INTEGRATED POWER CONTROL AND LINK ADAPTATION

• US 20100279701A1
• Filed: 07/10/2009
• Published: 11/04/2010
• Est. Priority Date: 04/30/2009
• Status: Active Grant

• Current Assignee: Telefonaktiebolaget LM Ericsson
• Original Assignee: Telefonaktiebolaget LM Ericsson
• Inventors: Chen, Dayong
• Granted Patent: US 8,275,406 B2
• Time in Patent Office: Days
• US Class Current: 455/452.2
• CPC Class Codes: H04L 1/0002 by adapting the transmission rate
• CPC Class Codes: H04L 1/0009 by adapting the channel coding H04L1/1812 takes precedence
• CPC Class Codes: H04L 1/0017 where the mode-switching is based on Quality of Service requirement
• CPC Class Codes: H04L 1/0025 Transmission of mode-switching indication
• CPC Class Codes: H04L 1/20 using signal quality detector
• CPC Class Codes: H04L 27/2089 with unbalanced quadrature channels
• CPC Class Codes: H04W 24/10 Scheduling measurement reports ; Arrangements for measurement reports
• CPC Class Codes: H04W 52/143 Downlink power control
• CPC Class Codes: H04W 52/346 distributing total power among users or channels
• CPC Class Codes: H04W 88/08 Access point devices

Abstract

A method and apparatus in a base station for jointly controlling sub-channel transmission power and assigned codec modes for a first and second mobile station utilizing Voice services over Adaptive Multi-user channel on One Slot (VAMOS). The base station receives signal quality information reports from the mobile stations every 480 ms using the Slow Associated Control Channel (SACCH), and receives codec mode requests from the mobile stations every 40 ms using Adaptive Multi-Rate (AMR) in-band signaling. The base station associates the requested codec modes with estimated levels of speech quality currently being experienced by the first and second mobile stations. The base station then allocates sub-channel transmission power and assigns codec modes to the first and second mobile stations based on the estimated levels of speech quality associated with the requested codec modes and the signal quality reports.

Claims

1. A method in a base station for jointly controlling sub-channel transmission power and assigned codec modes for a first mobile station and a second mobile station sharing the same frequency and time slot in a radio telecommunication system, said method comprising the steps of:

receiving a codec mode request from the first mobile station and a codec mode request from the second mobile station, each request requesting a codec mode for channel coding future downlink transmissions;

associating the requested codec modes with estimated levels of speech quality currently being experienced by the first and second mobile stations; and

allocating sub-channel transmission power and assigning codec modes to the first and second mobile stations based on the estimated levels of speech quality associated with the requested codec modes.

2. The method according to claim 1, wherein the step of receiving the codec mode requests includes periodically receiving the codec mode requests from the first mobile station and the second mobile station at the rate of Adaptive Multi-Rate (AMR) link adaptation.

3. The method according to claim 2, wherein the step of periodically receiving codec mode requests includes receiving codec mode requests from the first mobile station and the second mobile station utilizing AMR in-band signaling.

4. The method according to claim 3, further comprising receiving periodic measurement reports from the first and second mobile stations, each measurement report reporting a carrier-to-interference (C/I) ratio measured at each mobile station, wherein the measurement reports are received less frequently than the codec mode requests.

5. The method according to claim 4, further comprising estimating an updated speech quality level at each mobile station based on a last received measurement report and at least one subsequently received codec mode request.

6. The method according to claim 1, further comprising, prior to receiving the codec mode requests, the step of defining in the base station and the first and second mobile station, an Active Code Set (ACS) and associated speech quality thresholds for codec mode switching, wherein the ACS includes at least a high rate mode, a medium rate mode, and a low rate mode.

7. The method according to claim 6, wherein the step of defining speech quality thresholds for codec mode switching includes defining an upper threshold and a lower threshold for each transition between an associated higher codec mode and an associated lower codec mode, wherein a request to change to the higher codec mode is generated only when the associated speech quality is above the upper threshold, and a request to change to the lower codec mode is generated only when the associated speech quality is below the lower threshold, thereby reducing ping-ponging between the codec modes.

8. The method according to claim 1, wherein the step of allocating sub-channel transmission power to the first and second mobile stations includes:

determining from the requested codec modes that the first mobile station has a better estimated level of speech quality than the second mobile station; and

re-allocating sub-channel transmission power between the first and second mobile stations to balance the estimated levels of speech quality.

9. The method according to claim 8, wherein the step of re-allocating sub-channel transmission power includes shifting a portion of allocated power from the first mobile station to the second mobile station, wherein the size of the portion is selected to balance reaction time and over-shooting.

10. The method according to claim 9, further comprising the steps of:

estimating a Sub-Channel Power Imbalance Ratio (SCPIR) value based on the most recent allocation of sub-channel transmission power to the first and second mobile stations;

converting the SCPIR value to a corresponding α

value; and

passing the α

value to an α

-QPSK modulator in a transmitter in the base station.

11. A method in a base station for jointly controlling sub-channel transmission power and assigned codec modes for a first mobile station and a second mobile station sharing the same frequency and time slot in a radio telecommunication system, said method comprising the steps of:

allocating initial portions of the sub-channel transmission power to the first and second mobile stations and assigning initial codec modes to the first and second mobile station;

transmitting speech frames to the first and second mobile station;

receiving measured speech quality indications from the first mobile station and the second mobile station;

determining by the base station, new codec modes and a new allocation of sub-channel transmission power for the first and second mobile station based on the measured speech quality indications;

subsequently receiving codec mode requests from the first and second mobile stations;

upon receiving the codec mode requests from the first and second mobile stations, determining updated speech quality estimates for the first and second mobile stations based each mobile station'"'"'s requested codec mode;

determining by the base station, whether the updated speech quality estimates are acceptable and balanced at the first and second mobile stations;

upon determining that the updated speech quality estimates are acceptable and balanced, applying by the base station, the requested codec modes to a next speech frame while maintaining the initial allocation of transmitter power; and

upon determining that the updated speech quality estimates are not acceptable at one of the mobile stations or are not balanced, applying by the base station, the requested codec modes to the next transmission and shifting the transmitter power allocation from the mobile station with better speech quality to the mobile station with poorer speech quality.

12. The method according to claim 11, wherein measured speech quality indications are received from the first and second mobile stations at a first periodic rate, while codec mode requests are received from the first and second mobile stations at a second periodic rate which is faster than the first periodic rate.

13. The method according to claim 12, wherein the first periodic rate is once every 480 ms, and the second periodic rate is once every 40 ms.

14. The method according to claim 11, further comprising the step of:

upon determining that the updated speech quality estimates are not acceptable at both of the mobile stations, increasing the total power allocated to the two mobile stations.

15. The method according to claim 11, further comprising the step of:

upon determining that the updated speech quality estimates are not acceptable at both of the mobile stations, assigning one of the mobile stations to a separate time slot.

16. An apparatus in a base station for jointly controlling sub-channel transmission power and assigned codec modes for a first mobile station and a second mobile station sharing the same frequency and time slot in a radio telecommunication system, said apparatus comprising:

a receiver for receiving a codec mode request from the first mobile station and a codec mode request from the second mobile station, each request requesting a codec mode for channel coding future downlink transmissions;

means for associating the requested codec modes with estimated levels of speech quality currently being experienced by the first and second mobile stations; and

means for allocating sub-channel transmission power and assigning codec modes to the first and second mobile stations based on the estimated levels of speech quality associated with the requested codec modes.

17. The apparatus according to claim 16, wherein the receiver includes means for periodically receiving the codec mode requests from the first mobile station and the second mobile station at the rate of Adaptive Multi-Rate (AMR) link adaptation, wherein the codec mode requests are received utilizing AMR in-band signaling.

18. The apparatus according to claim 17, wherein the receiver includes means for receiving periodic measurement reports from the first and second mobile stations, each measurement report reporting a carrier-to-interference (C/I) ratio measured at each mobile station, wherein the measurement reports are received less frequently than the codec mode requests.

19. The apparatus according to claim 18, wherein the receiver receives the measurement reports once every 480 ms, and the receiver receives the codec mode requests once every 40 ms.

20. The apparatus according to claim 18, further comprising means for estimating an updated speech quality level at each mobile station based on a last received measurement report and at least one subsequently received codec mode request.

21. The apparatus according to claim 16, wherein the means for associating the requested codec modes with estimated levels of speech quality includes an Active Code Set (ACS) and associated speech quality thresholds for codec mode switching defined within the base station, wherein the ACS includes at least a high rate mode, a medium rate mode, and a low rate mode.

22. The apparatus according to claim 16, wherein the means for allocating sub-channel transmission power and assigning codec modes to the first and second mobile stations includes:

means for determining from the requested codec modes that the first mobile station has a better estimated level of speech quality than the second mobile station; and

means for re-allocating sub-channel transmission power between the first and second mobile stations to balance the estimated levels of speech quality.

23. The apparatus according to claim 22, wherein the means for re-allocating sub-channel transmission power includes means for shifting a portion of allocated power from the first mobile station to the second mobile station, wherein the size of the portion is selected to balance reaction time and over-shooting.

24. The apparatus according to claim 23, further comprising:

means for estimating a Sub-Channel Power Imbalance Ratio (SCPIR) value based on the most recent allocation of sub-channel transmission power to the first and second mobile stations;

means for converting the SCPIR value to a corresponding α

value; and

means for passing the α

value to an α

-QPSK modulator in a transmitter in the base station.

25. The apparatus according to claim 16, further comprising:

means for estimating an updated speech quality level at each mobile station based on a last received codec mode request;

means for determining whether the updated speech quality estimates are acceptable at the first and second mobile stations; and

means for increasing the total power allocated to the two mobile stations in response to a determination that the updated speech quality estimates are not acceptable at both of the mobile stations.

26. The apparatus according to claim 16, further comprising:

means for estimating an updated speech quality level at each mobile station based on a last received codec mode request;

means for determining whether the updated speech quality estimates are acceptable at the first and second mobile stations; and

means for assigning one of the mobile stations to a separate time slot in response to a determination that the updated speech quality estimates are not acceptable at both of the mobile stations.