Flexible Index Mapping Scheme for Packet-Level Index Modulation

Long range wide area network (LoRaWAN) attracts attention due to its ability to realize massive machine-type communication (MTC); however, the throughput is low due to its narrow-band transmission and chirp spread spectrum. Packet-level index modulation (PLIM) increases the throughput by utilizing a data packet’s frequency channel and transmission timing as an information-bearing index. This letter proposes a flexible index mapping scheme to fully utilize the available frequency channels and transmission timings to increase the number of bits transmitted by an index and avoid packet collision. Numerical results show that the proposed scheme improves the throughput and significantly reduces the required memory size of end nodes.