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Real-time occupancy information is valuable to the building industry for a wide variety of applications such as on-site safety management, energy conservation, emergency response and so on. With the emergence of various technologies that can potentially be used for indoor location sensing (ILS), the building industry is in search for an ILS solution to provide accurate and cost efficient occupancy information. This study assesses two ILS systems that are built on two promising modalities: radio frequency identification (RFID) and wireless sensor networks (WSNs). Two algorithms were proposed and tested in a computer lab with an area of 235 m 2 . Six occupants, who were attached with both RFID tags and WSN nodes, were tracked simultaneously. The occupants remained seated throughout the test, and the occupancy was monitored. The results show that the proposed systems were able to provide accurate room level occupancy information majority of the time, and that the choice of algorithm and technology affected the uniformity of the results.

Sequence-based localization (SBL) is a technique whereby a node is localized based on the ranked sequence of signal strengths obtained from a set of beacon nodes. SBL effectively partitions the area into regions corresponding to unique ranked sequences. Prior work has developed SBL under the assumption that all beacons have the same transmit power. In this work, we consider beacons with unequal transmit power for sequencebased localization and present heuristic algorithms for joint transmit power optimization and beacon placement. We show through comprehensive simulations that a novel enhancement of SBL utilizing optimized non-uniform transmit powers, coupled with careful beacon placement, which we refer to as NU-SBL, can dramatically improve the area partitioning compared to traditional SBL. However, in evaluating these schemes under stochastic fading, we find that the original SBL with optimized location performs nearly as well or slightly better than NU-SBL in many cases. We introduce another scheme, that we refer to as NU-SBL-ZOOM, which further allows the power levels to be optimized non-uniformly so as to focus in on a particular smaller region within the larger localization space. NU-SBL-ZOOM is found to perform much better in terms of both area partitioning as well as location error in the presence of fading.