Iterative RToF‐based localisation and time synchronisation in WLAN‐like systems

Abstract

Iterative localisation is currently arising as a solution to localise a mobile station in a cellular network. It is shown recently that iterating between the conventional delay estimation and multi-lateration steps allows one to approach the performance of direct localisation algorithms. Until now, the method has only been applied to the case of networks where the access points (APs) are perfectly synchronised with each other. A localisation and time synchronisation iterative algorithm suitable for networks is presented, where APs are not synchronised. It is shown numerically that iterating between the two conventional steps brings a significant performance gain.

Iterative ToA-Based Localization of Wireless Transmitters Using Dirichlet-Kernel-Based Range Representation

“…By inspecting (10), we can make two remarks. First, we consider that the noise term w k is uncorrelated with the transmitted signal s(δ k ); hence, at high SNR values, the second term in the right hand side of (10) will be smaller than the first one.…”

“…Second, the first term can be rewritten as a sum of cosines by developing the real part operator. The two remarks are applied to (10) and the new expression is…”

“…where xk , ỹk is the location of the maximum peak of the approximated log-posterior defined in (17); and not directly equal to (1 + 2P )/σ 2 w , to take into account the small effect of the discarded term in (10) over the magnitude of the peak of the Dirichlet kernel. Lastly, all the constant terms in (13) can be included/handled in the normalization of the distribution, and thus they are not taken into account in (15).…”

“…Moreover, the IPE algorithm introduces an iterative framework that has been extended and studied more in depth in [7] and [8] where the effect of multipath channels and time-misalignment between transmitter and receiver was studied over the algorithm. Finally, it has been also shown that the iterative framework proposed by the IPE algorithm could be used in different applications and scenarios such as angle of arrival (AOA)-based iterative localization [9] and localization on WLAN-like systems [10].…”