Method and device for signal decision, receiver and channel condition estimating method for a coding communication system

A signal decision device for a coding communication system and for identifying a code rate of a received signal encoded at any one of a plurality of code rates including a convolutional code rate and received on a channel, said device comprising:

• a plurality of Viterbi decoding means for respectively performing trellis tracings with said received signal in accordance with the plurality of code rates to thereby decode said received signal to a plurality of signals each having a particular code rate;
• a plurality of re-encoding means for respectively re-encoding said plurality of signals output from said plurality of Viterbi decoding means to corresponding convolutional codes;
• and
• a plurality of decision means for respectively performing signal decisions based on said convolutional codes output from said plurality of re-encoding means and said received signal;
• wherein said plurality of decision means respectively receive re-encoded symbol sequences from said plurality of re-encoding means and a received symbol sequence input to said plurality of Viterbi decoding means, multiply said re-encoded symbol sequences by a constant to produce products, produce differences between said products and the received symbol sequence, square said differences to produce squares, totalize said squares to produce totals, determine a smallest total of the totals produced, and estimate channel conditions of the channel based on said smallest total to thereby determine which of said plurality of signals output from said plurality of Viterbi decoding means is correct.

A signals deciding method for a coding communication system and for identifying a code rate of a received signal encoded at any one of a plurality of code rates including a convolutional code rate, said method comprising the step of:

• (a) performing trellis tracings with said received signal in accordance with the plurality of code rates to thereby decode said received signal to a plurality of signals having a particular code rate;
• (b) sequentially receiving a plurality of path metrics sequentially detected by the trellis tracings in step (a), and sequentially breaking off the trellis tracings of, among said plurality of path metrics unlikely paths to thereby detect M most probable paths over at least two of said trellis tracings, where M is a natural number;
• and
• (c) executing a final decision with path metrics of said M paths detected in step (b) to thereby identify the code rate of said received signal.

A channel condition estimating method for estimating channel conditions of a channel in the event of identification of a code rate of a received signal encoded at any one of a plurality of code rates including a convolutional code rate and received on the channel, said method comprising the steps of:

• (a) executing trellis tracings each corresponding to one of the plurality of code rates to thereby decode said received signal to a plurality of signals each having a particular code rate;
• (b) detecting path metrics of last stages of paths surviving after the trellis tracings;
• and
• (c) determining error probabilities of said plurality of signals output in step (a) by using said path metrics as indexes to thereby estimate the channel conditions.

A channel condition estimating method for estimating channel conditions of a channel in the event of identification of a code rate of a received signal encoded at any one of a plurality of code rates including a convolutional code rate and received on the channel, for thereby executing a signal decision, said method comprising the steps of:

• (a) executing trellis tracings each corresponding to one of the plurality of code rates to thereby decode said received signal to a plurality of signals each having a particular code rate;
• (b) re-encoding said plurality of signals produced in step (a) to output corresponding convolutional codes;
• and
• (c) executing a signal decision on the basis of said convolutional codes produced in step (b) and said received signal;
• wherein step (c) comprises (d) multiplying symbol sequences of said convolutional codes output in step (b) by a constant to produce products, producing differences between said products and a symbol sequence of said received signal, squaring said differences to produce squares, totalizing said squares to produce totals, determining a smallest total of the totals produced, and determining error probabilities of said convolutional codes on the basis of said smallest total to thereby estimate the channel conditions.

A receiver for a coding communication and for identifying a code rate of a received signal encoded at any one of a plurality of code rates including a convolutional code rate, said receiver comprising:

• a plurality of Viterbi decoding means for respectively performing trellis tracings with said received signal in accordance with the plurality of code rates to thereby decode said received signal to a plurality of signals each having a particular code rate;
• an M break-off means for sequentially receiving a plurality of path metrics sequentially detected by said plurality of Viterbi decoding means during the trellis tracings, and sequentially breaking off the trellis tracings of, among said plurality of path metrics, unlikely paths to thereby detect M most probable paths over at least two of said plurality of Viterbi decoding means, where M is a natural number;
• and
• a decision means for executing a final decision with the path metrics of said M paths, and tracing back a path corresponding to a result of said final decision to thereby output decoded bits.

A receiver for a coding communication system and for identifying a code rate of a received signal encoded at any one of a plurality of code rates including a convolutional code rate, said device comprising:

• a plurality of soft output Viterbi decoding means for respectively performing trellis tracings with the received signal in accordance with the plurality of code rates to thereby decode the received signal to a plurality of signals each having a particular rate, and for outputting together with said plurality of signals reliability information representative of likelihood of said plurality of signals;
• a decision means for determining, based on said reliability information received from said plurality of soft output Viterbi decoding means, which of said plurality of signals is correct;
• and
• a selecting means for selecting one of said plurality of signals on the basis of a result of decision of said decision means.

A receiver for a coding communication system and for identifying a code rate of a received signal encoded at any one of a plurality of code rates including a convolutional code rate and received on a channel, said device comprising:

• a plurality of Viterbi decoding means for respectively performing trellis tracing with said received signal in accordance with a plurality of code rates to thereby decode said received signal to a plurality of signals each having a particular code rate;
• a decision means for receiving path metrics of last states of paths surviving after the trellis tracings performed by said plurality of Viterbi decoding means, and estimating channel condition of the channel based on said path metrics to thereby determine which of said plurality of signals output from said plurality of Viterbi decoding means is correct;
• and
• a selecting means for selecting one of said plurality of signals on the basis of a result of decision of said decision means.

A receiver for a coding communication system and for identifying a code rate of received signal encoded at any one of a plurality of code rates including a convolutional code rate and received on a channel, said device comprising:

• a plurality of Viterbi decoding means for respectively performing trellis tracings with said received signal in accordance with the plurality of code rates to thereby decode said received signal to a plurality of signals each having a particular code rate;
• a plurality of re-encoding means for respectively re-encoding said plurality of signals output from said plurality of Viterbi decoding means to corresponding convolutional codes;
• a plurality of decision means for respectively performing signal decisions on the basis of said convolutional codes output from said plurality of re-encoding means and the said received signal;
• and
• a selecting means for selecting one of said plurality of signals output from said plurality of Viterbi decoding means on the basis of results of decisions of said plurality of decision means;
• wherein said plurality of decision means respectively receive re-encoded symbol sequences from the respective re-encoding means and a received symbol sequence input to the respective Viterbi decoding means, multiply said re-encoded symbol sequences by a constant to produce products, produce differences between said products and the received symbol sequence, square said differences to produce squares, totalize said squares to produce totals, determine a smallest total of the totals produced, and estimate channel conditions of the channel based on said smallest total to thereby determine which of said plurality of signals output from said plurality of Viterbi decoding means is correct.