Wireless Connectivity & IoT / Wi-SUN

Wi-SUN: Technology and Filter Requirements

Wi-Fi Certified Wi-SUN (Wireless Smart Ubiquitous Network) is the leading global standard for large-scale, interoperable mesh networks in critical infrastructure. Based on IEEE 802.15.4g, Wi-SUN primarily operates in sub-GHz ISM bands at 868 MHz (Europe) and 915 MHz (North America). The technology is characterized by its enormous scalability for millions of end nodes and high robustness through frequency hopping. The technical challenge lies in coexistence within the densely populated sub-GHz spectrum: since Wi-SUN networks are often operated in parallel with high-power cellular services like LTE Band 20 (800 MHz) or Band 8 (900 MHz), precise filtering of gateways and routers is critical for network stability.

Wainwright Instruments provides specialized high-performance filters for these demanding infrastructure applications, tailored exactly to the requirements of border routers and mesh nodes. Since Wi-SUN requires high receiver sensitivity to bridge distances of several kilometers in urban canyons, extreme skirt steepness is required to prevent receiver blocking by neighboring cellular signals. Our filter solutions ensure minimal insertion loss and excellent selectivity, sustainably securing the reliability of critical utility grids (smart grids).

Typical Deployment Scenarios:

Wi-SUN filters from Wainwright are indispensable components in systems requiring absolute availability and signal purity in large-scale outdoor networks.

Smart Grid & Grid Automation: In utility networks, our filters secure communication between transformer stations and smart meters in the 868 MHz band against massive electromagnetic interference.
Connected Street Lighting: In urban control systems, our filter solutions ensure interference-free signal transmission along long street sections, even in the vicinity of strong cellular towers.
Smart City Sensor Networks: For monitoring air quality and traffic flow, our RF components protect border routers from overloading by commercial LTE/5G small cells in urban areas.
Gas and Water Meter Infrastructure: In shafts and basements, our filters enable maximum receiver sensitivity to fully exploit the superior range and building penetration of Wi-SUN.
Industrial Remote Monitoring (IIoT): Within expansive industrial facilities, our filters secure data transmission from condition sensors against impulses from heavy-duty machinery and substations.
Renewable Energy (Solar & Wind Parks): In large-scale parks, our filters support the coordination of inverters and sensors, stabilizing signal quality over long distances.
Large-scale Farming: For managing irrigation systems and harvesting machinery in the 915 MHz band, our filter solutions eliminate interference from neighboring rural LTE stations.
Test and Certification Labs: For testing the interoperability and interference immunity of new Wi-SUN components, we supply high-precision reference filters to validate hardware performance under defined coexistence scenarios.

Suitable Filter Categories for Wireless Connectivity & IoT / Wi-SUN

High reliability requirements in outdoor infrastructure demand filter solutions that combine extraordinary quality factors with thermal robustness.

Band Pass Filters

Our Wi-SUN Band Pass filters enable precise selection for bands at 868 MHz and 915 MHz. They are specifically optimized for use in professional border routers and industrial infrastructure applications, featuring extremely steep rejection skirts to safely block neighboring cellular carriers. By minimizing insertion loss, these filters directly support the link budget of mesh nodes, reducing the number of required hops and improving network latency. The mechanical precision of our resonators ensures that the filter curve remains absolutely stable even under extreme climatic conditions at mast locations. Manufacturers of infrastructure components benefit from the high power handling and thermal stability of our filters.

Manually Tunable Band Pass Filters

For the development of Wi-SUN modules and field testing of mesh gateways, we offer manually tunable Band Pass filters covering the range from 400 MHz to 1000 MHz. Via high-precision mechanical tuning elements, the center frequency can be adjusted exactly to regional frequency plans. This flexibility allows engineers to investigate the robustness of their systems against specific local interference sources in the lab or during pilot projects in the field. The robust construction of our manually tunable filters guarantees permanent reproducibility of measurement results over long test series.

Digitally Tunable Band Pass Filters

Electronically controllable filters support modern SDR-based routers that must react agilely to various Wi-SUN frequency plans. Via digital interfaces such as SPI, filter parameters can be adjusted in real-time, which is particularly advantageous for automated test sequences checking channel selectivity. Our digitally tunable filters combine digital control precision with the necessary RF quality and are optimized for use in test environments and development systems. They enable rapid reconfiguration of automated test rigs without manual hardware swaps, supporting efficient quality assurance processes.

Band Reject Filters / Notch Filters

Our Wi-SUN notch filters serve to eliminate specific interfering signals located immediately adjacent to the utilized spectrum, such as strong LTE-800 signals at 862 MHz. They feature extremely deep stopband attenuation while the Wi-SUN passband remains nearly unaffected. This protection is fundamental to prevent saturation of receivers in border routers at sites with high cellular density. By using our notch filters, the robustness of the infrastructure against narrowband interferers is massively increased, significantly increasing the reliability of critical data flows.

Manually Tunable Band Reject Filters / Notch Filters

Frequency-tunable notch filters provide field technicians with a quick solution for suppressing unforeseen interference in the sub-GHz range. By manually adjusting the stopband frequency, interfering signals caused, for example, by poorly performing radio systems in the vicinity can be masked immediately. This ensures the availability of Wi-SUN services without waiting for new filter hardware. The mechanical precision of our filters guarantees that once a stopband frequency is found, it remains stable, which is particularly decisive for permanently installed devices in control cabinets.

Digitally Tunable Band Reject Filters / Notch Filters

In intelligent utility grids, digitally tunable notch filters enable an automated response to dynamic interference scenarios. Controlled by monitoring algorithms, these filters can dynamically mask interfering signals in real-time to maintain Quality of Service (QoS) for time-critical control commands. Their integration into automation concepts for radio optimization allows for autonomous radio optimization of entire districts. Thanks to remote controllability, operators can adjust filter characteristics centrally, reducing operating costs and massively increasing the resilience of Wi-SUN nodes against new interference sources.

Monoplexer / Diplexer / Duplexer / Triplexer

Combining Wi-SUN with other radio standards like LTE-M or NB-IoT on a shared antenna requires high-performance multiplexers with extremely high isolation. Our duplexers for the 900 MHz band are optimized for highest power handling combined with minimal PIM to prevent mutual blocking of receiver paths. Wainwright Instruments manufactures these components with the highest precision to ensure that multi-mode gateways develop their full performance across all utilized frequency ranges. Precise tuning prevents signal crosstalk and protects highly sensitive paths from overloading. Our multiplexers are optimized for use in professional utility grids and industrial infrastructure applications.

Absorptive Filters

Absorptive filters play a crucial role in the transmission infrastructure of high-performance border routers to protect amplifier linearity and effectively eliminate harmonics. Rather than conducting unwanted harmonics or reflections back to the power amplifier, these filters safely convert them into heat, preventing reflection damage. This is particularly important for complying with strict regulatory emission limits in crowded radio fields. Our absorptive filters are designed for continuous operation and increase hardware lifespan by consistently minimizing thermal stress.