Performance Evaluation of IEEE 802.15.4 SUN OFDM in VHF-band for Super-large Coverage Communication Systems

Next-generation Internet of Things systems based on IEEE 802.15.4 Smart Utility Network (SUN) require (1) higher data rates, (2) mobility support, and (3) simultaneous connection of many terminals compared to existing commercial systems in smart metering systems. For (1), the use of IEEE 802.15.4-2020 SUN orthogonal frequency division multiplexing (OFDM) is considered. For (2), reception schemes for the SUN OFDM in a mobile environment are proposed. To address (3), it is necessary to secure as large a communication area as possible. However, in the ultra-high frequency (UHF) band represented by 920 MHz, the maximum transmission distance of SUN OFDM with a transmit power of approximately 20 mW is a few kilometers, assuming fixed communication in a typical urban environment. To extend the transmission distance, it is necessary to use a frequency lower than the UHF band or to increase the transmission power. To solve this problem, this paper proposes the use of SUN OFDM in the very high frequency (VHF) band, which has the advantage of longer transmission distance owing to its longer wavelength than the UHF band. However, many delayed signals are received due to multiple reflections. In particular, the maximum delay time of delayed waves can be as long as 20 µs in a rural area. Therefore, it is necessary to receive high-quality signals even in an environment with long delay waves, and to meet the required packet error rate (PER) even when the terminal is moved. In this paper, we first propose an estimation method for the propagation channel of SUN OFDM in the VHF band propagation environment and evaluate the PER characteristics in fixed and mobile environments via computer simulation. Consequently, a transmission distance of more than 10 km could be achieved in the VHF band, even in a rural area with a moving speed of 80 km/h.