Extended Boolean functions (EBFs) are one of the most important tools in
cryptography and spreading sequence design in communication systems. In this
paper, we use EBFs to design new sets of spreading sequences for non-orthogonal
multiple access (NOMA), which is an emerging technique capable of supporting
massive machine-type communications (mMTC) in 5G and beyond. In this work,
first p-ary complementary sequences are constructed using EBFs and then,
these sequences are used to design new sets of non-orthogonal spreading
sequence sets having very low coherence and peak to average power ratio (PAPR).
The proposed spreading sequence sets are capable of supporting a large number
of active devices simultaneously. In fact, for a p-ary spreading sequence
set, we theoretically achieve an overloading factor of 2p, where p is an
odd prime. Specifically, for p=3, we achieve an overloading factor of 6,
which cannot be achieved through the existing constructions till date