Conference-2016

News

2016 Publications - Symposium, Conference, Workshop

PP.32

"Transmit power minimization in multi-user millimeter wave systems"

Authors: Samip Malla, Giuseppe Abreu

HIGHTS Partners: Jacobs

Published in: 2016 International Symposium on Wireless Communication Systems (ISWCS)

Date of Conference: 20-23 Sept. 2016

Abstract

The transmit beamforming for millimeter wave systems has become a promising strategy to achieve higher spectral efficiency. The beamforming design for such systems stems out from various network optimization criterions that strike a balance between quality of service and energy/cost incurred to the system. We offer a simple and comprehensive solution to one of such key network optimization problems, namely transmit power minimization in multi-user millimeter wave system constrained on users' desired quality of service. The minimum transmit power beamforming vector is designed via hybrid analog and digital precoder that satisfies the practical hardware constraints. The crux of simplicity of the proposed algorithm lies in the fact that the analog beamforming could be solved via equal gain transmission method and the digital beamforming via zero forcing and Perron-Frobenius theorem. We also present simulation results of the proposed algorithms illustrating the performance gain comparable to computationally expensive fully digital and unconstrained beamforming algorithms.

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PP.31

"Channel estimation in millimeter wave MIMO Systems: Sparsity enhancement via reweighting"

Authors: Samip Malla, Giuseppe Abreu

HIGHTS Partners: Jacobs

Published in: 2016 International Symposium on Wireless Communication Systems (ISWCS)

Date of Conference: 20-23 Sept. 2016

Abstract

The usage of the higher frequency band in the millimeter wave systems implies higher pathloss, despite its elegance in providing an enormous spectrum for future cellular networks. Such systems rely on beamforming and precoding/combining techniques with large number of antennas to achieve adequate operational link margin. The requirement of complete channel information is hence imperative for such systems to implement those routines to approach its capacity limit. Thanks to the millimeter wave band, the sparse nature of the channel can be well exploited such that the problem of channel estimation could be formulated as sparse signal recovery problem. In this paper, we offer a simple and comprehensive solution to the above mentioned problem using the principle of basis pursuit denoise (BPDN) that aims to find a sparse solution. The sparsity of the estimation problem is further enhanced via a simple iterative solution which involves reweighted ℓ1 minimization. Simulation results illustrate the performance gain achieved over the classical unweighted solutions.

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PP.30

"MISO TX-power minimization under imperfect instantaneous CSIT"

Authors: Samip Malla, Giuseppe Abreu

HIGHTS Partners: Jacobs

Published in: 2015 International Symposium on Wireless Communication Systems (ISWCS)

Date of Conference: 25-28 Aug. 2015

Abstract

The signal to interference and noise ratio (SINR)-constrained transmit (TX)-power minimization problem, incorporating perfect and instantaneous channel state information at the transmitter (CSIT), culminates in higher overhead and extensive backhauling, likewise average CSIT suffers from quality fluctuations. Also, methods relying on the statistical SINR constraints require several algebraic steps in converting those constraints to deterministic convex equivalents. This process not only loosens the constraint of the problem, but also significantly subtracts the potential performance. In contrary to above mentioned procedures, we account for imperfect instantaneous CSIT and propose a simple solution based on Perron-Frobenius (PF) theorem and uplink-downlink duality to address the problem in a multi-user multiple input single output (MISO) system under prescribed outage. We derive accurate models for the distribution of true SINR experienced by the receivers subject to imperfect CSIT and conditioned on constraint-matching SINR estimates. Simulation results demonstrate the significant performance gain achieved by the proposed solution when compared with the state of the art.

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PP.29

"MIMO power minimization with imperfect CSIT and prescribed outage"

Authors: Samip Malla, Jhanak Parajuli, Giuseppe Abreu

HIGHTS Partners: Jacobs

Published in: 2015 49th Asilomar Conference on Signals, Systems and Computers

Date of Conference: 8-11 Nov. 2015

Abstract

TThe usage of perfect and instantaneous CSIT in a SINR-constrained transmit power minimization requires excessive resources to acquire and distribute channel information. Recent works relying on statistical SINR constraints designed under prescribed outage loosens the original constraint in converting statistical inequalities to deterministic convex equivalents. In this paper, we offer a simple solution to this problem thereby deriving accurate models for true SINRs at the users subject to imperfect CSIT, conditioned on constraint matching estimates. Using these distributions, we design deterministic, instantaneous and convex SINR-constraints to compensate and meet the prescribed outage.

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PP.28

"Energy efficiency and base station selection in massive MIMO and small cell hybrid networks"

Authors: Samip Malla, Giuseppe Abreu

HIGHTS Partners: Jacobs

Published in: 2015 IEEE 6th International Workshop on Computational Advances in Multi-Sensor Adaptive Processing (CAMSAP)

Date of Conference: 13-16 Dec. 2015

Abstract

The usage of hybrid network consisting of massive multiple input multiple output (MIMO) co-existing with small cell networks (SCNs), are considered to be a key technique for the future wireless communication systems. However, the co-existing SCNs not only require on-site hardware installation, but also increase the static power of the system thereby reducing the energy efficiency (EE). To circumvent the problem, we account for base station (BS) selection to strategically turn on or off the SCN such that EE of the system is maximized, constrained on total transmit power and end-user rate requirement. Simulation results demonstrate the gain in EE by strategic BS selection over different network topologies, implying effectiveness of employing BS selection strategy in hybrid networks.

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PP.27

"Transmission strategies under imperfect instantaneous CSIT"

Authors: Samip Malla, Giuseppe Abreu

HIGHTS Partners: Jacobs

Published in: 2015 IEEE Wireless Communications and Networking Conference (WCNC)

Date of Conference: 9-12 March 2015

Abstract

We propose a simple solution based on Perron-Frobenius theorem and uplink-downlink duality to the longstanding problem of transmission strategies: maximize the minimum SINR or minimize the transmit power. In contrary of using perfect and instantaneous CSIT (requires higher overhead and backhauling), or using only average CSIT, e.g. channel covariance which suffers from quality fluctuations; we account for imperfect instantaneous CSIT. The solution emerges from the observation that the crux of the robustness problem is the construction of SINR estimates itself. We provide a MLE-based estimate which being sub-optimal and failing to incorporate the channel estimation error, we reinforce it by biasing the estimate, which not only achieves smaller error but is strictly conservative as well. We also consider both transmission strategy problems, and show that the biased estimates are not only robust compared to traditional unbiased estimates, but also substantially outperform the probabilistic method with Bernstein-type relaxation proposed in [1].

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PP.25

"Robust weighted sum-rate maximization over full-duplex multi-user MIMO systems under imperfect CSIT"

Authors: Yohannes Jote Tolossa, Giuseppe Abreu

HIGHTS Partners: Jacobs

Published in: 2016 International Symposium on Wireless Communication Systems (ISWCS)

Date of Conference: 20-23 Sept. 2016

Abstract

Abstract:
We consider a full-duplex (FD) multi-user multiple-input multiple-output (MIMO) system where the base-station (BS) serves multiple uplink (UL) and downlink (DL) users simultaneously. We address the robust weighted sum-rate maximization (WSRM) problem, in which the transmitted rate over an arbitrary link is maximized subject to transmit power constraints imposed at the FD base-station and UL users. A convergent iterative algorithm is proposed where the initial sum-rate and the transmit precoding are initialized primarily so as to obtain the initial weight matrices and receive filters. Afterwards, using these initial parameters, the beamforming vectors are calculated via solving the robust WSRM problem which can be casted as a second order cone programming (SOCP). At the end, the optimal achievable sum-rate is calculated from the designed parameters provided that a predefined stopping criteria is met. The proposed design is evaluated via numerical simulation.

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PP.24

"Physical layer security in cellular networks under modified MHCPP model"

Authors: Yohannes Jote Tolossa, Satyanarayana Vuppala, Giuseppe Abreu

HIGHTS Partners: Jacobs

Published in: 2015 IEEE 26th Annual International Symposium on Personal, Indoor, and Mobile Radio Communications (PIMRC)

Date of Conference: 30 Aug.-2 Sept. 2015

Abstract

The majority of recent literature characterizes the secrecy capacity of wireless random networks by relying on Poison Point Processes which model the spatial distribution of devices. However, the realistic topologies are distinct from uniform and random assumption of the base stations or users. It has been recently demonstrated that Matérn Hard-core Point Processes (MHCPP) - rather than Poison Point Processes - are better suited to characterize such random location of users and base-stations of cellular systems. In this paper, we perform an analysis of the Secrecy Outage probability of cellular random networks under fading channel by employing the modified MHCPP model. It is also shown that the base station deployment has a significant impact on the secrecy outage.

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PP.23

"Secrecy outage analysis of cognitive radio networks with power control"

Authors: Yohannes Jote Tolossa, Satyanarayana Vuppala, Giuseppe Abreu

HIGHTS Partners: Jacobs

Published in: 2015 International Symposium on Wireless Communication Systems (ISWCS)

Date of Conference: 25-28 Aug. 2015

Abstract

We examine the upper and lower bound of the secrecy outage probability of primary links in cognitive wireless sensor networks employing power control scheme. The power control law is adopted in order to govern the transmission power of a cognitive radio node and there by limit interference incurred to the neighboring cognitive radio user. An accurate expressions for the probability density function of the aggregate interference with fading and shadowing is also derived. It is shown that the secrecy outage bounds will become tight as the equivocation rate increases and when the density of the eavesdroppers decrease. Moreover, it is found that the presence of fading has a little impact on secrecy outage. The expressions derived can also be further used to obtain other analytical results such as secrecy rate and secrecy transmission capacity.

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PP.22

"Probabilistic based TX-beamformer design under partial CSIT using optimized SINR estimate"

Authors: Yohannes Jote Tolossa, Giuseppe Abreu

HIGHTS Partners: Jacobs

Published in: 2015 IEEE International Conference on Communications (ICC)

Date of Conference: 8-12 June 2015

Abstract

A long-standing problem in CoMP is that existing methods either require perfect and instantaneous CSIT which implies the need of excessive piloting and backhauling, so as to acquire and distribute CSIT accurately and timely. Thus, it is required to formulate a robust beamforming method to circumvent this drawbacks and has been the focus of many research papers recently. In this paper, a solution to the problem, which follows a relaxation-restriction (RAR) approach and emerges from the observation that the crux of the robustness problem is the construction of the SINR estimates themselves, subject to partial CSIT. Specifically, it is shown considering SINR-constrained transmit-power minimization that CoMP algorithms built using the biased estimator significantly outperform the best recent alternative method, namely the outage based probabilistic approach with Bernstein-type inequality relaxation of [1]. Our proposed alternative is also less relaxed as compared to existing literature. The level of conservatism can be further reduced through incorporating bisection method on top of the robust SINR-constrained optimization problem so that the required outage probability in this case is satisfied as per the user requirement and transmit power efficient solutions is obtained.

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PP.20

"On prototyping IEEE802.11p channel estimators in real-world environments using GNURadio"

Authors: Razvan-Andrei Stoica, Stefano Severi, Giuseppe Thadeu Freitas de Abreu

HIGHTS Partners: Jacobs

Published in: 2016 IEEE Intelligent Vehicles Symposium (IV)

Date of Conference: 19-22 June 2016

Abstract

The current advances in the Intelligent Transportation Systems (ITS) reveal new solutions which are in need of validation in real-world deployments. The practicality, implementability, latency and robustness of such methods are key insights into their wide acceptance, and finally, absorption by standardization organizations. This paper discusses an approach to rapidly prototype newly proposed Wireless Access in Vehicular Environments (WAVE) algorithms based on the open source community and the emergence of Software Defined Radio (SDR). Concretely, this work details the practical deployment of a new adaptive channel estimation method in the context of IEEE 802.11p based vehicular communications. The development steps are illustrated and some challenges involved by real-world deployment (e.g. the phase tracking problem) are treated. Consequently, practical methods to solve the observed impairments are derived and implemented for real-time operation and validation.

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PP.18

"Optimizing waveforms for positioning in 5G"

Authors: Armin Dammann, Thomas Jost, Ronald Raulefs, Michael Walter, Siwei Zhang

HIGHTS Partners: DLR

Published in: 2016 IEEE 17th International Workshop on Signal Processing Advances in Wireless Communications (SPAWC)

Date of Conference: 3-6 July 2016

Abstract

Today's mobile radio systems deploy reference signals which can be used or which are even dedicated for signal propagation delay-based mobile terminal positioning. Usually, the signal power of such reference signals is uniformly distributed over the available spectrum. It is known from estimation theory that such a uniform power distribution of reference signals is not optimal for signal propagation delay estimation. In this paper we consider mobile terminal positioning based on signal propagation delay estimation in the uplink case. For positioning, we introduce a parametric waveform. This waveform provides a scalar parameter for controlling the distribution of the available signal power over the spectrum. Using this waveform parameter we aim to minimize the positioning error. For optimization, we require a functional dependency between the waveform parameter and the positioning error we can expect. For the derivation of this function we combine the approaches of the Cramér-Rao and Ziv-Zakai bounds for position and propagation delay estimation. As an exemplary environment we consider a mobile terminal located in an area surrounded by 3 base stations. For this environment we show that the optimized waveform spends a significant part of the available power at the spectrum edges, leading to a performance gain of 37.3% at the center of the area between the base stations.

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PP.17

"The 5G Localization Waveform Ranging Accuracy over Time-Dispersive Channels – An Evaluation"

Authors: Armin Dammann, Emanuel Staudinger, Michael Walter

HIGHTS Partners: DLR

Published in: ION GNSS+ 2016

Date of Conference: Sept. 12-16, 2016

Abstract

Localization has increasingly become important for a variety of applications and context aware services. Today’s mobile communication terminals exploit existing reference signal structures for propagation delay based positioning. Recently, particular single-parametrized waveforms with adaptable power spectral densities (PSDs) haven been proposed in the context of 5G. These waveforms haven been investigated based on Cramer- ´ Rao lower bounds (CRLBs) and Ziv-Zakai lower bounds (ZZLBs) for multipath-free channels.
Time-dispersive channels have neither been investigated theoretically nor numerically. In this work, we make this gap smaller by numerical evaluations of the proposed waveforms. We focus on a simple correlation-based receiver and investigate the resulting ranging error. Our evaluations with varying root mean square (RMS) delay spread and fixed Rician K-factor clearly show, for which particular channels and signal bandwidths specific waveforms and their respective parameters should be chosen. A ranging error reduction of factor 1.2 to more than 5 compared to state of the art reference signals can be obtained. Hence, we pave the way to possibly place a new waveform within the 5G context for improved ranging accuracy compared to state of the art.

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PP.16

"Multipath Assisted Positioning in Vehicular Applications"

Authors: Ulmschneider, Markus und Raulefs, Ronald und Gentner, Christian und Walter, Michael

HIGHTS Partners: DLR

Published in: 2016 13th Workshop on Positioning, Navigation and Communications (WPNC)
Date of Conference: 19-20 Oct. 2016

Abstract

Precise localization and tracking in intelligent transportation systems has aroused great interest since it is required in a large variety of applications. The positioning accuracy of global navigation satellite systems is unreliable and insufficient enough for many use cases. In urban canyons or tunnels, the positioning performance degrades due to a low received signal power, multipath propagation, or signal blocking. Instead we exploit the ubiquitous access to cellular mobile radio networks. Cellular networks are designed to cover the access to the network in an area by a single link to reduce the risk of interference from neighboring base stations. The idea of Channel-SLAM is to exploit the numerous multipath components (MPCs) of a radio signal arriving at the receiver for positioning. Each MPC can be regarded as being sent from a virtual transmitter in a pure line-of-sight condition. Within this paper, we show how to apply multipath assisted positioning in an urban scenario. Therefore, we analyze how a road user equipped with a circular antenna array is tracked in an urban scenario in the presence of only one physical transmitter. We further jointly estimate the positions of the physical and the virtual transmitters to enrich maps.

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PP.15

"Location information driven formation control for swarm return-to-base application"

Authors: Siwei Zhang, Ronald Raulefs, Armin Dammann

HIGHTS Partners: DLR

Published in: 2016 24th European Signal Processing Conference (EUSIPCO)

Date of Conference: 29 Aug.-2 Sept. 2016

Abstract

On Mars there is no global positioning system available. In this paper we present an analysis of a relative localization system that acts as a moving swarm to estimate the location of its base. Our algorithm jointly processes two objectives. First to shape an optimized swarm structure to estimate the location of the base reliable and second to move the swarm together towards the base to return home. The estimate of the base location is used to return to it by controlled movements considering constraints such as the minimum distance between the swarm elements to avoid collisions. The performance comparison of our location information driven algorithm with goal approaching or flocking algorithm shows a robust behavior with a much higher efficiency.

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PP.13

"Multipath assisted positioning for pedestrians using LTE signals"

Authors: Markus Ulmschneider, Christian Gentner
HIGHTS Partners: DLR

Published in: Position, Location and Navigation Symposium (PLANS), 2016 IEEE/ION

Date of Conference: 11-14 April 2016

Abstract

The rapid growth of available services depending on location awareness has led to a more and more increasing demand for positioning in challenging environments. Global navigation satellite system (GNSS) based positioning methods may fail or show weak performance in indoor and urban scenarios due to blocking of the signals and multipath propagation. In contrast, cellular radio signals provide better reception in these scenarios due to a much higher transmit power. Also, they offer high coverage in most urban areas. However, they also undergo multipath propagation, which deteriorates the positioning performance. In addition, there are often only one or two base stations within communication range of the user. Both of these problems can be solved by means of a multipath-assisted positioning approach. The idea is to exploit multipath components (MPCs) arriving at the receiver via multiple paths due to scattering or reflections. Such approaches highly depend on the ability to resolve the MPCs at the receiver. This is why multipath-assisted positioning schemes typically assume ultra-wideband systems. Today's cellular radio systems work with much smaller bandwidths, though. The 3rd Generation Partnership Project (3GPP) Long Term Evolution (LTE) standard uses bandwidths up to 20 MHz. The aim of this paper is to show by means of measurements that multipath-assisted positioning is possible using 3GPP-LTE signals with only two base stations. We apply an advanced signal processing algorithm to track MPCs arriving at the mobile terminal, and to estimate the position of the mobile terminal. Since each of the MPCs can be regarded as being sent from some physical or virtual transmitter, we estimate the positions of transmitters in addition. Assuming only the starting position and direction of the mobile terminal to be known, the results show that the root mean square positioning error of the mobile terminal is always below 1.8 meters. In 90% of the cases, it is below 1.25 meters.

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PP.12

"Simultaneous localization and mapping in multipath environments"

Authors: Christian Gentner, Boxiao Ma, Markus Ulmschneider, Thomas Jost, Armin Dammann

HIGHTS Partners: DLR

Published in: Position, Location and Navigation Symposium (PLANS), 2016 IEEE/ION

Date of Conference: 11-14 April 2016

Abstract

This paper presents and extends the idea of multipath assisted positioning, named Channel-SLAM. Channel-SLAM uses multipath propagation to allow positioning for an insufficient number of transmitters or increase the accuracy otherwise. Channel-SLAM treats multipath components (MPCs) as signals from virtual transmitters (VTs) which are time synchronized to the physical transmitter and fixed in their position. To use the information of the MPCs, Channel-SLAM estimates the receiver position and the position of the VTs simultaneously using simultaneous localization and mapping (SLAM) and does not require any prior information such as room-layout or a database for fingerprinting. This paper investigates mapping, where we derive a probabilistic map representation based on the receiver positions. Thus, if the receiver knows its current location, the information in the probabilistic map helps to estimate the trajectory of further receiver movement. Hence, as soon as the receiver returns to an already mapped position, information of the probabilistic map can be used for the movement to obtain better estimations of the receiver position. The algorithm is evaluated based on measurements with one fixed transmitter and a moving pedestrian which moves on partially overlapping loops.

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PP.10

"Random-Phase Beamforming for Initial Access in Millimeter-Wave Cellular Networks"

Authors: Z. Abu-Shaban, H. Wymeersch, X. Zhou, G. Seco-Granados, T. D. Abhayapala

HIGHTS Partners: Chalmers

Published in: IEEE Global Communications Conference Workshops

Date of Conference: 10 Oct. 2016

Abstract

The utilization of the millimeter-wave frequency band (mm-wave) in the fifth generation (5G) of mobile communication
is a highly-debated current topic. Mm-wave MIMO systems will use arrays with large number of antennas at the transmitter and the receiver, implemented on a relatively small area. With the inherent high directivity of these arrays, algorithms
to help the user equipment find the base station and establish a communication link should be carefully designed. Towards that, we examine two beamforming schemes, namely, random-phase beamforming (RPBF) and directional beamforming (DBF), and
test their impact on the Cramer-Rao lower bounds (CRB) of jointly estimating the direction-of-arrival, direction-of-departure,
time-of-arrival, and the complex channel gain, under the lineof-sight channel model. The results show that the application of
RPBF is more appropriate in the considered scenario because it attains a lower CRB with fewer beams compared to DBF.

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PP.9

"Vehicle-to-Vehicle Communications with Urban Intersection Path Loss Models"

Authors: M. Abdulla, E. Steinmetz, H. Wymeersch

HIGHTS Partners: Chalmers

Published in: IEEE Global Communications Conference Workshops

Date of Conference: 10 Oct. 2016

Abstract

Vehicle-to-vehicle (V2V) communication can improve road safety and traffic efficiency, particularly around critical
areas such as intersections. We analytically derive V2V success probability near an urban intersection, based on empirically supported line-of-sight (LOS), weak-line-of-sight (WLOS), and nonline-of-sight (NLOS) channel models. The analysis can serve as a preliminary design tool for performance assessment over different system parameters and target performance requirements.

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PP.6

"Location-aided mm-wave channel estimation for vehicular communication"

Authors: Nil Garcia, Henk Wymeersch, Erik G. Strom, Dirk Slock

HIGHTS Partners: Chalmers

Published in: 2016 IEEE 17th International Workshop on Signal Processing Advances in Wireless Communications (SPAWC)

Date of Conference: 3-6 July 2016

Abstract

Millimeter-wave (mm-wave) communication is a promising technology for next-generation wireless systems. One challenging application lies in the vehicular domain, where mm-wave should support ultra-fast and high-rate data exchanges among vehicles and between vehicles and infrastructure. To achieve ultra-fast initial access between nodes, we propose a location-aided beamforming strategy and analyze the resulting performance in terms of antenna gain and latency. We find that location information can significantly speed up initial access.

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PP.1

"On communication aspects of particle-based cooperative positioning in GPS-aided VANETs"

Authors: Gia-Minh Hoang, Benoit Denis, Jerome Harri, Dirk T.M. Slock

HIGHTS Partners: CEA-Leti, EURECOM.

Published in: Intelligent Vehicles Symposium (IV), 2016 IEEE

Date of Conference: 19-22 June 2016

Abstract

Precise location services are seen as key enablers to future Intelligent Transport Systems (ITSs). Relying on Vehicle-to-Vehicle (V2V) communication links, one promising solution consists in performing distributed Cooperative Positioning (CP). More specifically, Cooperative Awareness Message (CAM) broadcasts from neighboring vehicles (seen as “virtual anchors”) are used to exchange positional information and to measure V2V radiolocation metrics such as the Received Signal Strength Indicator (RSSI). For the sake of fusing these nonlinear hybrid data, Particle Filters (PFs) represent the required positional information by a set of particles with associated weights. However, in a jointly cooperative and distributed context, the transmission of explicit particle clouds (required by receiving neighbors to update their own location estimates) is hardly affordable under limited V2V channel capacity with typical numbers of particles. In this paper we thus combine and compare several solutions in terms of message representation and adaptive transmission policy so as to reduce simultaneously CAM overhead, channel congestion and computational complexity. Proposals are made at both signal processing level (parametric density approximation) and protocol level (jointly adaptive transmission payload, power and rate), showing no impact on channel load in congested scenarios and negligible CP accuracy degradation in comparison with standard CAM transmission at critical rates.

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WP3-Q3

"Mobility-aware edge caching for connected cars"

Date: 20-22/01/16.

Authors: A. Mahmood, C. Casetti, C.F. Chiasserini, P. Giaccone, J. Härri.

HIGHTS Partners: EURECOM.

WONS 2016, 12th IEEE Conference on Wireless On-Demand Networks systems and Services, 20-22 January 2016, Cortina d'Ampezzo, Italy.

Abstract

Content caching on the edge of 5G networks is an emerging and critical feature to support the thirst for content of future connected cars. Yet, the compactization of 5G cells, the finite edge storage capacity and the need for content availability while driving motivate the need to develop smart edge caching strategies adapted to the mobility characteristics of connected cars. In this paper, we propose a Mobility-Aware Probabilistic (MAP) scheme, which optimally caches content at edge nodes where connected vehicles mostly require it. Unlike blind popularity decisions, the probabilistic caching used by MAP considers vehicular trajectory predictions as well as content service time by edge nodes. We evaluate our approach on realistic mobility datasets and against popularity-based edge approaches. Our MAP edge caching scheme provides up to 40% enhanced content availability, 70% increased cache throughput, and 40% reduced backhaul overhead compared to popularity-based strategies.

PP.14-WP5-Q3

"The 5G Localization Waveform"

Date: 27-28/01/16.

Authors: Ronald Raulefs, Armin Dammann, Thomas Jost, Michael Walter, Siwei Zhang.

HIGHTS Partners: DLR.

ETSI Workshop on Future Radio Technologies - Air Interfaces, Sophia- Antipolis, France.

Abstract

Todays cellular networks have distinct services that come with different requirements, figures of merit, etc. for each application. A communication service such as voice communi- cation relies on latency better than 150 ms and bit error rates lower than 10−2. A vehicular application that controls the brakes of cars in a demanding platoon constellation demands latency in the communication link of less than 1 ms to avoid a crash. Localization is another service which is gaining attention for several years and is mandatory for many applications nowadays. Ubiquitous applications that rely on precise location information are nowadays limited by the best possible accuracy in cellular networks. Only outdoors special GNSS receiver exploiting in- formation gathered from additional measurement units (RTK) allow a degree of precision in the cm-range. For 5G networks we expect to have distinct waveform that achieves a similar accuracy to enable plenty of applications. In the ETSI 22891- 100 [1] document different use cases describe a requirement on localization accuracy of less than 1m for a car and of up to 0.1 m for a robot. Nowadays such accuracy cannot by far be reached in the LTE system – even when considering the dedicated positioning reference signals (PRS). Therefore, the PRS pave the way for integrating localization as core feature which deserves an optimized waveform. In addition the new applications (especially with a control loop inside) demand to consider the time to first fix, which describes the latency of the positioning estimation process. Both of these key figures of merit, accuracy and time to first fix, depend on the chosen waveform for localization. Further, the signal structure needs to consider in a dense network the geometrical constellation in 3D of the participating nodes as it influences strongly the performance. The proposed waveform is a multicarrier waveform that jointly enables the access to the localization signal structure simultaneously for multiple nodes in conjunction with the distribution of power on dedicated bands.

WP3-Q5

"Multipath Assisted Positioning in Vehicular Applications"

Date: 19-20/10/16.

Authors: M. Ulmschneider,R. Raulefs, C. Gentner, and M. Walter.

HIGHTS Partners: DLR.

IEEE 13th Workshop on Positioning, Navigation and Communications (WPNC) 19-20. Oct. 2016, Bremen, Germany.

Abstract

Precise localization and tracking in intelligent transportation systems has aroused great interest since it is required in a large variety of applications. The positioning accuracy of global navigation satellite systems is unreliable and insufficient enough for many use cases. In urban canyons or tunnels, the positioning performance degrades due to a low received signal power, multipath propagation, or signal blocking. Instead we exploit the ubiquitous access to cellular mobile radio networks. Cellular networks are designed to cover the access to the network in an area by a single link to reduce the risk of interference from neighboring base stations. The idea of Channel-SLAM is to exploit the numerous multipath components (MPCs) of a radio signal arriving at the receiver for positioning. Each MPC can be regarded as being sent from a virtual transmitter in a pure line-of-sight condition. Within this paper, we show how to apply multipath assisted positioning in an urban scenario. Therefore, we analyze how a road user equipped with a circular antenna array is tracked in an urban scenario in the presence of only one physical transmitter. We further jointly estimate the positions of the physical and the virtual transmitters to enrich maps.

pp.4-WP3/WP5-Q5

"Cooperative Localization in GNSS-Aided VANETs with Accurate IR-UWB Range Measurements"

Date: 19-20/10/16.

Authors: G.M. Hoang, B. Denis, J. Härri, D.T.M. Slock.

HIGHTS Partners: CEA-Leti, EURECOM.

IEEE 13th Workshop on Positioning, Navigation and Communications (WPNC) 19-20. Oct. 2016, Bremen, Germany.

Abstract

Cooperative positioning based on Impulse Radio - Ultra WideBand (IR-UWB) is known to provide a centimeter- level accuracy when the positions of anchor nodes are perfectly known. In Vehicular Ad-Hoc Networks (VANETs), vehicles acting as “virtual anchor” nodes are highly mobile with imperfect position estimates delivered by the Global Navigation Satellite System (GNSS). The large difference between measurement noises of GNSS positioning and IR-UWB Vehicle-to-Vehicle (V2V) ranging creates a bias in the localization filter, which is cooperatively propagated to other to other vehicles, and therefore significantly attenuates the benefits of IR-UWB for Cooperative Localization (CLoc). This paper compensates this drawback by a novel 2- step CLoc fusion framework. It first selects the “virtual anchor” nodes with the lowest GNSS position uncertainty to mitigate and stop the propagation of the biases. Once all biases have been reduced, it refines localization accuracy through exhaustive fusion. This strategy increases the probability to reach a 40 cm accuracy from 25% (conventional IR-UWB) to 95%, and even a 20 cm accuracy from 5% to 40%.

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WP5/WP4-Q5

"The 5G Localization Waveform Ranging Accuracy over Time-Dispersive Channels – An Evaluation"

Date: 12-16/09/16.

Authors: Emanuel Staudinger, Michael Walter, and Armin Dammann

HIGHTS Partners: DLR.

Institute of Navigation GNSS 2016 (ION GNSS+’16), Portland, USA.

Abstract

Localization has increasingly become important for a variety of applications and context aware services. Today’s mobile communication terminals exploit existing reference signal structures for propagation delay based positioning. Recently, particular single-parametrized waveforms with adaptable power spectral densities (PSDs) haven been proposed in the context of 5G. These waveforms haven been investigated based on Crame ́r- Rao lower bounds (CRLBs) and Ziv-Zakai lower bounds (ZZLBs) for multipath-free channels.
Time-dispersive channels have neither been investigated theoretically nor numerically. In this work, we make this gap smaller by numerical evaluations of the proposed waveforms. We focus on a simple correlation-based receiver and investigate the resulting ranging error. Our evaluations with varying root mean square (RMS) delay spread and fixed Rician K-factor clearly show, for which particular channels and signal bandwidths specific waveforms and their respective parameters should be chosen. A ranging error reduction of factor 1.2 to more than 5 compared to state of the art reference signals can be obtained. Hence, we pave the way to possibly place a new waveform within the 5G context for improved ranging accuracy compared to state of the art.

WP5-Q5

"Localization-Driven Formation Control for Swarm Return-to-Base Application"

Date: 29/08/2016 - 02/09/2016

Authors: S. Zhang, R. Raulefs, and A. Dammann.

HIGHTS Partners: DLR.

2016 European Signal Processing Conference (EUSIPCO 2016), 29 Aug - 02- Sep, Budapest, Hungary.

Abstract

Goal-seeking and information-seeking are canonical problems in mobile agent swarms. We study the problem of collaborative goal-approaching under uncertain agent position information. We propose a framework that establishes location-aware formations, resulting in a controller that accounts for agent position uncertainty with a realistic ranging model. Simulation results confirm that, as the outcome of the controller, the swarm moves towards its goal, while emerging formations conducive to high-quality localization.