Fast fading power restriction

Patent metadata

Field	Value
Publication number	US-9961644-B2
Application number	US-201414760584-A
Country	US
Kind code	B2
Filing date	Jan 20, 2014
Priority date	Jan 18, 2013
Publication date	May 1, 2018
Grant date	May 1, 2018

Abstract

The present application discloses methods and apparatus for modifying a normal link adaptation process of a wireless device ( 200 ). The normal link adaptation process may be used to compensate for a fast fading dip detected by a base station ( 100 ). The present application teaches that the normal fast fading compensation may cause inter-cell interference and degrade system performance. The present application discloses imposing a fast fading restriction or limitation on the normal fast fading compensation can reduce inter-cell interference, improve system capacity, and extends the battery life of the wireless device.

First claim

What is claimed is:

1. A method, implemented at a wireless device, for modifying a link adaption process for an uplink transmission from the wireless device, the method comprising:
determining a slot transmit power for transmitting a radio signal on a radio channel;
calculating an average transmit power;
deriving a data rate based on a comparison of the slot transmit power and the average transmit power; wherein the deriving comprises:
determining a normal data rate that does not compensate for fast fading;
computing a ratio of the slot transmit power to the average transmit power;
computing a rate correction factor based on the ratio; and
modifying the normal data rate using the rate correction factor when the ratio is larger than a threshold; and

transmitting a data packet in accordance with the derived data rate.

2. The method of claim 1 , wherein the data packet is transmitted on an uplink Dedicated Physical Control Channel (DPCCH).

3. The method of claim 1 , wherein the modified data rate, if smaller than a minimum data rate, is set to the minimum data rate.

4. The method of claim 1 , wherein computing the rate correction factor comprises:
receiving a scaling factor from a base station for scaling the ratio of a transmit power to the average transmit power; and
computing the rate correction factor by scaling the ratio by the scaling factor.

5. The method of claim 4 , wherein the correction factor compensates for fast fading experienced by the wireless device.

6. A wireless device configured to modify a link adaptation process for an uplink transmission from the wireless device, the wireless device comprising:
a transceiver for receiving and transmitting signals; and
a processing circuit for modifying the link adaptation process, the processing circuit configured to:
determine a slot transmit power for transmitting a radio signal on a radio channel;
calculate an average transmit power;
derive a data rate based on a comparison of the slot transmit power and the average transmit power by:
determining a normal data rate that does not compensate for fast fading
computing a ratio of the slot transmit power to the average transmit power;
computing a rate correction factor based on the ratio; and
modifying the normal data rate using the rate correction factor when the ratio is larger than a threshold; and

cause the transceiver to transmit a data packet in accordance with the derived data rate.

7. The wireless device of claim 6 , wherein the data packet is transmitted on an uplink Dedicated Physical Control Channel (DPCCH).

8. The wireless device of claim 6 , wherein the modified data rate, if smaller than a minimum data rate, is set to the minimum data rate.

9. A method for controlling a modified link adaptation process of a wireless device, the method comprising:
determining one or more controlling parameters for the wireless device, wherein the one or more controlling parameters comprise a factor for scaling at the wireless device a ratio of a slot transmit power to an average transmit power, wherein the factor restricts the amount of modification the wireless device can modify a normal transmission parameter; and
transmitting the one or more controlling parameters to the wireless device to control the modified link adaptation process at the wireless device.

10. The method of claim 9 , wherein the one or more transmission parameters are transmitted to the wireless device via Radio Resource Control (RRC) signaling or broadcasting.

11. The method of claim 9 , wherein the factor restricts the amount of modification the wireless device can modify the normal transmission parameter by scaling the ratio to calculate a power correction factor that restricts modification of a transmit power level at the wireless device.

12. The method of claim 9 , wherein the factor restricts the amount of modification the wireless device can modify the normal transmission parameter by scaling the ratio to calculate a rate correction factor that restricts modification of a data rate at the wireless device.

13. The method of claim 9 , wherein the controlling parameters further comprise at least two factors for scaling at the wireless device a respective ratio of the slot transmit power to the average transmit power, the two factors used to modify at the wireless device a data rate and a transmit power level, respectively.

14. A base station configured to control a modified link adaptation process at a wireless device, the base station comprising:
a transceiver for transmitting data and control signals to the wireless device; and
a processing circuit configured to:
determine one or more controlling parameters, wherein the one or more controlling parameters comprise a factor for scaling at the wireless device a ratio of a slot transmit power to an average transmit power, wherein the factor restricts the amount of modification the wireless device can modify a normal transmission parameter; and
cause the transceiver to transmit the one or more controlling parameters to control the modified link adaption process at the wireless device.

15. The base station of claim 14 , wherein the one or more transmission parameters are transmitted to the wireless device via signaling.

Assignees

• Ericsson Telefon Ab L M

Inventors

• Karlsson Patrik
• Hogan Billy
• Kwong Waikwok

Classifications

• H04L5/0073

  Allocation arrangements that take into account other cell interferences · CPC title

• H04W52/146

  Uplink power control · CPC title

• H04W52/12 Primary

  Outer and inner loops · CPC title

• H04W52/225

  Calculation of statistics, e.g. average or variance · CPC title

• H04W52/367

  Power values between minimum and maximum limits, e.g. dynamic range · CPC title