Broadband satellite system for the simultaneous reception of multiple channels using shared iterative decoder
View Patent ↗Multiple channels of received data are processed by a multiple channel demodulation and error correction decoding engine. The statistical uncertainty of processing channels with an iterative decoder are averaged across all the channels to reduce the total processing power required of the decoding engine compared to processing each channel with a separate engine. A set of input buffers holds blocks of data for each channel needing decoding. A quality measure is computed on each input block to set the priority and iteration allocation of decoding in the common decoder. The input RF signal is digitized by a broadband tuner that processes some or all of the channels to feed the multiple channel demodulator and decoder. Multiple decoded video data streams are output.
1. A method of processing a plurality of satellite channels that are coded with error correction coding, the method comprising:
selecting the channels for processing using a tuner;
demodulating the channels to produce soft decision channel data streams;
storing each channel data stream in an input buffer;
measuring the quality of each channel signal;
estimating required decoder iterations for each channel using the quality measurement;
scheduling iterative decoder operations based on the required decoder iterations for each channel;
decoding the channel data steams by reading channel data streams from the input buffers and sequentially decoding each stream using at least one iterative decoder engine; and
storing the decoded channel data streams in an output buffer.
2. The method of claim 1 further comprising setting a limit to the number of iterations preformed by the decoder for each channel data stream based on the quality measured.
3. The method of claim 1 further comprising a plurality of iterative decoder engines wherein the number of decoder engines are smaller than the number of channels, wherein sequential blocks of data are read from the input buffers and decoded one block per available decoder engine.
4. The method of claim 1 wherein selecting the channel signals is performed with at least one broadband tuner, where the number of tuners is smaller than the number of selected channels.
5. The method of claim 1 where the quality measure is related to signal to noise ratio (SNR) of the channel signal, where channels are decoded in order of SNR and the highest SNR channel is decoded first.
6. The method of claim 1 where the quality measure is related to signal to noise ratio (SNR) of the channel signal where the channel requiring the fewest decoder iterations is decoded first.
7. The method of claim 1 where the quality measure is related to signal to noise ratio of the channel signal (SNR) where channels with SNR below a predetermined level are not decoded.
8. The method of claim 1 where the quality measure is related to signal to noise ratio of the channel signal (SNR) where channels with SNR below a predetermined level are not decoded and the channels are decoded in order of SNR and the lowest SNR channel is decoded first.
9. The method of claim 1 where a demodulating unit capable of demodulating more than one channel is employed.
10. The method of claim 2 further using a stopping criterion to stop the decoding before the limit is reached, where the stopping criteria indicates acceptable decoded data.
11. The method of claim 1 where:
the tuner selects at least two channels to produce a tuner output signal;
at least one analog to digital converter (A/D) digitizes the tuner output signal; and
a digital processor receives the A/Ds samples and demodulates the channels.
12. A multi-channel iterative decoder for processing data from a plurality of digital channels comprising:
a plurality of input buffers, each buffer capable of storing data from at least one digital channel data;
a selector to select data from one input buffer;
an iterative decoder coupled to the selector for accepting data from an input buffer, the iterative decoder performing error correction decoding on the digital data;
a controller operatively coupled to the selector and iterative decoder to schedule decoder operations on the data accepted from an input buffer;
an input module for determining digital channel data signal quality and communicating the determination to the controller for use in selecting and scheduling iterative decoder operations; and
an output module to store and format decoded data;
whereby digital data from a plurality of channels is decoded using the shared resource of the iterative decoder.
13. The multi-channel iterative decoder of claim 12 wherein the controller schedules decoder operations by scheduling the best signal quality channel first.
14. The multi-channel iterative decoder of claim 12 wherein the controller schedules decoder operations by scheduling the worth signal quality channel first while excluding channels with a signal quality below a level that decoding does not recover data.
15. The multi-channel iterative decoder of claim 12 wherein the signal quality is related to signal to noise ratio.