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

• US 7,016,431 B2
• Filed: 12/16/2000
• Issued: 03/21/2006
• Est. Priority Date: 12/23/1999
• Status: Expired due to Fees

• Current Assignee: Robert Bosch GmbH
• Original Assignee: Robert Bosch GmbH
• Inventors: Hentati, Nabil, Lochau, Mirko, Schrader, Marc, Harms, Lars
• Primary Examiner(s): DEPPE, BETSY LEE
• Application Number:
  US09/914,134
• Publication Number:
  US 20020168023A1
• Time in Patent Office: 1,921 Days
• Field of Search: 375/296, 375/295, 375/297, 375/298, 375/308, 375/260, 375/261, 330/149, 455/114.3, 332/107, 332/123, 332/124, 332/125
• US Class Current: 375/297
• CPC Class Codes: H03F 1/3247 using feedback acting on predistortion circuits H03F1/3264 takes precedence
• 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. Test signals are input at preset times into OFDM signals to be transmitted, and then test signals amplified by the amplifier (8) are compared with test signals buffered in a measurement module (12) 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 generated by a signal generator (13) is input into a synchronization symbol, with the amplitude of the test signal being increased incrementally or being large enough to determine the transfer properties of the amplifier (8). The test signal has an envelope which is not dependent on time.

Claims

1. A transmitter for sending a signal over a wireless channel, comprising:

a modulator for modulating the signal to produce a modulated signal that is distributed over a subcarrier;

a predistorter for predistorting the modulated signal distributed over the subcarrier according to an amplifier transfer property in order to produce a predistorted signal;

a mixer for converting the predistorted signal from a baseband frequency into an intermediate frequency in order to produce a converted signal;

an amplifier for amplifying the converted signal in order to produce an amplified signal;

an antenna for sending a first portion of the amplified signal;

a mixer for mixing a second portion of the amplified signal down from the intermediate frequency to the baseband frequency in order to produce a mixed-down signal;

a measurement module for comparing the mixed-down signal with the predistorted signal to determine the amplifier transfer property and for notifying the predistorter of the amplifier transfer property;

a signal generator for generating a test signal; and

an input element for inputting at preset times the test signal into one of the modulated signal, the predistorted signal, and the converted signal, wherein;

the measurement module compares the test signal in the mixed-down signal with the test signal in the one of the modulated signal, the predistorted signal, and the converted signal to obtain the amplifier transfer property, and

the signal generator generates the test signal having an envelope that is not dependent on time.

2. A method for sending a signal over a wireless channel, comprising the steps of:

modulating the signal to produce a modulated signal that is distributed over a subcarrier;

predistorting the modulated signal distributed over the subcarrier according to an amplifier transfer property in order to produce a predistorted signal;

converting the predistorted signal from a baseband frequency into an intermediate frequency in order to produce a converted signal;

amplifying the converted signal in order to produce an amplified signal;

sending a first portion of the amplified signal;

mixing a second portion of the amplified signal down from the intermediate frequency to the baseband frequency in order to produce a mixed-down signal;

comparing the mixed-down signal with the predistorted signal to determine the amplifier transfer property and for providing a notification of the amplifier transfer property;

generating a test signal;

inputting at preset times the test signal into one of the modulated signal, the predistorted signal, and the converted signal;

comparing the test signal in the mixed-down signal with the test signal in the one of the modulated signal, the predistorted signal, and the converted signal to obtain the amplifier transfer property; and

incrementally increasing an amplitude of the test signal up to a preset size to measure a control range of an amplifier.

3. The method according to claim 2, further comprising the step of:

inputting the test signal into a synchronization symbol.

4. A method for sending a signal over a wireless channel, comprising the steps of:

modulating the signal to produce a modulated signal that is distributed over a subcarrier;

predistorting the modulated signal distributed over the subcarrier according to an amplifier transfer property in order to produce a predistorted signal;

converting the predistorted signal from a baseband frequency into an intermediate frequency in order to produce a converted signal;

amplifying the converted signal in order to produce an amplified signal;

sending a first portion of the amplified signal;

mixing a second portion of the amplified signal down from the intermediate frequency to the baseband frequency in order to produce a mixed-down signal;

comparing the mixed-down signal with the predistorted signal to determine the amplifier transfer property and for providing a notification of the amplifier transfer property;

generating a test signal;

inputting at preset times the test signal into one of the modulated signal, the predistorted signal, and the converted signal; and

comparing the test signal in the mixed-down signal with the test signal in the one of the modulated signal, the predistorted signal, and the converted signal to obtain the amplifier transfer property,

wherein an amplitude of the test signal has a size such that control settings of an amplifier are at least fully adjusted by the test signal.

5. The method according to claim 4, further comprising the step of:

determining the amplifier transfer property in accordance with samples of the test signal.

6. The method according to claim 5, further comprising the step of:

inputting the test signal into a synchronization symbol.