System and method for closed loop uplink power control

Patent metadata

Field	Value
Publication number	US-10694468-B2
Application number	US-201815975922-A
Country	US
Kind code	B2
Filing date	May 10, 2018
Priority date	Feb 23, 2016
Publication date	Jun 23, 2020
Grant date	Jun 23, 2020

Abstract

Systems and methods are disclosed that provide a closed loop power control system including adaptively adjusting the desired target SINR over time so as to ultimately achieve a feasible SINR. In one implementation, a method is provided of optimizing uplink closed loop power control in a RAN in which one or more base stations each service a plurality of mobile stations, including: determining a power level for each mobile station for its respective uplink transmissions, including measuring a current achieved SINR for each mobile station; and for each mobile station, adjusting the power level to be sufficiently high to meet desired transmission characteristics but not so high as to cause unnecessary interference with transmissions from other mobile stations, by adjusting a desired target SINR based on factors selected from the following: current and prior achieved SINRs, current and prior interference measurements, and current and prior transmission power control commands.

First claim

The invention claimed is:

1. A method of optimizing uplink closed loop power control in a Radio Access Network (RAN) in which one or more base stations each service a plurality of mobile stations, the method comprising the steps of:
at each base station, for each mobile station connected to the base station, determining a transmit power level for the mobile station's uplink transmissions, wherein the determining of the transmit power level comprises measuring a current achieved signal to interference plus noise ratio (SINR) for each mobile station and wherein each mobile station has a desired target SINR;
updating the desired target SINR for each mobile station based on the current achieved SINR and prior SINR measurements to obtain a current desired target SINR; and
for each mobile station, adjusting the transmit power level by sending a transmission power control (TPC) command to the mobile station based on a difference between the current desired target SINR and the current achieved SINR,
wherein the desired target SINR is adaptively adjusted over time to ultimately approach a target SINR that is feasible.

2. The method of claim 1 , wherein the adjusting the transmit power level further comprises mapping the difference to a nearest entry in a set of possible TPC values.

3. The method of claim 1 , further comprising determining if the desired target SINR is feasible.

4. The method of claim 1 , further comprising determining if one or more mobile stations are progressing towards their desired target SINR.

5. The method of claim 1 , further comprising determining if a rise in a measured interference level over a prior duration exceeds a threshold, and if so, maintaining the desired target SINR, whereby situations may be identified when interference rises but it is undesired to reduce the desired target SINR.

6. The method of claim 1 , further comprising providing a lower bound on the desired target SINR, wherein the lower bound is a SINR value required to support reliable communication with a lowest possible modulation and coding rate combination.

7. The method of claim 1 , further comprising determining if the current achieved SINR is close to the desired target SINR, or if the transmit power level of the mobile station exceeds a certain threshold, and if one or both conditions are met, then sending a TPC command to the mobile station to instruct the mobile station to reduce its transmit power, whereby the transmit power level of the mobile station may be reduced when feasible without impacting performance of a link.

8. The method of claim 7 , wherein the current achieved SINR is determined to be close to the desired target SINR if the magnitude of their difference is lower than the smallest possible magnitude of a nonzero value TPC command.

9. The method of claim 1 , further comprising resetting the desired target SINR to a higher value, and transmitting a TPC command to a mobile station to cause its power level to increase, if determined interference levels are determined to have been reduced beyond a threshold level.

10. The method of claim 1 , further comprising periodically or occasionally resetting the desired target SINR to a value exceeding the current achieved SINR by a differential amount, whereby problems associated with increasing the desired target SINR based on a decrease in measured interference are substantially or wholly avoided.

11. The method of claim 10 , wherein the differential amount is a constant parameter or is a function of the current achieved SINR.

12. The method of claim 1 , further comprising providing an upper bound on the desired target SINR, wherein the upper bound is a SINR required to support a largest modulation and coding rate combination, or wherein the upper bound is adaptive over time and based on a largest anticipated modulation and coding parameter that would be used, given payload information.

13. A node for optimizing uplink closed loop power control in a Radio Access Network (RAN) in which one or more base stations each service a plurality of mobile stations, the node configured to:
at each base station, for each mobile station connected to the base station, determine a transmit power level for the mobile station's uplink transmissions, wherein the node is configured to determine the transmit power level by being configured to measure a current achieved signal to interference plus noise ratio (SINR) for each mobile station, and wherein each mobile station has a desired target SINR;
update the desired target SINR for each mobile station based on the current achieved SINR and prior SINR measurements to obtain a current desired target SINR; and
for each mobile station, adjust the transmit power level by sending a transmission power control (TPC) command to the mobile station based on a difference between the current desired target SINR and the current achieved SINR,
wherein the node is configured to adaptively adjust the desired target SINR over time to ultimately approach a target SINR that is feasible.

14. The node of claim 13 , wherein the node is configured to determine the desired target SINR at a current time when:
a TPC command sent at a prior time instructs a mobile station to increase its transmit power, and an achieved SINR at the current time does not exceed the achieved SINR at the prior time by a first threshold; and
an interference level measured at the current time exceeds an interference level measured at the prior time by a second threshold,
wherein the node is configured to determine the desired target SINR at the current time by being configured to reduce the desired target SINR at the prior time by an amount that is a function of a difference between the desired target SINR at the prior time and the achieved SINR at the current time.

15. The node of claim 13 , wherein the node is further configured to map the difference to a nearest entry in a set of possible TPC values.

16. The node of claim 13 , wherein the node is further configured to determine if the desired target SINR is feasible.

17. The node of claim 13 , wherein the node is further configured to determine if one or more mobile stations are progressing towards their desired target SINR.

18. The node of claim 13 , wherein the node is further configured to determine if a rise in a measured interference level over a prior duration exceeds a threshold, and if so, the node being configured to maintain the desired target SINR, whereby situations may be identified when interference rises but it is undesired to reduce the desired target SINR.

19. The node of claim 13 , wherein the node is further configured provide a lower bound on the desired target SINR, wherein the lower bound is a SINR value required to support reliable communication with a lowest possible modulation and coding rate combination.

20. The node of claim 13 , wherein the node is further configured to determine if the current achieved SINR is close to the desired target SINR, or if the mobile station transmit power level exceeds a certain threshold, and if one or both conditions are met, then the node being configured to send a TPC command to the mobile station to instruct the mobile station to reduce its transmit power, whereby the transmit power level of the mobile station may be reduced when feasible without impacting performance of a link.

21. The node of claim 20 , wherein the current achieved SINR is determined to be close to the desired target SINR if the magnitude of their difference is lower than the smallest po

Assignees

• Corning Optical Communications LLC

Inventors

• Dunn Brian
• Nama Hithesh
• Pinagapany Srinivas
• Singh Jaspreet

Classifications

• H04W52/146

  Uplink power control · CPC title

• H04W52/08 Primary

  Closed loop power control · CPC title

• H04W52/367

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

• H04W52/241

  taking into account channel quality metrics, e.g. SIR, SNR, CIR or Eb/lo · CPC title

• H04W52/221

  using past power control commands · CPC title