Method and apparatus for communications using turbo like codes

A method for performing data decoding comprising:

• obtaining soft channel metrics derived from a channel;
• and
• decoding the soft channel metrics using an outer soft-input-soft-output (SISO) decoder, an inner SISO decoder, a logical unit SISO decoder, an interleaver, and a de-interleaver to produce decoded soft outputs;
• wherein the logical unit SISO decoder receives a first number of soft inputs from an outer SISO decoder direction and produces a corresponding second number of soft outputs, the second number being less than the first number;
• and
• wherein the logical unit SISO decoder receives the second number of soft inputs from an inner SISO decoder direction and produces a corresponding first number of soft outputs.

An apparatus for performing data encoding comprising:

• an outer convolutional encoder capable of encoding data bits to produce outer encoded bits;
• an interleaver capable of processing data relating to the outer encoded bits to facilitate production of intermediate bits;
• a logical unit capable of processing data relating to the outer encoded bits to facilitate production of the intermediate bits, wherein the number of intermediate bits is less than the number of outer encoded bits;
• an inner convolutional encoder characterized by at least two states and capable of encoding the intermediate bits to produce inner encoded bits;
• and
• a combining unit capable of combining the data bits and the inner encoded bits to produce encoded outputs.

An apparatus for performing data decoding comprising:

• an outer soft-input-soft-output (SISO) decoder capable of processing soft channel metrics relating to data received from a channel;
• an interleaver coupled to the outer SISO decoder;
• a deinterleaver coupled to the outer SISO decoder;
• a logical unit SISO decoder coupled to the interleaver and the deinterleaver;
• and
• an inner SISO decoder coupled to the logical unit SISO decoder;
• wherein the outer SISO decoder, the interleaver, the deinterleaver, the logical unit SISO decoder, and the inner SISO decoder are capable of operating to decode the soft channel metrics to produce decoded soft outputs;
• wherein the logical unit SISO decoder in an outer SISO decoder direction is capable of receiving a first number of soft inputs and produces a corresponding second number of soft outputs, the second number being less than the first number;
• wherein the logical unit SISO decoder in an inner SISO decoder direction is capable of receiving the second number of soft inputs and produces a corresponding first number of soft outputs.

A system for performing data encoding comprising:

• means for encoding data bits according to an outer convolutional code to produce outer encoded bits;
• means for processing the outer encoded bits-to produce intermediate bits, wherein the number of intermediate bits is less than the number of outer encoded bits;
• means for encoding the intermediate bits according to an inner convolutional code to produce inner encoded bits, wherein the inner convolutional code is characterized by at least two states;
• and
• means for combining the data bits and the inner encoded bits to produce encoded outputs.

A system for performing data decoding comprising:

• means for obtaining soft channel metrics relating to data received from a channel;
• and
• means for decoding the soft channel metrics,
• wherein the means for decoding the soft channel metrics includes in an outer SISO decoder direction receiving a first number of soft inputs and producing a corresponding second number of soft outputs, the second number being less than the first number;
• and
• wherein the means for decoding the soft channel metrics includes in an inner SISO decoder direction receiving the second number of soft inputs and producing a corresponding first number of soft outputs.