Reliable congestion control in a CDMA-based mobile radio commmunications system

• US 6,799,045 B1
• Filed: 11/07/2000
• Issued: 09/28/2004
• Est. Priority Date: 11/07/2000
• Status: Expired due to Term

• Current Assignee: Telefonaktiebolaget LM Ericsson
• Original Assignee: Telefonaktiebolaget LM Ericsson
• Inventors: Brouwer, Frank
• Primary Examiner(s): Chin, Vivian
• Assistant Examiner(s): Persino, Raymond B.
• Application Number:
  US09/707,159
• Time in Patent Office: 1,421 Days
• Field of Search: 455/436, 455/442, 455/501, 455/552, 455/63.1, 455/67.11, 455/69, 455/561, 455/127.1, 455/13.4, 455/422.1, 455/423, 455/424, 455/434, 455/453, 370/310, 370/318
• US Class Current: 455/453
• CPC Class Codes: H04W 52/343 taking into account loading or congestion level

Abstract

The present invention provides an inexpensive and effective way to provide reliable cell congestion control. Transmit power control commands issued in the cell are detected, and the reliability of the issued transmit power commands is determined. A condition in the cell, e.g., congestion level, is controlled based on those issued transmit power commands which are determined to be reliable. Reliably issued transmit power control commands include those that are consistent with a corresponding transmit power control decision made by a receiver of the command, assuming the decision is not influenced by a maximum or minimum transmit power level. Those commands that are inconsistent with that decision are deemed unreliable, and therefore, are not considered in controlling the condition of the cell. In a preferred example implementation of the present invention, only reliably issued transmit power control commands are counted, and that count value is used to control the cell condition.

Claims

1. In a cellular mobile radio communications system supporting communications over a radio interface between a radio network and mobile terminals, a method comprising:

monitoring transmit power control commands issued in a cell in the radio network;

determining the reliability of issued transmit power commands;

monitoring a number of reliable increase transmit power commands issued in a cell over a time period relative to a total number of reliable transmit power commands issued in the cell for that time period; and

if the number of reliable increase transmit power commands relative to the total number of reliable transmit power commands exceeds a threshold, taking action to reduce the number of increase transmit power commands in the cell.

2. The method in claim 1, further comprising:

determining a load condition in the cell based on issued transmit power commands determined to be reliable; and

controlling the load condition in the cell based on issued transmit power commands determined to be reliable.

3. The method in claim 2, wherein the load condition relates to an interference or congestion level in the cell.

4. The method in claim 1, wherein a reliable issued transmit power control command includes an issued transmit power control command that is consistent with a corresponding transmit power control decision made by a receiver of the issued command, and wherein an unreliable issued transmit power control command includes an issued transmit power control command that is inconsistent with a corresponding transmit power control decision made by the receiver.

5. The method in claim 4, further comprising:

considering only reliable transmit power control commands in controlling the condition in the cell.

6. The method in claim 4, further comprising:

registering in a counter only reliable transmit power control commands.

7. The method in claim 1, further comprising:

identifying a diversity handover communication between a mobile terminal and first and second diversity base stations;

wherein unreliable transmit power control commands include issued transmit power commands from one of the diversity base stations ignored by the mobile terminal.

8. In a cellular mobile radio communications system supporting communications over a radio interface between a radio network and mobile terminals, a method comprising:

monitoring transmit power control commands issued in a cell in the radio network;

determining the reliability of issued transmit power commands;

controlling a condition in the cell based on issued transmit power commands determined to be reliable;

identifying a diversity handover communication between a mobile terminal and first and second diversity base stations, one of the diversity base stations being selected for each of multiple time periods during the diversity handover communication,

determining a frequency at which the first diversity base station is selected; and

if the frequency meets a threshold, treating transmit power control commands issued by the first diversity base station to the mobile terminal as reliable.

9. The method in claim 8, wherein the one diversity base station is selected by a mobile terminal using a site selection diversity transmission (SSDT) indicator.

10. In a cellular mobile radio communications system supporting communications over a radio interface between a radio network and mobile terminals, a method comprising:

monitoring transmit power control commands issued in a cell in the radio network;

determining the reliability of issued transmit power commands;

monitoring a first number of reliable increase transmit power commands issued in a cell over a time period relative to a second number of reliable decrease transmit power commands issued in the cell for that time period; and

if a difference between the number of reliable increase transmit power commands and the number of reliable decrease transmit power commands exceeds a threshold, taking action to reduce the number of increase transmit power commands in the cell.

11. The method in claim 10, further comprising:

measuring a value associated with the cell condition, and

using the measured value to aid in determining the reliability of issued transmit power control commands.

12. The method in claim 11, wherein the measured value is a received power level in the cell.

13. In a mobile radio communications system supporting communications over a radio interface between a radio network and mobile terminals, a method comprising:

identifying transmit power commands that are determined to be reliable without having to measure whether the commands contain errors, wherein the commands are sent from a base station in a cell in the radio network to mobile terminals;

detecting a first number of reliable transmit power increase commands from the radio network to mobile terminals in the cell in a time period;

detecting a second number of reliable transmit power commands from the radio network to mobile terminals in the cell in the time period;

determining a third number associated with the first and second numbers for the time period;

comparing the third number to a first threshold; and

if the third number exceeds the first threshold, signaling a congestion condition in the cell,

wherein the second number is a number of reliable decrease transmit power commands in the time period, and the third number is a difference between the first number and the second number.

14. The method in claim 13, wherein the second number is a total number of reliable transmit power commands in the time period, and the third number is a percentage of the first number to the second number.

16. The method in claim 13, further comprising:

measuring a signal level in the cell;

comparing the measured signal level in the cell to a level threshold; and

if the measured level in the cell exceeds the level threshold and if the third number exceeds the first threshold, signaling a congestion condition in the cell.

17. The method in claim 13, wherein a reliable transmit power control command includes a transmit power control command that is consistent with a transmit power control decision made by a receiver of the command, and wherein an unreliable transmit power control command includes a transmit power control command that is not inconsistent with a corresponding transmit power control decision made by the receiver.

18. The method in claim 13, further comprising:

identifying a diversity handover communication between a mobile terminal and first and second diversity base stations;

wherein unreliable transmit power control commands include issued transmit power commands from one of the diversity base stations ignored by the mobile terminal.

19. The method in claim 13, further comprising:

regulating a traffic condition of the cell if the congestion condition is signaled.

20. The method in claim 13, further comprising:

performing congestion control in the cell if the congestion condition is signaled.

15. The method in clam 13, further comprising:

determining an average of the third number over a predetermined time frame,

wherein the averaged third number is compared to the first threshold.

21. In a mobile radio communications system supporting communications over a radio interface between a radio network and mobile terminals, a method comprising:

identifying transmit power commands that are determined to be reliable without having to measure whether the commands contain errors, wherein the commands are sent from a base station in a cell in the radio network to mobile terminals;

detecting a first number of reliable transmit power increase commands from the radio network to mobile terminals in the cell in a time period;

detecting a second number of reliable transmit power commands from the radio network to mobile terminals in the cell in the time period;

determining a third number associated with the first and second numbers for the time period;

comparing the third number to a first threshold; and

if the third number exceeds the first threshold, signaling a congestion condition in the cell,

wherein the first number is detected by counting reliable transmit power increase commands and the second number is detected by counting reliable transmit power decrease commands.

22. In a mobile radio communications system supporting communications over a radio interface between a radio network and mobile terminals, a method comprising:

identifying transmit power commands sent from a base station in a cell in the radio network to mobile terminals that are determined to be reliable;

detecting a first number of reliable transmit power increase commands from the radio network to mobile terminals in a cell in a time period;

detecting a second number of reliable transmit power commands from the radio network to mobile terminals in a cell in the time period;

determining a third number associated with the first and second numbers for the time period;

comparing the third number to a first threshold; and

if the third number exceeds the first threshold, signaling an undesirable condition in the cell, the method further comprising;

identifying a diversity handover communication between a mobile terminal and first and second diversity base stations, one of the diversity base stations being selected for each of multiple time periods during the diversity handover communication;

determining a frequency at which the first diversity base station is selected; and

if the frequency meets a threshold, treating transmit power control commands issued by the first diversity base station to the mobile terminal as reliable.

23. The method in claim 22, wherein the one diversity base station is selected by a mobile station using a site selection diversity transmission (SSDT) indicator.

24. In a mobile radio communications system supporting communications over a radio interface between a radio network and mobile terminals, apparatus comprising:

electronic circuitry configured to determine a reliability of the transmit power commands issued from the radio network to mobile terminals in a cell in a predetermined time period without having to measure whether an error is present in the transmit power commands;

a counter configured to count a first number of reliable transmit power increase commands from the radio network to mobile terminals in a cell in the time period and a second number of reliable transmit power commands from the radio network to mobile terminals in the cell in the time period;

a first comparator configured to compare a third number associated with the first and second numbers for the time period with a first threshold; and

a controller configured to detect a load condition in the cell if the third number exceeds the first thresholds,

wherein the second number is a number of reliable decrease transmit power commands in the time period, and the third number is a difference between the first number and the second number, and wherein the counter is configured to be incremented with each reliable increase transmit power command and decremented for each reliable decrease transmit power command.

25. The apparatus in claim 24, wherein the second number is a total number of reliable transmit power commands in the time period, and the third number is a percentage of the first number to the second number.

26. The apparatus in claim 24, further comprising:

an averager configured to determine an average of the third number over a predetermined time frame,

wherein the first comparator is configured to compare the third number to the first threshold.

27. The apparatus in claim 24, where the apparatus is implemented in a radio network controller coupled to one or more base stations.

28. The apparatus in claim 24, where the apparatus is implemented in a base station.

29. The apparatus in claim 24, further comprising:

a sensor configured to measure a signal level in the cell, and

a second comparator configured to compare the measured signal level in the cell to a signal level threshold,

wherein if the measured signal level in the cell exceeds the signal level threshold and if the third number exceeds the first threshold, the controller is configured to detect the load condition in the cell.

30. The apparatus in claim 24, wherein the load condition is an overload condition.

31. The apparatus in claim 24, wherein the load condition is an excessive interference or power level in the cell.

32. The apparatus in claim 24, wherein the controller regulates a traffic condition of the cell if the load condition is detected.

33. In a mobile radio communications system supporting communications over a radio interface between a radio network and mobile terminals, apparatus comprising:

electronic circuitry configured to determine a reliability of the transmit power commands issued from the radio network to mobile terminals in a cell in a predetermined time period without having to measure whether an error is present in the transmit power commands;

a counter configured to count a first number of reliable transmit power increase commands from the radio network to mobile terminals in a cell in the time period and a second number of reliable transmit power commands from the radio network to mobile terminals in the cell in the time period;

a first comparator configured to compare a third number associated with the first and second numbers for the time period with a first threshold; and

a controller configured to detect a load condition in the cell if the third number exceeds the first threshold,

wherein the first number is detected by counting transmit power increase commands actually implemented by mobile terminals in the cell during the time period, and the second number is detected by counting transmit power decrease commands actually implemented by mobile terminals in the cell during the time period.

34. In a mobile radio communications system supporting communications over a radio interface between a radio network and mobile terminals, apparatus comprising:

electronic circuitry configured to determine a reliability of the transmit power commands issued from the radio network to mobile terminals in a cell in a predetermined time period;

a counter configured to count a first number of reliable transmit power increase commands from the radio network to mobile terminals in a cell in the time period and a second number of reliable transmit power commands from the radio network to mobile terminals in the cell in the time period;

a first comparator configured to compare a third number associated with the first and second numbers for the time period with a first threshold; and

a controller configured to detect an undesirable condition in the cell if the third

number exceeds the first threshold,

wherein the electronic circuitry is configured to operate when a diversity handover communication between a mobile station and first and second diversity base stations is established, one of the diversity base stations being selected for each of multiple time periods during the diversity handover communication, and wherein unreliable transmit power control commands include issued transmit power commands from one of the diversity base stations ignored by the mobile station, and

wherein the electronic circuitry is configured to determine a frequency at which the first diversity base station is selected, and if the frequency meets a threshold, treating transmit power control commands issued by the first diversity base station to the mobile terminal as reliable.

35. The apparatus in claim 34, wherein the one diversity base station is selected by a mobile station using a site selection diversity transmission (SSDT) indicator.

36. The apparatus in claim 35, the electronic circuitry includes:

a base station selection comparator for generating an output when an SSDT base station identifier matches with an identifier of the one diversity base station;

a threshold detector for generating an enabling signal when the base station selection comparator output exceeds a threshold; and

a logic detector for passing transmit power control commands to the counter when the enabling signal is received.

37. The apparatus in claim 36, the electronic circuitry includes:

an averager for averaging the base station selection comparator output and providing an averaged base station selection comparator output to the threshold detector.

38. The apparatus in claim 34, wherein the electronic circuitry includes:

means for determining the reliability of the observed transmit power control commands based on transmit power control commands actually implemented in the cell.

39. The apparatus in claim 34, wherein the electronic circuitry includes:

means for determining the reliability of the observed transmit power control commands based on a power level in the cell.