Defining Virtualization Based System Abstractions for an Indoor Assistive Living for Elderly Care
Nova Ahmed · 2009 · Proceedings of the 11th International ACM SIGACCESS Conference on Computers and Accessibility (Assets '09) · doi:10.1145/1639642.1639707
Summary
This short paper proposes a two-layer system architecture for monitoring and guiding elderly residents in an indoor assistive living centre using passive RFID technology. The system addresses the tension between providing adequate monitoring for safety and preserving residents' privacy. Rather than tracking the precise position of each person (which is privacy-invasive), the system uses a virtualisation approach where the environment is divided into regions, and residents are monitored as "virtual units of location" at a coarse granularity. The architecture consists of two layers: a lower Guidance Layer that runs on handheld devices carried by residents, providing local information about surroundings, nearby objects, and navigation directions using RFID reader signals from passive tags embedded in the environment; and an upper Monitoring Layer composed of distributed Virtual Stations (servers) that maintain global knowledge of the environment and receive periodic coarse-grain location digests from the Mobile Agents. A Name Server coordinates system-wide information sharing across Virtual Stations. The key privacy mechanism is that the Monitoring Layer only receives summarised location information (e.g., "user moved from region A to region B between 10:30 and 11:30 AM") rather than continuous precise tracking, while the Guidance Layer provides detailed local assistance.
Key findings
A proof-of-concept laboratory experiment used a single M220 RFID reader (via Bluetooth) with 25 passive IR Asset Tags. Testing showed RFID reader sensitivity ranged from -58 dB to 108 dB across eight programmable power levels. The reader-to-tag distance and angular position significantly affected detection performance, with lower power levels at reader-to-tag distances under 50cm and under 100cm showing distinct detection patterns. The experiment demonstrated that the system could successfully guide a user by matching the RFID reader power level to the inter-tag distance in the environment — for example, guiding a user when the reader detected a tag at power level 2 versus the lower power level 1. While preliminary, these results validated the basic technical feasibility of using passive RFID tags for coarse-grain indoor location awareness without requiring residents to wear sensor badges or tags.
Relevance
This early-stage research addresses an important design challenge in assistive living technology: how to provide safety monitoring for elderly residents while respecting their dignity and privacy. The virtualisation-based approach — abstracting physical locations into coarse-grained virtual regions rather than precise coordinates — offers a principled privacy-by-design strategy that remains relevant as smart home and IoT technologies become more prevalent in elder care. The decision to instrument the environment with passive tags rather than requiring residents to wear sensors reduces stigma and compliance burden. However, the paper is quite preliminary, presenting only basic RFID characterisation results without a full system implementation or user evaluation. The architecture's scalability, accuracy in real-world care facilities, and actual privacy guarantees remain unvalidated. Nevertheless, the conceptual framework of balancing monitoring granularity against privacy preservation provides a useful design lens for assistive living system developers.
Tags: aging · ambient assisted living · RFID · indoor positioning · privacy · monitoring · smart home · elderly care