Smart Lock Protocols: Bluetooth, Wi-Fi, Z-Wave, Zigbee, Thread, and Matter

Radios vs. Protocols

It helps to separate two layers:

• The radio and network: how data moves. Examples are Bluetooth LE, Wi-Fi, the IEEE 802.15.4 radio used by Thread and Zigbee, and Z-Wave's sub-1 GHz radio.
• The application protocol: the shared "language" devices use to describe themselves and accept commands such as lock, unlock, or report status.

Some technologies cover both layers. Z-Wave and Zigbee are full stacks. Others cover only one: Thread is a network layer, and Matter is an application layer that runs over several networks.

The Main Technologies

### Bluetooth LE

The Bluetooth SIG describes two radios: Bluetooth Classic, used mainly for audio streaming, and Bluetooth LE, "designed for very low power operation." Bluetooth LE transmits over 40 channels in the 2.4 GHz band and supports point-to-point, broadcast, and mesh topologies. Matter uses Bluetooth LE to onboard new devices (see below).

### Z-Wave

The Z-Wave Alliance describes Z-Wave as a low-power RF technology that supports full mesh networks and operates in the sub-1 GHz band. The Alliance notes this keeps it clear of interference from 2.4 GHz technologies such as Wi-Fi, Bluetooth, and Zigbee. Its physical and MAC layers are defined by ITU-T Recommendation G.9959. The Alliance lists data rates up to 100 kbps and AES-128 encryption. The Alliance notes its mesh works "without the need for a coordinator node" and publishes separate frequency coverage information by world region.

### Zigbee

Zigbee is maintained by the Connectivity Standards Alliance (CSA), which describes it as a full-stack solution, "from mesh network to the universal language that allows smart objects to work together." The CSA lists support for both 2.4 GHz and sub-GHz bands and a self-organizing, self-healing mesh.

### Thread

The Thread Group defines Thread as "an open standard for reliable, cost-effective, low-power, secure, wireless IPv6 communication." It uses the IEEE 802.15.4 radio "operating at 250 kbps in the 2.4 GHz band." Thread is a networking layer: "any low bandwidth application layer that can run over IPv6 can run over Thread."

A Thread network reaches the rest of the home through a Border Router, which the Thread Group's white paper defines as "a device that is able to route packets to and from the Thread mesh," most commonly between Wi-Fi and Thread.

### Matter

Matter is the CSA's open smart-home application protocol. The CSA's FAQ describes it as using "Bluetooth Low Energy for device setup and Wi-Fi, Thread, and Ethernet for connecting devices." Door locks are on the CSA's list of supported device categories. Setup uses numeric or QR codes, and the CSA notes some makers also support NFC tap-to-onboard.

Matter certification also requires certification of the underlying transport. A Matter-over-Thread lock must be Thread certified, for example.

How Thread, Zigbee, and Matter Relate

These three are often confused. The CSA's FAQ spells out the links:

• Thread and Zigbee share a radio. "Thread-based devices support the same 802.15.4 radio technology as Zigbee but use IP-based technology for the network stack."
• Matter borrows from Zigbee. "Matter's data model borrows heavily" from the Zigbee Cluster Library.
• Bridges connect older devices. Matter "supports bridges that allow devices using other protocols (such as Zigbee or Z-Wave) to participate in a Matter ecosystem."

Matter keeps evolving. The CSA announced Matter 1.4 on November 7, 2024. That release added certifiable Home Routers and Access Points (HRAP): routers, modems, access points, and set-top boxes that can provide the network infrastructure Matter devices rely on, such as a Thread Border Router.

Aliro: Digital Keys in the Phone Wallet

Matter controls a lock from a smart-home platform. Aliro addresses a different problem: using a phone or wearable as the credential at the door. The CSA announced the Aliro effort on November 9, 2023, and released Aliro 1.0 on February 26, 2026. According to the CSA, the specification supports:

• NFC for tap-to-access
• Bluetooth LE for user-initiated, longer-range communication
• Bluetooth LE plus Ultra-Wideband (UWB) for hands-free access

The CSA's release says Apple, Google, and Samsung have committed to wallet integration, and lists target uses including corporate offices, universities, hospitality venues, and single- and multi-family homes. Aliro is related to, but separate from, commercial access control credentials such as card readers and RFID.

Security Basics

Every standard above includes security mechanisms. Z-Wave lists AES-128, and the CSA describes Zigbee as "secure by design." The protocol is only one layer, though. Smart locks also depend on app accounts, firmware updates, and the mechanical lock behind the electronics. Mechanical durability and security grading is a separate question; see ANSI/BHMA lock grades.

Related Topics

• Smart locks: the consumer category
• Electronic locks: keypads, cards, and motorized locks
• Smart keys: proximity keys and fobs
• Access control: commercial credential systems
• RFID locks: card and fob credentials
• Card readers: reader technologies
• Keypad locks

Sources