Method and transmitter for transmitting radio signals

• US 7,308,041 B1
• Filed: 09/02/2000
• Issued: 12/11/2007
• Est. Priority Date: 09/17/1999
• Status: Expired due to Fees

• Current Assignee: Robert Bosch GmbH
• Original Assignee: Robert Bosch GmbH
• Inventors: Schrader, Marc, Hentati, Nabil
• Primary Examiner(s): Corrielus, Jean B.
• Application Number:
  US10/088,218
• Time in Patent Office: 2,656 Days
• Field of Search: 375/224, 375/225
• US Class Current: 375/296
• CPC Class Codes: H04L 27/2614 Peak power aspects
• CPC Class Codes: H04L 27/2644 with oversampling

Abstract

A method of transmitting wireless signals and a transmitter for transmitting wireless signals for optimally operate an amplifier of a transmitter in its linear range, signals being transmitted in orthogonal frequency division multiplexing (OFDM). The amplitudes of the OFDM signals that lie above a predefined threshold are eliminated using an additive correction signal, the phase of the OFDM signals being impressed on the additive correction signal. Furthermore, a correction signal is formed and subtracted from the OFDM signals, until there are no more amplitudes of the OFDM signal above the predefined threshold. Gauss pulses are used as correction signals due to their simple handling. Oversampling of the OFDM signals determines the amplitude values of the OFDM signals.

Claims

1. A method for transmitting a wireless signal using orthogonal frequency division multiplexing, the method comprising:

modulating the wireless signal using digital phase modulation;

sampling the wireless signal after modulation to generate a plurality of sampled values of the modulated wireless signal;

determining at least one amplitude value of the wireless signal using the plurality of sampled values;

comparing the at least one amplitude value to a predefined threshold to obtain a correction signal;

determining a phase of the wireless signal;

providing the correction signal with the phase of the wireless signal;

subtracting the correction signal from the wireless signal after providing the correction signal with the phase of the wireless signal to reduce the amplitude values of the wireless signal that lie above the predefined threshold to a value of the threshold to generate a corrected wireless signal;

pre-equalizing the corrected wireless signal;

converting the pre-equalized wireless signal into an analog wireless signal using at least one digital-analog converter;

amplifying the analog wireless signal; and

transmitting the amplified wireless signal.

2. The method of claim 1, wherein the correction signal is subtracted from the wireless signal a plurality of times, the correction signal being re-determined for each subtraction.

3. The method of claim 2, wherein the correction signal includes Gauss pulses.

4. The method of claim 2, wherein the correction signal is subtracted from the wireless signal, until the amplitudes of the corrected wireless signal are at most equal to the predefined threshold.

5. The method of claim 2, wherein a number of times the correction signal is to be subtracted from the wireless signal is predefined.

6. The method of claim 4, wherein the wireless signal is oversampled.

7. A transmitter for transmitting a digital signal, the transmitter comprising:

a modulator to perform orthogonal frequency division multiplexing (OFDM) and a phase modulation on the digital signal to be transmitted to form a modulated OFDM signal;

a processor to sample the modulated OFDM signal to generate a plurality of sampled values, determine at least one amplitude value of the modulated OFDM signal, compare the at least one amplitude value of the modulated OFDM signal to a predefined threshold to form a correction signal, determine a phase of the sampled modulated OFDM signal, provide the correction signal with the phase of the modulated OFDM signal, and subtract the correction signal from the modulated OFDM signal after providing the correction signal with the phase of the modulated OFDM signal to reduce the amplitude values of the modulated OFDM signal that lie above the predefined threshold to a value of the threshold to output a corrected modulated OFDM signal;

a pre-equalizer to pre-equalize the corrected modulated OFDM signal to output a pre-equalized corrected modulated OFDM signal; and

at least one digital/analog converter to convert the pre-equalized corrected modulated OFDM signal into an analog signal.

8. The transmitter of claim 7, wherein the processor is configured to subtract the correction signal from the modulated OFDM signal a plurality of times and to re-determine the correction signal for each subtraction.

9. The transmitter of claim 8, wherein the processor is configured to subtract the correction signal, until the amplitudes of the corrected modulated OFDM signal are at most equal to the predefined threshold.

10. The transmitter of claim 8, wherein the processor is configured to subtract the correction signal from the modulated OFDM signal a number of times indicated by a predefined value.

11. The transmitter of claim 9, wherein the processor is configured to generate the correction signal, and the correction signal includes Gauss pulses.

12. The transmitter of claim 11 wherein the processor is configured to perform oversampling on the modulated OFDM signal.