Rohm Semiconductor has introduced a Wi-Sun FAN (field area network) module for connecting up to 1000 nodes in mesh networks for smart city infrastructure applications.

The BP35C5 can eliminate the communication costs associated with conventional LPWA. At the same time, Wi-Sun ensures reliability through multi-hop networks that automatically switch destinations after performing signal verification. As such, this technology is expected to see widespread use in large-scale mesh networks for smart cities and smart grids.

In recent years, wireless technologies such as LPWA have been increasingly adopted in social infrastructure applications to configure large-scale area outdoor networks. However, conventional LPWA protocols such as Sigfox, LoRaWan and NB-IoT are vulnerable to changes in the surrounding environment such as new buildings, making them susceptible to problems that include decreased communication speeds, as well as communication failures.

In response, Japanese firm Rohm developed a device in-house that uses a 15.0 by 19.0 by 2.6mm FAN compatible wireless communication module. This is capable of connecting with up to 1000 devices such as traffic signals and streetlights, enabling the configuration of a remote wireless management system covering an entire city.

It also includes the necessary functions for carrying out secure communication, without the need for complicated control. Certifications acquired under the FCC and Arib allow for immediate use in the USA and Japan. Other countries and regions will be supported soon.

Wi-Sun FAN is a protocol that has seen more than 95 million units shipped worldwide, and is expected to have broad adoption as a network technology for achieving an IoT society, including infrastructure and transportation as well as electricity, gas and water meters.

Whereas conventional LPWA standards support only star-type networks, FAN enables the configuration of mesh networks capable of performing multi-hop transmission between relays while allowing for remote management of terminal-mounted applications via bidirectional communications between relays and terminals. This makes it possible to optimise the hop route automatically between relays, even in the event of communication failure due to newly constructed buildings or other surrounding obstacles.

The module is equipped with communication software on a wireless IC made by Lapis Technology. It has a 920MHz wireless communication function and pre-adjusted wireless transmission power, and is antenna diversity compatible.

A 35.0 by 50.0 by 14.0mm evaluation board with antenna connector (SMA) integrates the BP35C5.