Rate-Adaptive Cyclic Complex Spreading Sequence for Non-Binary Decoders

This paper presents rate-adaptive spreading sequences for Non-Binary (NB) decoders. The sequence’s rateadaptive property enables matching the data rate to the channel conditions. It is obtained by truncating codewords of a cyclic code shift keying (CCSK) sequence while keeping the NB decoder optimized at a fixed code rate. Each chip of the sequence is mapped to a q-ary constellation. The paper presents q-PSK sequence construction processes giving bi-orthogonal codewords at different levels of puncturing. Considering a 256-QAM CCSK modulation and 120 bits payload, the spectral efficiency range is from 0.02 to 6 bits/s/Hz for an SNR range from −15.5dB to 20 dB, with better FER performance than 5G for all SNR values.