Lessons Learned from Designing, Deploying and Testing an Accessible BLE Beacon-based Wayfinding System in a Multi-Floor Indoor Environment
Ajay Abraham · 2022 · Proceedings of the 24th International ACM SIGACCESS Conference on Computers and Accessibility (ASSETS '22) · doi:10.1145/3517428.3550415
Summary
This paper documents the practical guidelines and design decisions involved in deploying a Bluetooth Low Energy (BLE) beacon-based indoor wayfinding system in a three-story college campus building. The system builds on GuideBeacon, a previously developed proximity-based indoor navigation approach, and extends it to serve people with diverse disabilities — not just blind and visually impaired users but also wheelchair users, people who are hard of hearing, and those with cognitive disabilities. The wayfinding system works by placing BLE beacons at strategic points of interest (PoIs) throughout a building, creating a connected graph where beacons serve as vertices and walking paths serve as weighted edges. A proximity detection algorithm using Received Signal Strength Indicator (RSSI) readings with a weighted moving average localizes users to within 1-2 meters of nearby beacons. The system uses Dijkstra's algorithm to compute shortest paths, and includes automatic rerouting if a user deviates from the planned route. Mobile applications for both Android and iOS were developed, each featuring two modules: an exploration module for learning about nearby surroundings and a navigation module providing turn-by-turn guidance. The paper covers the full deployment lifecycle including beacon planning, placement, configuration (advertising intervals, transmission power), physical installation, and ongoing management through cloud-based monitoring tools.
Key findings
The deployment revealed several practical lessons for BLE beacon-based wayfinding systems. For beacon placement, ceiling mounting in the center of corridors provided the best proximity detection performance in narrow double-loaded corridors, while wall mounting was preferred for large open spaces with high ceilings. Beacons should be mounted at approximately 2.4 meters above the floor and at least 0.5 meters from metallic fixtures to avoid signal interference. The Gimbal Series 21 beacons used offered approximately 18 months of battery life on standard AA batteries, with an advertising interval of 100 milliseconds and initial transmission power of -8 dBm. Preliminary usability testing revealed distinct navigation information needs across disability groups: BVI users preferred very fast narration speeds and voice search over text input (since they held a smartphone in one hand and a white cane in the other), hard of hearing users wanted turn-by-turn directions displayed as text on screen, and wheelchair users needed routes that prioritized elevators over stairs. All user categories found the navigation module useful regardless of disability type. Converting distances from meters/feet to steps helped BVI users build mental spatial representations more easily. Haptic/tactile feedback through vibrations helped orient users in the right direction and reduced ambiguity compared to verbal left-right instructions alone. Switching from clock position references to left-right-forward directions was found to reduce navigational ambiguity. The paper also identifies key future directions including adding Pedestrian Dead Reckoning for smoother position tracking, layered information with user-selected priority levels to combat information overload, and integrating obstacle detection alongside wayfinding.
Relevance
This paper provides valuable practical guidance for anyone deploying indoor navigation systems in public buildings — a critical accessibility need given that GPS does not work indoors and static signage is inaccessible to many disabled people. The emphasis on serving diverse disability groups through a single infrastructure, rather than building separate systems for each disability type, offers a cost-effective model for community-scale deployment, particularly important in small and medium-sized communities with limited resources. For accessibility practitioners and facility managers, the detailed deployment guidelines — covering beacon placement heights, transmission power settings, mounting methods, management workflows, and distance metrics — represent hard-won practical knowledge that would otherwise require extensive trial and error. The finding that different user groups need different navigation information formats reinforces the importance of customizable, multi-modal interfaces in wayfinding applications. The system's limitation of using only proximity-based localization (rather than fingerprinting or computer vision) keeps the hardware requirements minimal and deployment straightforward, though it comes at the cost of continuous position tracking between beacons.
Tags: indoor navigation · wayfinding · BLE beacon · blind and low vision · mobile accessibility · localization · wheelchair accessibility · assistive technology