Florian Kaltenberger's research while affiliated with EURECOM and other places

Publications (108)

Article
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Satellites enable the provision of global 5G coverage utilizing a customized protocol stack for direct access of 5G devices. This paper reports the results of a field trial based on an Open Source Software (OSS) 5G protocol stack modified for Satellite Communications. 5G New Radio (NR) functions have been adapted to support 3GPP Non Terrestrial Net...
Preprint
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Satellite-enabled 5G services have the potential to provide worldwide connectivity. In this paper, we give an introduction on the roadmap in 3GPP standardization of 5G as well as on the enhancements to support non-terrestrial networks (NTN) in Release 17. We further provide first over-the-air test results of a successfully demonstrated extension of...
Article
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Spectrum sharing has been recognized as a key component for 5G and beyond wireless networks. Recent trials have revealed the business value of spectrum sharing via the licensed shared access model, wherein both the incumbent and the licensee operators are protected from harmful interference by sharing the available spectrum using long-term spectrum...
Article
OpenAirInterfaceTM (OAI) is an open-source project that implements the 3rd Generation Partnership Project (3GPP) technology on general purpose x86 computing hardware and Off-The-Shelf (COTS) Software Defined Radio (SDR) cards like the Universal Software Radio Peripheral (USRP). It makes it possible to deploy and operate a 4G Long-Term Evolution (LT...
Article
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Abstract Machine-to-machine (M2M) communication is one of the vertical sectors that will benefit from 5G communication systems, but today, these systems are still dominated by technologies such as ZigBee and WiFi. An M2M scenario will experience dense deployment of ZigBee and WiFi nodes in order to route the data from one end to the other. In the 2...
Conference Paper
Narrowband transmitters such as IEEE 802.15.4 (ZigBee) operating in 2.4 GHz ISM band cause significant degradation of throughput to the co-channel IEEE 802.11g (WiFi). The phenomenon is common in smart factories and smart homes which generously use ZigBee sensors for process monitoring and automation. This interferes with omnipresent WiFi in the sa...
Conference Paper
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In this paper we introduce the design of the "Rebot" (Relaying Robot) for future wireless networks. The Rebot concept is first of its kind in providing enhanced end-to-end LTE connectivity to ground users from a fixed base station via a flying relay which is enabled with an autonomous placement algorithm. The Rebot that we have built is a customize...
Conference Paper
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Energy consumption is one of the primary concerns of modern dense small cell networks. One of the key concepts to improve the energy efficiency of a dense network is to turn off a part of its base stations (BS) when they are idle or only lightly loaded, since even then a considerable amount of energy is consumed. In this paper we analytically inves...
Article
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Modern cellular networks are becoming denser, less regularly planned, and increasingly heterogeneous, making performance analysis challenging.We develop a flexible and accurate model of such heterogeneous networks (HetNets) consisting of $K$ tiers of randomly located Base Stations (BSs), with different densities, transmit powers and Radio Access Te...
Article
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One of the biggest challenges in operating massive multiple-input multiple-output systems is the acquisition of accurate channel state information at the transmitter. To take up this challenge, time division duplex is more favorable thanks to its channel reciprocity between downlink and uplink. However, while the propagation channel over the air is...
Article
Hybrid analog-digital (AD) beamforming structure is a very attractive solution to build low cost massive multiple-input multiple-output (MIMO) systems. Typically these systems use a set of fixed beams for transmission and reception to avoid the need to obtain channel state information at transmitter (CSIT) for each antenna element individually. How...
Article
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This editorial sums up relevant topics on the assessment of wireless communication systems covered by the especial issue entitled “Experimental Evaluation in Wireless Communications.” The topics include practical aspects on the implementation of distributed asynchronous non-linear kernel methods over wireless sensor networks; localization methods b...
Conference Paper
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In this paper, we develop a flexible and accurate analytical model of large networks with random base station (BS) placement, in order to understand the impact of key network parameters like BS density and load on the network performance. The main goal is to understand the flow level dynamics of such a system, assuming non-saturated users and study...
Article
Mobile networks will increasingly need to make use of heterogeneous access and spectrum opportunities to realize required capacity and quality of service. Moreover, aggregation of such resources will routinely be necessary, and there will be a clear need to develop a management architecture for that aggregation. Such an architecture should ascertai...
Conference Paper
Maximum-likelihood (ML) receivers are optimum receivers for MIMO systems, but their complexity grows exponentially with the modulation order of the codeword and the number of spatial layers. The Reduced Complexity ML (R-ML) receivers based on low complexity adaptation of the max-log MAP detector and reduction of searching space are a good compromis...
Conference Paper
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Machine to machine (M2M) and Internet of things (IoT) communication systems are characterized by short and bursty communication cycles. Devices may also have very low duty cycles to increase battery lifetime. Current 4G systems are not adapted to these kind of traffic characteristics. Even to send just a short packet, a user equipment (UE) first ne...
Article
This letter presents an analysis of intercarrier interference (ICI) in high-speed trains. The ICI is caused by the motion of the receiver together with the carrier frequency offset (CFO). It results in a degradation of the reliability of the OFDM transmission. The analysis is based on a channel sounding measurement campaign for cellular broadband w...
Conference Paper
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The 5G mobile standard will very likely include a new waveform that addresses scenarios like sporadic lowlatency traffic and dynamic spectrum access (DSA). In both cases the current 4G waveforms have some deficiencies, like the need for strict synchronicity and the high adjacent channel leakage ratio (ACLR) respectively. Several candidate waveforms...
Conference Paper
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Commoditization and virtualization of wireless networks are changing the economics of mobile networks to help network providers (e.g., MNO, MVNO) move from proprietary and bespoke hardware and software platforms toward an open, cost-effective, and flexible cellular ecosystem. In addition, rich and innovative local services can be efficiently create...
Chapter
To satisfy the demand of future mobile networks, they will need to make use of as much spectrum as possible. However, spectrum for wireless communication is scarce, fragmented, and the rules for its use are very heterogeneous. This chapter describes the state of the art in LTE-Advanced aggregation technologies, which are an effective means to explo...
Chapter
This chapter provides an overview of the OpenAirInterface (OAI) both in terms of its hardware and software elements and its usage in cognitive wireless networking applications based on long term evolution (LTE) technology. In particular, we show a design of a cognitive radio systems in the LTE framework that enables the deployment of cognitive radi...
Conference Paper
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The paper addresses the performance evaluation via the Cramer-Rao Lower Bound (CRLB) of power-based localiza-tion of a source in spatially-correlated log-normal propagation. The novel element is the inclusion and assessment of the impact of conditioning measurements on such performance. The proposed model parameterizes performance by both the senso...
Conference Paper
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5G mobile networks will very likely include features that allow for a dynamic spectrum access (DSA) in order to exploit spectrum holes of a primary system. The efficient utilization of spectrum holes with minimum impairment of the primary system requires a waveform with a very low adjacent channel leakage ratio as well as robustness to time and fre...
Conference Paper
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TV White Spaces (TVWS) technology allows wireless devices to opportunistically use locally-available TV channels enabled by a geolocation database. The UK regulator Ofcom has initiated a pilot of TVWS technology in the UK. This paper concerns a large-scale series of trials under that pilot. The purposes are to test aspects of white space technology...
Article
LTE 4G cellular networks are gradually being adopted by all major operators in the world and are expected to rule the cellular landscape at least for the current decade. They will also form the starting point for further progress beyond the current generation of mobile cellular networks to chalk a path towards fifth generation mobile networks. The...
Conference Paper
Multiuser (MU) MIMO is a promising technique to significantly increase the cell capacity in LTE systems. However, users scheduled for MU-MIMO may still experience strong MU interference if the channel state information at the base station is outdated or in small cells with a limited number of users available. Interference-aware (IA) receivers explo...
Conference Paper
Carrier Aggregation has been included in 4G systems such as 3GPP LTE-Advanced to allow the utilization of larger (up to 100MHz) and fragmented spectrum. Aggregation is happening at the MAC layer and each carrier is using the same PHY layer. Further, given the nature of LTE, each of these carriers must use a licensed frequency band. In the SOLDER pr...
Conference Paper
Wireless networks are evolving continuously and expected to provide seamless experience for multiple real-time internet applications. Quality-of-service is one of the major component associated with user experience. In this paper, we have considered the provisioning of desired QoS to mobile users that are capable of running multiple internet applic...
Conference Paper
Mobile devices have evolved remarkably over the last decade and are now being utilized to access much broader range of internet applications. Moreover, their capability to simultaneously run many applications has significantly transformed the traffic characteristics of mobile networks. Quality of service (QoS) is a fundamental component associated...
Conference Paper
We present an in-depth performance analysis of the gains of physical layer (PHY) abstraction when compared to a full implementation of the physical layer. The abstraction model uses either effective signal to noise plus interference (SINR) mapping or mutual information effective SINR mapping and covers different transmission modes as well as suppor...
Conference Paper
In this paper, we analyze the downlink performance of a multi-user system consisting of mobile users with wide range of velocity. We categorize these users into different groups on the basis of their velocity range and study the impact of feedback delay on each group for closed-loop transmit beamforming. Based on this analysis, we propose an adapti...
Conference Paper
Ray tracing (RT) is an accurate propagation prediction tool that has been widely used to simulate channel characteristics in indoor environments. To date, the developed RT tool includes not only specular reflection, penetration through dielectric blocks and diffraction, but also diffuse scattering mechanisms. The accuracy, provided by a detailed mo...
Conference Paper
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Within the scope of the European policy for Intelligent Transport Systems (ITS), the PLATA-PROTON project proposes a multi technology cooperative Advanced Driver Assistance System (ADAS), based on the integration of Software-Defined Radio (SDR) devices in vehicles. With the choice of significant road-safety related scenarios, V2V and V2I communicat...
Conference Paper
Relative calibration has been proposed as a simple way to practically exploit the reciprocity of the wireless channel. It is based on a simple convolutional model for the relationship between the channel impulse responses in both directions, and accounts for the discrepancies between transmit and receive radiofrequency components, without the need...
Article
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Cognitive radio, which enables smart use of wireless resources, is a key ingredient to achieve high spectral efficiency. LTE, the latest evolution of cellular standards, is widely adopted and also targets high spectral efficiency. Hence, to enable wide adoption of cognitive radio, using LTE as the physical layer is a natural choice. Targeting a rea...
Conference Paper
Multi-user MIMO communication can provide significant gains by exploiting spatial multiplexing. However, it requires better feedback to provide accurate channel state information at the transmitter (CSIT) for minimizing the multiuser interference. 3GPP LTE provides support for MU-MIMO, but it is not sufficient to extract sizable gains. In this pape...
Conference Paper
In this paper we present the complete methodology of expected effective SINR mapping (EESM) and mutual information effective SINR mapping (MIESM) based PHY abstraction for OpenAirInterface (OAI) LTE platform. The methodology consists of calibration of the ESM techniques using OAI link level simulator and then the validation of calibrated scheme on...
Conference Paper
Incremental redundancy hybrid automatic repeat request (IR-HARQ) scheme used in recent wireless communication standards such as 3GPP LTE provides higher benefits in terms of system capacity and robustness. To map these benefits into system level evaluations is of critical importance. Traditional link abstraction techniques are usually designed for...
Conference Paper
We present in this paper a software implementation of a cognitive radio (CR) communication based on long term evolution-time division duplex (LTE-TDD) channel reciprocity. We study the problem of calibration and beamforming design for a CR system in which a multiple-input single-output (MISO) secondary link, wants to opportunistically communicate w...
Article
The market success of broadband multimedia-enabled devices such as smart phones, tablets, and laptops is increasing the demand for wireless data capacity in mobile cellular systems. In order to meet such requirements, the introduction of advanced techniques for increasing the efficiency in spectrum usage was required. Multi User -Multiple Input Mul...
Article
Most of the recent wireless communication systems are interference limited rather than noise limited. In the case of a very strong interferer the conventional assumption of the interference as Gaussian is extremely suboptimal. However optimal (capacity achieving) receivers utilize some prior knowledge about the interference to reach optimality. The...
Article
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The simulation of frequency-selective multiple-input multiple-output (MIMO) channels is computationally expensive. Espe-cially on a real-time simulation platform the number of paths that can be realized is limited by the available processing power. This paper presents a new algorithm, that reduces the number of paths in the channel impulse response...
Article
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For developing embedded (control) software, gra- phical modeling languages based on the data flow paradigm are increasingly used, primarily due to the similarity with electronic (or electric, hydraulic etc.) circuit design. Here, software modules or functions, respectively, are essentially graphs with nodes repre- senting operations and edges repre...
Article
In multi-user multiple-input multiple-output (MU-MIMO) systems, spatial multiplexing can be employed to increase the throughput without the need for multiple antennas and expensive signal processing at the user equipments. In theory, MU-MIMO is also more immune to most of propagation limitations plaguing single-user MIMO (SU-MIMO) systems, such as...
Article
In this work we apply the spectral divergence to characterize the (dis-)similarity of different links in wide-band multi-user multiple-input multiple-output (MU-MIMO) channels. The spectral divergence measures the distance between strictly positive, non-normalized spectral densities, such as the power delay profile. The measurement data has been ac...
Article
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A relatively recent idea of extending the benefits of MIMO systems to multiuser scenarios seems promising in the context of achieving high data rates envisioned for future cellular standards after 3G (3rd Generation). Although substantial research has been done on the theoretical front, recent focus is on making Multiuser Multiple-Input Multiple-Ou...
Conference Paper
This paper focuses on the performance of LTE in rural areas which is based on a channel measurement campaign conducted with the Eurecom OpenAirInterface LTE testbed at 800MHz. This testbed is based on LTE release 8 PHY layer and implements transmission modes 1 (single antenna - SISO), 2 (transmit diversity), and 6 (single-user MIMO - closed loop ra...
Conference Paper
The work described in this paper proposes two Smart Hybrid-Automatic Repeat Request (SHARQ) schemes with incremental redundancy, that are developed for a dual-hop network of two relays implementing cooperative communication. In a dual-hop network consisting of multiple relays, one of the most challenging tasks is to determine an appropriate trade-o...
Conference Paper
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This demonstration highlights the capabilities of the OpenAirInterface platform in terms of Agile RF spectrum-access and rapidly-deployable networking technologies. With respect to application scenarios, the latter target broadband public-safety communications. We demonstrate the real-time baseband and RF capabilities of the platform components as...
Conference Paper
The use of distributed space-time codes in cooperative communications promises to increase the rate and reliability of data transmission. These gains were mostly demonstrated for ideal scenarios, where all nodes are perfectly synchronized. Considering a cooperative uplink scenario with asynchronous nodes, the system suffers from two effects: timing...
Conference Paper
Dynamic spectrum access supported by a low-latency wireless sensor network for spectrum usage monitoring is demonstrated using OpenAirInterface platform. The platform performs secondary communications in bands detected as free, thanks to its multi-band capability. With respect to application scenarios, the main target is to address agile broadband...
Article
The work described in this paper proposes two Smart Hybrid-Automatic Repeat Request (SHARQ) schemes with incremental redundancy, that are developed for a dual-hop network of two relays implementing cooperative communication. In a dual-hop network consisting of multiple relays, one of the most challenging tasks is to determine an appropriate trade-o...
Article
Multi-user MIMO and Spectrum Aggregation (also referred to Carrier Aggregation) are two key enablers of next generation wireless systems. Although those techniques were already quite well investigated at theoretical level, their practical implementation is not immediate and raises numerous challenges. The SAMURAI project aims at investigating such...
Conference Paper
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In this work we present low-complexity coded-modulation strategies for distributed relaying in 4G wireless networks. The primary goal of these strategies is to improve coverage on the uplink while retaining high spectral efficiency through multiuser spatial-multiplexing using two or more relays between the users and the base station. We contrast la...
Conference Paper
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Channel state information at the transmitter (CSIT) can greatly improve the capacity of a wireless MIMO communication system. In a time division duplex (TDD) system CSIT can be obtained by exploiting the reciprocity of the wireless channel. This however requires calibration of the radio frequency (RF) chains of the receiver and the transmitter, whi...
Conference Paper
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Wireless communication standards are developed at an ever-increasing rate of pace, and significant amounts of effort is put into research for new communication methods and concepts. On the physical layer, such topics include MIMO, cooperative communication, and error control coding, whereas research on the medium access layer includes link control,...