Data transmitting method with hybrid automatic repeat request in multi-carrier system

• US 7,864,745 B2
• Filed: 12/03/2004
• Issued: 01/04/2011
• Est. Priority Date: 12/19/2003
• Status: Expired due to Fees

• Current Assignee: Alcatel SA (Nokia Corporation)
• Original Assignee: Alcatel SA (Nokia Corporation)
• Inventors: Song, Pengpeng, Wan, Yan, Cai, Liyu
• Primary Examiner(s): Harper; Kevin C
• Application Number:
  US11/002,286
• Publication Number:
  US 20050135253A1
• Time in Patent Office: 2,223 Days
• Field of Search: 370/343, 370/480, 370/465, 714/746
• US Class Current: 370/343
• CPC Class Codes: H04L 1/0003 by switching between different modulation schemes
• CPC Class Codes: H04L 1/0009 by adapting the channel coding H04L1/1812 takes precedence
• CPC Class Codes: H04L 1/0021 in which the algorithm uses adaptive thresholds
• CPC Class Codes: H04L 1/0071 Use of interleaving interleaving per se H03M13/27
• CPC Class Codes: H04L 1/16 in which the return channel carries supervisory signals, e.g. repetition request signals
• CPC Class Codes: H04L 1/1812 Hybrid protocols; Hybrid automatic repeat request [HARQ]
• CPC Class Codes: H04L 1/1845 Combining techniques, e.g. code combining
• CPC Class Codes: H04L 5/0007 the frequencies being orthogonal, e.g. OFDM(A), DMT
• CPC Class Codes: H04L 5/0046 Determination of how many bits are transmitted on different sub-channels
• CPC Class Codes: H04L 5/006 Quality of the received signal, e.g. BER, SNR, water filling

Abstract

The present invention provides a data transmitting method with hybrid automatic repeat request in multi-carrier system. In this method, the signal-to-noise ratios of respective sub-carriers are compared with a threshold, the data on the sub-carriers having the signal-to-noise ratios lower than the threshold are selectively retransmitted by mapping these data onto the sub-carriers having the good channel conditions, and then the retransmitted data are combined hybrid-automatically in the receiver of the opposite terminal. By using the method the system throughput can be enhanced effectively without impairing the bit error rate of the system.

Claims

1. A data transmitting method with hybrid automatic repeat request in multi-carrier system, wherein, the said method comprises the steps of:

a. a transmitter of a local terminal transmitting data to a receiver of an opposite communication terminal, and the receiver of the opposite terminal receiving the data, estimating the signal-to-noise ratios of respective sub-carriers for carrying the data, feeding back the signal-to -noise ratios of respective sub-carriers to a transmitter of the local terminal through the transmitter of the opposite terminal and a receiver of the local terminal, weighting the received data, storing them and providing them to the receiver of the opposite terminal for judging;

b. the receiver of the opposite terminal judging whether the data are correct, and outputting the data and sending an acknowledgement (ACK) indication to the transmitter of the local terminal through the transmitter of the opposite terminal and the receiver of the local terminal if the data are correct or sending a negative acknowledgement (NACK) indication to the transmitter of the local terminal through the same route if the data are incorrect;

c. when receiving the acknowledgement (ACK) indication, the transmitter of the local terminal getting new data as the data to be transmitted and then returning to step a;

d. when receiving the negative acknowledgement (NACK) indication, the transmitter of the local terminal comparing the signal-to-noise ratios of respective sub-carriers for carrying the data fed back from the receiver of the opposite terminal with a threshold, picking out the sub-carriers having the signal-to-noise ratios lower than the threshold, mapping again the data carried by the sub-carriers having the signal-to-noise ratios lower than the threshold onto other sub-carriers having the higher signal-to-noise ratios according to a certain rule and retransmits them to the receiver of the opposite terminal;

e. the receiver of the opposite terminal receiving the data, estimating the signal-to-noise ratios of respective sub-carriers for carrying the data and feeding back the signal-to-noise ratios of respective sub-carriers to the transmitter of the local terminal through the transmitter of the opposite terminal and the receiver of the local terminal, at the same time, comparing the signal-to-noise ratios of respective sub-carriers transmitted last time with the same threshold as that in the transmitter of the local terminal, picking out the data of retransmitted part according to the same rule as that in the step d, weighting the retransmitted data, combining the weighted data with the data which are processed before, storing them and providing them to the receiver of the opposite terminal for judging, then returning to step b.

2. The data transmitting method with hybrid automatic repeat request in multi-carrier system according to claim 1, wherein said multi-carrier system is an orthogonal frequency dividing multiplexing system.

3. The data transmitting method with hybrid automatic repeat request in multi-carrier system according to claim 1, wherein the method further comprises a step for forward error correction (FEC) coding the data to be transmitted before the transmitter of the local terminal transmits the data to the receiver of the opposite terminal in step a, at the same time, the manner of forward error correction (FEC) coding needs to be adaptively regulated according to the values of the fed back signal-to-noise ratios of respective sub-carriers.

4. The data transmitting method with hybrid automatic repeat request in multi-carrier system according to claim 1, wherein the threshold in said step d is obtained through simulation calculation and is fed back along with the NACK indication from the opposite terminal to the transmitter of the local terminal.

5. The data transmitting method with hybrid automatic repeat request in multi-carrier system according to claim 1, wherein said estimating the signal-to-noise ratio of respective sub-carriers in step a and step e further includes steps for predicting the channel after the signal-to-noise ratios of the received data are estimated and adjusting the values of the signal-to-noise ratios according to the predicting result of the future channel performance.

6. The data transmitting method with hybrid automatic repeat request in multi-carrier system according to claim 1, wherein said weighting the data in step a and step b is that the data are weighted with the average SNR of all sub-carriers for carrying the data.

7. The data transmitting method with hybrid automatic repeat request in multi-carrier system according to claim 1, wherein said weighting the data in step a and step b is that each data symbol in the transmitted block of data is weighted by taking SNR of the sub-carrier for carrying the data symbol as weight factor.

8. The data transmitting method with hybrid automatic repeat request in multi-carrier system according to claim 1, wherein that said step d further includes that the sub-carriers which are not used to map the data to be retransmitted are used to transmit new data of the subscriber, or allocated dynamically to other subscribers in the case of multi-subscriber multiplex.

9. The data transmitting method with hybrid automatic repeat request in multi-carrier system according to claim 1, wherein the sub-carriers in the method can be substituted by sub-bands, and a signal-to-noise ratio of a sub-band is the average value of signal-to-noise ratios of all the sub-carriers in the sub-band.

10. An orthogonal frequency dividing multiplex communication system comprising a transmitter and a receiver, the said transmitter comprising a transmitter buffer unit and a multiplexing unit, the said receiver comprising a signal-to-noise ratio estimating unit, a receiver buffer unit, a de-multiplexing unit, a HARQ combining unit and a CRC checking unit, wherein said communication system further comprises a retransmission controller connected with the transmitter buffer unit and the multiplexing unit, and a de-multiplex controller coupled with the signal-to-noise ratio estimating unit and connected with the CRC checking unit and the de-multiplexing unit, wherein said retransmission controller is used to control the transmitter buffer unit to get new data and to control the multiplexing unit to map the new data to be transmitted when obtaining the ACK indication fed back from the opposite communication terminal, and to compare the signal-to-noise ratios of respective sub-carriers for carrying the data fed back from the signal-to-noise ratio estimating unit of the receiver of the opposite communication terminal with a threshold to pick out the sub-carriers having the signal-to-noise ratios lower than the threshold and to control the multiplexing unit to map again the data carried by the sub-carriers having the signal-to-noise ratios lower than the threshold onto other sub-carriers having the higher signal-to-noise ratios for retransmission according to a certain rule when receiving the NACK indication fed back from the receiver of the opposite communication terminal;

said de-multiplex controller is used to control the de-multiplexing unit to send the de-multiplexed data to the HARQ combining unit when obtaining the ACK indication output from the CRC checking unit, and to compare the signal-to-noise rations of respective sub-carriers transmitted last time sent from the signal-to-noise estimating unit with the same threshold as that in the transmitter of the opposite terminal and to control the de-multiplexing unit to send the de-multiplexed data of the retransmitted part to the HARQ combining unit according to the same rule as that in the transmitter of the opposite terminal in the case of the receiver receiving the retransmitted data when obtaining the NACK indication output from the CRC checking unit;

said receiver buffer unit clears the data for HARQ combining which are processed before and stored therein when obtaining the ACK indication output from the CRC checking unit;

said HARQ combining unit weights the data processed by said de-multiplexing unit, combines the weighted data with the data which are processed before and stored in the receiver buffer unit, and then stores the processed data in the receiver buffer unit;

when obtaining the ACK indication, the receiver outputs the data checked by the CRC checking unit.

11. The orthogonal frequency dividing multiplex communication system according to claim 10, wherein a channel predicting and regulating unit used to predict the channel performance in advance and regulate the values of the signal-to-noise ratios obtained by the signal-to-noise ratio estimating unit is connected to said signal-to-noise ratio estimating unit.

12. A transmitter in an orthogonal frequency dividing multiplex communication system, comprising a transmitter buffer unit and a multiplexing unit, wherein the transmitter further comprises a retransmission controller connected with the transmitter buffer unit and the multiplexing unit and used to control the transmitter buffer unit to get new data and to control the multiplexing unit to map the data for transmitting when receiving an ACK indication fed back from an opposite communication terminal, and used to compare signal-to-noise ratios of respective sub-carriers for carrying the data fed back from a receiver of the opposite communication terminal with a threshold to pick out the sub-carriers having the signal-to-noise ratios lower than the threshold and to control the multiplexing unit to map the data carried by the sub-carriers having the signal-to-noise ratios lower than the threshold onto other sub-carriers having the higher signal-to-noise ratios for retransmission according to a certain rule when receiving a NACK indication fed back from the receiver of the opposite communication terminal.

15. The transmitter in the orthogonal frequency dividing multiplex communication system according to claim 12, wherein only data carried by the sub-carriers having the signal-to-noise ratios lower than the threshold is retransmitted.

13. A receiver in an orthogonal frequency dividing multiplex communication system comprising a signal-to-noise ratio estimating unit, a receiver buffer unit, a de-multiplexing unit, a HARQ combining unit and a CRC checking unit, wherein the receiver further comprises a de-multiplex controller coupled with the signal-to-noise ratio estimating unit, and connected with the de-multiplexing unit and the CRC checking unit and used to control the de-multiplexing unit to send the de-multiplexed data to the HARQ combining unit when obtaining a ACK indication output from the CRC checking unit, and used to compare the signal-to-noise ratios of respective sub-carriers transmitted last time from the signal-to-noise estimating unit with the same threshold as that in a transmitter of an opposite terminal and to control the de-multiplexing unit to send the de-multiplexed data of the retransmitted part to the HARQ combining unit according to the same rule as that in the transmitter of the opposite terminal in the case of the receiver receiving the retransmitted data when obtaining the NACK indication output from the CRC checking unit, wherein said receiver buffer unit clears the data which are processed before and stored in the unit for HARQ combining when obtaining the ACK indication output from the CRC checking unit, said HARQ combining unit weights the data processed by said de-multiplexing unit and combines the weighted data with the data which are processed before and stored in the receiver buffer unit and then stores the processed data in the receiver buffer unit, at the same time, when obtaining the ACK indication, the receiver outputs the data checked by the CRC checking unit.

14. The receiver in the orthogonal frequency dividing multiplex communication system according to claim 13, wherein a channel predicting and regulating unit used to predict the channel performance in advance and regulate the values of the signal-to-noise ratios obtained by the signal-to-noise ratio estimating unit is connected to said signal-to-noise ratio estimating unit.

16. An orthogonal frequency dividing multiplex communication system comprising:

a transmitter transmitting data and comprising a multiplexing unit and a retransmission controller; and

a receiver receiving data and comprising a signal-to-noise ratio determining unit that determines the signal-to-noise ratio of the received data,

wherein, if the receiver determines that the data received from the transmitter is incorrect, the retransmission controller compares a signal-to-noise ratio of at least one sub-carrier carrying the received data with a threshold value, select at least one of said sub-carrier having signal-to-noise ratios lower than the threshold value, and controls the multiplexing unit to remap the data carried by the sub-carriers having the signal-to-noise ratios lower than the threshold onto other sub-carriers having higher signal-to-noise ratios for retransmission.

17. The orthogonal frequency dividing multiplex communication system according to claim 16, wherein the receiver further comprises a hybrid automatic repeat request combining unit that combines the retransmitted data with the data received previously.

18. A transmitter in an orthogonal frequency dividing multiplex communication system, comprising:

a multiplexing unit; and

a retransmission controller,

wherein, if the transmitter determines that data received from a transmitter of an opposite terminal is incorrect, the transmitter compares a signal-to-noise ratio of at least one sub-carrier carrying the received data with a threshold value, and controls the multiplexing unit to remap data carried by at least one sub-carrier having a signal-to-noise ratio lower than the threshold value onto other sub-carriers having higher signal-to-noise ratios for retransmission.

19. A receiver in an orthogonal frequency dividing multiplex communication system, comprising:

a signal-to-noise ratio estimating unit;

a de-multiplexing unit;

a de-multiplexing controller; and

a hybrid automatic repeat request combining unit,

wherein;

if the receiver determines that received data is incorrect, the de-multiplexing controller compares signal-to-noise ratios of at least one sub-carrier transmitted previously with a threshold value and controls the de-multiplexing unit to send de-multiplexed data of a retransmitted part to the hybrid automatic repeat request combining unit; and

if the receiver determines that the received data is correct, the hybrid automatic repeat request combining unit weights retransmitted data processed by the de-multiplexing unit and combines the weighted data with data received previously.