Multi-Access Communication Technique Based on Joint Time-Frequency Increment Index Modulation for IoT Networks

Different classes of index modulation (IM) based on multi-access techniques have been investigated for Internet of Things (IoT) devices, especially, non-time sensitive applications (i.e., telemetry, smart metering). This paper proposes a joint time-frequency increment IM (TFIIM) by considering time and frequency increment domains for multi-access communication. Specifically, we activate the indices of frequency diverse array (FDA) antennas with their corresponding frequency increments
$\Delta f$
across the elements and the modulated complex symbol to radiate information bits at a specific time slot. The proposed scheme utilized the time slot to convey extra bits. The implementation of time slots depends on the incoming bits which is different from time division multiple access (TDMA) method. The proposed TFIIM transmitter allows concurrent transmissions to different IoT devices along the angle-range position since the time slot can be selected individually by the activated FDA antennas. Furthermore, the average bit error rate (ABER), green saving, probability of collision (PoC), throughput and system capacity are derived and evaluated. With the simulation results disclosed in this paper, the proposed TFIIM would constitute an excellent nominee for IoT device applications where high spectral efficiency, energy-efficiency, low-complexity, angle-range information beamspace, and data security are paramount.