ROHM launches Wi-SUN FAN products and modules

ROHM has developed the new Wi-SUN FAN (Field Area Network) module for infrastructure applications, which is capable of connecting up to 1,000 nodes in a mesh network.

Wi-SUN FAN is the latest Wi-SUN international wireless communication standard that eliminates the communication costs associated with conventional LPWA (Low Power Wide Area) wireless standards. At the same time, Wi-SUN ensures excellent reliability through a frequency-hopping network that automatically switches destinations after signal verification. In this way, this communication technology is expected to be widely used in large-scale mesh networks for smart cities and smart grids.

In recent years, wireless technologies such as LPWA have been increasingly used in infrastructure applications to configure large-scale outdoor area networks. However, traditional LPWA protocols (such as Sigfox, LoRaWAN, NB-IoT) are susceptible to changes in the surrounding environment (i.e. new building development), making them prone to problems including reduced communication speeds and communication failures.

To meet these challenges, ROHM has developed the in-house ultra-small (15.0mm × 19.0mm size) Wi-SUN FAN module BP35C5. This solution can connect up to 1,000 nodes (such as traffic lights and street lights), making it possible to configure a remote wireless management system covering the entire city. The BP35C5 also includes the necessary security functions to enable secure communication without complex control. Certifications obtained under the FCC (Federal Communications Commission) and ARIB (Association of Radio Industries and Businesses) allow immediate use in the United States and Japan. Other countries and regions will be supported in the near future.

The BP35C5 module and BP35C5-T01 evaluation board will be available through online distributors Digi-Key and Mouser from mid-February 2021. A variety of documentation and user guides are available now on ROHM’s website.

What is Wi-SUN FAN?

Wi-SUN FAN (Wireless Smart Utility Network Profile for Local Area Networks) is the latest protocol under the Wi-SUN international communication standard, with cumulative global shipments exceeding 95 million units. By providing superior reliability for various systems used to build smart cities and smart grids, including infrastructure, advanced transportation systems, electricity, gas and water meters, etc., Wi-SUN FAN is expected to be widely used as a network technology to realize the IoT society. 

Considering that conventional LPWA standards only support star networks, Wi-SUN FAN supports the configuration of a mesh network capable of performing multi-hop transmissions, while allowing remote management of applications installed on terminals through two-way communication between relays and terminals. In this way, in the event of communication failure due to new buildings or other surrounding obstacles, the hopping path between relays can be automatically optimized. Unlike the communication cost per terminal of other LPWA standards, Wi-SUN FAN has little or no operating cost.

Comparison of Wi-SUN FAN Mesh network functions based on LPWA communication standards

main feature

1. Support large mesh networks

The ROHM Wi-SUN FAN module solution consists of the in-house developed BP35C5 ultra-small (15.0mm × 19.0mm size) Wi-SUN FAN wireless communication module. By installing the Wi-SUN FAN stack in the MCU gateway for large systems, up to 1,000 simultaneous connections can be achieved (20 hops between relays, each relay supports up to 64 terminals). Implementing this solution in infrastructure equipment (i.e. smart meters, traffic lights, and street lights) enables large-scale mesh network topologies that can be remotely managed and monitored in real time.

In addition, the Wi-SUN FAN stack stored in the built-in memory of the BP35C5 gives users the option to build a small system of up to 16 devices, allowing the modules to be easily controlled from an MCU gateway.

2. Radio certification + secure communication = reduced development costs

The built-in security function of BP35C5 enables communication encryption and security key update on the wireless communication module side, making it easy to perform secure communication without complex control. In addition, it is immediately available in the United States and Japan through FCC and ARIB certification. BP35C5 offers the same package size as the mass-produced BP35C0-J11 (conventional Wi-SUN module), significantly reducing development costs by leveraging existing design assets.

BP35C5 and module pictures

Schematic