Feasibility Analysis of UWB Smart Lock Systems Under the Current Smartphone Ecosystem

Current State of UWB Capabilities in Smartphones: An Engineering Prerequisite for Door Lock Systems

With the gradual adoption of UWB technology in smartphones, certain high-end models have integrated UWB as a standard hardware capability, enabling applications such as digital car keys and precise spatial positioning for high-security, short-range use cases. This development provides a practical foundation for the system design of UWB smart locks.

However, it must be clearly stated that the presence of UWB in smartphones does not imply that its capabilities are fully open to third-party applications. In the current ecosystem:

• UWB functionality is typically managed by system-level services or manufacturer-provided SDKs
• Significant differences exist in interface openness across brands and models
• UWB prioritizes secure and trusted interactions rather than general-purpose connectivity

Therefore, when evaluating UWB smart lock solutions, the “UWB smartphone ecosystem” should be regarded as an engineering prerequisite, not a default, universally accessible capability.

Is a UWB Smart Lock Feasible? Defining System Boundaries First

From a wireless technology perspective, UWB is well suited for high-security smart lock scenarios due to:

• Centimeter-level distance determination
• Clearly defined spatial boundaries (designated area outside the door)
• Native resistance to relay attacks

However, in real engineering practice, the feasibility of a UWB smart lock system does not depend on a single module or terminal. Instead, it depends on whether system boundaries are correctly understood and designed.

While UWB smart locks are technically feasible, this does not mean that any UWB-enabled smartphone can directly function as a door key. This distinction directly impacts system architecture, module selection, and deployment strategy.

Technical Foundations of UWB Smart Lock Feasibility

The feasibility of a UWB smart lock system is not determined by whether it “supports UWB,” but by whether the system can reliably complete the closed loop of approach detection + identity verification + unlock control under controllable protocols and verifiable ranging results.

In current engineering practice, UWB smart lock systems typically follow the IEEE 802.15.4-2020 / 802.15.4z standards and use Two-Way Ranging (TWR) or enhanced variants to determine true physical distance. This capability forms the foundation of system security, rather than being an optional feature.

1. True Distance Determination Based on ToF

UWB smart locks use Time of Flight (ToF) ranging, calculating physical distance by measuring the signal propagation time through the air. Since time measurement is directly tied to signal propagation speed, this approach does not rely on empirical models such as RSSI estimation and can achieve centimeter-level accuracy under good line-of-sight conditions.

For smart lock applications, this means the system can explicitly determine whether a user is physically located within a defined area outside the door, rather than merely detecting the presence of a wireless connection.

2. Physical-Layer Protection Against Relay Attacks

In implementations compliant with the IEEE 802.15.4z secure ranging process, distance verification is completed through a challenge–response TWR procedure between the lock and the digital key. Any form of signal forwarding or relay inevitably introduces additional propagation delay, resulting in abnormal ranging values.

As a result, protection against relay attacks in UWB smart locks is achieved at the physical layer through time constraints, rather than through application-layer rules. This is a fundamental difference that traditional Bluetooth smart locks cannot sustainably compensate for through software alone.

System Architecture Design of a UWB Smart Lock

1. System Components and Role Definition

A deployable UWB smart lock system typically consists of the following components:

• Lock-side UWB node
  Responsible for initiating ranging, performing identity verification, and controlling the unlock mechanism; it serves as the core security decision unit of the system
• Digital key terminal
  Either a UWB-enabled smartphone or an independent UWB tag / key device
• Management and configuration system (optional)
  Used for access control management, log recording, policy configuration, and operational support

In this architecture, UWB is not used primarily for communication itself, but for enabling highly reliable spatial judgment—this is the fundamental design principle.

2. Typical Operating Workflow

1. The user carrying a digital key enters the lock’s sensing area
2. The lock initiates a UWB two-way ranging procedure
3. The system evaluates distance results, identity validity, and policy conditions
4. Upon successful verification, the unlock action is executed

This workflow supports hands-free unlocking while maintaining clear and auditable security boundaries.

Engineering Implementation of the Lock-Side UWB Ranging Module(Using UWB650Pro as an Example)

In a UWB smart lock system, the lock side is responsible for initiating ranging, determining distance, and cooperating with the main control system for decision making. Therefore, the UWB module used on the lock side must meet the following engineering requirements:

• Support standardized UWB ranging protocols
• Provide stable and verifiable ranging results
• Enable easy integration with the lock’s main MCU or secure element

In practical engineering implementations, UWB650Pro can serve as one of the foundational module solutions for lock-side UWB ranging and communication.

1. Module Capabilities and Applicable Scope

UWB650Pro is a standard UWB module based on the Qorvo DW3000 chipset. It supports IEEE 802.15.4-2020 / 802.15.4z compliant two-way ranging (TWR) and provides the fundamental communication and ranging capabilities required to build a UWB smart lock system.

It must be emphasized that UWB650Pro is not a complete UWB smart lock solution, nor is it an “plug-and-play” smartphone lock module.

Its engineering positioning is more appropriately defined as:

• A lock-side UWB ranging and communication foundation module
• A building block for system-level solution design, not a replacement for system integration work

2. Engineering Boundaries of Direct Smartphone UWB Interaction

In real projects, whether direct UWB ranging interaction with smartphones is possible is not solely determined by the lock-side module. It largely depends on:

• The smartphone manufacturer’s system-level UWB access policies
• Availability of third-party UWB SDKs or interface permissions
• Differences in permission granularity and security policies across brands and models

Therefore, at the current stage, UWB smart lock systems must adopt a layered adaptation strategy rather than assuming that all UWB-enabled smartphones can directly function as keys.

3. Typical Deployment Paths

Under current ecosystem conditions, typical application paths for UWB650Pro in smart lock systems include:

• Direct integration with smartphone models that expose UWB ranging interfaces
  Suitable for ecosystem-specific cooperation or targeted projects
• Integration through official smartphone digital key ecosystems
  Enabling UWB interaction within manufacturer-authorized frameworks
• Use of independent UWB tags / keys as digital credentials
  Ensuring system completeness and controllability when smartphone interfaces are restricted

This approach ensures deployability while reserving upgrade paths for broader smartphone UWB openness in the future.

Key Engineering Considerations

1. Antenna and Mechanical Design

• Avoid placing metal structures near the UWB antenna radiation direction
• Prefer non-conductive, RF-friendly enclosure materials
• Clearly define the primary radiation direction and ranging area outside the door

2. Power Consumption and Ranging Strategy

By adopting event-triggered ranging, limiting ranging window duration, and properly configuring TWR parameters, power consumption can be effectively controlled while maintaining a smooth unlocking experience, meeting the battery life requirements of smart lock products.

Supplementary Explanation: Why UWB and Bluetooth Smart Locks Differ in Engineering Capabilities

Bluetooth solutions remain widely used in the smart lock market, so UWB smart locks are often compared with Bluetooth smart locks during project evaluations. It is important to note that the two differ fundamentally in design objectives and technical foundations.

This comparison is intended solely to illustrate the technical advantages of UWB smart locks in high-security, short-range scenarios. It does not imply that Bluetooth solutions are unsuitable for all applications. In scenarios with higher security and spatial accuracy requirements, UWB provides greater engineering determinism.