Transmitter-receiver pair for wireless network power-code operating point is determined based on error rate

• US 6,072,990 A
• Filed: 05/08/1997
• Issued: 06/06/2000
• Est. Priority Date: 05/08/1997
• Status: Expired due to Term

• Current Assignee: Lucent Technologies, Inc. (Nokia Corporation)
• Original Assignee: Lucent Technologies, Inc. (Nokia Corporation)
• Inventors: Yajnik, Shalini, Agrawal, Prathima, Narendran, Balakrishnan, Sienicki, James Paul
• Primary Examiner(s): Urban, Edward F.
• Assistant Examiner(s): Gesesse, Tilahun
• Application Number:
  US08/848,392
• Time in Patent Office: 1,125 Days
• Field of Search: 455/69, 455/88, 455/522, 455/67.1, 455/67.3, 455/63, 455/515, 455/434
• US Class Current: 455/69
• CPC Class Codes: H04W 24/00 Supervisory, monitoring or testing arrangements
• CPC Class Codes: H04W 52/20 using error rate
• CPC Class Codes: H04W 52/30 using constraints in the total amount of available transmission power

Abstract

A method and system for adaptively determining an operating point for a transmitter-receiver pair in a wireless communication network. The receiver receives data over an uplink and measures an average observed word error rate avg_-- WER of the received data and transmits the average observed word error rate avg_-- WER over a downlink to the transmitter when the average observed word error rate avg_-- WER is not within an acceptable word error rate range. The transmitter receives the average observed word error rate avg_-- WER over the downlink and determines a power-code pair (P,c) for the transmitter based on the average observed word error rate avg_-- WER. The power code pair (P,c) defines an operating point of the transmitter, where P of the power-code pair is a selected transmit power level of the transmitter and c of the power-code pair is a selected forward error correcting code used for encoding the data. The receiver can also determine a predicted word error rate WER_pred for a first timeframe based on the observed word error rate WER_obs for a second timeframe, and determines whether the predicted word error rate WER_pred is within the acceptable word error rate WER range.

Claims

1. A method of determining an operating point of a transmitter of a transmitter-receiver pair in a wireless communication network, the method comprising the steps of:

averaging an observed word error rate WER_obs for data transmitted during a plurality of timeframes over a link between a transmitter-receiver pair for a predetermined number of timeframes to generate an average observed word error rate avg_-- WER;

determining whether the averaged word error rate avg_-- WER is within an acceptable word error rate WER range; and

determining a power-code pair (P,c) for a transmitter of the transmitter-receiver pair when the average observed word error rate avg_-- WER of the link between the transmitter-receiver pair is not within the acceptable word error rate WER range, the power code pair (P,c) defining the operating point of the transmitter, P of the power-code pair being a selected transmit power level of the transmitter and c of the power-code pair being a selected forward error correcting code used for encoding the data.

2. The method according to claim 1, further comprising the steps of:

encoding the data based on the selected forward error correcting code c; and

transmitting the encoded data at the selected power level P.

3. The method according to claim 2, wherein the predetermined number of timeframes varies between an predetermined initial number of timeframes and a predetermined maximum number of timeframes.

4. The method according to claim 2, wherein the wireless communication system includes a plurality of transmitter-receiver pairs, and wherein the predetermined number of timeframes used for averaging the observed word error rate WER_obs for each transmitter-receiver pair varies between a predetermined initial number of timeframes for each respective transmitter-receiver pair and a predetermined maximum number of timeframes for each respective transmitter-receiver pair.

5. The method according to claim 4, wherein the predetermined number of timeframes used for averaging the observed word error rate WER_obs for each transmitter-receiver pair varies between the respective predetermined initial number of timeframes and the predetermined maximum number of timeframes independently from other transmitter-receiver pairs.

6. The method according to claim 2, wherein the step of determining whether the average observed word error rate avg_-- WER is within the acceptable word error rate WER range is performed at a receiver of the transmitter-receiver pair, and

wherein the step of determining the power-code pair (P,c) is performed at the transmitter.

7. The method according to claim 6, wherein the step of determining the average observed word error rate avg_-- WER includes the step of measuring an observed word error rate WER_obs over the predetermined number of timeframes.

8. The method according to claim 7, wherein the step of determining the average observed word error rate avg_-- WER further includes the steps of:

measuring an observed power P_obs at the receiver; and

measuring an observed interference I_obs at the receiver.

9. The method according to claim 8, further comprising the steps of:

transmitting the average observed word error rate avg_-- WER, the observed power P_obs and the observed interference I_obs from the receiver to the transmitter, and

determining the power-code pair (P,c) for the transmitter based on the average observed word error rate avg_-- WER, the observed power P_obs and the observed interference I_obs.

10. The method according to claim 9, wherein the step of determining the power-code pair (P,c) includes the step of selecting the forward error correcting code c from a plurality of forward error correcting codes, the selected forward error correcting code providing a desired word error rate WER_des.

11. The method according to claim 10, wherein the step of determining the power-code pair (P,c) includes the step of selecting the transmit power level P to be between a minimum transmit power level and a maximum transmit power level of the transmitter.

12. The method according to claim 11, further comprising the steps of:

selecting the forward error correcting code from the plurality of forward error correcting codes that provides the maximum forward error correction capability when no power code pair (P,c) provides the desired word error rate WER_des ;

selecting the maximum transmit power level of the transmitter when no power code pair (P,c) provides the desired word error rate WER_des ;

encoding the data based on the selected forward error correcting code providing the maximum forward error correction capability; and

transmitting the encoded data at the maximum transmit power level of the transmitter.

13. A method of determining an operating point of a transmitter of a transmitter-receiver pair in a wireless communication network, the method comprising the steps of:

determining a predicted word error rate WER_pred for data transmitted during a plurality of timeframes over a link between a transmitter-receiver pair, the predicted word error rate WER_pred being for a first timeframe of the plurality of timeframes based on an observed word error rate WER_obs for a second timeframe of the plurality of timeframes, the second timeframe preceding the first timeframe in time;

determining whether the predicted word error rate WER_pred is within an acceptable word error rate WER range; and

determining a power-code pair (P,c) for a transmitter of the transmitter-receiver pair when the observed predicted word error WER_pred of the link between the transmitter-receiver pair is not within the acceptable word error rate WER range, the power code pair (P,c) defining the operating point of the transmitter, P of the power-code pair being a selected transmit power level of the transmitter and c of the power-code pair being a selected forward error correcting code used for encoding the data.

14. The method according to claim 13, further comprising the steps of:

encoding the data based on the selected forward error correcting code c; and

transmitting the encoded data at the selected power level P.

15. The method according to claim 14, wherein the step of determining whether the predicted word error rate WER_pred is within the acceptable word error rate WER range is performed at a receiver of the transmitter-receiver pair, and

wherein the step of determining the power-code pair (P,c) is performed at the transmitter.

16. The method according to claim 15, wherein the step of determining the predicted word error rate WER_pred includes the step of measuring the observed word error rate WER_obs of the second timeframe.

17. The method according to claim 16, wherein the step of determining the observed word error rate WER_obs further includes the steps of:

measuring an observed power P_obs at the receiver; and

measuring an observed interference I_obs at the receiver.

18. The method according to claim 17, further comprising the steps of:

transmitting the observed word error rate WER_obs, the observed power P_obs and the observed interference I_obs from the receiver to the transmitter, and

determining the power-code pair (P,c) for the transmitter based on the observed word error rate WER_{obs 5}, the observed power P_obs and the observed interference I_obs.

19. The method according to claim 18, wherein the step of determining the power-code pair (P,c) includes the step of selecting the forward error correcting code c from a plurality of forward error correcting codes, the selected forward error correcting code providing a desired word error rate WER_des.

20. The method according to claim 19, wherein the step of determining the power-code pair (P,c) includes the step of selecting the transmit power level P to be between a minimum transmit power level and a maximum transmit power level of the transmitter.

21. The method according to claim 20, further comprising the steps of:

selecting the forward error correcting code from the plurality of forward error correcting codes that provides the maximum forward error correction capability when no power code pair (P,c) provides the desired word error rate WER_des ;

selecting the maximum transmit power level of the transmitter when no power code pair (P,c) provides the desired word error rate WER_des ;

encoding the data based on the selected forward error correcting code providing the maximum forward crror correction capability; and

transmitting the encoded data at the maximum transmit power level of the transmitter.

22. A transmitter-receiver pair in a wireless communication network, the transmitter-receiver pair comprising:

a receiver receiving data over an uplink, the receiver measuring an observed word error rate WER_obs for a predetermined number of timeframes, and determining whether an averaged word error rate avg_-- WER of the word error rate WER_obs for the predetermined number of timeframes is within the acceptable word error rate WER range, and transmitting the average observed word error rate avg_-- WER over a downlink when the average observed word error rate avg_-- WER is not within an acceptable word error rate WER, the uplink being associated with the downlink; and

a transmitter transmitting the data over the uplink, the transmitter receiving the average observed word error rate avg_-- WER over the downlink and determining a power-code pair (P,c) for the transmitter based on the average observed word error rate avg_-- WER, the power code pair (P,c) defining an operating point of the transmitter, P of the power-code pair being a selected transmit power level of the transmitter and c of the power-code pair being a selected forward error correcting code used for encoding the data, and the transmitter encoding the data based on the selected forward error correcting code c and transmitting the encoded data at the selected power level P;

wherein the wireless communication network includes a plurality of transmitter-receiver pairs, each transmitter-receiver pair having an uplink and a downlink; and

wherein the predetermined number of timeframes used for averaging the observed word error rate WER_obs for each transmitter-receiver pair varies between a predetermined initial number of timeframes corresponding to each transmitter-receiver pair and a predetermined maximum number of timeframes corresponding to each transmitter-receiver pair.

23. The transmitter-receiver pair according to claim 22, wherein the predetermined number of timeframes used for averaging the observed word error rate WER_obs for each transmitter-receiver pair varies independently from other transmitter-receiver pairs.

24. A transmitter-receiver pair in a wireless communication network, the transmitter-receiver pair comprising:

a receiver receiving data over an uplink, the receiver measuring an observed word error rate WER_obs for a predetermined number of timeframes, and determining whether an averaged word error rate avg_-- WER of the word error rate WER_obs for the predetermined number of timeframes is within the acceptable word error rate WER range, and transmitting the average observed word error rate avg_-- WER over a downlink when the average observed word error rate avg_-- WER is not within an acceptable word error rate WER, the uplink being associated with the downlink; and

a transmitter transmitting the data over the uplink, the transmitter receiving the average observed word error rate avg_-- WER over the downlink and determining a power-code pair (P,c) for the transmitter based on the average observed word error rate avg_-- WER, the power code pair (P,c) defining an operating point of the transmitter, P of the power-code pair being a selected transmit power level of the transmitter and c of the power-code pair being a selected forward error correcting code used for encoding the data, and the transmitter encoding the data based on the selected forward error correcting code c and transmitting the encoded data at the selected power level P;

wherein the receiver further measures an observed power P_obs and an observed interference lobs of the received data, and transmits the observed power P_obs and the observed interference I_obs over the downlink with the observed word error rate WER_obs, and

wherein the transmitter determines the power-code pair (P,c) further based on the observed power P_obs and the observed interference I_obs.

25. The transmitter-receiver pair according to claim 24, wherein the transmitter includes a memory storing a plurality of forward error correcting codes, the transmitter selecting the forward error correcting code c from the plurality of forward error correcting codes, the selected forward error correcting code c providing a desired word error rate WER_des.

26. The transmitter-receiver pair according to claim 25, wherein the transmitter has a minimum transmit power level and a maximum transmit power level, and

wherein the transmitter selects the transmit power level P to be between the minimum transmit power level and the maximum transmit power level.

27. The transmitter-receiver pair according to claim 26, wherein the transmitter selects the forward error correcting code from the plurality of forward error correcting codes, the selected forward error correcting code providing the maximum forward error correction capability when no power code pair (P,c) provides the desired word error rate WER_des, and

wherein the transmitter selects the maximum transmit power level of the transmitter when no power code pair (P,c) provides the desired word error rate WER_des.

28. A transmitter-receiver pair in a wireless communication network, the transmitter-receiver pair comprising:

a receiver receiving data over an uplink, the receiver measuring an observed word error rate WER_obs of the received data, determining a predicted word error rate WER_pred for a first timeframe based on the observed word error rate WER_obs for a second timeframe, and determining whether the predicted word error rate WER_pred is within the acceptable word error rate WER range, the second timeframe preceding the first timeframe in time, and transmitting the predicted word error rate WER_pred over a downlink when the predicted word error rate WER_pred is not within the acceptable word error rate WER, the uplink being associated with the downlink; and

a transmitter transmitting the data over the uplink, the transmitter receiving the observed word error rate WER_obs over the downlink and determining a power-code pair (P,c) for the transmitter based on the observed word error rate WER_obs, the power code pair (P,c) defining an operating point of the transmitter, P of the power-code pair being a selected transmit power level of the transmitter and c of the power-code pair being a selected forward error correcting code used for encoding the data, and the transmitter encoding the data based on the selected forward error correcting code c, and transmitting the encoded data at the selected power level P.

29. The transmitter-receiver pair according to claim 28, wherein the wireless communication network includes a plurality of transmitter-receiver pairs, each transmitter-receiver pair having an uplink and a downlink.

30. The transmitter-receiver pair according to claim 28, wherein the receiver further measures an observed power P_obs and an observed interference I_obs of the received data, and transmits the observed power P_obs and the observed interference I_obs over the downlink with the observed word error rate WER_obs, and

wherein the transmitter determines the power-code pair (P,c) further based on the observed power P_obs and the observed interference I_obs.

31. The transmitter-receiver pair according to claim 30, wherein the transmitter includes a memory storing a plurality of forward error correcting codes, the transmitter selecting the forward error correcting code c from the plurality of forward error correcting codes, the selected forward error correcting code c providing a desired word error rate WER_des.

32. The transmitter-receiver pair according to claim 31, wherein the transmitter has a minimum transmit power level and a maximum transmit power level, and

wherein the transmitter selects the transmit power level P to be between the minimum transmit power level and the maximum transmit power level.

33. The transmitter-receiver pair according to claim 31, wherein the transmitter selects the forward error correcting code from the plurality of forward error correcting codes, the selected forward error correcting code providing the maximum forward error correction capability when no power code pair (P,c) provides the desired word error rate WER_des, and

wherein the transmitter selects the maximum transmit power level of the transmitter when no power code pair (P,c) provides the desired word error rate WER_des.