signals at predefined points in time to compare the OFDM symbol, which has been multiplied by the test signal, upstream and downstream from the amplifier to determine the transfer characteristic of the amplifier (8). This transfer characteristic of the amplifier (8) is used by a predistorter (4) to predistort the signals according to this transfer characteristic. The test signal, which is generated by a signal generator (13), is input into a symbol of the fast information channel, the test signal having an amplitude which drives the multiplied symbol into the saturation range of the amplifier (8) with regard to its amplitude.

Claims

1. A transmitter for sending signals over wireless channels, a modulator (3) performing a modulation of the signals to be sent and distributing the modulated signals among various subcarriers, a predistorter (4) predistorting the signals, distributed among various subcarriers, according to the transfer properties of an amplifier (8), a mixer (7) converting the predistorted signals from a baseband into an intermediate frequency, the amplifier (8) amplifying the converted signals, an antenna (9) sending a first portion of the amplified signals, a mixer (10) mixing a second portion of the amplified signals down from the intermediate frequency to the baseband, a measuring module (12) comparing the mixed-down signals with the predistorted signals to determine the transfer properties of the amplifier (8) and notifying the predistorter (4) of the transfer properties of the amplifier (8),

wherein a signal generator (13) generates a test signal, a multiplier (5) multiplies the test signal by the signals in predefined time intervals, and the measuring module (12) compares the test signal in the mixed-down signals with the test signal in the signals to obtain the transfer properties of the amplifier (8).

2. The transmitter according to claim 1,

wherein the multiplier (5) multiplies the test signal by the predistorted signals in the predefined time intervals.

3. The transmitter according to claim 1,

wherein the multiplier (5) multiplies the test signal upstream from the predistorter (4) by the signals in the predefined time intervals.

4. The transmitter according to claim 1,

wherein the modulator (3) performs a differential phase modulation, preferably a differential quadrature phase shift keying.

5. The transmitter according to claim 1,

wherein the signal generator (13) generates the test signal as an identical signal in the predefined intervals, an amplitude of the identical signal driving the amplifier into saturation.

6. The transmitter according to claim 5,

wherein the multiplier multiplies the test signal by a certain symbol in the signals.

7. A method of sending signals over wireless channels, the signals to be sent being modulated, the modulated signals being distributed among subcarriers, the signals distributed among the subcarriers being predistorted according to the transfer properties of an amplifier (8), the predistorted signals being converted from a baseband into an intermediate frequency, the converted signals being amplified, a first portion of the amplified signals being sent over the wireless channels, a second portion of the amplified signals being converted from an intermediate frequency to the baseband, the predistorted signals and the signals converted to the baseband being compared to determine the transfer properties of the amplifier (8), and then this information being sent to a predistorter (4),

wherein test signals are generated, the test signals being multiplied by the signals, and the test signal in the signals being compared with the test signal of the signals amplified and converted to the baseband to determine the transfer properties of the amplifier (8).

8. The method according to claim 7,

wherein the test signals are multiplied by the predistorted signals.

9. The method according to claim 7,

wherein the test signals are multiplied by the signals upstream from the predistorter (4).

10. The method according to claim 7,

wherein the amplitude of the test signal is such that the amplifier (8) is at least fully driven by the test signal.

11. The method according to claim 10,

wherein the test signal is multiplied by a fast information channel symbol.