431 research outputs found
Robust Localization from Incomplete Local Information
We consider the problem of localizing wireless devices in an ad-hoc network
embedded in a d-dimensional Euclidean space. Obtaining a good estimation of
where wireless devices are located is crucial in wireless network applications
including environment monitoring, geographic routing and topology control. When
the positions of the devices are unknown and only local distance information is
given, we need to infer the positions from these local distance measurements.
This problem is particularly challenging when we only have access to
measurements that have limited accuracy and are incomplete. We consider the
extreme case of this limitation on the available information, namely only the
connectivity information is available, i.e., we only know whether a pair of
nodes is within a fixed detection range of each other or not, and no
information is known about how far apart they are. Further, to account for
detection failures, we assume that even if a pair of devices is within the
detection range, it fails to detect the presence of one another with some
probability and this probability of failure depends on how far apart those
devices are. Given this limited information, we investigate the performance of
a centralized positioning algorithm MDS-MAP introduced by Shang et al., and a
distributed positioning algorithm, introduced by Savarese et al., called
HOP-TERRAIN. In particular, for a network consisting of n devices positioned
randomly, we provide a bound on the resulting error for both algorithms. We
show that the error is bounded, decreasing at a rate that is proportional to
R/Rc, where Rc is the critical detection range when the resulting random
network starts to be connected, and R is the detection range of each device.Comment: 40 pages, 13 figure
Signal Processing and Propagation for Aeroacoustic Sensor Networking,” Ch
Passive sensing of acoustic sources is attractive in many respects, including the relatively low signal bandwidth of sound waves, the loudness of most sources of interest, and the inherent difficulty of disguising or concealing emitted acoustic signals. The availability of inexpensive, low-power sensing and signal-processing hardware enables application of sophisticated real-time signal processing. Among th
XR-RF Imaging Enabled by Software-Defined Metasurfaces and Machine Learning: Foundational Vision, Technologies and Challenges
We present a new approach to Extended Reality (XR), denoted as iCOPYWAVES,
which seeks to offer naturally low-latency operation and cost-effectiveness,
overcoming the critical scalability issues faced by existing solutions.
iCOPYWAVES is enabled by emerging PWEs, a recently proposed technology in
wireless communications. Empowered by intelligent (meta)surfaces, PWEs
transform the wave propagation phenomenon into a software-defined process. We
leverage PWEs to i) create, and then ii) selectively copy the scattered RF
wavefront of an object from one location in space to another, where a machine
learning module, accelerated by FPGAs, translates it to visual input for an XR
headset using PWEdriven, RF imaging principles (XR-RF). This makes for an XR
system whose operation is bounded in the physical layer and, hence, has the
prospects for minimal end-to-end latency. Over large distances,
RF-to-fiber/fiber-to-RF is employed to provide intermediate connectivity. The
paper provides a tutorial on the iCOPYWAVES system architecture and workflow. A
proof-of-concept implementation via simulations is provided, demonstrating the
reconstruction of challenging objects in iCOPYWAVES produced computer graphics
Spatial Division Multiplexed Microwave Signal processing by selective grating inscription in homogeneous multicore fibers
[EN] The use of Spatial Division Multiplexing for Microwave Photonics signal processing is proposed and experimentally demonstrated, for the first time to our knowledge, based on the selective inscription of Bragg gratings in homogeneous multicore fibers. The fabricated devices behave as sampled true time delay elements for radiofrequency signals offering a wide range of operation possibilities within the same optical fiber. The key to processing flexibility comes from the implementation of novel multicavity configurations by inscribing a variety of different fiber Bragg gratings along the different cores of a 7-core fiber. This entails the development of the first fabrication method to inscribe high-quality gratings characterized by arbitrary frequency spectra and located in arbitrary longitudinal positions along the individual cores of a multicore fiber. Our work opens the way towards the development of unique compact fiber-based solutions that enable the implementation of a wide variety of 2D (spatial and wavelength diversity) signal processing functionalities that will be key in future fiber-wireless communications scenarios. We envisage that Microwave Photonics systems and networks will benefit from this technology in terms of compactness, operation versatility and performance stability.We thank Prof. Jose Capmany for the thoughtful discussions and recommendations that greatly contribute to this work. This research was supported by the Spanish MINECO Projects TEC2014-60378-C2-1-R and TEC2015-62520-ERC, the Valencian Research Excellency Award Program GVA PROMETEO 2013/012, the Spanish MECD FPU Scholarship (FPU13/04675) for J. Hervas, and the Spanish MINECO Ramon y Cajal Program (RYC-2014-16247) for I. Gasulla.Gasulla Mestre, I.; Barrera Vilar, D.; Hervás-Peralta, J.; Sales Maicas, S. (2017). 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