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

• US 20040162097A1
• Filed: 02/18/2003
• Published: 08/19/2004
• Est. Priority Date: 02/18/2003
• Status: Active Grant

• Current Assignee: Qualcomm, Inc.
• Original Assignee: Qualcomm, Inc.
• Inventors: Vijayan, Rajiv, Agrawal, Avneesh, Jha, Sanjay
• Granted Patent: US 8,422,434 B2
• Time in Patent Office: Days
• US Class Current: 455/522
• 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 the terminal; and

allocating to each terminal a specific number of carriers that is less than or equal to the maximum number of carriers determined for the terminal.

2. The method of claim 1, wherein the determining for each terminal includes

comparing the required transmit power for the terminal against maximum allowed powers for different numbers of carriers, and 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.

3. The method of claim 1, wherein the determining for each terminal includes

computing a difference between a maximum transmit power for the terminal and the required transmit power for the terminal, and wherein the maximum number of carriers that may be allocated to the terminal is determined based on the computed difference.

4. The method of claim 3, wherein the determining for each terminal further includes

comparing the computed difference against required back-offs for different numbers of carriers, and wherein the maximum number of carriers that may be allocated to the terminal is equal to the number of carriers associated with a largest required back-off that is smaller than the computed difference.

5. The method of claim 1, further comprising:

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

6. The method of claim 5, wherein a terminal associated with a higher required transmit power is assigned carriers located near the middle of an operating band and a terminal associated with a lower required transmit power is assigned carriers located near an edge of the operating band.

7. The method of claim 5, wherein the assigning specific carriers to each terminal includes

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

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

8. The method of claim 1, further comprising:

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

9. The method of claim 1, further comprising:

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

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

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

12. The method of claim 11, wherein the at least one additional factor includes a factor that relates to amount of data to transmit.

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

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

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

16. A method of allocating carriers to manage peak-to-average power ratio (PAPR) in a wireless communication system that implements orthogonal frequency division multiplexing (OFDM), 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 the terminal;

allocating to each terminal a specific number of carriers that is less than or equal to the maximum number of carriers determined for the terminal; and

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

17. 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 for the terminal; and

means for allocating to each terminal a specific number of carriers that is less than or equal to the maximum number of carriers determined for the terminal.

18. The apparatus of claim 17, further comprising:

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

19. The apparatus of claim 17, further comprising:

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

20. The apparatus of claim 17, further comprising:

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

21. 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 for the terminal, allocate to each terminal a specific number of carriers that is less than or equal to the maximum number of carriers determined for the terminal, and provide carrier assignments indicative of the specific number of carriers allocated to each terminal; and

a transmit data processor operative to process the carrier assignments for transmission to the plurality of terminals.

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

receiving an allocation of a specific number of carriers to be used for data transmission, wherein the specific number of carriers is less then 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 a required transmit power for the data transmission; and

transmitting data using the specific number of carriers.

23. The method of claim 22, wherein data is transmitted on specific carriers that have been assigned to reduce out-of-band emissions.

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

means for receiving an allocation of a specific number of carriers to be used for data transmission, wherein the specific number of carriers is less then 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 a required transmit power for the data transmission; and

means for transmitting data using the specific number of carriers.