High performance error control coding in channel encoders and decoders

A method of encoding a bitstream for transmission over a time division multiplexed radio channel, the radio channel being divided into a series of time slots and subject to fading, the method comprising the steps of:

• classifying incoming bits from the bitstream into at least three classes, which include a Class 1, a Class 2 and a Class 3;
• generating check bits using a nonlinear convolutional code for a subset of the incoming bits classified as Class 1 bits;
• encoding the Class 1 bits and the generated check bits using a first block encoder using a nonlinear block code (NBC);
• encoding the Class 2 bits using a second block encoder using an NBC;
• and
• interleaving the encoded and the nonencoded bits in an interleaving matrix over a plurality of time slots,
• wherein the first block encoder is a rate 8/16 NBC encoder and the second block encoder is a rate 8/14 NBC encoder.

A method of decoding a bitstream received from a time division multiplexed radio channel, the channel being divided into a series of time slots, the method comprising the steps of:

• receiving interleaved encoded and nonencoded bits;
• deinterleaving the received bits and placing them in a matrix array;
• extracting and classifying the deinterleaved bits into at least three classes, which include a Class 1, a Class 2 and a Class 3;
• classifying each decoded Class 1 bit into one of a plurality of subclasses, wherein a first subclass is designated as perceptually most significant bits (PMSBs) and a second subclass is designated as nonlinear convolutional code bits;
• using the PMSBs, generating check bits for the Class 1 bits classified in the PMSB subclass using a nonlinear convolutional code;
• comparing the generated check bits with the transmitted check bits;
• generating an error signal if the generated check bits are not equal to the transmitted check bits;
• decoding the Class 1 bits in a first nonlinear block decoder;
• decoding the Class 2 bits in a second nonlinear block decoder;
• and
• multiplexing the decoded and nonencoded bits into a frame.

A radio channel decoder for a time division multiplexed radio channel divided into a series of time slots and subject to fading comprising:

• a receiver receiving interleaved encoded and nonencoded bits and placing the received bits from at least two different time slots in a deinterleaving matrix array, the encoded and nonencoded bits corresponding to multiple distinct classes, bits of a most important one of said classes being referred to as Class 1 bits;
• a two slot deinterleaver extracting the encoded and nonencoded bits from the deinterleaving matrix array;
• a first block decoder decoding the Class 1 bits and any check bits applied to a subset of the Class 1 bits, the subset consisting of perceptually most significant bits (PMSBs) all of which were encoded using a nonlinear block code (NBC);
• a second block decoder decoding other encoded bits which were also encoded using an NBC;
• and
• a multiplexer combining the decoded Class 1 bits, other decoded bits, and nonencoded bits in a frame comprising a fixed number of data bits.