Retransmission ordering method, wireless communication system, receiver and transmitter

• US 20050210355A1
• Filed: 03/21/2005
• Published: 09/22/2005
• Est. Priority Date: 03/22/2004
• Status: Active Grant

• Current Assignee: Sony Corporation (Sony Group Corp.)
• Original Assignee: Sony Ericsson Mobile Communications Japan Incorporated (Sony Group Corp.)
• Inventors: Itoh, Katsutoshi, Nagase, Taku
• Granted Patent: US 7,434,137 B2
• Time in Patent Office: Days
• US Class Current: 714/748
• CPC Class Codes: H03M 13/29 combining two or more codes or code structures, e.g. product codes, generalised product codes, concatenated codes, inner and outer codes
• CPC Class Codes: H03M 13/6306 Error control coding in combination with Automatic Repeat reQuest [ARQ] and diversity transmission, e.g. coding schemes for the multiple transmission of the same information or the transmission of incremental redundancy H03M13/3761, H03M13/3769 and H03M13/635 take precedence
• CPC Class Codes: H04L 1/0065 Serial concatenated codes
• CPC Class Codes: H04L 1/1812 Hybrid protocols; Hybrid automatic repeat request [HARQ]
• CPC Class Codes: H04L 1/1854 Scheduling and prioritising arrangements
• CPC Class Codes: H04L 1/1874 Buffer management

Abstract

Disclosed is a wireless communication system wherein frame data is encoded with an outer code and then divided into predetermined number of blocks which are encoded with an inner code into transmission data which a receiver receives by wireless In the receiver, a decoder decodes the received transmission data in accordance with the inner code, a retransmission order determining unit determines whether or not to perform a retransmission order in units of blocks based on the likelihood information (decoded soft-decision value). At this time, the retransmission order determining unit inhibits the retransmission order for the block if the number of inner-code errors in a frame consisting of predetermined number of blocks stays within a limit of what the outer code can correct at a decoder and determines that a retransmission is necessary if the number of inner-code errors in the frame exceeds the limit. An average value of absolute values of the likelihood information within a block, for example, can be used as an evaluation value.

Claims

1. A retransmission ordering method in a receiver for receiving transmission data by wireless, frame data being encoded with an outer code and then divided into predetermined number of blocks which are encoded with an inner code into the transmission data, the retransmission ordering method comprising the steps of:

receiving transmission data;

storing received transmission data in a buffer;

decoding the transmission data stored in the buffer in accordance with the inner code and outputting a decode result and likelihood information thereof;

creating frame data by combining decoded blocks;

decoding the frame data in accordance with the outer code;

determining whether or not to perform a retransmission order in units of blocks based on the likelihood information; and

transmitting a retransmission order for an applicable block if it is determined that a retransmission is necessary according to the step of determining whether or not to perform a retransmission order,

wherein at the step of determining whether or not to perform a retransmission order, the retransmission order for the block is inhibited if the number of inner-code errors in a frame consisting of the predetermined number of blocks stays within a limit of what the outer code can correct and it is determined that a retransmission is necessary if the number of inner-code errors in the frame exceeds the limit.

2. The retransmission ordering method according to claim 1, wherein the step of determining whether or not to perform a retransmission order comprises the steps of:

finding an average value of absolute values of the likelihood information within a block as an evaluation value; and

determining whether or not the block needs to be retransmitted by comparing the evaluation value with a predetermined threshold value.

3. The retransmission ordering method according to claim 1, wherein the step of determining whether or not to perform a retransmission order comprises the steps of:

finding the number of bits that lead to absolute values of the likelihood information that are not more than a specified threshold value, as an evaluation value; and

determining whether or not the block needs to be retransmitted by comparing the evaluation value with a predetermined threshold value.

4. The retransmission ordering method according to claim 2, wherein an evaluation value corresponding to the number of errors N/M allocated to each inner code is the predetermined threshold value in the case where error correction capability of the outer code can correct N errors and one piece of frame data is divided into M pieces.

5. The retransmission ordering method according to claim 3, wherein an evaluation value corresponding to the number of errors N/M allocated to each inner code is the predetermined threshold value in the case where error correction capability of the outer code can correct N errors and one piece of frame data is divided into M pieces.

6. The retransmission ordering method according to claim 4, an error detecting code being added to the frame data which is then encoded with the outer code, the retransmission ordering method further comprising the steps of:

performing error detection for a decode result in accordance with the error detecting code after frame data obtained by decoding in accordance with the inner code is decoded in accordance with the outer code; and

changing the predetermined threshold value in units of data frames in such a way that the retransmission order for the block occurs easily if an error is detected in the step of performing error detection and in such a way that the retransmission order for the block hardly occurs if no error is detected.

7. The retransmission ordering method according to claim 4, further comprising the step of changing the predetermined threshold value in units of blocks in a data frame using a threshold adjustment updated by updating the number of errors N/M allocated to each inner code based on the number of accumulated errors as to sequential blocks in one data frame.

8. The retransmission ordering method according to claim 1, an error detecting code being added to the frame data which is then encoded with the outer code, the retransmission ordering method further comprising the steps of:

performing error detection for a decode result in accordance with the error detecting code after frame data obtained by decoding in accordance with the inner code is decoded in accordance with the outer code; and

transmitting a retransmission order for applicable frame data in accordance with an error detection result in the step of performing error detection.

9. A wireless communication system comprising a transmitter and a receiver,

wherein after encoding frame data with an outer code, the transmitter divides the frame data into predetermined number of blocks which are further encoded with an inner code, and the transmitter transmits the encoded data to the receiver by wireless;

and

wherein the receiver receives transmitted data, stores received data in a buffer, decodes transmission data stored in the buffer in accordance with the inner code, creates frame data by combining decoded blocks, decodes the frame data in accordance with the outer code, outputs a decode result and likelihood information thereof, determines whether or not to perform a retransmission order in units of blocks based on the likelihood information, and transmits a retransmission order for an applicable block if it is determined that a retransmission is necessary based on the determining whether or not to perform a retransmission order, and in the case of determining whether or not to perform a retransmission order, the receiver inhibits the retransmission order for the block if the number of inner-code errors in a frame consisting of the predetermined number of blocks stays within a limit of what the outer code can correct and determines that a retransmission is necessary if the number of inner-code errors in the frame exceeds the limit.

10. A receiver for receiving transmission data by wireless, frame data being encoded with an outer code and then divided into predetermined number of blocks which are encoded with an inner code into the transmission data, the receiver comprising:

a buffer for storing received transmission data;

first decoding means for decoding the transmission data stored in the buffer in accordance with the inner code and outputting a decode result and likelihood information thereof;

frame combining means for creating frame data by combining decoded blocks;

second decoding means for decoding the frame data in accordance with the outer code;

retransmission order determining means for determining whether or not to perform a retransmission order in units of blocks based on the likelihood information from the first decoding means; and

retransmission order transmitting means for transmitting a retransmission order for an applicable block if the retransmission order determining means determines that a retransmission is necessary,

wherein the retransmission order determining means inhibits the retransmission order for the block if the number of inner-code errors in a frame consisting of the predetermined number of blocks stays within a limit of what the outer code can correct at the second decoding means and determines that a retransmission is necessary if the number of inner-code errors in the frame exceeds the limit.

11. The receiver according to claim 10, wherein the retransmission order determining means comprises:

means for finding an average value of absolute values of the likelihood information within a block as an evaluation value; and

means for determining whether or not the block needs to be retransmitted by comparing the evaluation value with a predetermined threshold value.

12. The receiver according to claim 10, wherein the retransmission order determining means comprises:

means for finding the number of bits that lead to absolute values of the likelihood information that are not more than a specified threshold value, as an evaluation value; and

means for determining whether or not the block needs to be retransmitted by comparing the evaluation value with a predetermined threshold value.

13. The receiver according to claim 11, wherein an evaluation value corresponding to the number of errors N/M allocated to each inner code is the predetermined threshold value in the case where error correction capability of the outer code can correct N errors and one piece of frame data is divided into M pieces.

14. The receiver according to claim 12, wherein an evaluation value corresponding to the number of errors N/M allocated to each inner code is the predetermined threshold value in the case where error correction capability of the outer code can correct N errors and one piece of frame data is divided into M pieces.

15. The receiver according to claim 13, an error detecting code being added to the frame data which is then encoded with the outer code, the receiver further comprising:

error detecting means for performing error detection in accordance with the error detecting code; and

first threshold changing means for changing the predetermined threshold value in units of data frames in such a way that the retransmission order for the block occurs easily if the error detecting means detects an error and in such a way that the retransmission order for the block hardly occurs if the error detecting means detects no error.

16. The receiver according to claim 13, further comprising second threshold changing means for changing the predetermined threshold value in units of blocks in a data frame using a threshold adjustment updated by updating the number of errors N/M allocated to each inner code based on the number of accumulated errors as to sequential blocks in one data frame.

17. The receiver according to claim 10, an error detecting code being added to the frame data which is then encoded with the outer code, the receiver further comprising:

error detecting means for performing error detection in accordance with the error detecting code; and

retransmission order controlling means for creating a retransmission order for applicable frame data in accordance with an error detection result by the error detecting means.

18. A transmitter comprising:

first encoding means for encoding frame data to be transmitted with an outer code;

frame dividing means for dividing output of the first encoding means into predetermined number of blocks;

a first retransmission buffer for storing output of the frame dividing means;

second encoding means for further encoding frame data in the first retransmission buffer with an inner code;

modulating means for modulating output of the second encoding means;

transmitting means for transmitting a modulated signal; and

retransmission controlling means for making the first retransmission buffer retransmit block data stored in the first retransmission buffer according to a signal received from outside.

19. The transmitter according to claim 18, further comprising a second retransmission buffer for storing the frame data to be transmitted, wherein the retransmission controlling means makes the first retransmission buffer retransmit block data stored in the first retransmission buffer or makes the second retransmission buffer retransmit frame data stored in the second retransmission buffer, according to a signal received from outside.

20. The transmitter according to claim 18, further comprising error detecting code adding means for adding an error detecting code to the frame data to be transmitted.