Index Modulation Aided Uplink NOMA for Massive Machine Type Communications

Abstract

Single-carrier frequency-division multiple access (SC-FDMA) based index modulation (IM), referred here as SC-IM, allows users to implicitly transmit a part of their data bits by switching on some of their allocated subcarriers, followed by M-ary constellation symbols transmission over the activated subcarriers. This sparse use of subcarriers provides better energy efficiency and error rate. Using these benefits, this article exploits SC-IM with uplink power domain non-orthogonal multiple access (NOMA), where all users with the same allocated subcarrier set can simultaneously transmit their SC-IM data with different power levels, which are exploited by the receiver to perform multiuser detection. Performance of the proposed technique is analyzed and compared with conventional NOMA. It is shown that the proposed scheme can achieve energy efficient massive connectivity, which is a primary requirement for massive machine-type communications. Index Terms-Index modulation (IM), non-orthogonal multiple access (NOMA), single-carrier frequency-division multiple access (SC-FDMA), massive machine-type communications (mMTC).