A distributed positioning system based on real-time RSSI enabling decimetric precision in unmodified IEEE 802.11 networks

Abstract

Abstract-In this paper we present a distributed positioning system for indoor environments based on a network of compact independent anchor nodes operating as specialized WiFi access points. Each node is built with component-off-the-shelves and it is capable of standard IEEE 802.11 connectivity at 2.45 GHz. The enabling technology for the localization is the Switched Beam Antenna (SBA) equipped in each node, which permits a space division multiple access at network-level.The positional information is the result of a maximum likeli hood estimation driven by the expected signal space partition of the constellation, and it is tolerant to noisy power measurements, such as Received Signal Strength Indicator, thanks to angular filtering capability of the SBA, which in addition operates in circular polarization.Experimental validations demonstrate the performance of a 3-anchors network, operating within the IEEE 802.11 protocol, monitoring a single nomadic node inside a 7 m 2 indoor square area. It results that 68% of the square area is covered with a localization error below 50 cm, with a mean error of 47 cm.Inside the triangular mesh defined by the three anchors, the mean error drops to 39cm, with 88% of the area being below 50 cm. In addition, the maximum error is always below 77 cm.Index Terms-Indoor positioning system, Received Signal Strength Indicator (RSSI), Switched beam antenna.

CRLBs for Location and Velocity Estimation for MIMO Radars in CES-Distributed Clutter

“…Additionally, to assess the maximum achievable accuracy of the considered MIMO radar over the area of interest, we define the errors (Maddio et al, 2015;Passafiume et al, 2017;Cidronali et al, 2020)…”

An Improved Approach for RSSI-Based only Calibration-Free Real-Time Indoor Localization on IEEE 802.11 and 802.15.4 Wireless Networks

“…In [ 17 , 18 ], COTS-only hardware for transparent indoor localization was proposed for use in a distributed network of IEEE 802.15.4 anchor nodes hanging from the ceiling, which offer Ethernet-to-ZigBee connectivity. Every anchor node is capable of transferring packets between any LAN host and each ZigBee node ( Figure 1 ), while the LAN host collects all the localization-related data.…”

“…A reference table for complete anchor networks is built in the LAN host, containing the position of each anchor node. As shown in [ 18 , 19 ], an ideal two-dimensional map of the expected RSSI is collected for each antenna and anchor (considering the user node as the transmitter), directly projecting each oriented polar ideal antenna pattern to the plane, with the height being the mean height of the TAG nodes (i.e., a typical height of 1.10 m from the floor is considered).…”

“…In [ 18 , 19 ], the maximum accuracy limit is stated performing an analytical Cramer–Rao-bound (CRB) computation [ 37 ], as presented in [ 16 ], but CRB analysis places only an ideal accuracy limit given by the geometrical distributions of antenna gains over the space. CRB analysis evaluates the minimum achievable error for the localization space, supposing that the only source of idealization is the RSSI AWGN added to the obtained steering vector (modelled by the equivalent noise parameter as in [ 19 ]).…”