Research and Development on Indoor Distributed Local 5G Systems and LPWAN Downlink Communications
This booth presents research from the Yamazaki Laboratory, Tokai University.
(1) Local 5G: Experimental evaluation of radio propagation and communication performance in indoor distributed base station environments, with exploration of applications.
(2) LPWAN: Study of LoRaWAN downlink communications through theory and experiments, clarifying performance and design insights.
| Address | 2-3-23 Takanawa, Minato-ku, Tokyo 108-8619 |
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| Site URL | https://s-yamazaki87.github.io/ |
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Radio Propagation and Communication Quality of Indoor Distributed Local 5G Systems in Underground Environments
A local 5G system consisting of three radio units (RUs) has been deployed in the underground area of our Shinagawa campus. Each RU is configured with a different physical cell identity (PCI) and operates on the same frequency, resulting in inter-cell co-channel interference in the downlink as a key challenge.
Based on this, we conduct evaluations through field experiments and real-system measurements. Specifically, we measure the received signal strength within the target area to identify cell boundary regions that are susceptible to interference from multiple RUs, as well as the corresponding communication performance in those areas.
Furthermore, by focusing on the observation that the relationship between synchronization signal reference signal received power (SS-RSRP) and synchronization signal signal-to-interference ratio (SS-SIR) can be expressed as a simple linear function on a logarithmic scale, we propose a novel performance analysis method for radio propagation.
Experimental Validation and Theoretical Analysis of LoRaWAN Class B Mode
Assuming smart city applications as a representative IoT use case, we investigate LoRaWAN downlink communications (Class B mode), an LPWAN technology operating in unlicensed bands, from both theoretical and experimental perspectives.
First, from a theoretical standpoint, we extend our previously developed energy consumption model for uplink communications (Class A mode) to include downlink communications (Class B mode), and construct a comprehensive mathematical model. Using this model, energy consumption and energy efficiency associated with communication can be easily estimated based on key parameters such as beacon period, number of ping slots, and spreading factor. This work has been presented at IEEE WCNC 2026.
In addition, from an experimental perspective, we design and develop sensor nodes compliant with the LoRaWAN Class B specification. Using these nodes, we successfully achieve downlink communication and control over distances of up to approximately 2.4 km in an outdoor urban environment (Shinagawa area, Tokyo).