Granted Patent B2

US 7,778,347 · App. 11/465,976 · Granted Aug 17, 2010

Abstract

Claims (48)

1. A method for power de-rating reduction in a transmitter of a wireless communication device, comprising:

mapping N first samples of a first discrete Fourier transform (DFT) of a group of coded symbols to M sub-carriers according to a first predetermined sub-carrier mapping rule, where M is greater than N;

performing a first inverse DFT (IDFT) on the M sub-carriers to provide M second samples;

clipping the M second samples according to a clipping rule to provide M third samples;

performing a second DFT on the M third samples;

de-mapping, following the second DFT, the M third samples to N fourth samples; and

mapping the N fourth samples to O sub-carriers according to a predetermined second sub-carrier mapping rule, where O is greater than or equal to M, wherein a peak of a respective one of the M second samples is clipped when the peak of the respective one of the M second samples is above a high threshold, and wherein a null of a respective one of the M second samples is clipped when a null of the respective one of the M second samples is below a low threshold.

2. The method of claim 1 , further comprising:

performing the first DFT on the group of coded symbols to provide the N first samples;

performing a second IDFT on the O sub-carriers to provide O fifth samples; and

adding a cyclic prefix to the fifth samples.

3. The method of claim 1 , further comprising:

clipping only the M second samples that are greater than a predetermined threshold.

4. The method of claim 1 , further comprising:

clipping only the M second samples that are less than a predetermined threshold.

5. The method of claim 1 , wherein the transmitter is an uplink transmitter that utilizes a single carrier-frequency division multiple access (SC-FDMA) transmission scheme.

6. The method of claim 5 , wherein the uplink transmitter implements one of a phase shift keying (PSK) or a quadrature amplitude modulation (QAM) data modulation scheme.

7. The method of claim 1 , wherein the first IDFT predicts a time-domain signal and the second DFT smoothes clipping noise.

8. The method of claim 1 , wherein the clipping rule reduces a peak-to-null ratio of a clipped one of the M second samples.

9. A communication device, comprising:

an input device; and

a processor coupled to the input device to receive samples, wherein the processor is programmed to:

map N first samples of a first discrete Fourier transform (DFT) of a group of coded symbols to M sub-carriers according to a first sub-carrier mapping rule, where M is greater than N;

perform a first inverse DFT (IDFT) on the M sub-carriers to provide M second samples;

clip the M second samples according to a clipping rule to provide M third samples;

perform a second DFT on the M third samples;

de-map, following the second DFT, the M third samples to N fourth samples; and

map the N fourth samples to O sub-carriers according to a predetermined second sub-carrier mapping rule, where O is greater than or equal to M, wherein a peak of a respective one of the M second samples is clipped when the peak of the respective one of the M second samples is above a high threshold, and wherein a null of a respective one of the M second samples is clipped when a null of the respective one of the M second samples is below a low threshold.

10. The communication device of claim 9 , wherein the processor is further programmed to:

perform the first DFT on the group of coded symbols to provide the N first samples;

perform a second IDFT on the O sub-carriers to provide O fifth samples;

add a cyclic prefix to the fifth samples to provide a discrete time-domain signal for transmission; and

convert the discrete time-domain signal to an analog signal for transmission.

11. The communication device of claim 10 , wherein the communication device utilizes a single carrier-frequency division multiple access (SC-FDMA) transmission scheme for transmission of the analog signal.

12. The communication device of claim 11 , wherein the communication device implements one of a phase shift keying (PSK) or a quadrature amplitude modulation (QAM) data modulation scheme.

13. The communication device of claim 9 , wherein the clipping rule reduces a peak-to-null ratio of a clipped one of the M second samples.

14. A system comprising:

a transmitter configured to transmit signals, wherein the transmitter includes:

a mapping module that maps N first samples of a first discrete Fourier transform (DFT) of a group of coded symbols to M sub-carriers according to a first predetermined sub-carrier mapping rule, where M is greater than N;

a first transform module that performs a first inverse DFT (IDFT) on the M sub-carriers to provide M second samples;

a clipping module that clips the M second samples according to a clipping rule to provide M third samples;

a second transform module that performs a second DFT on the M third samples;

a de-mapping module that de-maps, following the second DFT, the M third samples to N fourth samples; and

a second mapping module that maps the N fourth samples to O sub-carriers according to a predetermined second sub-carrier mapping rule, where O is greater than or equal to M, wherein a peak of a respective one of the M second samples is clipped when the peak of the respective one of the M second samples is above a high threshold, and wherein a null of a respective one of the M second samples is clipped when a null of the respective one of the M second samples is below a low threshold.

15. The system of claim 14 , wherein the transmitter is further configured to:

perform the first DFT on the group of coded symbols to provide the N first samples;

perform a second IDFT on the O sub-carriers to provide O fifth samples; and

add a cyclic prefix to the fifth samples.

Assignments (22)