Wi-SUN: the New Wireless Standard Rivaling LoRaWAN and NB-IoT in Smart Cities

July 07, 2020 by Tyler Charboneau

A new connectivity protocol shows promise for IoT designs, rivaling LoRaWAN and NB-IoT.

In the U.S. alone, roughly 84% of the populace resides in city centers. Since 2011, an organization known as the Wi-SUN Alliance has united with a central goal in mind: create connected smart cities through interoperable smart utility networks and smart utilities.


Wi-SUN certification

Wi-SUN certification. Screenshot used courtesy of the Wi-SUN Alliance

Wi-SUN differs distinctly from LoRaWAN or Narrowband IoT with claims of low power consumption and low latency. However, the ubiquity of this new technology (and its IoT influence) will depend heavily on hardware compatibility. 


Wi-SUN’s Place in the Connectivity Ecosystem

Wi-SUN isn’t the only architect of technological standards out there. Notable counterparts like the LoRa Alliance and the GSMA have brought forth their own connectivity protocols. While each technology does meet a specific need, organizations are pushing for widespread adoption of their proprietary solutions—believing them to be the best path forward.

The two largest competitors to Wi-SUN FAN are:

  • LoRaWAN: Long-range, wide-area network (WAN) coverage
  • Narrowband IoT (NB-IoT): A low-power WAN approach, which currently has widespread support

LoRaWAN is also a low-power, wide-area networking (LPWAN) protocol that targets battery-operated devices. While many wireless connectivity protocols use LTE bands, Semtech designed LoRaWAN for use with the industrial, scientific, and medical (ISM) band. This communication highway is unlicensed. 


Wi-SUN compares to LoRaWAN and NB-IoT

How Wi-SUN compares to LoRaWAN and NB-IoT in terms of data rate and latency. Image used courtesy of the Wi-SUN Alliance

NB-IoT is similar to LoRaWAN because it’s also an LPWAN protocol. However, this technology operates in three unique ways: independently, on unused 200-kHz (GSM) bands, or on LTE base stations. These stations typically reserve resource blocks for related operations, often within guard bands. Guard bands are the narrow bands that separate larger bands already in use, protecting against interference and congestion. These only make up roughly 10% of the available bandwidth in LTE networks.


Wi-SUN-FAN Enters the Fray

Wi-SUN is designated as a field area network (FAN), which leverages existing devices to enable long-distance connectivity. Those wide service areas make wired connections too expensive or logistically impossible. FANs will interface between networks, personal devices, and wireless routers to provide connectivity chains.

Wi-SUN FAN itself operates as a mesh network. This differs from traditional LTE and Wi-Fi setups. Devices don’t communicate with one another within these “star” networks. The Wi-SUN Alliance also claims that Wi-SUN solution is unique in that it’s “self-healing.” When connection pathways fail, the network can re-route itself. Wi-SUN powers numerous services requiring reliability and consistent performance. All connectivity nodes are communicative with one another, yet they’re not interdependent from a networking standpoint.


The New Protocol's Leverage on Power and Latency

One of Wi-SUN’s chief focus areas is power consumption. The devices that connect with Wi-SUN FAN are battery-driven—thus, depletion and longevity are top considerations, especially considering that IoT device batteries tend to last three to ten years.

Wi-SUN FAN polls devices frequently at 10-second intervals. Despite that level of activity, the protocol draws under 2 microamps while resting, and 8 milliamps while listening. Fewer than 14 milliamps are drawn while sending. Comparatively, LoRaWAN draws 50% more power while listening, albeit at 128-second intervals. NB-IoT devices vary purposefully in their execution, though these draw 120 to 300 milliamps at peak current. They also draw 2.5 times more power at rest—5 microamps.


Wi-SUN ecosystem

Wi-SUN FAN can integrate with smart utility setups. Image courtesy of the Telecom Engineering Center


Wi-SUN FAN is designed for applications requiring constant communication. 

When dealing with any network, latency (or responsiveness vs. delays) is a crucial measure of performance. Real-time monitoring (as desired by utility companies and the like) benefits greatly from peak responsiveness. You might also refer to this as a “ping.” Wi-SUN FAN claims +10dBm while sending.


The Wi-SUN Alliance: Titans of the Smart Industry

Wi-SUN consists of over 230 members from more than 26 countries. Each member can gain admission as either a promoter, contributor, observer, or adopter. 

Promoters form Wi-SUN’s board are headlined by big names like Silicon Labs, Arm, Cisco, and Toshiba. They directly impact the formation of new specifications or the hardware development standards that Wi-SUN champions.

Wi-SUN’s members accordingly hold key knowledge in the following areas:

  • Smart meter manufacturing
  • Smart utility network management
  • Wireless network diagnostics
  • Smart sensor manufacturing
  • Semiconductor manufacturing
  • Utility corporations, including gas, water, and power
  • Government and regulatory agencies

Over 95 million global devices are compatible with Wi-SUN standards—each powered by multiple, internal components. 


Where Does Wi-SUN Go From Here?

The Wi-SUN Alliance says a major benefit of Wi-SUN FAN is its expandability. According to the organization, FAN technology gains reliability as more nodes (devices) are added. Performance is also environment agnostic. These networks are said to accommodate millions of devices simultaneously, making it useful for cities. By comparison, LoRaWAN and NB-IoT are more prone to interference or rollout issues, respectively. 

The protocol can support smart meter communication devices, networking infrastructure, consumer electronics, and modules. Device makers must test their designs for compatibility, and submit for official certification through the Wi-SUN Alliance. 


 Wi-SUN supports wide-spread connectivity through mesh networking

Wi-SUN supports wide-spread connectivity through mesh networking. Screenshot used courtesy of the Wi-SUN Alliance

The Alliance has received a boost via a new partnership with Silicon Labs. The company has more than 15 years of experience with mesh networking, having deployed over 250 million mesh nodes. Silicon Labs has voiced its support for Wi-SUN’s smart metering and smart city capabilities. It’s recent appointment to Wi-SUN’s board of directors affirms that commitment—financially and strategically.

Both parties will design solutions according to the IEEE 802.15.4(g) standard.