| CPC H04L 27/3405 (2013.01) [H04L 5/0007 (2013.01); H04L 5/023 (2013.01)] | 6 Claims |
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1. A coding method based on multiple-mode orthogonal frequency division multiplexing with index modulation (MM-OFDM-IM), comprising:
(1) acquiring a to-be-encoded source sequence input from a transmitter, and encoding, by an encoder, the to-be-encoded source sequence to generate a coded bit sequence;
(2) performing bit-splitting on the coded bit sequence according to a preset constellation modulation order and a preset constellation mode number, such that the coded bit sequence is divided into an index-layer sequence and a symbol-layer sequence; wherein the index-layer sequence is configured to transmit full permutation information of the plurality of constellation modes, and the symbol-layer sequence is configured to transmit constellation symbol information carried by a plurality of subcarriers; and
determining, according to the index-layer sequence and the symbol-layer sequence, a plurality of constellation modes respectively corresponding to the plurality of subcarriers and which one of a plurality of constellation symbols respectively corresponding to the plurality of constellation modes is carried by each of the plurality of subcarriers; wherein a constellation mode permutation corresponding to each of the plurality of subcarriers is in a symmetrical distribution;
(3) converting, by a constellation symbol mapper, the coded bit sequence into the plurality of constellation symbols according to a correspondence relationship between the plurality of subcarriers and the plurality of constellation modes and a correspondence relationship between the plurality of constellation modes and the plurality of constellation symbols; and loading the plurality of constellation symbols respectively to the plurality of subcarriers for transmission; and
(4) combining, by a frequency-domain multiplexer, the plurality of subcarriers into an orthogonal frequency division multiplexing (OFDM) transmission block; performing transmission preprocessing on the OFDM transmission block followed by up-conversion; and
sending, by an antenna array, the OFDM transmission block to a receiver via a transmission channel; and performing, by the receiver, inverse processing on the OFDM transmission block to obtain a source estimation sequence;
wherein the plurality of constellation modes and the plurality of constellation symbols are determined through steps of:
according to the plurality of constellation modes, performing data blocking on the index-layer sequence to generate a plurality of index-layer subsequences with a fixed length;
according to the preset constellation modulation order, performing symbol segmentation on the symbol-layer sequence to generate a plurality of first symbol-layer subsequences with a fixed length; performing rearrangement on the plurality of first symbol-layer subsequences according to the plurality of constellation modes and the number of the plurality of first symbol-layer subsequences, so as to obtain a plurality of second symbol-layer subsequences with a fixed length; wherein the number of the plurality of second symbol-layer subsequences is equal to a product of the number of the plurality of constellation modes and the number of the plurality of first symbol-layer subsequences; and
determining the plurality of constellation modes respectively corresponding to the plurality of subcarriers according to the plurality of index-layer subsequences, and determining which one of the plurality of constellation symbols respectively corresponding to the plurality of constellation modes is carried by each of the plurality of subcarriers according to the plurality of second symbol-layer subsequences, so as to determine a permutation of the plurality of constellation modes respectively corresponding to the plurality of subcarriers;
the permutation of the plurality of constellation modes respectively corresponding to the plurality of subcarriers is determined through steps of:
determining a median constellation symbol among the plurality of constellation symbols according to the number of the plurality of constellation modes and the preset constellation modulation order, wherein the median constellation point is located at a middle position of a collection of the plurality of constellation symbols;
performing constellation symbol division on the plurality of constellation symbols by means of sequentially extracting constellation symbols from the plurality of constellation symbols at preset intervals from the median constellation symbol to both sides, so that the plurality of constellation symbols are divided into two constellation symbol subsets, one of which consists of extracted constellation symbols and the other of which consists of unextracted constellation points;
determining whether the number of times that the constellation symbol division has been performed is less than the preset constellation modulation order; if yes, performing a next round of the constellation symbol division on individual constellation symbol subsets obtained from a current round of the constellation symbol division until the number of times that the constellation symbol division has been performed is not less than the preset constellation modulation order, so as to obtain desired constellation symbol subsets; if not, outputting the constellation symbol subsets obtained from the current round of the constellation symbol division as the desired constellation symbol subsets; and
outputting the desired constellation symbol subsets as the plurality of constellation modes.
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