ARQ method with adaptive transmittal data block positions
View Patent ↗In a communication system a transmission-end input data flow with serially successive data is transmitted via a time-variant transmission channel. The transmission-end input data flow is divided into individual words. An a-priori reliability value is determined for each position of a transmittal data block by transmission-end modulation methods and coding methods, and the words of the input data flow are associated with corresponding positions of the transmittal data block according to the a-priori reliability values, and transmitted. An a-posteriori reliability value is formed on the receiving end for each word of the transmittal data block. The words having an a-posteriori reliability value falling below a pre-determined minimum value are re-requested and re-transmitted by acknowledgement of the corresponding positions.
1. A method for the transmission of data,
dividing a transmission-end input data stream into individual words;
determining a-priori reliability values for positions of a transmittal data block based on transmission-end modulation methods and coding methods;
allocating the words of the input data stream and transmitting in corresponding positions of the transmittal data block based on the a-priori reliability values;
forming, at a receiving end, an a-posteriori reliability value for each word of the transmittal data block; and
re-requesting received words having a minimum value falling below the a-posteriori reliability value, and re-transmitting from the transmission end.
2. A method according to claim 1 ,
wherein a first word of the input data stream, allocated to a first position of the transmittal data block with a maximum a-priori reliability value, is transmitted first, and
wherein an nth word of the input data stream, allocated to an nth position of the transmittal data block with a minimum a-priori reliability value, is transmitted last.
3. A method according to claim 2 ,
wherein said forming at the receiving end includes determining an ith word at an ith position in the transmittal data block having an a-posteriori reliability value below the minimum value for the first time, and
wherein said re-requesting includes transmitting the ith position of the ith word to the transmission end.
4. A method according to claim 3 , wherein said re-transmitting includes forming at the transmission end a new transmittal data block in which the ith word of the transmittal data block transmitted previously is allocated to the first position for re-transmission and positions following the first position are occupied with following words of the transmittal data block transmitted previously that occupied positions greater than the ith position.
5. A method according to claim 4 , wherein said re-requesting uses a return channel to transmit the ith position from the receiving end to the transmission end.
6. A method according to claim 5 , further comprising:
storing error words of a first transmission considered to be in error at the receiving end; and
combining the error words with re-transmitted words of a second transmission by using one of a maximum ratio combining method and a code combining method.
7. A method according to claim 6 , wherein said forming of the a-posteriori reliability values at the receiving end uses a soft output decoding method.
8. A method according to claim 7 , wherein said forming of the a-posteriori reliability values at the receiving end uses a trellis decoding method.
9. A method according to claim 8 , wherein said transmitting of the transmittal data block is a modulated transmission using one of a PSK, a 16QAM and a higher-level modulation method.
10. A method according to claim 9 , further comprising adding one of a checksum and a CRC data block as a prefix to the transmittal data block for error detection.