this paper, we describe an algorithm for the positioning of nodes in an ad hoc network that does not use GPS. The algorithm provides a position information to the nodes in the scenarios where an infrastructure does not exist and GPS cannot be used. GPS-free positioning is also desirable, when

to the localization of sensor networks in which each node can estimate the distance to each of its neighbors, but no absolute position reference such as GPS or fixed anchor nodes is available. We implemented the algorithm on a physical sensor network and empirically assessed its accuracy and performance. Also

Many sensor network applications require location awareness, but it is often too expensive to include a GPS receiver in a sensor network node. Hence, localization schemes for sensor networks typically use a small number of seed nodes that know their location and protocols whereby other nodes

comprehensive analysis of the geometry of

With the growing prevalence of sensor and wireless networks comes a new demand for location-based access control mechanisms. We introduce the concept of secure location verification, and we show how it can be used for location-based access control. Then, we present the Echo protocol, a simple

from two sensors and a variable gain to adapt to the changing signal-to-noise ratio environment. The TDOA is obtained directly on a sample-by-sample basis and no interpolation is necessary. The proposed algorithm gives an unbiased delay estimate and its performance for both stationary and nonstationary

Localization is of great importance in mobile and wireless network applications. TDOA is one of the widely used localization schemes, in which a to-be-located object emits a signal and a number of receivers record the arriving time of the signal. By calculating the time difference of different

Localization is of great importance in mobile and wireless network applications. TDOA is one of the widely used localization schemes, in which a to-be-located object emits a signal and a number of receivers record the arriving time of the signal. By calculating the time difference of different

mismatch. Our extensive simulation results illustrate a good performance for the introduced TDOA fingerprinting paradigm as well as a significant detection gain for the enhanced model. Index Terms—Multi-source localization, TDOA fingerprinting, sparse reconstruction. I.

, analysis of achievable synchronisation precision and processing of narrowband signals that can enable localization down to a meter. Keywords-localization, narrow band signals, TOA, TDOA I.