Fundamentals of statistical signal processing: estimation theory
Fundamentals of statistical signal processing: estimation theory
A directionality based location discovery scheme for wireless sensor networks
WSNA '02 Proceedings of the 1st ACM international workshop on Wireless sensor networks and applications
UCS'04 Proceedings of the Second international conference on Ubiquitous Computing Systems
Indoor geolocation science and technology
IEEE Communications Magazine
Ranging in a dense multipath environment using an UWB radio link
IEEE Journal on Selected Areas in Communications
I am the antenna: accurate outdoor AP location using smartphones
MobiCom '11 Proceedings of the 17th annual international conference on Mobile computing and networking
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We present the implementation of a directional beacon-based positioning algorithm using radio frequency signals. This algorithm allows each mobile node to compute its position with respect to a set of reference nodes which are equipped with a rotating directional antenna. The use of directional beacon-based algorithm for position location eliminates the need for strict synchronization between the reference nodes and the mobile node. In contrast to positioning algorithms that rely on signal propagation time and bandwidth, the proposed algorithm depends on the beam-width and rotational speed of the directional antenna. We will show that these parameters can be optimized with a low cost solution that provides good positioning accuracy. The system implementation is based on the GNU Radio software platform and the Universal Software Radio Peripheral as the hardware component. We present an enhanced maximum likelihood method for estimating the received signal amplitude profile. To deal with obstructed line-of-sight scenarios, we do not rely purely on the received signal strength and instead formulate a least squares problem to estimate the line-of-sight component in a multipath environment. These advanced signal processing techniques yield a more accurate estimate of the bearing of the mobile node with respect to each of the reference nodes. We also show that the proposed positioning algorithm is tolerant to errors in timing and synchronization. We demonstrate the ability to obtain mobile node position estimates with sub-meter accuracy by transmitting a narrowband signal of 1 kHz bandwidth in the 2.4-2.5 GHz band. The experimental results show a mean position error of 0.759m, in a field measuring 55m by 43m, using eight 90° rotations of the antenna.