Zigbee 4.0 introduces ”Suzi” Sub-GHz connectivity and security enhancements

The Connectivity Standards Alliance (CSA) has just announced the release of Zigbee 4.0, integrating security and interoperability improvements, as well as the Suzi Zigbee’s Sub-GHz feature operating in the 800 MHz (Europe) or 900 MHz (North America) band for longer range and lower interference compared to the traditional 2.4 GHz band.

Highlights of Zigbee 4.0 release:

• Simplified certification processes
• Enhanced information exchange for smart home solutions.
  • Formalized Parent Selection, Unique Link Key Monitoring, and Trust Center Connectivity improve network resilience
  • Standardized network-level retries, more reliable data polling for sleepy end devices, and expanded use of APS acknowledgements increase overall network performance and reduce message loss.
  • Sleepy-to-sleepy communication using Coordinated Sample Listening (CSL) allows direct, low-power exchanges between devices, optimizing energy and further extending battery life
• Security updates aligned with evolving international security standards
  • Dynamic Link Key, Device Interview, and Smart Energy Authentication Level Control for stronger device authentication, selective communication based on security levels, and ensuring only trusted devices join the network.
  • New tools such as Restricted Mode, Secured Channel, PAN ID Changes, and Trust Center Swap Out prevent unauthorized network changes.
  • Advanced Frame Counter Synchronization prevents replay attacks and synchronizes precise message validation between endpoints.
• With Suzi, Zigbee 4.0 introduces support for the European 800 MHz and North American 900 MHz PHY for increased signal strength, range, and coverage.
• Introduced in Zigbee 3.0, Zigbee Direct is now a mandatory feature in 4.0. It allows users to onboard and control Zigbee devices via BLE without a hub
• Backward compatibility with Zigbee 3.0 and Smart Energy.

The biggest change here is the introduction of Suzi, enabling long-range mesh networking in ISM bands similar to LoRa Mesh solutions. I used to think that the 802.15.4 standard only supported 2.4 GHz, but amendments also enable sub-GHz frequencies, so Zigbee 4.0 with Suzi will still rely on 802.15.4 radios, possibly with one at 2.4 GHz and another sub-GHz 802.15.4 radio. The latter is already supported in the Microchip SAMR30 MCU module/SiP.

Suzi still relies on the existing proven Zigbee network layer, but enables long-range, low power consumption, and multi-vendor interoperability for residential, commercial, and industrial applications. The CSA especially highlights large buildings, security applications, smart grids, and smart cities. The Suzi Certification Program should start in the first half of 2026, and actual products should become available shortly after.

You’ll find more details about the Zigbee 4.0 release on the download page with four new documents:

• Zigbee Base Device Behavior v3.1 Specification
• Zigbee Core R23.2 Specification
• Zigbee Device Type Library v1.0 Specification
• Zigbee Direct v1.1 Specification

Additional details about Suzi are available on a dedicated page.  The announcement may also have a few extra tidbits of information.

Thanks to TLS and Hedda for the tip.

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