Received signal quality determination method and systems for convolutionally encoded communication channels

• US 6,141,388 A
• Filed: 03/11/1998
• Issued: 10/31/2000
• Est. Priority Date: 03/11/1998
• Status: Expired due to Term

• Current Assignee: Ericsson, Inc. (Telefonaktiebolaget LM Ericsson)
• Original Assignee: Ericsson, Inc. (Telefonaktiebolaget LM Ericsson)
• Inventors: Servais, Frederic Henri, Johnson, Phillip Marc
• Primary Examiner(s): Pham, Chi H.
• Assistant Examiner(s): Bayard, Emmanuel
• Application Number:
  US09/038,602
• Time in Patent Office: 965 Days
• Field of Search: 375/259, 375/262, 375/265, 714/756, 714/759, 714/780, 714/792, 714/795, 714/796
• US Class Current: 375/262
• CPC Class Codes: H03M 13/39 Sequence estimation, i.e. using statistical methods for the reconstruction of the original codes
• CPC Class Codes: H03M 13/4161 implementing path management
• CPC Class Codes: H03M 13/6325 Error control coding in combination with demodulation
• CPC Class Codes: H04L 1/0054 Maximum-likelihood or sequential decoding, e.g. Viterbi, Fano, ZJ algorithms
• CPC Class Codes: H04L 1/203 Details of error rate determination, e.g. BER, FER or WER

Abstract

Received signal quality (bit error rate) estimates for a communication channel are provided by a receiver apparatus which is connected to the communication channel and which includes a convolutional decoder providing an estimate of a transmitted data frame and an associated final decision metric. The bit error rate estimate is generated by a bit error rate estimation circuit which includes a memory containing values for mapping the final decision metric to a corresponding bit error rate estimate. The bit error rate estimate may be provided to a control node of the communication channel which may use the provided estimate to take a corrective action such as determining whether a handover to a different communication channel should be initiated based upon the bit error rate. The communication channel may be an allocated channel of a cellular radio communication network servicing a mobile terminal receiver apparatus with the control nodes being the base stations of the cellular network. The convolutional decoder may be a Viterbi decoder.

Claims

1. A method for estimating a received signal quality for a communication channel comprising the steps of:

convolutionally encoding a data frame;

transmitting the encoded data frame over the communication channel from a control node to the receiver;

receiving the transmitted data frame at the receiver;

decoding the received data frame to provide an estimate of the transmitted data frame and an associated final decision metric of at least a portion of a decoder bit path selected for the data frame;

mapping the final decision metric at the receiver to provide the received signal quality estimate;

providing the received signal quality estimate to the control node; and

determining at the control node whether a corrective action should be taken prior to transmission of a subsequently transmitted data frame from the control node to the receiver based on the received signal quality estimate.

2. The method of claim 1 wherein the received signal quality estimate is a bit error rate estimate.

3. The method of claim 2 wherein the communication channel is a radio communication channel and wherein the control node is a terrestrial base station and wherein the corrective action comprises selecting a different communication channel for a subsequently transmitted data frame based on the bit error rate estimate.

4. The method of claim 2 wherein the communication channel is a radio communication channel and wherein the control node is a terminal.

5. The method of claim 2 wherein the communication channel is a radio communication channel and wherein the control node is a satellite station and wherein the corrective action comprises selecting a different communication channel for a subsequently transmitted data frame based on the bit error rate estimate.

7. The method of claim 5 wherein said averaging step comprises the step of averaging a plurality of associated final decision metrics using at least one of a moving average routine, an autoregressive routine or a combination autoregressive moving average routine.

6. A method for estimating a received signal quality for a communication channel comprising the steps of:

convolutionally encoding a plurality of data frames;

transmitting the plurality of encoded data frames over the communication channel;

receiving the plurality of transmitted data frames;

decoding the plurality of received data frame to provide estimates of the transmitted data frame and an associated plurality of final decision metrics;

averaging the plurality of associated final decision metrics; and

mapping the averaged plurality of associated final decision metrics to provide the bit error rate estimate.

8. A method for estimating a received signal quality for a communication channel comprising the steps of:

convolutionally encoding a plurality of data frames;

transmitting the plurality of encoded data frames over the communication channel;

receiving the plurality of transmitted data frames;

decoding the plurality of received data frame to provide estimates of the transmitted data frame and an associated plurality of final decision metrics;

mapping ones of the plurality of final decision metrics to provide a plurality of bit error estimates;

averaging the plurality of bit error estimates to provide an averaged bit error estimate; and

providing the averaged bit error estimate to a control node associated with the communication channel.

9. The method of claim 8 wherein said averaging step comprises the step of averaging the plurality of bit error estimates using at least one of a moving average routine, an autoregressive routine or a combination autoregressive moving average routine.

10. A method for estimating a received signal quality for a communication channel comprising the steps of:

convolutionally encoding a data frame;

transmitting the encoded data frame over the communication channel;

receiving the transmitted data frame;

decoding the received data frame to provide an estimate of the transmitted data frame and an associated final decision metric;

convolutionally encoding a control frame;

transmitting the encoded control frame over the communication channel;

receiving the transmitted control frame;

decoding the received control frame to provide an estimate of the transmitted control frame and a second associated final decision metric of at least a portion a decoder bit path selected for the control frame;

determining which of said final decision metric associated with the voice frame and said second final decision metric indicates a better match; and

mapping the better match final decision metric to provide a bit error rate estimate.

11. A communication system for communicating over a communication channel comprising:

means for convolutionally encoding a data frame;

means for transmitting the encoded data frame over the communication channel;

means for receiving a transmitted data frame;

means for decoding the received data frame to provide an estimate of the transmitted data frame and an associated final decision metric of at least a portion of a decoder bit path selected for the data frame;

means for mapping the final decision metric to provide a bit error rate estimate;

means for providing the bit error rate estimate to a control node over the communication channel; and

means for determining whether a corrective action should be taken prior to transmission of a subsequently transmitted encoded data frame based on the bit error rate estimate.

12. The communication system of claim 11 further comprising means for storing a plurality of associated final decision metrics and wherein said means for mapping comprises means for averaging the plurality of associated final decision metrics and mapping the averaged plurality of associated final decision metrics to provide the bit error rate estimate.

13. The communication system of claim 11 further comprising:

means for averaging a plurality of bit error rate estimates from a plurality of data frames to provide the bit error rate estimate.

14. The communication system of claim 11 wherein the communication channel is a radio communication channel and wherein the control node is a base station.

15. The communication system of claim 11 wherein the communication channel is a radio communication channel and wherein the control node is a satellite station.

19. The communication system of claim 14 wherein the convolutional decoder includes means for considering a plurality of paths to provide a plurality of associated final decision metrics and wherein said means for basing the estimate of bit error rate on a final decision metric associated with an estimate of transmitted data having no error indication comprises means for selecting one of said plurality of associated final decision metrics as the final decision metric on which the estimate of bit error rate is based.

16. A communication system comprising:

a receiver device including;

a receiver which receives a data frame over a communication channel;

a convolutional decoder coupled to said receiver, said convolutional decoder providing an estimate of transmitted data from the received data frame and an associated final decision metric for the estimate of transmitted data;

a bit error rate estimation circuit coupled to the decoder that provides an estimate of bit error rate based on the final decision metric;

a transmitter that transmits the estimate of bit error rate over the

communication channel; and

a control node including;

a transmitter that transmits the data frame over the communication channel;

a receiver that receives the estimate of bit error rate over the communication channel;

a controller that determines whether a corrective action should be taken prior to transmission of a subsequently transmitted data frame from the control node to the receiver device based on the estimate of bit error rate.

17. The communication system of claim 16 wherein the convolutional decoder is a Viterbi decoder.

18. The communication system of claim 17 wherein the bit error rate estimation circuit further comprises means for determining if the final decision metric is associated with an estimate of transmitted data containing an error indication and means for basing the estimate of bit error rate on a final decision metric of a second decoder bit path associated with an estimate of transmitted data having no error indication.

20. The communication system of claim 16 wherein the bit error rate estimation circuit comprises:

a memory that stores reference values that convert the associated final decision metric to a corresponding bit error rate estimate for the communication channel; and

a controller for mapping the associated final decision metric to the stored reference values to provide an estimate of bit error rate.

21. The communication system of claim 20 wherein the reference values are predefined and stored in the memory and wherein the memory is a non-volatile memory.

22. The communication system of claim 16 wherein the bit error rate estimation circuit comprises means for calculating the bit error estimate by evaluating a predetermined function having the associated final decision metric as an input.

23. The communication system of claim 16 wherein the communication channel is a radio communication channel.

24. The communication system of claim 16 wherein the receiver comprises a mobile terminal and the control node comprises part of a cellular radio communication network and wherein the corrective action comprises selecting a different communication channel for a subsequently transmitted data frame based on the bit error rate estimate.