Quality dependent data communications channel
View Patent ↗A data channel to transmit data from a transmitter to one or more of a plurality of receivers, each of which intermittently reports to the transmitter its reception quality of signals transmitted by the transmitter. The transmitter transmits the data in frames which include at least one block. Each block includes the same predefined number of traffic symbols, and includes a header portion and a payload portion. The header portion of each block is packaged for transmission in a robust manner, enhancing the probability that each receiver will be able to recover it and the header portion includes information required to recover the payload portion. The payload portion is, in accordance with the reception quality reported by the intended receiver, packaged to make efficient use of the transmission resources while ensuring a reasonable probability that the intended receiver will be able to recover the payload. The header portion can include indications of the modulation, forward error correction and repetition utilized to package the payload and can indicate the length of the payload.
1. A system for transmitting data comprising:
a base station operable to transmit a radio signal to a plurality of subscriber stations, the signal including frames each having a same fixed duration and each comprising a plurality of data blocks, each data block including a header and a corresponding payload portion having a length, wherein each header includes information required to recover the corresponding payload portion;
wherein the base station is arranged and configured to:
receive reports intermittently from each of the plurality of subscriber stations regarding the reception quality of the subscriber stations;
package each data block individually for transmission to an intended subscriber station,
package each payload portion of each data block in a manner that is, for the intended subscriber station, a data rate efficient combination as determined according to a reception quality reported by the intended recipient subscriber station, and
package the corresponding header of each data block in a manner that is determined in accordance with an intention that the header be receivable by all subscriber stations that have at least a predetermined minimum reception quality.
2. The system of claim 1 wherein each data block contains a same preselected number of traffic symbols.
3. The system of claim 2 , wherein the base station, in packaging data into a data block for transmission, processes header bits and payload information bits separately from each other and in parallel, the header formed by first applying forward error correction coding to the header bits and then mapping the header bits onto traffic symbols, and the payload portion formed by calculating a cyclic redundancy check (CRC) value for the payload information bits, applying forward error correction coding to the payload information bits and bits of the CRC value to produce coded bits, interleaving the coded bits to produce interleaved bits, mapping the interleaved bits into symbols using an M-ary modulation scheme while adding padding bits if the number of bits to be mapped is not divisible by log 2 (M), applying symbol repetition to the resulting symbols, padding the result of the symbol repetition with discontinuous transmission (DTx) padding symbols if necessary for the data block to contain the preselected number of traffic symbols, and interleaving the resulting traffic symbols.
4. The system of claim 1 wherein the header of each data block includes a portion indicating the packaging employed for the corresponding payload portion and a portion indicating a length of the corresponding payload portion.
5. The system of claim 1 wherein the packaging employed for each payload portion includes a combination of forward error correction coding, modulation, and traffic symbol repetition rate.
6. The system of claim 1 , wherein the base station is further configured to receive from each subscriber station reports of its reception quality at agreed intervals.
7. The system of claim 1 , wherein the payload portion of each data block includes an identification of the intended recipient subscriber station.
8. A method for transmitting data from a base station to a plurality of subscriber stations using a radio signal, the radio signal including frames each having a same fixed duration and comprising a plurality of data blocks, each data block including a header and a corresponding payload portion having a length, the header including information required to recover the corresponding payload portion, and the method comprising:
receiving intermittent reports from each of the plurality of subscriber stations, each report including a reception quality of the respective subscriber station; and
packaging each data block individually for transmission to an intended recipient subscriber station including
packaging each payload portion in a manner that is a data rate efficient combination as determined according to a reception quality reported by the intended recipient subscriber station, and
packaging each header in a manner that is determined in accordance with an intention that the header be receivable by all subscriber stations that have at least a predetermined minimum reception quality.
9. The method of claim 8 wherein each data block contains a same preselected number of traffic symbols.
10. The method of claim 9 , wherein the step of packaging each data block individually for transmission further comprises processing header bits and payload information bits separately from each other and in parallel, the header being formed by first applying forward error correction coding to the header bits and then mapping the header bits onto traffic symbols, and the payload portion being formed by calculating a cyclic redundancy check (CRC) value for the payload information bits, applying forward error correction coding to the payload information bits and bits of the CRC value to produce coded bits, interleaving the coded bits to produce interleaved bits, mapping the interleaved bits into symbols using an M-ary modulation scheme while adding padding bits if the number of bits to be mapped is not divisible by log 2 (M), applying symbol repetition to the resulting symbols, padding the result of the symbol repetition with discontinuous transmission (DTx) padding symbols if necessary for the data block to contain the preselected number of traffic symbols, and interleaving the resulting traffic symbols.
11. The method of claim 8 wherein the header of each data block includes a portion indicating the packaging employed for the corresponding payload portion and a portion indicating a length of the corresponding payload portion.
12. The method of claim 8 wherein packaging each payload portion includes applying a combination of forward error correction coding, modulation, and traffic symbol repetition rate to that payload portion.
13. The method of claim 8 , wherein the step of receiving intermittent reports further comprises receiving the intermittent reports at predetermined intervals.
14. The method of claim 8 , wherein the payload portion of each data block includes an identification of the intended recipient subscriber station.