A pervasive assistive environment for visually impaired people using wireless sensor network infrastructure

Wireless sensor networks (WSNs) have been identified as a promising technology for supporting assistive environments. This article introduces PROTECT, a system that employs autonomous software objects referred to as mobile agents (MAs) able of locating and informing visually impaired persons for potential risks. PROTECT utilizes a 3-tier architecture where the first tier comprises a base station (BS), the second tier mobile sinks (MS) (carried by blind people on their sticks) and the third tier stationary sensor nodes. This WSN is deployed in an urban environment. In the event of an alarm issued by a sensor node, the BS launches a number of MAs supplied with a near-optimal itineraries that visit the nodes in the alarm's surrounding area and notifies, through Wi-Fi (IEEE 802.11), visually impaired people for potential hazards in their proximity. In the event of communication problems (e.g. failure of some sensor nodes) PROTECT modifies the itineraries of the MAs to bypass the problematic areas avoiding disruption of the data collection process from working sensors. Simulation results confirm the high effectiveness of our proposed scheme in WSNs used in assistive environments and its performance gain over alternative MA-based approaches proposed for data fusion tasks.