Adaptive Power Control Data Transmission Systems and Methods

• US 20080254760A1
• Filed: 09/27/2006
• Published: 10/16/2008
• Est. Priority Date: 09/30/2005
• Status: Active Grant

• Current Assignee: Apple Inc.
• Original Assignee: Apple Inc.
• Inventors: Wu, Jianming, Tong, Wen, Zhu, Peiying
• Granted Patent: US 8,204,532 B2
• Time in Patent Office: Days
• US Class Current: 455/343.1
• CPC Class Codes: H04W 52/262 taking into account adaptive modulation and coding [AMC] scheme AMC per se H04L1/0001

Abstract

Systems and methods of performing power control in combination with AMC are provided. AMC is performed on the basis of an AMC parameter such as CINR. Once the AMC is set to a highest available AMC for transmission to a given receiver, if the CINR indicates that the highest AMC could be transmitted with less transmit power, the power is reduced. For receivers that are not receiving the highest available AMC for that receiver, they may have their transmit power increased.

Claims

1. A method comprising:

receiving a respective reported AMC (adaptive modulation and coding) parameter from each of a plurality of receivers;

decreasing a transmit power used to transmit to a given receiver of the plurality of receivers when the reported AMC parameter received from that receiver reflects better channel conditions than needed for a highest available AMC code set for that receiver.

2. The method of claim 1 further comprising:

increasing a transmit power used to transmit to a given receiver of the plurality of receivers when the reported AMC parameter received from that receiver is below an APC (adaptive power control) threshold for the receiver, subject to a transmission power cap for the given receiver.

3. The method of claim 1 further comprising:

determining an AMC code set to use for transmissions to each receiver based on the respective reported AMC parameter.

4. The method of claim 1 further comprising:

transmitting a composite signal for multiple receivers of said plurality of receivers, the composite signal containing a respective component for each of the multiple receivers, each component being transmitted with the transmit power determined for that receiver.

5. The method of claim 4 wherein each component is used to transmit a respective data packet or portion of a packet.

6. The method of claim 4 wherein the composite signal comprises an OFDM signal, and wherein each respective component comprises at least one sub-channel defined within the OFDM signal.

7. The method of claim 1 wherein the reported AMC parameter is a reported CINR (carrier to interference and noise ratio), and the method further comprising:

for each receiver, comparing the reported CINR to an AMC threshold for the receiver to determine whether the receiver has a reported AMC parameter reflecting better channel conditions than needed for the highest available AMC code set for that receiver.

8. The method of claim 2 further comprising:

setting the transmission power cap to be an equal value for a set of the receivers.

9. The method of claim 2 further comprising:

adaptively setting the transmission power cap for at least one receiver.

10. The method of claim 9 wherein adaptively setting the transmission power cap for at least one receiver comprises:

determining a value from received block error rate and/or channel variation and/or coverage information;

scaling the value determined so as to reflect how many receivers will be transmitted to during a given period to produce the transmission power cap.

11. The method of claim 9 wherein adaptively setting the transmission power cap for each receiver is performed subject to an overall maximum transmit power constraint for the receivers collectively.

12. A method comprising:

determining an AMC (adaptive modulation and coding) parameter for each of a plurality of transmitters;

sending a power control command to decrease a transmit power used to transmit by a given transmitter of the plurality of transmitters when the AMC parameter determined for that transmitter reflects better channel conditions than needed for a highest available AMC code set for that transmitter.

13. The method of claim 12 further comprising:

sending a power control command to increase a transmit power used to transmit by a given transmitter of the plurality of transmitters when the AMC parameter determined for that transmitter is below an APC (adaptive power control) threshold for the transmitter, subject to a transmission power cap for the given transmitter.

14. The method of claim 12 further comprising:

receiving a composite signal for multiple transmitters of said plurality of transmitters, the composite signal containing a respective component for each of the multiple transmitters added together over the air, each component being transmitted with the transmit power determined for that transmitter.

15. The method of claim 14 wherein each component is used to transmit a respective packet or portion of a packet.

16. The method of claim 15 wherein the composite signal comprises an OFDM signal, and wherein each respective component comprises at least one sub-channel defined within the OFDM signal.

17. The method of claim 12 wherein the determined AMC parameter is a CINR (carrier to interference and noise ratio), and the method further comprising:

for each transmitter, comparing the determined CINR to an AMC threshold for the transmitter to determine whether the transmitter has a AMC parameter reflecting better channel conditions than needed for the highest available AMC code set for the transmitter.

18. The method of claim 13 further comprising:

setting the transmission power cap to be an equal value for a set of the transmitters.

19. The method of claim 13 further comprising:

adaptively setting the transmission power cap for each transmitter.

20. A transmitter comprising:

an adaptive modulation and coder that performs adaptive modulation and coding using a selected AMC code set;

a first power controller that performs power control for transmissions as a function of a first AMC parameter to produce a power controlled signal;

at least one antenna for transmitting the power controlled signal.

21. A base station comprising the transmitter of claim 20 wherein:

an AMC (adaptive modulation and coding) parameter extraction and processing module for DL (downlink) that extracts the first AMC parameter as an AMC parameter for DL from a received signal and determines the selected AMC code set use in transmissions to a given receiver;

the first power controller is a DL power controller that performs DL power control for downlink transmissions as a function of the AMC parameter for DL to produce the power controlled signal.

22. The base station of claim 21 further comprising:

an AMC parameter determination module for UL (uplink) that determines an AMC parameter for UL in respect of a received signal; and

a UL power controller that performs UL power control as a function of the AMC parameter for UL;

wherein the at least one antenna is used for receiving the received signal and transmitting the power controlled signal.

23. The base station of claim 22 wherein:

the DL power controller performs DL power control for downlink transmissions as a function of the AMC parameter for DL by;

a) decreasing a transmit power used to transmit to a given receiver of the plurality of receivers when the reported AMC parameter for DL received from that receiver reflects better channel conditions than needed for a highest available AMC code set for the receiver; and

b) increasing a transmit power used to transmit to a given receiver of the plurality of receivers when the reported AMC parameter for DL received from that receiver is below an APC (adaptive power control) threshold for the receiver, subject to a transmission power cap for the given receiver;

the UL power controller power control performs UL power control as a function of the AMC parameter for UL by;

c) sending a power control command to decrease a transmit power used to transmit by a given transmitter of the plurality of transmitters when the AMC parameter for UL determined for that transmitter reflects better channel conditions than needed for a highest available AMC code set for the transmitter; and

d) sending a power control command to increase a transmit power used to transmit by a given transmitter of the plurality of transmitters when the AMC parameter for UL determined for that transmitter is below an APC (adaptive power control) threshold for the transmitter, subject to a transmission power cap for the given transmitter.

24. A mobile station comprising the transmitter of claim 20 further comprising:

an AMC parameter determination module for DL that determines an AMC parameter for DL in respect of a received signal and sends this to a base station;

the mobile station further comprising;

a power control and AMC command extraction and processing module that extracts AMC commands and power control commands from the received signal;

an adaptive modulation and coder that performs adaptive modulation and coding using a code set identified by the AMC command;

wherein the first power controller is a UL power controller that performs power control using the power control commands to produce the power controlled signal;

wherein the at least one antenna is used for receiving the received signal and transmitting the power controlled signal.