Ultra-Wideband (UWB) in Smart Locks: Solving Security Challenges

Current smart locks, which use technologies like Bluetooth, Wi-Fi, and NFC, have some real problems. Their limitations stem from the inherent characteristics of these technologies. For instance, Bluetooth and Wi-Fi primarily rely on Received Signal Strength Indicator (RSSI) for distance estimation, which is highly susceptible to interference, attenuation, and environmental variability (e.g., presence of people, furniture). This makes them not very accurate when figuring out how far away you are. Consequently, they’re vulnerable to tricky “relay” attacks where someone can intercept and retransmit an authentication signal, simulating proximity to trick the lock into opening. Furthermore, these technologies don’t really know your exact location or direction, making precise access control difficult. These issues collectively make current smart locks less secure and inconvenient to use. Ultra-Wideband (UWB) is a new technology that can fix these problems. It offers much more precise location sensing and significantly better security. This article explains how UWB works in smart locks, how it solves key security issues, and how it can make access control smoother and safer for everyone.

Technical Foundations of Ultra-Wideband in Access Control

Ultra-Wideband is a wireless communication technology that utilizes a very broad frequency band (from 3.1 GHz to 10.6 GHz) to transmit data using short, low-power radio pulses. These unique physical properties of the UWB signal are the foundation of its advantage in applications requiring high location precision and interference immunity.

 Ultra-Wideband Distance Measurement (Time-of-Flight – ToF)

The core principle of Ultra-Wideband (UWB) operation in the context of precise access control is the Time-of-Flight (ToF) method. This involves measuring the extremely short propagation time of a radio signal between two devices – for example, a smart lock and a user’s smartphone. The distance (d) is calculated using a simple yet highly effective physical formula: d=c⋅t, where c is the speed of light in a given medium (approximately 3×108 m/s in a vacuum), and t is the precisely measured signal flight time.

In contrast to RSSI-based methods, which infer distance from the received signal strength and are highly susceptible to interference, attenuation, and environmental variability (e.g., presence of people, furniture), ToF measurement is significantly more resilient to these factors. The direct measurement of signal propagation time translates into fundamentally higher accuracy and reliability.

Centimeter-level Measurement Precision

Ultra-Widebands (UWB) ability to achieve centimeter-level distance measurement precision is its greatest competitive advantage. This is made possible by two key factors:

• Short Pulses: UWB utilizes extremely short radio pulses, often lasting only nanoseconds. The shorter the pulse, the more precisely its transmission and reception times can be determined, directly impacting the accuracy of the time-of-flight measurement.
• Wide Bandwidth: The Ultra-Wideband (UWB) frequency band is very broad (3.1 GHz to 10.6 GHz), which, according to Fourier transform principles, enables the generation of very short pulses. The wide bandwidth also increases signal discernibility, crucial for eliminating multipath interference.

This unparalleled precision (typical accuracy of a few to a dozen centimeters) is critical in access control applications where precise positioning of the user relative to the access point is required.

Resistance to Interference and Multipath Issues

Indoor environments are full of obstacles (walls, furniture, people) that cause radio signal reflections – a phenomenon known as multipath. In traditional technologies (e.g., Wi-Fi, Bluetooth), reflected signals can overlap with the direct signal, leading to errors in distance measurement and packet loss.

UWB handles this problem exceptionally well due to:

• Wide Bandwidth: Ultra-Wideband (UWB) operates in a significantly wider band than Wi-Fi or Bluetooth, making it much less susceptible to their interference.
• Pulsed Nature: UWB’s short pulses are transmitted in a way that allows the receiver to distinguish the direct signal from reflected signals, as they arrive at different times. A UWB receiver can identify and utilize the first arriving signal (usually the direct one), ignoring delayed reflections. This increases measurement reliability even in densely built environments, such as offices or hotels.

Directional Awareness (Angle of Arrival – AoA)

In addition to precise distance measurement, Ultra-Wideband (UWB) technology also allows for determining the direction from which a signal originates – a feature called Angle of Arrival (AoA). This is achieved by using an antenna array and analyzing phase or time differences in how the signal arrives at individual antenna elements.

The AoA function is revolutionary in the context of access control, as it allows for:

• Preventing Access from the Wrong Side: The system can determine whether a user is approaching a door from the outside (requiring unlock) or from inside the room (lock or no action). This eliminates the problem of accidental door unlocking when a user is inside the building, but their phone is detected by the lock.
• Implementing Truly “Hands-Free” Access: By combining ToF and AoA, doors can automatically unlock only when an authorized person approaches them from the correct direction, without the need to take out a phone or perform any additional actions.

Ultra-Wideband Energy Efficiency

Despite its advanced capabilities, UWB boasts low power consumption. This is possible due to the short duration of its pulses and a relatively low duty cycle (brief periods of signal transmission). Low power consumption is crucial for extended battery life in both smart locks and mobile devices (smartphones, smartwatches) that function as virtual keys.

Comparison of Wireless Communication Technologies in Access Control

The table below presents a comparison of key parameters for technologies used in smart locks:

Enhanced Security with Ultra-Wideband (UWB)- Powered Locks

The implementation of UWB in smart locks significantly elevates the level of security by addressing and eliminating critical vulnerabilities inherent in older wireless technologies.

Elimination of “Relay” Attack Vulnerabilities

One of the most serious threats to access systems based on low-precision technologies (such as BLE or RFID) are “relay” attacks. This type of attack involves intercepting an authentication signal (e.g., from a car key or access card) and retransmitting it over a greater distance, simulating the proximity of an authorized device to deceive the system.

UWB, thanks to its precise Time-of-Flight (ToF) measurement, effectively neutralizes these attacks. Since Ultra-Wideband (UWB) measures the actual, absolute signal flight time, any attempt at retransmission by an intermediary device will immediately lengthen the measured ToF.

An access control system equipped with UWB will be able to detect an unnaturally long flight time, which will immediately signal an attempt at fraud and block access. The inability to alter the measured distance through signal retransmission makes UWB inherently resistant to such attacks.

Secure Communication Protocols and Authentication

UWB’s security is further reinforced by robust communication protocols and authentication mechanisms, developed and standardized by leading industry consortia such as the FiRa Consortium and the Car Connectivity Consortium (CCC). These protocols include:

• Mutual Cryptographic Verification: Ensures that both the smart lock and the mobile device (e.g., smartphone) mutually verify each other’s identity using cryptographic keys. This prevents communication with unauthorized or impersonating devices.
• Cryptographic Challenge-Response Mechanisms: Protect against replay attacks, where previously intercepted authentication data is retransmitted to gain access. Each communication session uses unique, randomly generated “challenges” to which the device must provide a correct, cryptographically secured “response.”
• Encryption and Data Integrity: All UWB communication is encrypted using strong cryptographic algorithms, protecting data from eavesdropping and manipulation. Additionally, checksum mechanisms and authentication codes ensure the integrity of transmitted information.

These layers of security make UWB communication not only precise but also highly resistant to hacking attempts and manipulation.

Defining Precise Access Zones ( Geofencing with Ultra-Wideband )

UWB enables the configuration of extremely granular access zones, which is crucial for advanced security control. Thanks to centimeter-level precision, administrators can define very detailed “geofences,” e.g., “unlock only if the phone is within 1 meter of the door, but exclusively on the inside of the office space”.

This capability for precise positioning and activation zone definition offers several key benefits:

• Reduced Accidental Unlocks: Eliminates situations where doors open accidentally when a user is nearby but not intending to enter (e.g., walking down a corridor past an office door).
• Increased Control: Allows for the creation of complex access scenarios, such as activating an alarm if someone approaches the door from the wrong side, or granting access only during specific hours and only from authorized zones.
• Contextual Access: The system can dynamically react to the user’s location, offering seamless access only when the context (distance, direction, zone) is correct.

Aliro Standard: Interoperability and Security in Access Control Ecosystems

The development of UWB technology is accelerating, and the Aliro standard, developed by the FiRa Consortium in collaboration with the Connectivity Standards Alliance (CSA – formerly Zigbee Alliance), plays a crucial role in its standardization and mass adoption.

What is Aliro?

Aliro is a new communication protocol specifically designed for smart locks and access control systems, leveraging the potential of Ultra-Wideband (UWB) while also supporting other technologies. Its goal is to create a unified, secure, and interoperable ecosystem for digital keys.

Solving the Fragmentation Problem

Currently, the smart lock market is highly fragmented, with various manufacturers using proprietary, often closed, communication protocols. This leads to compatibility issues and limits choice for consumers and businesses. Companies often find themselves “locked in” to a single vendor’s ecosystem.

Aliro aims to solve this problem by offering a consistent and reliable way to unlock doors, regardless of the lock manufacturer or mobile device. This paves the way for mass adoption and standardization.

Technology-Independent and Security-Oriented

Aliro distinguishes itself by being technology-independent, meaning it can operate on various physical protocols, including:

• NFC: For quick, proximity-based “tap-to-open” unlocking, e.g., by touching a smartphone to the lock.
• Bluetooth LE: For basic connectivity and wider-range detection.
• UWB: For precise, secure, and touchless “hands-free” access.

However, Aliro’s central focus is its strong emphasis on security. The protocol utilizes advanced cryptographic mechanisms:

• Asymmetric Cryptography: Based on public/private key pairs, ensuring strong authentication and data integrity.
• Digital Key Management: Aliro enables the secure issuance, management, and revocation of virtual keys stored in Secure Elements within smartphones and other devices. This ensures that keys are resistant to cloning and unauthorized use. (Source)

Concrete Technical and Business Benefits for Enterprises with UWB

Implementing the Aliro standard, especially in conjunction with UWB, will bring significant benefits to enterprises:

• Simplified Integration: Easier connection of new smart locks with existing Building Management Systems (BMS), Access Control Systems (ACS), and IoT platforms.
• Wider Device Compatibility: The ability to use various smartphones and mobile devices as keys, without dependence on a single manufacturer.
• Easier Deployment and Management: Standardization of installation and access management processes, which lowers operational costs and increases system scalability.
• Increased Innovation: The open standard promotes faster development of new features, applications, and services within the access control ecosystem.

Practical Steps for Business Implementation and Ultra-Wideband Integration

Successful implementation of Ultra-Wideband (UWB) in access control systems requires a thoughtful approach and consideration of several key technical and operational aspects.

Smart Lock Hardware Assessment

The first step is a careful evaluation of available hardware solutions. It is important to look for smart locks with integrated UWB transceivers and FiRa/Aliro certification. This certification guarantees compliance with standards, and thus interoperability and security levels.

Additionally, key considerations include:

• Optimal UWB Antenna Design and Placement: Antennas must be designed and positioned within the lock to ensure maximum precision in distance and direction measurement, minimizing interference from metallic door components or frames.
• Assessing UWB Impact on Battery Life: Although UWB is energy-efficient, its integration’s overall impact on the lock’s battery autonomy must be assessed to ensure long-lasting and reliable operation without frequent battery replacement.

Integration with Existing Infrastructure

UWB deployment does not always mean a complete replacement of existing infrastructure. In many cases, UWB systems can be integrated with already operational networks and devices.

• Need for External UWB Anchors: In large installations, such as office complexes, hospitals, or warehouses, additional external Ultra-Wideband (UWB) anchors may be necessary to ensure full coverage and even higher location precision in complex environments. These anchors can be strategically placed in corridors or at entrances to enhance positioning accuracy.
• Reliable Network Connectivity: All system components (locks, anchors, management servers) require reliable network connectivity. This can be an existing Wi-Fi network, Ethernet, or even dedicated cellular networks (e.g., 5G Private Networks) or LoRaWAN networks for IoT device communication. Stable connectivity is crucial for centralized management and monitoring of the system.

Software and System Integration

A robust software platform is a critical component for the successful implementation of UWB, managing the entire smart lock system. This platform should offer:

• Centralized Access Management: The ability to remotely and dynamically grant, modify, and revoke access permissions for individual users, groups, or based on schedules.
• Integration with Existing IT Systems: Seamless integration is essential with:
  • Access Control Systems (ACS): To manage user identities and permissions in a centralized manner.
  • Building Management Systems (BMS): For coordination with other building systems, such as lighting, HVAC, or alarm systems. For example, unlocking a door can automatically turn on the lights in a room.
  • IoT Platforms: To collect data from locks and analyze it within the broader context of the smart building ecosystem.
• Mobile Applications Utilizing UWB: The development of intuitive and secure mobile applications that leverage UWB functionality in users’ smartphones is crucial. These applications should provide seamless access, allow for personal settings management, and receive notifications.

Tangible Business Benefits and Technical Applications with Ultra-Wideband

The implementation of Ultra-Wideband (UWB) in smartlocks brings concrete and measurable benefits across diverse sectors. The flexibility and precision of this technology make it a universal solution, whose potential is limited only by imagination.

Corporate Environments

• Increased Security: UWB enables precise access control, eliminating the risk of “tailgating” (unauthorized entry following another person). Thanks to directional awareness (AoA), the system knows whether an employee is approaching a door from the outside (requiring unlock) or from inside the office (no action or lock), which prevents accidental openings and enhances data and asset protection.
• Improved Employee Experience: Seamless and touchless (“hands-free”) access to offices, conference rooms, or parking areas enhances comfort and work efficiency, eliminating the need to search for access cards or keys. Personalized access permissions can be granted for individual employees or teams.
• Space Optimization: UWB systems can collect anonymous data on room occupancy and employee flow. This data is invaluable for facility managers, allowing for better utilization of office space, optimization of room layouts, and planning of flexible workstations.

Hospitality Sector (Hotels, Resorts)

• Keyless Guest Access: Guests can use their smartphones as secure, virtual keys to open hotel rooms, eliminating the need to check-in at the reception and collect physical cards. The “hands-free” function further enhances convenience, allowing doors to unlock automatically when a guest approaches with luggage.
• Staff Efficiency: Hotel staff gain easier and faster access to rooms, storage areas, and technical rooms, streamlining operations and enabling quicker guest service.
• Increased Guest Room Security: Precise access control and monitoring of entry attempts to enhance guest security and privacy, minimizing the risk of unauthorized access.

Residential Construction (Multi-family Buildings, Estates)

• Premium Offering for Tenants: Modern access solutions, such as UWB-based keyless systems, represent an attractive differentiating factor in the real estate market, increasing property value and appeal to potential tenants.
• Simplified Management: Property managers gain the ability to remotely issue digital keys to new tenants, cleaning companies, suppliers, or technical services, significantly simplifying access management processes.
• Integration with Smart Home Systems: The UWB system can seamlessly interact with other smart home devices, e.g., automatically activating lighting, air conditioning, or music upon entering an apartment.

Industry/Warehouses

• Secure Equipment Lockers: Ultra-Wideband (UWB) allows for precise access control to expensive tools, specialized machinery, sensitive components, or documents. The system can record who accessed a specific locker and when, enabling a full audit.
• Access to Restricted Areas: Restricting access to high-risk zones, dangerous areas, or sensitive data exclusively to authorized personnel significantly enhances workplace safety and minimizes the risk of accidents or theft.
• Optimization of Logistics Processes: UWB can support precise location of goods in a warehouse, automation of vehicle entry and exit (e.g., forklifts), and even verification of employee positions to ensure safety in dynamic environments.

The examples above are merely a glimpse of the possibilities offered by UWB. The precision of localization, resistance to interference, and inherent security that UWB brings make this technology a universal tool, capable of transforming almost any industry where access control, location awareness, and contextual positioning play a crucial role. Its potential is limited only by imagination.

Measuring Success and Creating Value for Ultra-Wideband

The value of UWB implementation can be measured through several key performance indicators (KPIs) that directly translate into business benefits and return on investment (ROI).

Operational Efficiency

• Increased Workflow Speed: Elimination of delays associated with manually searching for keys or access cards, or waiting for authorization. Faster door opening means less downtime and smoother operations.
• Reduced Access Management Time: Automation of processes for granting, modifying, and revoking access permissions, significantly reducing the administrative burden on IT and security departments.
• Optimized Resource Utilization: Better management of space, personnel, and assets due to precise location and access data.

Cost Reduction

• Lower Administrative Costs: Reduced labor associated with issuing, managing, and monitoring physical keys or access cards.
• Fewer Lost Keys and Cards: Decreased expenses for their replacement, re-encoding, or unlocking doors in case of loss. Minimization of security risks associated with access to lost credentials.
• Reduction in Security Incidents: Prevention of unauthorized entries, theft, or breaches, leading to fewer financial and reputational losses.

Security Level

• Prevention of Unauthorized Access Attempts: High resistance to “relay” attacks and spoofing makes the system significantly harder to breach.
• Overall Security Increase: Precise location, directional awareness, and advanced encryption significantly enhance access control and minimize the risk of breaches.
• Regulatory Compliance: The ability to easily meet stringent security and audit requirements in regulated industries.

User Satisfaction

• Convenience: A seamless, touchless, and intuitive access experience for employees, guests, and residents. Elimination of frustration associated with searching for keys or difficulties in unlocking.
• Increased Sense of Security: Users feel safer knowing that the system is advanced and resistant to fraud.
• Modern Image: Implementing such advanced technology builds a company’s image as innovative and committed to comfort and security.

Conclusion on Ultra-Wideband in Smart Locks

Ultra-Wideband (UWB) represents a strategic and forward-looking choice for access control systems, offering unparalleled precision, radically enhanced security, and significant user benefits. Its ability to precisely measure distance (ToF) and direction (AoA), along with its inherent resistance to “relay” attacks, fundamentally changes the paradigm of secure access.

Although current UWB deployment costs may be higher than those of older technologies, and the ecosystem is still maturing, market trends clearly indicate its growing dominance. 

Rapid adoption of UWB in popular mobile devices (e.g., latest generations of smartphones and smartwatches), projected component cost reductions as production scales, and the dynamic development and standardization of protocols such as Aliro, are accelerating its widespread adoption.

For enterprises looking to “future-proof” their infrastructure and gain a competitive edge in the era of smart buildings and spaces, a strategic recommendation is to thoroughly consider investing in UWB-based smart locks. The key is not just the technology itself, but primarily focusing on solving specific business problems – whether through radically increasing security, optimizing operational efficiency, or significantly improving user experiences.

Investing in UWB is an investment in the future, which will provide not only a higher level of protection but also significant process optimization and enhanced user comfort in an increasingly connected world.