1,206 research outputs found
Massive MIMO-based Localization and Mapping Exploiting Phase Information of Multipath Components
In this paper, we present a robust multipath-based localization and mapping
framework that exploits the phases of specular multipath components (MPCs)
using a massive multiple-input multiple-output (MIMO) array at the base
station. Utilizing the phase information related to the propagation distances
of the MPCs enables the possibility of localization with extraordinary accuracy
even with limited bandwidth. The specular MPC parameters along with the
parameters of the noise and the dense multipath component (DMC) are tracked
using an extended Kalman filter (EKF), which enables to preserve the
distance-related phase changes of the MPC complex amplitudes. The DMC comprises
all non-resolvable MPCs, which occur due to finite measurement aperture. The
estimation of the DMC parameters enhances the estimation quality of the
specular MPCs and therefore also the quality of localization and mapping. The
estimated MPC propagation distances are subsequently used as input to a
distance-based localization and mapping algorithm. This algorithm does not need
prior knowledge about the surrounding environment and base station position.
The performance is demonstrated with real radio-channel measurements using an
antenna array with 128 ports at the base station side and a standard cellular
signal bandwidth of 40 MHz. The results show that high accuracy localization is
possible even with such a low bandwidth.Comment: 14 pages (two columns), 13 figures. This work has been submitted to
the IEEE Transaction on Wireless Communications for possible publication.
Copyright may be transferred without notice, after which this version may no
longer be accessibl
Fundamental Limits of Wideband Localization - Part II: Cooperative Networks
The availability of positional information is of great importance in many
commercial, governmental, and military applications. Localization is commonly
accomplished through the use of radio communication between mobile devices
(agents) and fixed infrastructure (anchors). However, precise determination of
agent positions is a challenging task, especially in harsh environments due to
radio blockage or limited anchor deployment. In these situations, cooperation
among agents can significantly improve localization accuracy and reduce
localization outage probabilities. A general framework of analyzing the
fundamental limits of wideband localization has been developed in Part I of the
paper. Here, we build on this framework and establish the fundamental limits of
wideband cooperative location-aware networks. Our analysis is based on the
waveforms received at the nodes, in conjunction with Fisher information
inequality. We provide a geometrical interpretation of equivalent Fisher
information for cooperative networks. This approach allows us to succinctly
derive fundamental performance limits and their scaling behaviors, and to treat
anchors and agents in a unified way from the perspective of localization
accuracy. Our results yield important insights into how and when cooperation is
beneficial.Comment: To appear in IEEE Transactions on Information Theor
Performance Limits and Geometric Properties of Array Localization
Location-aware networks are of great importance and interest in both civil
and military applications. This paper determines the localization accuracy of
an agent, which is equipped with an antenna array and localizes itself using
wireless measurements with anchor nodes, in a far-field environment. In view of
the Cram\'er-Rao bound, we first derive the localization information for static
scenarios and demonstrate that such information is a weighed sum of Fisher
information matrices from each anchor-antenna measurement pair. Each matrix can
be further decomposed into two parts: a distance part with intensity
proportional to the squared baseband effective bandwidth of the transmitted
signal and a direction part with intensity associated with the normalized
anchor-antenna visual angle. Moreover, in dynamic scenarios, we show that the
Doppler shift contributes additional direction information, with intensity
determined by the agent velocity and the root mean squared time duration of the
transmitted signal. In addition, two measures are proposed to evaluate the
localization performance of wireless networks with different anchor-agent and
array-antenna geometries, and both formulae and simulations are provided for
typical anchor deployments and antenna arrays.Comment: to appear in IEEE Transactions on Information Theor
Indoor wireless communications and applications
Chapter 3 addresses challenges in radio link and system design in indoor scenarios. Given the fact that most human activities take place in indoor environments, the need for supporting ubiquitous indoor data connectivity and location/tracking service becomes even more important than in the previous decades. Specific technical challenges addressed in this section are(i), modelling complex indoor radio channels for effective antenna deployment, (ii), potential of millimeter-wave (mm-wave) radios for supporting higher data rates, and (iii), feasible indoor localisation and tracking techniques, which are summarised in three dedicated sections of this chapter
Inter-Node Distance Estimation from Multipath Delay Differences of Channels to Observer Nodes
We study the estimation of distance d between two wireless nodes by means of
their wideband channels to a third node, called observer. The motivating
principle is that the channel impulse responses are similar for small d and
drift apart when d increases. Following this idea we propose specific distance
estimators based on the differences of path delays of the extractable multipath
components. In particular, we derive such estimators for rich multipath
environments and various important cases: with and without clock
synchronization as well as errors on the extracted path delays (e.g. due to
limited bandwidth). The estimators readily support (and benefit from) the
presence of multiple observers. We present an error analysis and, using ray
tracing in an exemplary indoor environment, show that the estimators perform
well in realistic conditions. We describe possible localization applications of
the proposed scheme and highlight its major advantages: it requires neither
precise synchronization nor line-of-sight connection. This could make wireless
user tracking feasible in dynamic indoor settings.Comment: To appear at IEEE ICC 2019. This work has been submitted to the IEEE
for possible publication. Copyright may be transferred without notice, after
which this version may no longer be accessibl
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