NOMA With Index Modulation for Uplink URLLC Through Grant-Free Access

• Published in: IEEE journal of selected topics in signal processing 2019-10, Vol.13 (6), p.1249-1257
• Main Authors: Dogan, Seda, Tusha, Armed, Arslan, Huseyin
• Format: Article
• Language: English
• Subjects: Bit error rate; Broadband; Communication; Computer simulation; Grant-based transmission; grant-free transmission; Interference; Long Term Evolution; Modulation; Narrowband; NOMA; OFDM; OFDM-IM; Orthogonal Frequency Division Multiplexing; Reliability; Reliability analysis; Subcarriers; URLLC; waveform-domain NOMA; Wireless communication
• ISSN: 1932-4553; 1941-0484
• DOI: 10.1109/JSTSP.2019.2913981

This paper proposes nonorthogonal sharing of available resources between latency-critical and latency-tolerant communication for fulfilling tight requirements of ultrareliable low-latency communication (URLLC) as well as avoiding inefficient spectrum utilization of grant-based (GB) access for sporadic URLLC traffic. In the proposed system, grant-free (GF) access is adopted for URLLC to reduce transmission latency, whereas GB access is used for latency-tolerant communication. Due to GF access, collision emerges between the communications, and use of OFDM technology for both communications leads to wideband interference (WB-I) on URLLC. Therefore, a novel nonorthogonal multiple accessing (NOMA) scheme based on orthogonal frequency division multiplexing (OFDM) and OFDM with index modulation (OFDM-IM) is proposed in order to reduce the impact of the collision on URLLC, that requires 99.999% success probability within 1 ms. OFDM-IM technology is used for latency-tolerant communication since WB-I is converted to either narrowband dominant interference or narrowband interference by fractional subcarrier activation in OFDM-IM. In this way, URLLC is partially affected by latency-tolerant communication. It is shown that the proposed NOMA scheme significantly reduces the latency in comparison to classical NOMA scheme based on pure OFDM while guaranteeing 10 -5 reliability for URLLC, via both computer-based simulations and theoretical analysis.