Super-large Coverage IEEE 802.15.4g-FSK-based Wireless IoT System in VHF-band

Wireless Internet of things (IoT) systems represented by a smart metering system using the UHF band, i.e., Sub-1GHz, have been examined. Many of these systems adopt IEEE 802.15.4g and standardized Frequency Shift Keying (FSK). Although IEEE 802.15.4g-FSK is a suitable transmission scheme for the transmission of numerical data, static image data, etc., the maximum transmission distance is 2 km in the range from 50 kbps to several 100 kbps, and further transmission distance is required for several 100 kbps. In this paper, we propose a modified IEEE 802.15.4g-FSK scheme to enable wide-area transmission. In particular, we propose an IEEE 802.15.4g-FSK with four modifications: (1) the use of the VHF band, (2) an extension of convolutional codes, (3) a simple method for calculating the soft decision for Viterbi decoding, (4) a method for MRC diversity without decoding the received signal. The transmission characteristics were evaluated by computer simulation. According to the simulation results, despite the presence of long delay waves exceeding 20 μs even at vehicle speeds of 80 km/h, the required packet error rate was achieved, and transmission distances of over 12.0 km in a metropolitan environment and 66.0 km in a rural environment were achieved.