Multirate serial viterbi decoder for code division multiple access system applications

A method of providing decoded bit data in response to a transmission of code symbol data which represents original bit data having a data rate R.sub.i, where R.sub.i is one data rate of two or more predetermined original bit data rates, the method being executable using a decoder apparatus including an input buffer, a convolutional decoder, and an output buffer, the method including the steps of:

• transmitting said code symbol data in frames of predetermined time duration wherein the transition between each said successive frame of said code symbol data is forced to a predetermined state;
• receiving and storing successive portions of said transmission of said code symbol data in said input buffer;
• and
• decoding any portion of said successive portions in said convolutional decoder in two or more passes to obtain two or more packets {P.sub.i } of decoded bit data, each packet P.sub.i being decoded during a respective pass of said two or more passes, each packet P.sub.i including:
• decoded bit data I.sub.i corresponding to original bit data having said data rate R.sub.i ;
• and
• quality metric data Q.sub.i representing symbol error conditions in said any portion and data error conditions in said decoded bit data;
• and storing said two or more packets in said output buffer,
• wherein said code symbol data representing said original bit data encoded according to a coding algorithm, the method further including the steps of
• recoding each of said at least two decoded bit data packets {P.sub.i } according to said coding algorithm to create a packet of local code symbol data (L.sub.i);
• comparing said code symbol data with each of said at least two local code symbol data packets {L.sub.i } to produce a qualitative measure (Q.sub.i) of the number of differences there between;
• and
• storing at least two qualitative measures {Q.sub.i } in said output data buffer.

A method of providing decoded bit data in response to a transmission of code symbol data which represents original bit data having a data rate R.sub.i, where R.sub.i is one data rate of two or more predetermined original bit data rates, the method being executable using a decoder apparatus including an input buffer, a convolutional decoder, and an output buffer, the method including the steps of:

• transmitting said code symbol data in frames of predetermined time duration wherein the transition between each said successive frame of said code symbol data is forced to a predetermined state;
• receiving and storing successive portions of said transmission of said code symbol data in said input buffer;
• and
• decoding any portion of said successive portions in said convolutional decoder in two or more passes to obtain two or more packets {P.sub.i } of decoded bit data, each packet P.sub.i being decoded during a respective pass of said two or more passes, each packet P.sub.i including:
• decoded bit data I.sub.i corresponding to original bit data having said data rate R.sub.i ;
• and
• quality metric data Q.sub.i representing symbol error conditions in said any portion and data error conditions in said decoded bit data;
• and storing said two or more packets in said output buffer,
• wherein frames of data having a first bit data rate include packets of encoded data bits, each packet including cyclic redundancy check bits, the method comprising the additional unordered steps of:
• determining an error rate for said packets of data bits using said cyclic redundancy check bits;
• producing a qualitative measure (Q.sub.i) indicating said error rate;
• and
• storing at least two qualitative measures {Q.sub.i } in said output buffer.

In a communication system in which original bit data, provided at one of a first plurality of predetermined original bit data rates {R.sub.i }, is encoded to provide code symbol data, and wherein said code symbol data is provided in frames comprising code symbol data when said original bit rate is less than a predetermined maximum data rate and wherein said frames comprise said first version of said coded symbol data when said original bit rate is said predetermined maximum data rate, a method for decoding said code symbol data comprising the steps of:

• (a) receiving and storing code symbol data in an input data buffer;
• (b) decoding said code symbol data in at least two passes to create in each pass a packet (P.sub.i) of said decoded bit data corresponding to a respective one of at least two of said first plurality of predetermined original bit data rates {R.sub.i };
• and
• (c) storing said at least two decoded bit data packets {P.sub.i } in an output data buffer;
• (d) recoding each of said at least two decoded bit data packets {P.sub.i } according to said first coding algorithm to create a packet of local code symbol data (L.sub.i);
• (e) comparing said code symbol data with each of said at least two local code symbol data packets {L.sub.i } to create a qualitative measure (Q.sub.i) of the number of differences therebetween;
• and
• (f) storing each of said at least two qualitative measures {Q.sub.i } in said output data buffer.

In a communication system in which original bit data, provided at one of a first plurality of predetermined original bit data rates {R.sub.i }, is encoded to provide code symbol data, and wherein said code symbol data is provided in frames comprising a first version and (N.sub.i -1) repeated versions of code symbol data when said original bit rate is less than a predetermined maximum data rate and wherein said frames comprise said first version of said coded symbol data when said original bit rate is said predetermined maximum data rate, wherein a multirate decoder for creating decoded bit data corresponding to said first version of said coded original bit data at an output, said multirate decoder comprising:

• input buffer means for accepting and storing said code symbol data;
• decoder means coupled to said input buffer means for decoding said code symbol data in at least two passes to create in each pass a packet (P.sub.i) of decoded bit data corresponding to a respective one of at least two said predetermined original bit data rates {R.sub.i } responsive to said code symbol data;
• output buffer means couvled to said sequential decoder means for storing said at least two packets {P.sub.i } of said decoded bit data;
• symbol transfer means in said input buffer means for selecting a set (S.sub.i) of said code symbol data corresponding to said first version of said coded original bit data for each of at least two of said predetermined original bit data rates {R.sub.i } and for transferring said set (S.sub.i) to said sequential decoder means;
• and
• quality metric means in said decoder means for creating a quality measure (Q.sub.i) for each said decoded bit data packet (P.sub.i), said quality measure (Q.sub.i) representing the number of code symbol data errors associated with said each decoded data bit packet (P.sub.i),
• wherein said decoder means comprises:
• symbol metric means for assigning a symbol metric value to each said code symbol in accordance with a second coding algorithm;
• branch metric calculator means coupled to said symbol metric means for creating a pair of branch metric values representing the weighted probability for an original data bit transition corresponding to said each code symbol from said input buffer means, responsive to the corresponding said symbol metric value;
• decision path means coupled to said branch metric calculator means for creating and storing a state metric decision value for each possible original data bit transition corresponding to said each code symbol from said input buffer means, responsive to the corresponding said branch metric values;
• and
• path chain-back means coupled to said decision path means for selecting the most probable decision path for each said original data bit transition and for creating a corresponding said decoded data bit.

In a communication system in which original bit data, provided at one of a first plurality of predetermined original bit data rates {R.sub.i }, is encoded to provide code symbol data, and wherein said code symbol data is provided in frames comprising a first version and (N.sub.i -1) repeated versions of code symbol data when said original bit rate is less than a predetermined maximum data rate and wherein said frames comprise said first version of said coded symbol data when said original bit rate is said predetermined maximum data rate, wherein a multirate decoder for creating decoded bit data corresponding to said first version of said coded original bit data at an output, said multirate decoder comprising:

• input buffer means for accepting and storing said code symbol data;
• decoder means coupled to said input buffer means for decoding said code symbol data in at least two passes to create in each pass a packet (P.sub.i) of decoded bit data corresponding to a respective one of at least two said predetermined original bit data rates {R.sub.i } responsive to said code symbol data;
• output buffer means coupled to said sequential decoder means for storing said at least two packets {P.sub.i } of said decoded bit data;
• symbol transfer means in said input buffer means for selecting a set (S.sub.i) of said code symbol data corresponding to said first version of said coded original bit data for each of at least two of said predetermined original bit data rates {R.sub.i } and for transferring said set (S.sub.i) to said sequential decoder means;
• and
• quality metric means in said decoder means for creating a quality measure (Q.sub.i) for each said decoded bit data packet (P.sub.i), said quality measure (Q.sub.i) representing the number of code symbol data errors associated with said each decoded data bit packet (P.sub.i),
• wherein said multirate decoder is embodied essentially in a single monolithic integrated circuit.

A multi rate decoder for decoding code symbol data received at an input to yield decoded bit data at an output, where said code symbol data represent original bit data according to a first coding algorithm, said code symbol data being transmitted at a rate equivalent to one of a first plurality of predetermined original bit data rates {R.sub.i }, wherein said code symbol data comprises a representation of said original bit data according to a first coding algorithm when said original bit rate is a predetermined maximum and wherein said code symbol data represents a first version and (N.sub.i -1) repeated versions of coded original bit data, where N.sub.i and i are non-zero positive integers, said multirate sequential decoder comprising:

• input buffer means coupled to said input for accepting and storing code symbol data;
• decoder means coupled to said input buffer means for decoding said code symbol in at least two passes to create, in each pass a packet (P.sub.i) of said decoded bit data corresponding to a respective one of at least two said predetermined original bit data rates {R.sub.i } responsive to said code symbol data;
• output buffer means coupled to said output and to said sequential decoder means for storing said at least two decoded bit data packets {P.sub.i };
• first selection means coupled to said input buffer means for selecting one of a plurality of decoding modes each corresponding to a different said first coding algorithm;
• and
• second selection means coupled to said input buffer means for selecting one of said first and second channel modes corresponding to continuous and framed original bit data.

In a communication system in which original bit data, provided at one of a first plurality of predetermined original bit data rates {R.sub.i }, is encoded to provide code symbol data, and wherein said code symbol data is provided in frames comprising a first version and (N.sub.i -1) repeated versions of code symbol data when said original bit rate is less than a predetermined maximum data rate and wherein said frames comprise said first version of said coded symbol data when said original bit rate is said predetermined maximum data rate, wherein a multirate decoder for creating decoded bit data corresponding to said first version of said coded original bit data at an output, said multirate decoder comprising:

• input buffer means for accepting and storing said code symbol data;
• decoder means coupled to said input buffer means for decoding said code symbol data in at least two passes to create in each pass a packet (P.sub.i) of decoded bit data corresponding to a respective one of at least two said predetermined original bit data rates {R.sub.i } responsive to said code symbol data;
• output buffer means coupled to said sequential decoder means for storing said at least two packets {P.sub.i } of said decoded bit data;
• symbol transfer means in said input buffer means for selecting a set (S.sub.i) of said code symbol data corresponding to said first version of said coded original bit data for each of at least two of said predetermined original bit data rates {R.sub.i } and for transferring said set (S.sub.i) to said sequential decoder means;
• and
• quality metric means in said decoder means for creating a quality measure (Q.sub.i) for each said decoded bit data packet (P.sub.i), said quality measure (Q.sub.i) representing the number of code symbol data errors associated with said each decoded data bit packet (P.sub.i),
• wherein said quality metric means comprises:
• data recoder means for recoding each of said at least two decoded bit data packets {P.sub.i } according to said first coding algorithm to create a packet of local code symbol data (L.sub.i);
• and
• comparison means coupled to said data recoder means for comparing each said local code symbol data packet (L.sub.i) with each said code symbol data set (S.sub.i) and for counting the number of differences therebetween.

In a communication system in which original bit data, provided at one of a first plurality of predetermined original bit data rates {R.sub.i }, is encoded to provide code symbol data, and wherein said code symbol data is provided in frames comprising a first version and (N.sub.i -1) repeated versions of code symbol data when said original bit rate is less than a predetermined maximum data rate and wherein said frames comprise said first version of said coded symbol data when said original bit rate is said predetermined maximum data rate, wherein a multirate decoder for creating decoded bit data corresponding to said first version of said coded original bit data at an output, said multirate decoder comprising:

• input buffer means for accepting and storing said code symbol data;
• decoder means coupled to said input buffer means for decoding said code symbol data in at least two passes to create in each pass a packet (P.sub.i) of decoded bit data corresponding to a respective one of at least two said predetermined original bit data rates {R.sub.i } responsive to said code symbol data;
• output buffer means coupled to said sequential decoder means for storing said at least two packets {P.sub.i } of said decoded bit data;
• symbol transfer means in said input buffer means for selecting a set (S.sub.i) of said code symbol data corresponding to said first version of said coded original bit data for each of at least two of said predetermined original bit data rates {R.sub.i } and for transferring said set (S.sub.i) to said sequential decoder means;
• and
• quality metric means in said decoder means for creating a quality measure (Q.sub.i) for each said decoded bit data packet (P.sub.i), said quality measure (Q.sub.i) representing the number of code symbol data errors associated with said each decoded data bit packet (P.sub.i),
• wherein said code symbol data provided to said input buffer comprises a first version and (N.sub.i -1) repeated versions of code symbol data when said original bit rate is less than a predetermined maximum data rate.

In a communication system in which original bit data, provided at one of a first plurality of predetermined original bit data rates {R.sub.i }, is encoded to provide code symbol data, and wherein said code symbol data is provided in frames comprising a first version and (N.sub.i -1) repeated versions of code symbol data when said original bit rate is less than a predetermined maximum data rate and wherein said frames comprise said first version of said coded symbol data when said original bit rate is said predetermined maximum data rate, wherein a multirate decoder for creating decoded bit data corresponding to said first version of said coded original bit data at an output, said multirate decoder comprising:

• input buffer means for accepting and storing said code symbol data;
• decoder means coupled to said input buffer means for decoding said code symbol data in at least two passes to create in each pass a packet (P.sub.i) of decoded bit data corresponding to a respective one of at least two said predetermined original bit data rates {R.sub.i } responsive to said code symbol data;
• output buffer means coupled to said sequential decoder means for storing said at least two packets {P.sub.i } of said decoded bit data;
• symbol transfer means in said input buffer means for selecting a set (S.sub.i) of said code symbol data corresponding to said first version of said coded original bit data for each of at least two of said predetermined original bit data rates {R.sub.i } and for transferring said set (S.sub.i) to said sequential decoder means;
• and
• quality metric means in said decoder means for creating a quality measure (Q.sub.i) for each said decoded bit data packet (P.sub.i), said quality measure (Q.sub.i) representing the number of code symbol data errors associated with said each decoded data bit packet (P.sub.i),
• wherein ones of the first version of said coded symbol data and said (N-1) repeated versions of said coded symbol data are deleted to provide to said input buffer said code symbol data containing one remaining version of said coded symbol data.

In a communication system in which original bit data, provided at one of a first plurality of predetermined original bit data rates {R.sub.i }, is encoded to provide code symbol data, and wherein said code symbol data is provided in frames comprising a first version and (N.sub.i -1) repeated versions of code symbol data when said original bit rate is less than a predetermined maximum data rate and wherein said frames comprise said first version of said coded symbol data when said original bit rate is said predetermined maximum data rate, wherein a multirate decoder for creating decoded bit data corresponding to said first version of said coded original bit data at an output said multirate decoder comprising:

• input buffer means for accepting and storing said code symbol data;
• decoder means coupled to said input buffer means for decoding said code symbol data in at least two passes to create in each pass a packet (P.sub.i) of decoded bit data corresponding to a respective one of at least two said predetermined original bit data rates {R.sub.i } responsive to said code symbol data;
• output buffer means coupled to said sequential decoder means for storing said at least two packets {P.sub.i } of said decoded bit data;
• symbol transfer means in said input buffer means for selecting a set (S.sub.i) of said code symbol data corresponding to said first version of said coded original bit data for each of at least two of said predetermined original bit data rates {R.sub.i } and for transferring said set (S.sub.i) to said sequential decoder means;
• and
• quality, metric means in said decoder means for creating a quality measure (Q.sub.i) for each said decoded bit data packet (P.sub.i), said quality measure (Q.sub.i) representing the number of code symbol data errors associated with said each decoded data bit packet (P.sub.i),
• wherein ones of the first version of said coded symbol data and said (N-1) repeated versions of said coded symbol data are deleted to provide to said input buffer said code symbol data containing one remaining version of said coded symbol data.