APPARATUS AND METHOD FOR CLASSIFYING MODULATIONS IN MULTIPATH ENVIRONMENTS

• US 20100098193A1
• Filed: 03/16/2007
• Published: 04/22/2010
• Est. Priority Date: 03/16/2007
• Status: Active Grant

• Current Assignee: InterDigital Madison Patent Holdings (InterDigital, Inc.)
• Original Assignee: Thomson Licensing (Vantiva SA)
• Inventors: Liu, Peng, Zou, Li
• Granted Patent: US 8,385,473 B2
• Time in Patent Office: Days
• US Class Current: 375/340
• CPC Class Codes: H04L 27/0012 arrangements for identifying the type of modulation
• CPC Class Codes: H04L 27/2601 Multicarrier modulation systems

Abstract

A receiver supports a single carrier (SC) form of modulation and a multi-carrier form of modulation such as orthogonal frequency division multiplexing (OFDM). Upon receiving a signal, the receiver determines a maximum fluctuation range (MFR) as a function of at least a fourth-order cumulant of a received signal; and classifies a modulation type of the received signal as a function of the determined maximum fluctuation range. After determining the modulation type of the received signal, the receiver switches to that modulation mode to recover data from the received signal.

Claims

1. A method for use in a receiver, the method comprising:

determining a fluctuation range as a function of at least a fourth-order cumulant of a received signal; and

classifying a modulation type of the received signal as a function of the determined fluctuation range.

2. The method of claim 1, where the fluctuation range is a maximum fluctuation range (MFR).

3. The method of claim 1, wherein at least one modulation type is a single carrier form of modulation and another modulation type is a multi-carrier form of modulation.

4. The method of claim 3, wherein the multi-carrier form of modulation is orthogonal frequency division multiplexing.

5. The method of claim 3, wherein the single carrier form of modulation is at least one of binary phase shift keying, quadrature phase shift keying, 16 quadrature amplitude modulation, 64 quadrature amplitude modulation and 256 quadrature amplitude modulation.

6. The method of claim 1, further comprising the step of:

switching to the classified modulation type to recover data from the received signal.

7. The method of claim 1, wherein the determining step includes the steps of:

determining a second-order cumulant of the received signal;

determining a normalized fourth-order cumulant of the received signal from the second-order cumulant and the fourth-order cumulant; and

determining the fluctuation range from the normalized fourth-order cumulant of the received signal.

8. The method of claim 7, wherein the determining the fluctuation range from the normalized fourth-order cumulant of the received signal includes the step of:

filtering the normalized fourth-order cumulant of the received signal before determining the fluctuation range.

9. The method of claim 1, wherein the determining step includes the step of:

downconverting the received signal to base-band before determining the fluctuation range.

10. The method of claim 1, wherein the classifying step includes the steps of:

classifying the received signal as a multi-carrier form of modulation if the determined fluctuation range is less than a threshold value; and

classifying the received signal as a single carrier form of modulation if the determined fluctuation range is greater than a threshold value.

11. Apparatus comprising:

a demodulator for providing at least two demodulation modes for processing a received signal; and

a processor for determining a modulation type of the received signal as a function of at least a fourth-order cumulant of the received signal and for setting the demodulator to a corresponding one of the demodulation modes in accordance with the determined modulation type.

12. The apparatus of claim 11, further comprising:

a down converter for processing a received broadcast signal to provide the received signal.

13. The apparatus of claim 11, wherein the processor operates to (a) determine a maximum fluctuation range (MFR) as a function of the fourth-order cumulant of the received signal and (b) classify the modulation type of the received signal as a function of the determined maximum fluctuation range.

14. The apparatus of claim 13, wherein the processor classifies the received signal as a multi-carrier form of modulation if the determined maximum fluctuation range is less than a threshold value;

and classifies the received signal as a single carrier form of modulation if the determined maximum fluctuation range is greater than a threshold value.

15. The apparatus of claim 11, wherein the processor operates to (a) determine the fourth-order cumulant of the received signal, (b) determine a second-order cumulant of the received signal;

(c) determine a normalized fourth-order cumulant of the received signal from the second-order cumulant and the fourth-order cumulant, (d) determine a maximum fluctuation range (MFR) as a function of the normalized fourth-order cumulant of the received signal and (e) classify the modulation type of the received signal as a function of the determined maximum fluctuation range.

16. The apparatus of claim 15, wherein the processor classifies the received signal as a multi-carrier form of modulation if the determined maximum fluctuation range is less than a threshold value;

and classifies the received signal as a single carrier form of modulation if the determined maximum fluctuation range is greater than a threshold value.

17. The apparatus of claim 15, wherein the processor filters the normalized fourth-order cumulant of the received signal before determining the maximum fluctuation range.

18. The apparatus of claim 11, wherein at least one modulation type is a single carrier form of modulation and another modulation type is a multi-carrier form of modulation.

19. The apparatus of claim 18, wherein the multi-carrier form of modulation is orthogonal frequency division multiplexing.

20. The apparatus of claim 18, wherein the single carrier form of modulation is at least one of binary phase shift keying, quadrature phase shift keying, 16 quadrature amplitude modulation, 64 quadrature amplitude modulation and 256 quadrature amplitude modulation.

21. The apparatus of claim 11, wherein the processor operates to determine a maximum fluctuation range as a function of the fourth-order cumulant and classifies the received signal as a multi-carrier form of modulation if the determined maximum fluctuation range is less than a threshold value;

and classifies the received signal as a single carrier form of modulation if the determined maximum fluctuation range is greater than a threshold value.

22. The apparatus of claim 11, wherein the processor operates to (a) determine the fourth-order cumulant of the received signal, (b) determine a second-order cumulant of the received signal;

(c) determine a normalized fourth-order cumulant of the received signal from the second-order cumulant and the fourth-order cumulant, (d) determine a maximum fluctuation range (MFR) as a function of the normalized fourth-order cumulant of the received signal and (e) classify the received signal as a multi-carrier form of modulation if the determined maximum fluctuation range is less than a threshold value; and

classifies the received signal as a single carrier form of modulation if the determined maximum fluctuation range is greater than a threshold value.