The impact of NLOS components in Time-of-Flight networks for indoor positioning systems

On the possibility to use leaky feeders for positioning in chirp spread spectrum technologies

“…They are now capable to provide a reasonable accuracy also under harsh indoor environments, as could be shown in [1], [2] and many others. [3], [4] show that applications can even include safety-related underground longwall mining infrastructure.…”

“…Propagation losses of electromagnetic waves in free space P L F S (d) for a point-like radio source in far field might be described by the following equation according to Free Space Equation from Friis [10]: (1) where: P L -path loss -the difference between the output RF power of a transmitter and the measured signal strength 978-1-4799-6722-3/14/$31.00 ©2014 IEEE at a receiver, i.e. P L = P T X − P RX ; d 0 -reference distance, for example, 1 m; P L(d 0 ) -path loss at the reference distance d 0 ; d -distance between the leaky feeder and receiver; β -path loss exponent, β = 2 for free space; X σ -a variable, depending on the multipath interference at a receiver side, including fast fading effect and given antenna pattern.…”