Automatic power control in uncoordinated frequency-hopping radio systems

• US 6,519,236 B1
• Filed: 09/18/1998
• Issued: 02/11/2003
• Est. Priority Date: 09/18/1998
• Status: Expired due to Term

• Current Assignee: Unwired Planet LLC (JP Morgan Chase & Co)
• Original Assignee: Telefonaktiebolaget LM Ericsson
• Inventors: Haartsen, Jacobus Cornelis, Mattisson, Sven
• Primary Examiner(s): Marcelo, Melvin
• Assistant Examiner(s): MEHRA, INDER P
• Application Number:
  US09/156,695
• Time in Patent Office: 1,607 Days
• Field of Search: 370/328, 370/331, 370/332, 370/349, 370/252, 375/102, 375/130, 375/132, 455/69, 455/522, 455/422, 455/67.1, 455/70, 455/127, 455/226.1, 455/225.2, 455/226.3, 455/296
• US Class Current: 370/332
• CPC Class Codes: H04W 52/367 Power values between minimum and maximum limits, e.g. dynamic range
• CPC Class Codes: H04W 52/42 in systems with time, space, frequency or polarisation diversity

Abstract

Transmission power in a frequency-hopping radio system that transmits packets from a sending radio unit to a receiving radio unit, wherein each packet includes an address designating the receiving radio unit, is controlled by measuring received signal strength of packets whose addresses were successfully received in the receiving radio unit, regardless of whether other portions of the respective packets were successfully received. An average signal strength value is generated from the received signal strength measurements. The mathematical difference between the average signal strength value and a target value associated with the receiving radio unit is then determined and used as a basis for deciding whether to send a power control message from the receiving radio unit to the sending radio unit. In order to provide a hysteresis in the power control process, a power control message is sent from the receiving radio unit to the sending radio unit if the mathematical difference is greater than a first decision boundary, or if the mathematical difference is less than a second decision boundary. The power control message may itself include the mathematical difference which, when received by the sending radio unit, is used as a basis for determining a transmission power level adjustment amount. The target value, against which the average signal strength value is compared, may be based on the receiver sensitivity adjusted to account for implementation losses and other inaccuracies.

Claims

1. A method of controlling transmission power in a frequency-hopping radio system that transmits packets from a sending radio unit to a receiving radio unit, wherein each packet includes an address designating the receiving radio unit, the method comprising the steps of:

measuring received signal strength of packets whose addresses were successfully received in the receiving radio unit, regardless of whether other portions of the respective packets were successfully received;

generating an average signal strength value from the received signal strength measurements;

determining a mathematical difference between the average signal strength value and a target value associated with the receiving radio unit; and

using the mathematical difference as a basis for deciding whether to send a power control message from the receiving radio unit to the sending radio unit.

2. The method of claim 1, wherein the step of using the mathematical difference as a basis for deciding whether to send a power control message from the receiving radio unit to the sending radio unit comprises the steps of:

sending a power control message from the receiving radio unit to the sending radio unit if the mathematical difference is greater than a first decision boundary; and

sending the power control message from the receiving radio unit to the sending radio unit if the mathematical difference is less than a second decision boundary.

3. The method of claim 1, wherein the power control message includes the mathematical difference.

4. The method of claim 3, further comprising the steps of:

receiving the power control message in the sending radio unit; and

adjusting a transmission power level in the sending radio unit by an amount based on the mathematical difference.

5. The method of claim 4, wherein the step of adjusting the transmission power level in the sending radio unit by an amount based on the mathematical difference comprises:

determining whether the amount based on the mathematical difference would cause an adjusted transmission power level to exceed a predefined maximum transmission power level;

if the amount based on the mathematical difference would cause the adjusted transmission power level to exceed the predefined maximum transmission power level, then adjusting the transmission power level in the sending radio unit to be no more than the predefined maximum transmission power level.

6. The method of claim 5, further comprising the step of:

sending a control message from the sending radio unit to the receiving radio unit informing that a maximum transmission power level has been reached.

7. The method of claim 6, further comprising the step of:

in the receiving radio unit, in response to the control message from the sending radio unit informing that a maximum transmission power level has been reached, sending no further power control messages to the sending radio unit that instruct the sending radio unit to further increase its transmission power level.

8. The method of claim 4, wherein the step of adjusting the transmission power level in the sending radio unit by an amount based on the mathematical difference comprises:

determining whether the amount based on the mathematical difference would cause an adjusted transmission power level to fall below a predefined minimum transmission power level;

if the amount based on the mathematical difference would cause the adjusted transmission power level to fall below the predefined minimum transmission power level, then adjusting the transmission power level in the sending radio unit to be no less than the predefined minimum transmission power level.

9. The method of claim 8, further comprising the step of:

sending a control message from the sending radio unit to the receiving radio unit informing that a minimum transmission power level has been reached.

10. The method of claim 9, further comprising the step of:

in the receiving radio unit, in response to the control message from the sending radio unit informing that a minimum transmission power level has been reached, sending no further power control messages to the sending radio unit that instruct the sending radio unit to further decrease its transmission power level.

11. The method of claim 1, wherein the target value associated with the receiving radio unit is based on the receiver sensitivity.

12. The method of claim 1, wherein the target value associated with the receiving radio unit is based on the receiver sensitivity adjusted to account for implementation losses and other inaccuracies.

13. The method of claim 1, wherein the step of generating the average signal strength value from the received signal strength measurements comprises the step of:

averaging signal strength values from the received signal strength measurements over a period of time extending over at least two frequency hops.

14. The method of claim 1, further comprising the step of:

when it is decided to send the power control message from the receiving radio unit to the sending radio unit, sending the power control message on a control channel established between the receiving radio unit and the sending radio unit.

15. The method of claim 1, further comprising the step of:

when it is decided to send the power control message from the receiving radio unit to the sending radio unit, including the power control message in a return packet that is transmitted from the receiving radio unit to the sending radio unit.

16. The method of claim 1, further comprising the step of:

when it is decided to send the power control message from the receiving radio unit to the sending radio unit, always using a highest permissible transmit power level to send the power control message from the receiving radio unit to the sending radio unit.

17. The method of claim 1, further comprising the step of:

when it is decided to send the power control message from the receiving radio unit to the sending radio unit, initially using a first transmit power level to send the power control message from the receiving radio unit to the sending radio unit, and then gradually increasing the power control message transmit power level from the first transmit power level to successively higher levels until a reception signal strength level at the receiving radio unit has reached a predefined acceptable level.

18. An apparatus for controlling transmission power in a frequency-hopping radio system that transmits packets from a sending radio unit to a receiving radio unit, wherein each packet includes an address designating the receiving radio unit, the apparatus comprising:

means for measuring received signal strength of packets whose addresses were successfully received in the receiving radio unit, regardless of whether other portions of the respective packets were successfully received;

means for generating an average signal strength value from the received signal strength measurements;

means for determining a mathematical difference between the average signal strength value and a target value associated with the receiving radio unit; and

means for using the mathematical difference as a basis for deciding whether to send a power control message from the receiving radio unit to the sending radio unit.

19. The apparatus of claim 18, wherein the means for using the mathematical difference as a basis for deciding whether to send a power control message from the receiving radio unit to the sending radio unit comprises:

means for sending a power control message from the receiving radio unit to the sending radio unit if the mathematical difference is greater than a first decision boundary; and

means for sending the power control message from the receiving radio unit to the sending radio unit if the mathematical difference is less than a second decision boundary.

20. The apparatus of claim 18, wherein the power control message includes the mathematical difference.

21. The apparatus of claim 20, further comprising:

means for receiving the power control message in the sending radio unit; and

means for adjusting a transmission power level in the sending radio unit by an amount based on the mathematical difference.

22. The apparatus of claim 21, wherein the means for adjusting the transmission power level in the sending radio unit by an amount based on the mathematical difference comprises:

means for determining whether the amount based on the mathematical difference would cause an adjusted transmission power level to exceed a predefined maximum transmission power level;

means, response to a determination that the amount based on the mathematical difference would cause the adjusted transmission power level to exceed the predefined maximum transmission power level, for adjusting the transmission power level in the sending radio unit to be no more than the predefined maximum transmission power level.

23. The apparatus of claim 22, further comprising:

means for sending a control message from the sending radio unit to the receiving radio unit informing that a maximum transmission power level has been reached.

24. The apparatus of claim 23, further comprising:

in the receiving radio unit, means, responsive to the control message from the sending radio unit informing that a maximum transmission power level has been reached, for sending no further power control messages to the sending radio unit that instruct the sending radio unit to further increase its transmission power level.

25. The apparatus of claim 21, wherein the means for adjusting the transmission power level in the sending radio unit by an amount based on the mathematical difference comprises:

means for determining whether the amount based on the mathematical difference would cause an adjusted transmission power level to fall below a predefined minimum transmission power level;

means, responsive to a determination that the amount based on the mathematical difference would cause the adjusted transmission power level to fall below the predefined minimum transmission power level, for adjusting the transmission power level in the sending radio unit to be no less than the predefined minimum transmission power level.

26. The apparatus of claim 25, further comprising:

means for sending a control message from the sending radio unit to the receiving radio unit informing that a minimum transmission power level has been reached.

27. The apparatus of claim 26, further comprising the step of:

in the receiving radio unit, means, responsive to the control message from the sending radio unit informing that a minimum transmission power level has been reached, for sending no further power control messages to the sending radio unit that instruct the sending radio unit to further decrease its transmission power level.

28. The apparatus of claim 18, wherein the target value associated with the receiving radio unit is based on the receiver sensitivity.

29. The apparatus of claim 18, wherein the target value associated with the receiving radio unit is based on the receiver sensitivity adjusted to account for implementation losses and other inaccuracies.

30. The apparatus of claim 18, wherein the means for generating the average signal strength value from the received signal strength measurements comprises:

means for averaging signal strength values from the received signal strength measurements over a period of time extending over at least two frequency hops.

31. The apparatus of claim 18, further comprising:

means, responsive to a decision to send the power control message from the receiving radio unit to the sending radio unit, for sending the power control message on a control channel established between the receiving radio unit and the sending radio unit.

32. The apparatus of claim 18, further comprising:

means, responsive to a decision to send the power control message from the receiving radio unit to the sending radio unit, for including the power control message in a return packet that is transmitted from the receiving radio unit to the sending radio unit.

33. The apparatus of claim 18, further comprising:

means, responsive to a decision to send the power control message from the receiving radio unit to the sending radio unit, for always using a highest permissible transmit power level to send the power control message from the receiving radio unit to the sending radio unit.

34. The apparatus of claim 18, further comprising:

means, responsive to a decision to send the power control message from the receiving radio unit to the sending radio unit, for initially using a first transmit power level to send the power control message from the receiving radio unit to the sending radio unit, and then gradually increasing the power control message transmit power level from the first transmit power level to successively higher levels until a reception signal strength level at the receiving radio unit has reached a predefined acceptable level.