초록 ▼

A method for synchronizing receivers that receive turbo encoded signals to a received signal. Turbo encoding may enable signals to be decoded at a much lower signal to noise ratio than previously practical. A traditional method of synchronizing a receiver to an incoming signal is to use a slicer to

A method for synchronizing receivers that receive turbo encoded signals to a received signal. Turbo encoding may enable signals to be decoded at a much lower signal to noise ratio than previously practical. A traditional method of synchronizing a receiver to an incoming signal is to use a slicer to determine a received symbol and then to compare the determined symbol to the incoming waveform, in order to adjust the phase of the slicer with respect to the incoming signal. At signal low levels, at which turbo encoded signals may be decoded, this slicing method may be prone to errors that may disrupt the synchronization of the receiver to the incoming signal. By replacing the slicer by a Viterbi decoder with zero traceback (i.e. one which does not consider future values of the signal only past values) a prediction as to what the incoming signal is can be made. Because the Viterbi decoder can consider past signal values it can predict the present symbol being received with higher reliability than by using a slicer, which considers only the present value of the incoming signal.

대표청구항 ▼

What is claimed is: 1. An apparatus, comprising: a first communication device that includes a turbo encoder having: a first trellis encoder that is operable to encode data thereby generating first encoded data; an interleaver that is operable to interleave the data thereby generating interleaved da

What is claimed is: 1. An apparatus, comprising: a first communication device that includes a turbo encoder having: a first trellis encoder that is operable to encode data thereby generating first encoded data; an interleaver that is operable to interleave the data thereby generating interleaved data; a second trellis encoder that is operable to encode the interleaved data thereby generating interleaved encoded data; an inverse interleaver that is operable to unscramble the interleaved encoded data that has been generated by the second trellis encoder thereby generating second encoded data; and a switch that is operable alternatively to select symbols from the first encoded data and the second encoded data; and a second communication device, coupled to the first communication device via a communication channel, that receives a signal that includes the first encoded data and the second encoded data and that includes a turbo decoder and a synchronization module that includes a Viterbi decoder, a phase detector, and a voltage controlled oscillator, wherein: the synchronization module is operable to recover a first symbol, a second symbol, and a third symbol from the signal; the first symbol is followed by the second symbol; the second symbol is followed by the third symbol; the Viterbi decoder operating with a zero traceback depth; and the turbo decoder that is operable to decode the first symbol, the second symbol, and the third symbol that are provided from the synchronization module to make best estimates of information bits encoded therein. 2. The apparatus of claim 1, further comprising: a multiplier, whose mixing frequency is governed by the voltage controlled oscillator, that is operable to multiply the signal by the mixing frequency to match a carrier frequency of the signal to assist in recovery of the first symbol, the second symbol, and the third symbol from the signal. 3. The apparatus of claim 1, wherein: the Viterbi decoder is operable to consider the first symbol when estimating the second symbol; and the Viterbi decoder is operable to consider the first symbol and the second symbol when estimating the third symbol. 4. The apparatus of claim 1, further comprising: a multiplier, whose mixing frequency is governed by the voltage controlled oscillator, that is operable to multiply the signal by the mixing frequency to match a carrier frequency of the signal to assist in recovery of the first symbol, the second symbol, and the third symbol from the signal; and wherein: the Viterbi decoder is operable to consider the first symbol and the second symbol when estimating the third symbol; and the phase detector is operable to employ at least one of the first symbol, the second symbol, and the third symbol to determine whether recovery of symbols from the signal, as performed by the synchronization module, is lagging or leading actual symbols within the signal and to adjust the voltage controlled oscillator based on any lagging or leading. 5. The apparatus of claim 1, further comprising: a multiplier, whose mixing frequency is governed by the voltage controlled oscillator, that is operable to multiply the signal by the mixing frequency to match a carrier frequency of the signal to assist in recovery of the first symbol, the second symbol, and the third symbol from the signal; and wherein: the Viterbi decoder is operable to consider the first symbol and the second symbol when estimating the third symbol; the phase detector is operable to employ at least one of the first symbol, the second symbol, and the third symbol to determine whether recovery of symbols from the signal, as performed by the synchronization module, is lagging or leading actual symbols within the signal and to adjust the voltage controlled oscillator based on any lagging or leading; and the adjustment of the voltage controlled oscillator is operable to make the mixing frequency to be substantially equal to the carrier frequency of the signal. 6. The apparatus of claim 1, further comprising: a multiplier, whose mixing frequency is governed by the voltage controlled oscillator, that is operable to multiply the signal by the mixing frequency to match a carrier frequency of the signal to assist in recovery of the first symbol, the second symbol, and the third symbol from the signal; and wherein: the third symbol output from the multiplier is provided simultaneously to both the Viterbi decoder and the phase detector; the Viterbi decoder is operable to consider the first symbol and the second symbol when estimating the third symbol; and the phase detector is operable to compare the third symbol output from the multiplier and the estimate of the third symbol as made by the Viterbi decoder to determine whether recovery of symbols from the signal, as performed by the synchronization module, is lagging or leading actual symbols within the signal and to adjust the voltage controlled oscillator based on any lagging or leading. 7. The apparatus of claim 1, wherein: the communication device is coupled to at least one additional communication device via the communication channel; the at least one additional communication device includes a turbo encoder that is operable to encode at least one information bit thereby generating at least one of the first symbol, the second symbol, and the third symbol of the signal; and the at least one additional communication device is operable to launch the signal into the communication channel. 8. The apparatus of claim 1, wherein: the Viterbi decoder successively processes each of the alternatively selected symbols. 9. The apparatus of claim 1, wherein: the signal is received by the second communication device; and the communication channel couples the second communication device to a relay satellite. 10. The apparatus of claim 1, wherein: the communication channel includes a relay satellite; the second communication device is a satellite communication receiver; and the first at least one additional communication device is a communication transmitter. 11. A method for processing a signal, the method comprising: performing first trellis encoding of data thereby generating first encoded data; interleaving the data thereby generating interleaved data; performing second trellis encoding of the interleaved data thereby generating interleaved encoded data; performing inverse interleaving to unscramble the interleaved encoded data thereby generating second encoded data; alternatively selecting symbols from the first encoded data and the second encoded data thereby generating a signal: launching the signal into the communication channel; receiving the signal from the communication channel; recovering a first symbol, a second symbol, and a third symbol from the signal by performing frequency mixing of the signal and subsequent Viterbi decoding and phase detection of symbols generated by the frequency mixing, wherein: the first symbol is followed by the second symbol; the second symbol is followed by the third symbol; the Viterbi decoding operating with a zero traceback depth; and employing a turbo decoder to decode the first symbol, the second symbol, and the third symbol that are recovered from the signal to make best estimates of information bits encoded therein. 12. The method of claim 11, further comprising: multiplying the signal by a mixing frequency to match a carrier frequency of the signal to assist in recovery of the first symbol, the second symbol, and the third symbol from the signal. 13. The method of claim 11, wherein: when performing Viterbi decoding, considering the first symbol when estimating the second symbol; and when performing Viterbi decoding, considering the first symbol and the second symbol when estimating the third symbol. 14. The method of claim 11, further comprising: multiplying the signal by a mixing frequency to match a carrier frequency of the signal to assist in recovery of the first symbol, the second symbol, and the third symbol from the signal; when performing Viterbi decoding, considering the first symbol and the second symbol when estimating the third symbol; employing at least one of the first symbol, the second symbol, and the third symbol when performing phase detection to determine whether recovery of symbols from the signal is lagging or leading actual symbols within the signal; and adjusting the mixing frequency based on any lagging or leading. 15. The method of claim 11, further comprising: multiplying the signal by a mixing frequency to match a carrier frequency of the signal to assist in recovery of the first symbol, the second symbol, and the third symbol from the signal; when performing Viterbi decoding, considering the first symbol and the second symbol when estimating the third symbol; employing at least one of the first symbol, the second symbol, and the third symbol when performing phase detection to determine whether recovery of symbols from the signal is lagging or leading actual symbols within the signal; adjusting the mixing frequency based on any lagging or leading; and wherein: the adjustment of the mixing frequency is operable to make the mixing frequency to be substantially equal to the carrier frequency of the signal. 16. The method of claim 11, further comprising: multiplying the signal by a mixing frequency to match a carrier frequency of the signal to assist in recovery of the first symbol, the second symbol, and the third symbol from the signal; simultaneously providing the third symbol for use in Viterbi decoding and phase detection; when performing Viterbi decoding, considering the first symbol and the second symbol when estimating the third symbol; when performing phase detection, comparing the third symbol output from the multiplying and the estimate of the third symbol as made in accordance with Viterbi decoding to determine whether recovery of symbols from the signal is lagging or leading actual symbols within the signal; and adjusting the mixing frequency based on any lagging or leading. 17. The method of claim 11, wherein: the method is performed in a first communication device and a second communication device; the first communication device is coupled to the second communication device via the communication channel; the first communication device includes a turbo encoder that is operable to encode at least one information bit thereby generating at least one of the first symbol, the second symbol, and the third symbol of the signal; and the first communication device is operable to launch the signal into the communication channel. 18. The method of claim 11, wherein: when performing Viterbi decoding, successively processing each of the alternatively selected symbols. 19. The method of claim 11, wherein: the method is performed in at least one communication device. 20. The method of claim 11, wherein: the method is performed in a first communication device and a second communication device; the first communication device is coupled to the second at least one additional communication device via the communication channel; the communication channel includes a relay satellite; the second communication device is a satellite communication receiver; and the first communication device is a communication transmitter. 21. An apparatus, comprising: a first communication device that includes a turbo encoder having: a first trellis encoder that is operable to encode data thereby generating first encoded data; an interleaver that is operable to interleave the data thereby generating interleaved data; a second trellis encoder that is operable to encode the interleaved data thereby generating interleaved encoded data; an inverse interleaver that is operable to unscramble the interleaved encoded data that has been generated by the second trellis encoder thereby generating second encoded data; and a switch that is operable alternatively to select symbols from the first encoded data and the second encoded data; and a second communication device, coupled to the first communication device via a communication channel, that receives a signal that includes the first encoded data and the second encoded data and that includes a turbo decoder, a multiplier, and a synchronization module, wherein: the multiplier is operable to multiply the signal by a mixing frequency to match a carrier frequency of the signal to assist in recovery of a first symbol, a second symbol, and a third symbol from the signal; the synchronization module includes a Viterbi decoder, a phase detector, and a voltage controlled oscillator, wherein: the Viterbi decoder and the phase detector each receive the mixed signal output from the multiplier; the synchronization module is operable to recover the first symbol, the second symbol, and the third symbol from the signal; the first symbol is followed by the second symbol; the second symbol is followed by the third symbol; the mixing frequency of the multiplier is governed by the voltage controlled oscillator; and the Viterbi decoder operating with a zero traceback depth; and the turbo decoder is operable to decode the first symbol, the second symbol, and the third symbol that are provided from the synchronization module to make best estimates of information bits encoded therein. 22. The apparatus of claim 21, wherein: the Viterbi decoder is operable to consider the first symbol when estimating the second symbol; and the Viterbi decoder is operable to consider the first symbol and the second symbol when estimating the third symbol. 23. The apparatus of claim 21, wherein: the Viterbi decoder is operable to consider the first symbol and the second symbol when estimating the third symbol; and the phase detector is operable to employ at least one of the first symbol, the second symbol, and the third symbol to determine whether recovery of symbols from the signal, as performed by the synchronization module, is lagging or leading actual symbols within the signal and to adjust the voltage controlled oscillator based on any lagging or leading. 24. The apparatus of claim 21, wherein: the Viterbi decoder is operable to consider the first symbol and the second symbol when estimating the third symbol; the phase detector is operable to employ at least one of the first symbol, the second symbol, and the third symbol to determine whether recovery of symbols from the signal, as performed by the synchronization module, is lagging or leading actual symbols within the signal and to adjust the voltage controlled oscillator based on any lagging or leading; and the adjustment of the voltage controlled oscillator is operable to make the mixing frequency to be substantially equal to the carrier frequency of the signal. 25. The apparatus of claim 21, wherein: the third symbol output from the multiplier is provided simultaneously to both the Viterbi decoder and the phase detector; the Viterbi decoder is operable to consider the first symbol and the second symbol when estimating the third symbol; and the phase detector is operable to compare the third symbol output from the multiplier and the estimate of the third symbol as made by the Viterbi decoder to determine whether recovery of symbols from the signal, as performed by the synchronization module, is lagging or leading actual symbols within the signal and to adjust the voltage controlled oscillator based on any lagging or leading. 26. The apparatus of claim 21, wherein: the first communication device is coupled to the second communication device via the communication channel; the first at least one additional communication device includes a turbo encoder that is operable to encode at least one information bit thereby generating at least one of the first symbol, the second symbol, and the third symbol of the signal; and the first communication device is operable to launch the signal into the communication channel. 27. The apparatus of claim 21, wherein: the Viterbi decoder successively processes each of the alternatively selected symbols. 28. The apparatus of claim 21, wherein: the signal is received by the second communication device; and the communication channel couples the second communication device to a relay satellite. 29. The apparatus of claim 21, wherein: the communication channel includes a relay satellite; the second communication device is a satellite communication receiver; and the first communication device is a communication transmitter. 30. A method for processing a signal, the method comprising: performing first trellis encoding of data thereby generating first encoded data; interleaving the data thereby generating interleaved data; performing second trellis encoding of the interleaved data thereby generating interleaved encoded data; performing inverse interleaving to unscramble the interleaved encoded data thereby generating second encoded data; alternatively selecting symbols from the first encoded data and the second encoded data thereby generating a signal; launching the signal into the communication channel; receiving the signal from the communication channel; recovering a first symbol, a second symbol, and a third symbol from the signal from the signal by multiplying the signal by a mixing frequency to match a carrier frequency of the signal and subsequent Viterbi decoding and phase detection of symbols generated by the frequency mixing, wherein: the multiplied signal is simultaneously provided for Viterbi decoding and phase detection; the first symbol is followed by the second symbol; the second symbol is followed by the third symbol; the Viterbi decoding operating with a zero traceback depth; and when performing Viterbi decoding, considering the first symbol when estimating the second symbol; when performing Viterbi decoding, considering the first symbol and the second symbol when estimating the third symbol; and employing a turbo decoder to decode the first symbol, the second symbol, and the third symbol that are recovered from the signal to make best estimates of information bits encoded therein. 31. The method of claim 30, further comprising: employing at least one of the first symbol, the second symbol, and the third symbol when performing phase detection to determine whether recovery of symbols from the signal is lagging or leading actual symbols within the signal; and adjusting the mixing frequency based on any lagging or leading. 32. The method of claim 30, further comprising: employing at least one of the first symbol, the second symbol, and the third symbol when performing phase detection to determine whether recovery of symbols from the signal is lagging or leading actual symbols within the signal; adjusting the mixing frequency based on any lagging or leading; and wherein: the adjustment of the mixing frequency is operable to make the mixing frequency to be substantially equal to the carrier frequency of the signal. 33. The method of claim 30, further comprising: when performing phase detection, comparing the third symbol output from the multiplying and the estimate of the third symbol as made in accordance with Viterbi decoding to determine whether recovery of symbols from the signal is lagging or leading actual symbols within the signal; and adjusting the mixing frequency based on any lagging or leading. 34. The method of claim 30, wherein: the method is performed in a first communication device and a second communication device; the first communication device is coupled to the communication device via the communication channel; the first communication device includes a turbo encoder that is operable to encode at least one information bit thereby generating at least one of the first symbol, the second symbol, and the third symbol of the signal; and the first communication device is operable to launch the signal into the communication channel. 35. The method of claim 30, wherein: when performing Viterbi decoding, successively processing each of the alternatively selected symbols. 36. The method of claim 30, wherein: the method is performed in at least one communication device. 37. The method of claim 30, wherein: the method is performed in a first communication device and a second communication device; the first communication device is coupled to the second at least one additional communication device via the communication channel; the communication channel includes a relay satellite; the second communication device is a satellite communication receiver; and the first communication device is a communication transmitter. 38. An apparatus, comprising: a first communication device that includes a turbo encoder having: a first trellis encoder that is operable to encode data thereby generating first encoded data; an interleaver that is operable to interleave the data thereby generating interleaved data; a second trellis encoder that is operable to encode the interleaved data thereby generating interleaved encoded data; an inverse interleaver that is operable to unscramble the interleaved encoded data that has been generated by the second trellis encoder thereby generating second encoded data; and a switch that is operable alternatively to select symbols from the first encoded data and the second encoded data; and a second communication device, coupled to the first communication device via a communication channel, that receives a signal that includes the first encoded data and the second encoded data and that includes a turbo decoder, a multiplier, and a synchronization module, wherein: the multiplier is operable to multiply the signal by a mixing frequency to match a carrier frequency of the signal to assist in recovery of a first symbol, a second symbol, and a third symbol from the signal; the synchronization module includes a Viterbi decoder, a phase detector, and a voltage controlled oscillator, wherein: the Viterbi decoder and the phase detector each receive the mixed signal output from the multiplier; the synchronization module is operable to recover the first symbol, the second symbol, and the third symbol from the signal; the first symbol is followed by the second symbol; the second symbol is followed by the third symbol; the mixing frequency of the multiplier is governed by the voltage controlled oscillator; the Viterbi decoder is operable to consider the first symbol when estimating the second symbol; the Viterbi decoder is operable to consider the first symbol and the second symbol when estimating the third symbol; the Viterbi decoder operating with a zero traceback depth; and the phase detector is operable to employ at least one of the first symbol, the second symbol, and the third symbol to determine whether recovery of symbols from the signal, as performed by the synchronization module, is lagging or leading actual symbols within the signal and to adjust the voltage controlled oscillator based on any lagging or leading; and the turbo decoder is operable to decode the first symbol, the second symbol, and the third symbol that are provided from the synchronization module to make best estimates of information bits encoded therein. 39. The apparatus of claim 38, wherein: the adjustment of the voltage controlled oscillator is operable to make the mixing frequency to be substantially equal to the carrier frequency of the signal. 40. The apparatus of claim 38, wherein: the third symbol output from the multiplier is provided simultaneously to both the Viterbi decoder and the phase detector. 41. The apparatus of claim 38, wherein: the communication device is coupled to at least one additional communication device via the communication channel; the at least one additional communication device includes a turbo encoder that is operable to encode at least one information bit thereby generating at least one of the first symbol, the second symbol, and the third symbol of the signal; and the at least one additional communication device is operable to launch the signal into the communication channel. 42. The apparatus of claim 38, wherein: the Viterbi decoder successively processes each of the alternatively selected symbols. 43. The apparatus of claim 38, wherein: the signal is received by the second communication device; the communication channel couples the second communication device to a relay satellite. 44. The apparatus of claim 38, wherein: the communication channel includes a relay satellite; the second communication device is a satellite communication receiver; and the first communication device is a communication transmitter. 45. A method for processing a signal, the method comprising: performing first trellis encoding of data thereby generating first encoded data; interleaving the data thereby generating interleaved data; performing second trellis encoding of the interleaved data thereby generating interleaved encoded data; performing inverse interleaving to unscramble the interleaved encoded data thereby generating second encoded data; alternatively selecting symbols from the first encoded data and the second encoded data thereby generating a signal; launching the signal into the communication channel; receiving the signal from the communication channel; recovering a first symbol, a second symbol, and a third symbol from the signal from the signal by multiplying the signal by a mixing frequency to match a carrier frequency of the signal and subsequent Viterbi decoding and phase detection of symbols generated by the frequency mixing, wherein: the multiplied signal is simultaneously provided for Viterbi decoding and phase detection; the first symbol is followed by the second symbol; the second symbol is followed by the third symbol; the phase detection involves employing at least one of the first symbol, the second symbol, and the third symbol to determine whether recovery of symbols from the signal is lagging or leading actual symbols within the signal and adjusting the mixing frequency based on any lagging or leading; and the Viterbi decoding operating with a zero traceback depth; and when performing Viterbi decoding, considering the first symbol when estimating the second symbol; when performing Viterbi decoding, considering the first symbol and the second symbol when estimating the third symbol; and employing a turbo decoder to decode the first symbol, the second symbol, and the third symbol that are recovered from the signal. 46. The method of claim 45, wherein: the adjustment of the mixing frequency is operable to make the mixing frequency to be substantially equal to the carrier frequency of the signal. 47. The method of claim 45, further comprising: when performing phase detection, comparing the third symbol output from the multiplying and the estimate of the third symbol as made in accordance with Viterbi decoding to determine whether recovery of symbols from the signal is lagging or leading actual symbols within the signal. 48. The method of claim 45, wherein: the method is performed in a first communication device and a second communication device; the first communication device is coupled to the second communication device via the communication channel; the first communication device includes a turbo encoder that is operable to encode at least one information bit thereby generating at least one of the first symbol, the second symbol, and the third symbol of the signal; and the first communication device is operable to launch the signal into the communication channel. 49. The method of claim 45, wherein: when performing Viterbi decoding, successively processing each of the alternatively selected symbols. 50. The method of claim 45, wherein: the method is performed in at least one communication device. 51. The method of claim 45, wherein: the method is performed in a first communication device and a second communication device; the first communication device is coupled to the second communication device via the communication channel; the communication channel includes a relay satellite; the second communication device is a satellite communication receiver; and the first communication device is a communication transmitter. 52. An apparatus, comprising: a first communication device that includes a turbo encoder having: a first trellis encoder that is operable to encode data thereby generating first encoded data; an interleaver that is operable to interleave the data thereby generating interleaved data; a second trellis encoder that is operable to encode the interleaved data thereby generating interleaved encoded data; an inverse interleaver that is operable to unscramble the interleaved encoded data that has been generated by the second trellis encoder thereby generating second encoded data; and a switch that is operable alternatively to select symbols from the first encoded data and the second encoded data; and a second communication device, coupled to the first communication device via a communication channel, that receives a signal that includes the first encoded data and the second encoded data and that includes a turbo decoder, a multiplier, and a synchronization module, wherein: the multiplier is operable to multiply the signal by a mixing frequency to match a carrier frequency of the signal to assist in recovery of a first symbol, a second symbol, and a third symbol from the signal; the synchronization module includes a Viterbi decoder, a phase detector, and a voltage controlled oscillator, wherein: the Viterbi decoder and the phase detector each receive the mixed signal output from the multiplier; the output of the Viterbi decoder is provided to the phase detector; the synchronization module is operable to recover the first symbol, the second symbol, and the third symbol from the signal such that the first symbol is followed by the second symbol and the second symbol is followed by the third symbol; the Viterbi decoder is operable to consider the first symbol when estimating the second symbol; the Viterbi decoder is operable to consider the first symbol and the second symbol when estimating the third symbol; the Viterbi decoder operating with a zero traceback depth; the phase detector is operable to employ at least one of the first symbol, the second symbol, and the third symbol to determine whether recovery of symbols from the signal, as performed by the synchronization module, is lagging or leading actual symbols within the signal and to adjust the voltage controlled oscillator based on any lagging or leading; and the adjustment of the mixing frequency by the voltage controlled oscillator is operable to make the mixing frequency to be substantially equal to the carrier frequency of the signal; and the turbo decoder is operable to decode the first symbol, the second symbol, and the third symbol that are provided from the synchronization module to make best estimates of information bits encoded therein. 53. The apparatus of claim 52, wherein: the first communication device is coupled to the second communication device via the communication channel; the first communication device includes a turbo encoder that is operable to encode at least one information bit thereby generating at least one of the first symbol, the second symbol, and the third symbol of the signal; and the first communication device is operable to launch the signal into the communication channel. 54. The apparatus of claim 52, wherein: the signal is received by the second communication device; the communication channel couples the second communication device to a relay satellite.