Peak-to-average power ratio management for multi-carrier modulation in wireless communication systems

• US 8,811,973 B2
• Filed: 07/10/2008
• Issued: 08/19/2014
• Est. Priority Date: 02/18/2003
• Status: Active Grant

• Current Assignee: Qualcomm, Inc.
• Original Assignee: Qualcomm, Inc.
• Inventors: Vijayan, Rajiv, Agrawal, Avneesh, Jha, Sanjay
• Primary Examiner(s): West, Lewis
• Assistant Examiner(s): Chan, Richard
• Application Number:
  US12/170,560
• Publication Number:
  US 20090040975A1
• Time in Patent Office: 2,231 Days
• Field of Search: 455/329, 455/522, 455/69, 455/450, 455/63.1, 455/407
• US Class Current: 455/422.1
• CPC Class Codes: H04L 27/2614 Peak power aspects
• CPC Class Codes: H04L 5/0007 the frequencies being orthogonal, e.g. OFDM(A), DMT
• CPC Class Codes: H04L 5/0037 Inter-user or inter-terminal allocation
• CPC Class Codes: H04L 5/0066 Requirements on out-of-channel emissions
• CPC Class Codes: H04W 52/343 taking into account loading or congestion level
• CPC Class Codes: H04W 52/367 Power values between minimum and maximum limits, e.g. dynamic range
• CPC Class Codes: H04W 72/0453 Resources in frequency domain, e.g. a carrier in FDMA

Abstract

Techniques for managing peak-to-average power ratio (PAPR) for multi-carrier modulation in wireless communication systems. Different terminals in a multiple-access system may have different required transmit powers. The number of carriers to allocate to each terminal is made dependent on its required transmit power. Terminals with higher required transmit powers may be allocated fewer carriers (associated with smaller PAPR) to allow the power amplifier to operate at higher power levels. Terminals with lower required transmit powers may be allocated more carriers (associated with higher PAPR) since the power amplifier is operated at lower power levels. The specific carriers to assign to the terminals may also be determined by their transmit power levels to reduce out-of-band emissions. Terminals with higher required transmit powers may be assigned with carriers near the middle of the operating band, and terminals with lower required transmit powers may be assigned with carriers near the band edges.

Claims

1. A method of managing peak-to-average power ratio (PAPR) for multi-carrier modulation in a wireless multi-carrier communication system, comprising:

determining a maximum number of carriers that may be allocated to each terminal in a plurality of terminals based on a required transmit power for said each terminal;

wherein the determining comprises comparing the required transmit power for said each terminal against a plurality of maximum allowed powers associated with a corresponding plurality of numbers of carriers, wherein the maximum number of carriers that may be allocated to said each terminal is equal to the number of carriers associated with a smallest maximum allowed power that is higher than the required transmit power; and

allocating multiple carriers to a specific terminal that is capable of multi-carrier modulation, wherein a specific number of the multiple carriers is less than or equal to the maximum number of carriers determined for the specific terminal.

2. The method of claim 1, further comprising:

assigning specific carriers to said each terminal in a manner to reduce out-of-band emissions.

3. The method of claim 2, wherein a first terminal associated with a higher required transmit power is assigned carriers located near the middle of an operating band and a second terminal associated with a lower required transmit power is assigned carriers located near an edge of the operating band.

4. The method of claim 2, wherein the assigning specific carriers to said each terminal includes

determining a set of carriers that can be assigned to said each terminal based on the required transmit power for said each terminal, and

selecting the specific carriers to assign to said each terminal from the set of carriers.

5. The method of claim 1, further comprising:

transmitting data for said each terminal on the specific number of carriers allocated to the terminal and at the required transmit power for said each terminal.

6. The method of claim 1, further comprising:

receiving a data transmission from said each terminal on the specific number of carriers allocated to said each terminal.

7. The method of claim 1, wherein the specific number of carriers allocated to said each terminal is further based on a total number of carriers available for allocation to the plurality of terminals.

8. The method of claim 1, wherein the specific number of carriers allocated to said each terminal is further based on at least one additional factor.

9. The method of claim 8, wherein the at least one additional factor includes a factor that relates to amount of data to transmit.

10. The method of claim 1, wherein the required transmit power for said each terminal is determined based on a required received signal quality for said each terminal.

11. The method of claim 1, wherein the required transmit power for said each terminal is determined based on a power control loop maintained for said each terminal.

12. The method of claim 1, wherein the wireless communication system implements orthogonal frequency division multiplexing (OFDM).

24. The method of claim 1, further comprising:

selecting from the corresponding plurality of numbers of carriers the number of carriers associated with the smallest maximum allowed power that is higher than the required transmit power for the specific terminal as the maximum number of carriers that may be allocated to the specific terminal.

13. An apparatus in a wireless multi-carrier communication system, comprising:

means for determining a maximum number of carriers that may be allocated to each terminal in a plurality of terminals based on a required transmit power of said each terminal;

wherein the means for determining comprises means for comparing the required transmit power of said each terminal against a plurality of maximum allowed powers associated with a corresponding plurality of numbers of carriers, wherein the maximum number of carriers that may be allocated to said each terminal is equal to the number of carriers associated with a smallest maximum allowed power that is higher than the required transmit power; and

means for allocating multiple carriers to a specific terminal that is capable of multi-carrier modulation, wherein a specific number of the multiple carriers is less than or equal to the maximum number of carriers determined for the specific terminal.

14. The apparatus of claim 13, further comprising:

means for assigning specific carriers to said each terminal in a manner to reduce out-of-band emissions.

15. The apparatus of claim 13, further comprising:

means for receiving a data transmission from said each terminal on the specific number of carriers allocated to said each terminal.

16. The apparatus of claim 13, further comprising:

means for transmitting data to said each terminal on the specific number of carriers allocated to said each terminal and at the required transmit power for said each terminal.

17. An access point in a wireless multi-carrier communication system, comprising:

a scheduler operative to determine a maximum number of carriers that may be allocated to each terminal in a plurality of terminals based on a required transmit power of said each terminal based on comparison of the required transmit power of said each terminal against a plurality of maximum allowed powers associated with a corresponding plurality of numbers of carriers, wherein the maximum number of carriers that may be allocated to said each terminal is equal to the number of carriers associated with a smallest maximum allowed power that is higher than the required transmit power, to allocate multiple carriers to a specific terminal that is capable of multi-carrier modulation, wherein a specific number of the multiple carriers is less than or equal to the maximum number of carriers determined for the specific terminal, and to provide carrier assignments indicative of the specific number of carriers allocated to the specific terminal; and

a transmit data processor operative to process the carrier assignments for transmission to the specific terminal.

18. A method of transmitting data using multi-carrier modulation in a wireless communication system, comprising:

receiving an allocation of multiple carriers to be used for data transmission by a terminal that is capable of multi-carrier modulation, wherein a specific number of the multiple carriers is less than or equal to a maximum number of carriers that may be used for data transmission, and wherein the maximum number of carriers is determined based on comparing a required transmit power for the terminal against a plurality of maximum allowed powers associated with a corresponding plurality of numbers of carriers, wherein the maximum number of carriers that may be allocated to the terminal is equal to the number of carriers associated with a smallest maximum allowed power that is higher than the required transmit power; and

transmitting data using the specific number of carriers.

19. The method of claim 18, wherein data is transmitted on specific carriers that have been assigned to reduce out-of-band emissions.

20. An apparatus in a wireless multi-carrier communication system, comprising:

means for receiving an allocation of multiple carriers to be used for data transmission by a terminal that is capable of multi-carrier modulation, wherein a specific number of the multiple carriers is less than or equal to a maximum number of carriers that may be used for data transmission, and wherein the maximum number of carriers is determined based on comparing a required transmit power for the terminal against a plurality of maximum allowed powers associated with a corresponding plurality of numbers of carriers, wherein the maximum number of carriers that may be allocated to the terminal is equal to the number of carriers associated with a smallest maximum allowed power that is higher than the required transmit power; and

means for transmitting data using the specific number of carriers.

21. A non-transitory computer-readable medium, comprising:

code for causing a computer to;

determine a maximum number of carriers that may be allocated to each terminal in a plurality of terminals based on a required transmit power of said each terminal;

wherein the code for causing the computer to determine comprises code to compare the required transmit power of said each terminal against a plurality of maximum allowed powers associated with a corresponding plurality of numbers of carriers, wherein the maximum number of carriers that may be allocated to said each terminal is equal to the number of carriers associated with a smallest maximum allowed power that is higher than the required transmit power; and

allocate multiple carriers to a specific terminal that is capable of multi-carrier modulation, wherein a specific number of the multiple carriers is less than or equal to the maximum number of carriers determined for the specific terminal.

22. A non-transitory computer-readable medium, comprising:

code for causing a computer to;

receive an allocation of multiple carriers to be used for data transmission by a terminal that is capable of multi-carrier modulation, wherein a specific number of the multiple carriers is less than or equal to a maximum number of carriers that may be used for data transmission, and wherein the maximum number of carriers is determined based on comparing a required transmit power for the terminal against a plurality of maximum allowed powers associated with a corresponding plurality of numbers of carriers, wherein the maximum number of carriers that may be allocated to the terminal is equal to the number of carriers associated with a smallest maximum allowed power that is higher than the required transmit power; and

transmit data using the specific number of carriers.

23. An apparatus for use in a wireless communication system, comprising:

a receiver configured to receive an allocation of multiple carriers to be used for data transmission by a terminal that is capable of multi-carrier modulation, wherein a specific number of the multiple carriers is less than or equal to a maximum number of carriers that may be used for data transmission, and wherein the maximum number of carriers is determined based on comparing a required transmit power for the terminal against a plurality of maximum allowed powers associated with a corresponding plurality of numbers of carriers, wherein the maximum number of carriers that may be allocated to the terminal is equal to the number of carriers associated with a smallest maximum allowed power that is higher than the required transmit power; and

a transmitter configured to transmit data using the specific number of carriers.