Method and Apparatus for Modifying a Complex-Valued Signal, and Mobile Communication Device

• US 20140226756A1
• Filed: 02/11/2013
• Published: 08/14/2014
• Est. Priority Date: 02/11/2013
• Status: Active Grant

• Current Assignee: Intel Corporation
• Original Assignee: Intel Deutschland GmbH (Intel Corporation)
• Inventors: Menkhoff, Andreas, Sahlin, Staffan
• Granted Patent: US 8,923,434 B2
• Time in Patent Office: Days
• US Class Current: 375/302
• CPC Class Codes: H04L 27/20 Modulator circuits; Transmitter circuits

Abstract

A method and an apparatus for modifying a complex-valued signal are described, the complex-valued signal representing a first symbol and a second symbol. A signal trajectory of the complex-valued signal between the first and second symbols is determined, and, if the signal trajectory passes nearby the constellation origin, the signal trajectory is altered to run closer to the constellation origin.

Claims

1. A method for modifying a complex-valued signal representing a first symbol and a second symbol, comprising:

determining a signal trajectory of the complex-valued signal between the first symbol and the second symbol; and

if the signal trajectory passes nearby the constellation origin, altering the signal trajectory to run closer to the constellation origin.

2. The method of claim 1, wherein passing of the signal trajectory nearby the constellation origin is determined when a predefined characteristic of the signal trajectory fulfills a predefined first criterion.

3. The method of claim 2,

wherein the predefined characteristic of the signal trajectory comprises at least one of a relative phase angle between the first symbol and the second symbol, a momentary frequency of the complex-valued signal and a distance between the signal trajectory and a constellation origin;

and

wherein the method comprises altering the signal trajectory to run closer to the constellation origin, if the predefined characteristic of the signal trajectory fulfills the predefined first criterion.

4. The method of claim 3, further comprising:

determining whether the predefined characteristic of the signal trajectory fulfills a second criterion, and

if the predefined characteristic of the signal trajectory fulfills the second criterion but not the first criterion, altering the signal trajectory to run farther from the constellation origin.

5. The method of claim 3,

wherein, for the predefined characteristic of the signal trajectory comprising the relative phase angle, the criterion comprises a phase angle threshold, and the method comprises altering the signal trajectory to run closer to the constellation origin if the relative phase angle exceeds a phase angle threshold;

and

wherein, for the predefined characteristic of the signal trajectory comprising the momentary frequency, the criterion comprises a frequency threshold, and the method comprises altering the signal trajectory to run closer to the constellation origin if the momentary frequency exceeds a frequency threshold.

6. The method of claim 3, wherein, for the predefined characteristic of the signal trajectory comprising the relative phase angle, the criterion comprises a phase angle threshold, and the method comprises altering the signal trajectory to run closer to the constellation origin, if the relative phase angle is between a first phase angle threshold and a second phase angle threshold.

7. The method of claim 1, wherein altering the signal trajectory to run closer to the constellation origin comprises combining an enhancement pulse with at least one of the first symbol and the second symbol.

8. The method of claim 1, wherein the complex-valued signal comprises an I/Q-signal or a polar signal.

9. The method of claim 1, wherein altering the signal trajectory to run closer to the constellation origin comprises altering the signal trajectory to run through the constellation origin.

10. The method of claim 1, wherein altering the signal trajectory to run closer to the constellation origin comprises altering the signal trajectory to run closer to the constellation origin by a predetermined amount.

11. The method of claim 10, wherein the predetermined amount is set to process the modified complex-valued signal in accordance with the processing capabilities of a signal processing stage receiving the modified complex-valued signal.

12. The method of claim 4, further comprising altering the signal trajectory to run farther from the constellation origin to process the modified complex-valued signal in accordance with the processing capabilities of a signal processing stage receiving the modified complex-valued signal.

13. The method of claim 12, wherein the first criterion is selected, when altering the signal trajectory to run closer to or farther from the constellation origin, to have substantially the same error being introduced into the complex-valued signal.

14. The method of claim 1, wherein the complex-valued signal is based on an input signal to be transmitted via an antenna coupled to a transmitter, the method comprising:

outputting the modified complex-valued signal to the transmitter for generating a transmission signal.

15. A method for providing a transmit signal to be transmitted via an antenna of a mobile communication device, comprising:

receiving an input signal, the input signal comprising a complex-valued signal representing at least a first symbol and a second symbol;

modifying the complex-valued signal by determining a distance of a signal trajectory of the complex-valued signal from a constellation origin based on a relative phase angle between the first symbol and the second symbol, and combining an enhancement pulse with at least one of the first symbol and the second symbol for altering the signal trajectory to run closer to the constellation origin, if the relative phase angle is between a first threshold angle and a second threshold angle, and

based on the modified complex-valued signal, generating the transmit signal.

16. The method of claim 15, wherein the modified complex-valued signal is provided in polar coordinates, and wherein generating the transmit signal further comprises:

detecting, based on a phase value of the modified complex-valued signal, a frequency peak; and

in response to detecting the frequency peak, changing a sign of a radius value of the modified complex-valued signal.

17. The method of claim 15, wherein the complex-valued signal is provided as an I/Q-signal, and wherein the method further comprises transforming the modified I/Q-signal into polar coordinates and wherein generating the transmit signal further comprises:

detecting, based on a phase value of the modified complex-valued signal, a frequency peak; and

in response to detecting the frequency peak, changing a sign of a radius value of the modified complex-valued signal.

18. The method of claim 15, wherein the complex-valued signal is provided as a polar-coordinate signal.

19. An apparatus for modifying a complex-valued signal representing a first symbol and a second symbol, the apparatus comprising:

a signal processor, configured to determine a signal trajectory of the complex-valued signal between the first symbol and the second symbol, and, if the signal trajectory passes nearby the constellation origin, to alter the signal trajectory to run closer to the constellation origin.

20. An apparatus for providing a transmit signal to be transmitted by an antenna of a mobile communication device, the apparatus comprising:

an input for receiving an input signal, the input signal comprising a complex-valued signal represent at least a first symbol and a second symbol;

a signal processor configured to modify the complex-valued signal by determining a distance of a signal trajectory of the complex-valued signal from a constellation origin based on a relative phase angle between the first symbol and the second symbol, and combining an enhancement pulse with at least one of the first symbol and the second symbol for altering the signal trajectory to run closer to the constellation origin, and

an output stage configured to generate the transmit signal based on the modified complex-valued signal.

21. The apparatus of claim 20, wherein the complex-valued signal is provided as an I/Q-signal, and wherein the output stage comprises:

a transforming circuit configured to produce the modified complex-valued signal in polar coordinates, and

a peak detector configured to detect, based on a phase value of the modified complex-valued signal, a frequency peak, and to change a sign of a radius value of the modified complex-valued signal in response to detecting the frequency peak.

22. A mobile communication device comprising an apparatus for modifying a complex-valued signal representing a first symbol and a second symbol, the apparatus comprising:

a signal processor, configured to determine a signal trajectory of the complex-valued signal between the first symbol and the second symbol, and, if the signal trajectory passes nearby the constellation origin, alter the signal trajectory to run closer to the constellation origin.

23. A mobile communication device comprising an apparatus for providing a transmit signal to be transmitted by an antenna of a mobile communication device, the apparatus comprising:

an input for receiving an input signal, the input signal comprising a complex-valued signal represent at least a first symbol and a second symbol;

a signal processor configured to modify the complex-valued signal by determining a distance of a signal trajectory of the complex-valued signal from a constellation origin based on a relative phase angle between the first symbol and the second symbol, and combining an enhancement pulse with at least one of the first symbol and the second symbol to alter the signal trajectory to run closer to the constellation origin, and

an output stage configured to generate the transmit signal based on the modified complex-valued signal.