ROHM Module Casts Confidence on Wi-SUN FAN, the New Long-range Protocol on the Block

March 02, 2021 by Jake Hertz

Wi-SUN FAN may be a worthwhile alternative to LoRaWAN and NB-IoT. Now, ROHM has developed a Wi-SUN FAN module with the promise of increased reliability and security in LPWA mesh networks.

As IoT continues to develop, the question of the best means of connecting all of these devices continues to be a debated topic. Two popular IoT communication protocols are LoRaWAN and NB-IoT, which each offer their own individual benefits and shortcomings.


An image of the different types of IoT protocols.

The various types of protocols available for IoT. Image used courtesy of ROHM Semiconductor


Another competing technology is called Wi-SUN FAN, which has been the subject of much R&D in recent years, promising to offer a high-speed, high-reliability IoT network. Now, ROHM Semiconductor has continued this development with the release of a new Wi-SUN FAN module


Shortcomings of LoRaWAN and NB-IoT 

In a previous article, AAC contributor Tyler Charboneau explains that while both LoRaWAN and NB-IoT are popular IoT protocols, they are not without their limitations.

LoRaWAN is a long-range, wide area network protocol designed by Semtech for battery-operated devices, making it useful for IoT designs. However, one of the big problems with LoRaWAN is that it has a relatively low speed. With a data rate of about 0.1 Mbps, LoRaWAN is not an effective choice for most real-time applications such as turning the lights on in your house or real-time communication. 


A chart depicting the differences between Wi-SUN FAN, LoRaWAN, and NB-IoT.

A chart showing the differences in data rate and latency in Wi-SUN FAN, LoRaWAN, and NB-IoT. Image used courtesy of Wi-SUN Alliance


NB-IoT is another low-power, wide area network that can operate independently on unused 200-kHz (GSM) bands or LTE base stations. Offering better data rates than LoRaWAN, NB-IoT is a apt solution for static devices like meters. Where NB-IoT comes up short, however, is in reliability. For this protocol, network and tower handoff ability is an issue, meaning any devices that are not static will struggle to stay connected on the network. 



One up-and-coming alternative to LoRaWAN and NB-IoT is Wi-SUN FAN, which the Wi-SUN Alliance developed. The Wi-SUN Alliance consists of over 230 members, including Silicon Labs, Arm, Cisco, and Toshiba.

Wi-SUN FAN is a field area network that offers a large range, low power, high reliability, and high speeds—mitigating many issues with both NB-IoT and LoRaWAN. The protocol works as a mesh network, interfacing between accessible networks, devices, and wireless routers to provide constant and dynamic connectivity chains. In this way, the network can achieve very long distances for more than just static devices, updating its connectivity chains as needed.


The use of Wi-SUN FAN in a factory/commercial facility.

The use of Wi-SUN FAN in a factory/commercial facility. Image used courtesy of ROHM Semiconductor


Wi-SUN FAN is also significantly faster than LoRaWAN, offering up to ten times data rate improvements, and low power, consuming ~2 uA at rest, 8 mA while listening, and less than 14 mA while sending. 


ROHM’s New Wi-SUN FAN Module: BP35C5 

To help bolster the development of Wi-SUN FAN, ROHM Semiconductor has recently released a new module specifically for the protocol


Block diagram of the BP35C5

Block diagram of the BP35C5. Image used courtesy of ROHM Semiconductor

Its new module, the BP35C5, comes in an extremely small 15.0 mm × 19.0 mm size, allowing for connectivity of up to 1,000 devices. In a network of these modules, ROHM claims that the BP35C5 can cover an entire city, providing obstacle avoidance, high range, and high reliability.



The BP35C5 from ROHM Semiconductor. Image used courtesy of ROHM Semiconductor


Any good wireless network also needs substantial security measures, and the BP35C5 addressed this problem with built-in encryption and security key updates on the wireless communication module side. 


An Up-and-Comer in Embedded Design? 

The BP35C5 from ROHM is significant because it allows for eased Wi-SUN FAN development at a small form factor, making the device feasible for many IoT applications. With IoT devices developing at such a staggering rate, communication protocols like Wi-SUN FAN may soon become a recognizable player in embedded designs.  

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