Reduced soft output information packet selection

A method of reducing a soft output information packet generated by a soft symbol output generator, said method comprising the steps of:

• pre-computing a symbol competitor table comprising the most likely symbol competitors for each possible symbol decision;
• looking up in said symbol competitor table, for each hard decision, the most likely symbol competitors corresponding to each of m bit positions;
• generating and outputting soft symbol decision values corresponding to each of said m symbol competitors;
• and
• wherein m is a positive integer.

A method of generating soft bit decisions from hard decisions for an M-ary symbol alphabet, said method comprising the steps of:

• pre-computing a symbol competitor table comprising the most likely symbol competitors for each possible symbol decision;
• looking up in said symbol competitor table, for each hard decision, the most likely symbol competitors corresponding to each of m bit positions;
• calculating soft output values corresponding to each symbol competitor;
• calculating a soft bit decision value for each of m bits as a function of the hard decision and the competitor symbols corresponding to the particular bit position;
• and
• wherein m and M are positive integers.

A communications receiver for receiving and decoding an M-ary transmitted signal, comprising:

• a radio frequency (RF) front end circuit for receiving and converting said M-ary transmitted signal to a baseband signal;
• a demodulator adapted to receive said baseband signal and to generate a received signal therefrom in accordance with the M-ary modulation scheme used to generate said transmitted signal;
• a first decoder operative to receive said received signal and to generate a sequence of soft symbol decisions therefrom;
• a soft output computation module comprising processing means programmed to:
• pre-compute a symbol competitor table comprising the most likely symbol competitors for each possible symbol decision;
• look up in said symbol competitor table, for each hard decision, the most likely symbol competitors corresponding to each of m bit positions;
• calculate soft output values corresponding to each symbol competitor;
• calculate a soft bit decision value for each of m bits as a function of the hard decision and the competitor symbols corresponding to the particular bit position;
• a second decoder adapted to receive said soft bit values and to generate binary received data therefrom;
• and
• wherein m and M are positive integers.

A computer readable storage medium having a computer program embodied thereon for causing a suitably programmed system to generate soft bit decisions from hard decisions by performing the following steps when such program is executed on said system:

• providing a symbol competitor table comprising the most likely symbol competitors for each possible symbol decision;
• looking up in said symbol competitor table, for each hard decision, the most likely symbol competitors corresponding to each of m bit positions;
• calculating soft output values corresponding to each symbol competitor;
• calculating a soft bit decision value for each of m bits as a function of the hard decision and the competitor symbols corresponding to the particular bit position;
• and
• wherein m is a positive integer.

A method of generating soft bit decisions from hard decisions for an M-ary symbol alphabet, said method comprising the steps of:

• generating a full soft information packet comprising a soft decision for each possible symbol in said alphabet;
• pre-computing a symbol competitor table comprising the most likely symbol competitors for each possible symbol decision;
• looking up in said symbol competitor table, for each hard decision, the most likely symbol competitors corresponding to each of q bit positions;
• calculating a soft bit decision value for each of q bits for the soft symbol decisions in a partial reduced soft information packet comprising soft symbol decisions corresponding to said most likely symbol competitors;
• and
• wherein q and M are positive integers.