Receiver for receiving data in a broadcast system using redundancy data
A receiver for receiving data in a broadcast system includes a broadcast receiver that receives, via the broadcast system, a receiver input data stream including plural channel symbols represented by constellation points in a constellation diagram. A demodulator demodulates the channel symbols into codewords and a decoder decodes the codewords into output data words. A broadband receiver obtains redundancy data via a broadband system, the redundancy data for a channel symbol including one or more least robust bits of the channel symbol or a constellation subset identifier indicating a subset of constellation points including the constellation point representing the channel symbol. The demodulator and/or the decoder is configured to use the redundancy data to demodulate the respective channel symbol and to decode the respective codeword, respectively.
1. A receiver device for receiving data, comprising:
a first receiver configured to receive an input data stream received from an Orthogonal Frequency Division Multiplexing (OFDM) broadcast, via a first input interface, the input data stream comprising a plurality of channel symbols represented by Quadrature Amplitude Modulation (QAM) constellation points in a constellation diagram from a first network;
a demodulator configured to demodulate said channel symbols into codewords;
a decoder configured to attempt Forward Error Correction (FEC) decoding of the codewords and to determine success of the FEC decoding and, if success is determined, to output decoded data, the FEC decoding including a Low Density Parity Check (LDPC) decoding;
a second receiver configured to obtain redundancy data via a second input interface from a second network which is different to the first network, if the decoder is unsuccessful in performing FEC decoding;
wherein the decoder is further configured to determine the positions of the redundancy data with respect the codewords and output decoded data from a combination of the redundancy data and codewords derived from the input data stream.
2. The receiver device as claimed in claim 1 , wherein the decoder is configured to attempt Forward Error Correction (FEC) decoding of the codewords using further information associated with the codeword.
3. The receiver device as claimed in claim 2 , wherein the further information associated with the codeword is received via the first receiver.
4. The receiver device as claimed in claim 2 , wherein the further information associated with the codeword is received via the first receiver as broadcast information.
5. The receiver device as claimed in claim 1 , wherein the first receiver is a broadcast receiver and the second receiver is a broadband receiver.
6. The receiver device as claimed in claim 1 , wherein the redundancy data is signaled to the receiver device as an application layer service.
7. The receiver device as claimed in claim 1 , wherein the second receiver is configured to first request specific redundancy data before obtaining the redundancy data.
8. The receiver device as claimed in claim 7 , wherein the redundancy data requested corresponds to specific bit positions in the input data stream.
9. The receiver device as claimed in claim 7 , wherein the redundancy data requested corresponds to specific positions amongst the codewords.
10. The receiver device as claimed in claim 7 , wherein the second receiver is configured to request an amount of redundancy data required to successfully decode codewords demodulated by the demodulator.
11. The receiver device as claimed in claim 7 , wherein the second receiver is configured to request an amount of redundancy data required to successfully decode the input data stream, the input data stream having been broadcast to the receiver device.
12. The receiver device as claimed in claim 1 , wherein the decoder is configured to determine the positions of the redundancy data as bits with respect to the codewords.
13. The receiver device as claimed in claim 1 , wherein the decoder is configured to determine the positions of the redundancy data as bits within a codeword.
14. The receiver device as claimed in claim 1 , wherein the redundancy data is received as unicast data.
15. A terrestrial television device comprising the receiver device as claimed in claim 1 .
16. A method comprising:
receiving an input data stream received from an Orthogonal Frequency Division Multiplexing (OFDM) broadcast, via a first input interface, the input data stream comprising a plurality of channel symbols represented by Quadrature Amplitude Modulation (QAM) constellation points in a constellation diagram from a first network;
demodulating said channel symbols into codewords;
attempting Forward Error Correction (FEC) decoding of the codewords and determining success of the FEC decoding and, if success is determined, outputting decoded data, the FEC decoding including a Low Density Parity Check (LDPC) decoding;
obtaining redundancy data via a second input interface from a second network which is different to the first network, if FEC decoding is unsuccessful; and
determining the positions of the redundancy data with respect the codewords and output decoded data from a combination of the redundancy data and codewords derived from the input data stream.
17. The method as claimed in claim 16 , comprising attempting Forward Error Correction (FEC) decoding of the codewords using further information associated with the codeword.
18. The method as claimed in claim 16 , comprising receiving the input data stream via broadcast and obtaining the redundancy data via broadband.
19. The method as claimed in claim 16 , comprising receiving signalling information indicating the redundancy information is an application layer service.
20. The method as claimed in claim 16 , comprising request an amount of redundancy data required to successfully decode the input data stream received via broadcast.
21. The method as claimed in claim 16 , comprising determining the positions of the redundancy data as bits with respect to the codewords.