Direct Wideband Coherent Localization by Distributed Antenna Arrays

Abstract

We address wideband direct coherent localization of a radio transmitter by a distributed antenna array in a multipath scenario with spatially-coherent line-of-sight (LoS) signal components. Such a signal scenario is realistic in small cells, especially indoors in the mmWave range. The system model considers collocated time and phase synchronized receiving front-ends with antennas distributed in 3D space at known locations connected to the front-ends via calibrated coaxial cables or analog radio frequency over fiber links. The signal model assumes spherical wavefronts. We propose two ML-type algorithms (for known and unknown transmitter waveforms) and a subspace-based SCM-MUSIC algorithm for wideband direct coherent position estimation. We demonstrate the performance of the methods by Monte Carlo simulations. The results show that even in multipath environments, it is possible to achieve localization accuracy that is much better (by two to three orders of magnitude) than the carrier wavelength. They also suggest that the methods that do not exploit knowledge of the waveform have mean-squared errors approaching the Cramér–Rao bound.

5G SLAM Using the Clustering and Assignment Approach with Diffuse Multipath

“…Using the raw measurements directly in SLAM is challenging, due to the high dimensionality of the measurement, the complex nonlinear relation to the user and landmark states, and the fact that not all paths may be resolvable, due to a limited number of transmitter and receiver antennas and bandwidth. While such direct localization has performance benefits [ 45 , 46 , 47 ], we instead consider a layered approach , visualized in Figure 3 , comprising the following steps after downlink transmission of the signals .…”

Performance Limits of Direct Wideband Coherent 3D Localization in Distributed Massive MIMO Systems

“…According to the experimental results in [ 2 ], the range (mmWave) has great potential for spatially coherent localization, because the non-line-of-sight (NLoS) components are at least below the LoS component. Methods for passive wideband localization in spatially coherent setups have been proposed in [ 18 ], but CRBs for them have not been addressed yet.…”

“…Their performance approaches the CRB, and they solve the ambiguity problem inherent to coherent localization in distributed massive MIMO. There are also direct wideband coherent methods for localization of a non-cooperative transmitter via a distributed antenna array in environments with multipath propagation and interference [ 18 ].…”

“…In this paper, we derive the CRBs of localization of an arbitrarily wideband stationary radio frequency (RF) transmitter (Tx) in a spatially coherent scenario (such as the one in [ 18 ]). The receiving channels are phase- and time-synchronized, but time synchronization between the Tx and the receiving system is not required, unlike for ToA-based methods [ 17 ].…”

“…The localization system can use an unknown-sequence method (a method suited to random signals) to localize a non-cooperative source in the area of interest, that is completely independent from the system, or a known-sequence method to localize cooperative terminals, especially if they are a part of the communication network that also performs this localization (see different methods in [ 18 ]). Known-sequence-based methods can be numerically more complex, but they provide a processing gain which suppresses all interference orthogonal to the searched sequence (similar to CDMA (code-division multiple access) systems).…”