Characterization of Iterative PLIM for Environmental Observations and Transmission Design

In LPWA(Low Power Wide Area), a low-power, long-distance communication method, throughput degradation is an issue due to transmission time limitations. PLIM (Packet Level Index Modulation), which transmits packet transmission timings and access channels as an index of information, can be added to packet data. However, as LPWA is in a competitive access environment, missing information due to packet collisions is a challenge. To minimize packet collisions, a method has been proposed to design the mapping, which is the allocation relationship between the index and sensor information, by mathematical optimization. This method cannot sufficiently suppress missing packets, which require information collection with non-optimal mappings, because the statistical trend of sensor information is estimated in advance. In this paper, an iterative statistical estimation of sensor information and mapping design method is proposed, where the statistical trend of sensor information is estimated sequentially and the mapping is redesigned. The effectiveness of the method is demonstrated by computer simulations.