Encoding and decoding techniques for bandwidth-efficient communication

An integrated circuit comprising:

• an encoder having multiple encoder output terminals, the encoder to encode data into a sequence of consecutive codewords, each codeword expressed as a first set of symbols of a first symbol type on a first set of the encoder output terminals and a second set of symbols of a second symbol type on a second set of the encoder output terminals;
• wherein symbol transitions between a current codeword and an immediately subsequent codeword occur on a first subset of the encoder output terminals;
• wherein symbol transitions between the subsequent codeword and an immediately following codeword occur on a second subset of the encoder output terminals, which is different that the first subset of the encoder output terminals;
• and
• wherein symbols on the first subset of the encoder output terminals are unchanged between the subsequent codeword and the immediately following codeword.

An integrated circuit comprising:

• input nodes to receive a series of parallel symbols sets over a series of time intervals, including a current symbol set in a current time interval, a preceding symbol set in an immediately preceding time interval, and a bi-preceding symbol set in a bi-preceding time interval immediately preceding the preceding time interval;
• wherein each symbol in the symbol sets represents one of multiple symbol values;
• comparison circuits, each comparison circuit having first and second input terminals, coupled to respective ones of a pair of the input nodes to receive the symbols, and a comparison-circuit output node to provide comparison results;
• and
• a decoder having decoder input terminals, each decoder input terminal coupled to a respective one of the comparison-circuit output nodes;
• wherein the decoder identifies which of the comparison circuits provided comparison results corresponding to symbol transitions between the bi-preceding symbol set and the preceding symbol set;
• and
• wherein the decoder decodes the current symbol set using comparison results from other comparison circuits than the identified comparison circuits, which provide comparison results corresponding to symbol transitions between the preceding symbol set and the current symbol set.

A method of decoding a sequence of parallel codewords, each codeword including symbols of a first symbol type and symbols of a second symbol type, the method comprising:

• receiving a first of the codewords on nodes;
• receiving a second of the codewords on the nodes;
• identifying a first set of the nodes expressing symbol transitions between the first of the codewords and the second of the codewords;
• receiving a third of the codewords on the nodes;
• comparing at least two pairs of symbols on a second set of the nodes, which is different than the first set of the nodes, to produce second comparison results;
• wherein at least two of the second set of nodes express symbol transitions between the second of the codewords and the third of the codewords;
• and
• decoding the third of the codewords based on the second comparison results.

An integrated circuit comprising:

• input nodes to receive a series of parallel symbols sets over a series of time intervals, including a current symbol set in a current time interval, a preceding symbol set in an immediately preceding time interval, and a bi-preceding symbol set in a bi-preceding time interval immediately preceding the preceding time interval;
• wherein each symbol in the symbol sets represents one of multiple symbol values;
• comparison circuits, each comparison circuit having first and second input terminals, coupled to respective ones of a pair of the input nodes to receive the symbols, and a comparison-circuit output node to provide comparison results;
• and
• means for identifying, for each current time interval, which of the comparison circuits provided comparison results corresponding to symbol transitions between the bi-preceding symbol set and the preceding symbol set, and for decoding the current symbol set using comparison results from other comparison circuits than the identified comparison circuits, which provide comparison results corresponding to symbol transitions between the preceding symbol set and the current symbol set.

A system comprising:

• a first integrated circuit that includes an encoder having multiple encoder output terminals, the encoder to encode data into a sequence of consecutive codewords, each codeword expressed as a first set of symbols of a first symbol type on a first set of the encoder output terminals and a second set of symbols of a second symbol type on a second set of the encoder output terminals;
• wherein symbol transitions between a current codeword and an immediately subsequent codeword occur on a first subset of the encoder output terminals;
• wherein symbol transitions between the subsequent codeword and an immediately following codeword occur on a second subset of the encoder output terminals, which is different that the first subset of the encoder output terminals;
• and wherein symbols on the first subset of the encoder output terminals are unchanged between the subsequent codeword and the immediately following codeword;
• and
• a second integrated circuit having:
• input nodes to receive a series of parallel symbols sets, corresponding to the consecutive codewords, over a series of time intervals, including a current symbol set in a current time interval, a preceding symbol set in an immediately preceding time interval, and a bi-preceding symbol set in a bi-preceding time interval immediately preceding the preceding time interval;
• wherein each symbol in the symbol sets represents one of multiple symbol values;
• comparison circuits, each comparison circuit having first and second input terminals, coupled to respective ones of a pair of the input nodes to receive the symbols, and a comparison-circuit output node to provide comparison results;
• and
• a decoder having decoder input terminals, each decoder input terminal coupled to a respective one of the comparison-circuit output nodes;
• wherein the decoder identifies which of the comparison circuits provided comparison results corresponding to symbol transitions between the bi-preceding symbol set and the preceding symbol set;
• and
• wherein the decoder decodes the current symbol set using comparison results from other comparison circuits than the identified comparison circuits, which provide comparison results corresponding to symbol transitions between the preceding symbol set and the current symbol set.

A method of encoding a sequence of data patterns into consecutive M-symbol codewords, each codeword expressed in parallel as M logic-zero and logic-one signal levels on M respective signal nodes, the method comprising:

• for each consecutive group of three temporally adjacent ones of the codewords on the signal nodes, each group of three including a current codeword in a current time interval, a preceding codeword immediately preceding the current codeword in a preceding time interval, and a bi-preceding codeword immediately preceding the preceding codeword in a bi-preceding time interval, encoding one of the data patterns into the current codeword by:
• maintaining a state indicative of the ones of the signal nodes that transitioned to either the logic-zero or logic-one signal level between the bi-preceding codeword and the preceding codeword;
• preventing the ones of the signal nodes that transitioned to either the logic-zero or logic-one signal level between the bi-preceding codeword and the preceding codeword from transitioning between the preceding codeword and the current codeword;
• and
• encoding the one of the data patterns as transitions between the signal levels on ones of the signal nodes that did not transition between the signal levels from the bi-preceding codeword to the preceding codeword.

A method of decoding a sequence of M-symbol codewords, each codeword expressed in parallel as M logic-zero and logic-one signal levels on M respective signal nodes, the method comprising:

• for each consecutive group of three temporally adjacent ones of the codewords on the signal nodes, each group of three including a current codeword in a current time interval, a preceding codeword immediately preceding the current codeword in a preceding time interval, and a bi-preceding codeword immediately preceding the preceding codeword in a bi-preceding time interval, decoding data from the current codeword by:
• maintaining a state indicative of the ones of the signal nodes that did not transition to either the logic-zero or logic-one signal level between the bi-preceding codeword and the preceding codeword;
• identifying, based upon the state, pairs of the ones of the signal nodes that did not transition between the bi-preceding and preceding codewords;
• comparing the signal levels on the identified pairs of the signal nodes to produce comparison results;
• and
• decoding the data from the comparison results.