Achievable Rate Enhancement Based on Multi-Packet Indexing in Packet-Level Index Modulation

The low-power wide area (LPWA) limits the access duration defined by the duty cycle (DC) to avoid mutual interference among the systems. Packet-level index modulation (PLIM) uses the frequency channel and the transmission timing of a packet as an information-bearing index. LPWA with PLIM can increase the number of information bits without changing the wireless communication standards despite adherence to the DC limits. However, there is still a gap between the achievable rate and the channel capacity. Multi-packet indexing determines an information-bearing index based on multiple packets. Thus, it can exploit the channel more efficiently, which results in an increased achievable rate. This study derives a mathematical formula for the achievable rate of PLIM with multi-packet indexing and clarifies the rate enhancement brought by it.