Methods and apparatus for length-adaptive encoding of polar codes

An encoding apparatus for use in a communication system (300), the apparatus comprising:

• a length-adapter, configured to receive length-adapter input parameters and generate length-adapter output parameters, wherein the length-adapter input parameters comprise a data word length A and a length-adapted codeword length E, wherein the length-adapter output parameters comprise a primary data word length AP, a secondary data word length AS, a primary codeword length EP, and a secondary codeword length ES, wherein the data word length A and the length-adapted codeword length E are positive integers, wherein the length-adapter output parameters satisfy either a first set of the conditions or a second set of conditions, wherein the first set of conditions comprise AP≥A/2, AS>0, A, +AS=A, 0<EP<E, 0<ES≤E, and EP+ES>E, and the second set of conditions comprise AP=A, AS=0, EP=E, and ES=0, wherein the first set of conditions are satisfied for a non-empty collection of the length-adapter input parameters;
• a splitter, configured to receive a data word and split the data word in accordance with splitter parameters into a primary data word and a secondary data word, wherein the splitter parameters comprise the primary data word length AP and the secondary data word length AS;
• a primary encoder, configured to encode the primary data word in accordance with primary encoder parameters to generate a primary codeword from a primary code, wherein the primary encoder parameters comprise the primary data word length AP and the primary codeword length EP;
• a secondary encoder, configured to encode the secondary data word in accordance with secondary encoder parameters to generate a secondary codeword from a secondary code, wherein the secondary encoder parameters comprise the secondary data word length AS and the secondary codeword length ES;
• a combiner, configured to combine the primary codeword and the secondary codeword in accordance with combiner parameters to generate a length-adapted codeword and transmit the length-adapted codeword via a channel to a decoder in the communication system, wherein the combiner parameters comprise the primary codeword length EP, the secondary codeword length ES, and the length-adapted codeword length E.