Christian Schneider

• Dipl.-Ing.
• Senior Researcher at Technische Universität Ilmenau

As integrated sensing and communication (ISAC) capabilities become more prevalent in the mobile 6G radio landscape, there is a substantial opportunity to enhance situational awareness across diverse applications through multi-static radar sensing within meshed ISAC networks. To facilitate the development and testing of detection and localization al...

The use of future communication systems for sensing offers the potential for a number of new applications. In this paper, we show that leveraging user data payloads in multi-node Orthogonal Frequency Division Multiple Access (OFDMA) networks for estimating target delay and Doppler-shift parameters can yield a significant advantage in SNR and addres...

Integrated Communication and Sensing (ICAS) is a key technology that enables sensing functionalities within the next-generation mobile communication (6G). Joint design and optimization of both functionalities could allow coexistence, therefore it advances toward joint signal processing and using the same hardware platform and common spectrum. Contr...

Integrated Sensing and Communication (ISAC) in cellular vehicle-to-everything (C-V2X) systems presents a promising solution for enhancing road safety and traffic efficiency. However, it also poses significant challenges in radio resource management, particularly in efficiently allocating time-frequency (TF) resources to meet distinct Quality of Ser...

Integrated Sensing and Communication (ISAC) is a technology paradigm that combines sensing capabilities with communication functionalities in a single device or system. In vehicle-to-everything (V2X) sidelink, ISAC can provide enhanced safety by allowing vehicles to not only communicate with one another but also sense the surrounding environment by...

Integrated Sensing and Communication (ISAC) is a technology paradigm that combines sensing capabilities with communication functionalities in a single device or system. In vehicle-to-everything (V2X) sidelink, ISAC can provide enhanced safety by allowing vehicles to not only communicate with one another but also sense the surrounding environment by...

In this paper, we explore the impact of different antenna positions and radiation patterns on the channel performance of an Integrated Communication and Sensing (ICAS) extended model in a highway environment. We have considered a 3-dB omnidirectional Transmitter (Tx) and a directive Receiver (Rx) for our analysis. The antenna radiation patterns of...

Integrated Communication and Sensing (ICAS) represents an exciting new research field that combines communication and radar sensing functionalities under a single platform. This convergence leverages the similarities in signal processing, spectrum utilization, and system design between the two functionalities. The main difference between sensing an...

The integration of wireless communication and radar sensing is gaining the interest of researchers from wireless communication and radar societies. Sensing in Integrated Communication and Sensing (ICAS) systems differs from the traditional radar system in the configuration of transmitter-target-receiver, the operating frequency bands, and the trans...

Harmonic retrieval techniques are the foundation of radio channel sounding, estimation and modeling. This paper introduces a Deep Learning approach for joint delay-and Doppler estimation from frequency and time samples of a radio channel transfer function. Our work estimates the two-dimensional parameters from a signal containing an unknown number...

The upcoming 3GPP global mobile communication standard 6G strives to push the technological limits of radio frequency (RF) communication even further than its predecessors: Sum data rates beyond 100 Gbit/s, RF bandwidths above 1 GHz per link, and sub-millisecond latency necessitate very high performance development tools. We propose a new SDR firmw...

Integrated Sensing and Communication (ISAC) has emerged as a key technology in future cellular networks as it allows the integration of radar sensing capabilities into mobile networks by sharing the same spectral and hardware resources. This paper discusses the integration of radar sensing capabilities into 5G Vehicle-to-Everything (V2X) sidelink c...

Harmonic retrieval techniques are the foundation of radio channel sounding, estimation and modeling. This paper introduces a Deep Learning approach for two-dimensional spectral estimation from frequency and time samples of a radio channel transfer function. Our work can estimate two-dimensional parameters from a signal containing an unknown number...

This paper presents an experimental measurement platform for the research and development of unmanned aerial vehicles (UAVs) localization algorithms using radio emission and reflectivity. We propose a cost-effective, flexible testbed made from commercial off-the-shelf (COTS) devices to allow academic research regarding the upcoming integration of U...

The statistical study of target detectability is crucial in radar system design. In this regard, signal-to-noise ratio (SNR) of the received signal at the radar's receiver is a key parameter and therefore every influence on SNR should be taken into account. One of the main influences is the fluctuation of the target scattering/reflectivity to the i...

In this contribution, we investigate how changes in received power for a vehicle to infrastructure (V2I) communication scenario in an urban environment can be modeled. Significant changes are not only observed for line of sight (LoS) to none line of sight (NLoS) transitions but also when the mobile station travels from a narrow street onto a crossr...

This study proposes a new strategy of extracting parameters for tapped delay line (TDL) channel models from vehicle to infrastructure channel measurements. The proposed approach is based on an already existing method to derive parameters for a non‐stationary model using first‐order Markov chains. It will be shown that with the proposed method, the...

In this paper, an orthogonal frequency-division multiplexing (OFDM) waveform radar sensing approach is demonstrated based on field measurements at C-band. We demonstrate a concept that is based on the exploitation of typical wireless communication transmissions to perform passive, distributed radar sensing. Our concept is based on an OFDM radar tha...

In this paper, impact of antenna directivity and bandwidth on the small scale fading statistics have been analyzed for millimeter-wave (mmWave) radio channels. For this purpose, small-scale fading measurements at the mmWave frequency band (58–62 GHz) are carried out using transmit and receive antennas with different antenna directivities (emulated...

Wireless vehicular communications and sensing technologies are key to enabling more advanced intelligent transportation systems (ITSs) with improved safety and efficiency. Within the realm of wireless communication, millimeter-wave (mmwave) technology has recently received much attention, providing rich spectrum resources to support the timely tran...

5G promises many new vertical service areas beyond simple communication and data transfer. We propose cooperative passive coherent location (CPCL), a distributed MIMO radar service, which can be offered by mobile radio network operators as a service for public user groups. CPCL comes as an inherent part of the radio network and takes advantage of t...

In this paper, a novel three dimensional (3D) hybrid ray tracing (HRT) method for wave propagation simulation for large indoor and small cell urban environment is proposed. HRT combines two image based ray tracing (RT) methods: "standard" ray tracing (i.e., the rigorous and conventional image ray tracing) with high accuracy and "intelligent" ray tr...

The individual Radar Cross Section (RCS) of each vehicle is very important for detection, tracking, and classification in automotive radar applications. Apart from these typical radar applications, the bistatic RCS of vehicles can be applied as a scattering model within wireless propagation channel modelling for the evaluation of vehicular communic...

Polarization diversity at mm-waves is under consideration for the new 3GPP release. Since mm-waves systems have higher resolution in the time and angular domain, more accurate intra-cluster models are needed, in which path properties as polarization becomes more deterministic. In the present paper we discuss the limitations of the current modelling...

We introduce simultaneous multi-band ultra wide-band directional measurements at 6.75 GHz, 30 GHz, and 60 GHz in an indoor environment with different visibility conditions. Large scale parameters and path-loss has been analysed for the different bands considering the propagation channel, and later the influence of the system aspects in the radio ch...

This contribution investigates the stationarity of the vehicle to vehicle (V2V) channel in terms of distance and time. Due to high inherent mobility, the channel can not be assumed to follow the wide sense stationary (WSS) and uncorrelated scattering (US) assumption. Therefore, new evaluation methods have to be applied. We assess the stationarity f...

In general, the zero-forcing (ZF) precoding suffers from a severe receive signal-to-noise ratio (SNR) degradation in the high interference regime. However, recent evidences from realistic measurements demonstrated that millimeter wave (mmWave) systems are mainly noise-limited as high gain antennas behave as spatial filters to the interference signa...

Second-order statistics of indoor directional channels are investigated using millimeter wave (mmWave) band (30.4 to 37.1 GHz) ultra-wideband (UWB) channel measurements. Considering two main mmWave system assumptions (high bandwidth and high beamforming gain), this paper aims to investigate validity of the Rayleigh/Rice fading models for the cluste...

Vehicle-to-Vehicle (V2V) channels exhibit unique properties, due to the highly dynamic environment and low elevation of the antennas at both ends of the link. Of particular importance for the behavior of V2V channels, and consequent reliability of the communication link, is the severity and dynamics of blockage of both line-of-sight (LOS) and other...

Multidimensional characterization of outdoor urban macrocellular propagation channels is essential for the analysis and design of next-generation (5G and beyond) cellular massive MIMO (multiple-input-multiple-output) systems. Since most massive MIMO arrays will extend in two or three dimensions, an understanding of 3-D parameters (i.e., azimuth and...

Using Sum-Of-Cisoids (SOC) principle along with a deterministic parameter computation method, this paper provides studies on modeling of the intra-cluster number of scattered multi-path components (MPC) $N$ and their amplitudes $c_n$. Modeling objective is to ensure that the fading statistics of the receive (Rx) signal magnitude of the measured bea...

5G promises many new vertical service areas beyond simple communication and data transfer. We propose CPCL (Cooperative Passive Coherent Location) being a distributed MIMO radar service which can be offered by mobile radio network operators as a service for public user groups. CPCL comes as an inherent part of the radio network and takes advantage...

This contribution presents propagation measurements at 60 GHz in indoor non-line of sight scenarios. Besides analysing the measurements, the authors have considered several system aspects, such as bandwidth and directivity in order to investigate the small-scale behaviour of the radio channel after beam-forming. The results show that due to the hig...

This paper presents 70-77 GHz wideband channel characteristics of delay, spatial and polarimetric domains for small office and entrance hall scenarios. Based on measured multi-dimensional power spectra of delay, directions ( i.e. azimuth and elevation) of departure and of arrival, multipath clusters were detected using the K-means, threshold-based,...

In this paper, directional small scale fading measurements are used to extract the fading statistics of the received signal magnitude and the parameters of the underlying stochastic (Rayleigh/Rician) model. After that sum-of-cisoids (SOC) principle is used to model the deterministic samples (channel snapshots) of the stochastic model with a special...

Large absolute channel bandwidths at millimeter wave (mmWave) frequencies and more directional antenna gains may lead to quasi-deterministic (less random) channel fading behavior. Cross polarization discrimination (XPD) is an attribute related to the channel fading characteristics. In narrow-band channels, it is usually modeled as a log-normal rand...

If a channel is frequency dependent then Uncorrelated Scattering (US) (a narrow-band assumption) don't hold. This has a significant impact at the considered channel modeling methodology as delay and angular dispersion of waves can no longer be studied independently because the small scale fading of individual multipath components become correlated....

A wireless channel is always composed of both deterministic and stochastic multi-path components. A high Rician K-factor increases the contribution of deterministic channel components, thereby reducing the significance of stochastic parts of a channel. This paper focus at the investigative analysis of fading depth and K-factor to analyze the determ...

3-dimensional Multiple-Input Multiple-Output (3D MIMO) systems have received great interest recently because of the spatial diversity advantage and capability for full-dimensional beamforming, making them promising candidates for practical realization of massive MIMO. In this paper, we present a low-cost test equipment (channel sounder) and post-pr...

In the present paper we analyse small-scale fading of reflections at 60 GHz using different antennas and bandwidths. The aim is to investigate the deterministic property of the channel in view of modelling and deployment of systems with larger bandwidths and higher directivity. We have investigated the scattering effect of a reflection on a wall em...

In the present paper we introduce the architecture of a hybrid digital / analog beam-forming with polarization compensation. To evaluate the performance of this architecture we use double-directional, ultra wideband dual- polarized channel measurements at 70 GHz that have been carried out in a small-office environment scenario at the TU Ilmenau. Di...

Vehicle-to-vehicle (V2V) communication links differ significantly from conventional cellular deployments, since both link ends are moving and the antennas are close to the ground level. For reliable performance predictions accurate channel models are required. Based on two different V2V channel sounding campaigns the directional multipath propagati...

Beam-forming at millimeter wave frequencies (mmwave) is a key technology to fulfill the fifth generation (5G) high data rate requirements. In this paper, we describe a novel hybrid architecture for mm-wave beam-forming, which addresses the mm-wave specific propagation channel characteristics that are identified in recent measurement campaigns. This...

V2V and V2I channel modeling became recently more of interest. To provide realistic radio channels either expensive measurements or complex ray tracing simulations are mostly used. Stochastic channel models are of low complexity but do not offer that deterministic repeatable realism. Based on the WINNER channel model and a simple single path model,...

In this paper, we have analyzed the spatial correlation statistics of different antenna polarization setups for uniform linear and circular antenna arrays. We have compared correlation statistics of different MIMO orders. We are motivated to understand pair-by-pair correlation behavior of MIMO channel as it plays a vital role in defining the channe...

Within this contribution we have focused on selection of number of active RF chains under particular channel correlation and SNR dynamics. Study is based on maximizing the volume of the submatrix to be selected. We have proposed a maximum volume submatrix selection (MVC) procedure, that determines the cardinality of number of transmit antennas to b...

Existing fast antenna selection algorithms have either low performance gains or they are efficient only for the selection of particular size sub-matrices. Our motivation to the study of NP-Hard antenna selection problem is two-fold. First, we intend to propose an optimal algorithm that is equally efficient for each possible subset cardinality of th...

When a MIMO wireless channel matrix $\boldsymbol{H}$ is rank deficient, it is often required to select a submatrix $\boldsymbol{H}_p\in \boldsymbol{H} $ such that the columns of $\boldsymbol{H}_p $ lie close to the optimal subspace that constructs $\boldsymbol{H}$. Main motivation for the selection of $\boldsymbol{H}_p$ is to gain the same spectral...

This work studies the dependency of MIMO performance figures on two characteristic multipath cluster parameters, the innercluster Angular Spread of Arrival (ASA) and the number of clusters. Both these parameters play a vital role in geometric based stochastic channel models as from the WINNER or COST families. Our motivation to the study these para...

Double-directional, ultra wideband dual-polarized channel measurements at 70 GHz have been carried out in a small-office environment. The aim of these measurements is to study the temporal, directional, and polarization properties of the channel for modelling purposes of the future wireless communication systems at mm-waves. A highly deterministic...

Owing to the limitation in bandwidth of currently used frequency bands, future fifth generation (5G) mobile networks will need to operate at higher frequencies. However, one important step in the research activities for the next generation of mobile networks is the broadband fully polarimetric analysis of the multipath propagation in dynamic single...

We consider two approaches for real-time end-toend over-the-air testing for intelligent traffic systems using virtual radio environments. One approach is based on coherent wavefield synthesis, while the other aims at emulating the essential features of a realistic radio channel in vehicular ad-hoc networks. Due to finite hardware resources, the for...

A wideband, fully polarimetric and directional radio channel sounding campaign conducted at 70 GHz is presented. Measurement site was chosen as an entrance hall, featuring femtocell size. Transmitter and receiver were placed according to an access-point scenario. Initial large-scale parameters like excess-delay, delay-spread and angular spread are...

Pencil-beam forming techniques based on large antenna arrays are becoming a crucial asset to cope with the very high throughput density requirements and high path-loss constraints of future millimeter-wave gigabit-wireless applications. Directional, polarimetric 60 GHz indoor measurements are used in the present work to modify and calibrate a 3D ra...

In this paper, we have proposed a link adaptation scheme based on adaptive switching of the number of active RF modules such that MIMO channel capacity is maximized at low computational cost. We have proposed an approximated analytical solution for the selection of the MIMO order (MOS) depending on the full channel matrix and the signal-to-noise ra...

The use of large-size antenna arrays to implement pencil-beam forming techniques is becoming a key asset to cope with the very high throughput density requirements and high path-loss of future millimeter-wave gigabit-wireless applications. Sub-optimal beamforming strategies based on search on discrete set of beams (steering vectors) are proposed an...

Directional, dual-link, quad-polarized 60GHz channel measurements have been carried out in a small-office environment. Purpose of the measurements is to study the directional properties of the channel in view of future multi-gigabit system adopting beam-forming or macro-diversity solutions. The impact of polarization on the characteristics of the c...

This paper provides an overview of over-the-air (OTA) testing for Car-to-Car (C2C) and Car-to-Infrastructure (C2I) communication. We identify the requirements for OTA tests in virtual electromagnetic environments (OTAinVEE) for C2C/C2I communication scenarios, where emulation of known and unknown interference in addition to multipath becomes a high...

Increasing data rates in mobile networks require new technologies for the next generation of mobile communication systems such as massive MIMO, device-centric architectures, smarter devices, machine-2-machine communication etc. However, one important step to reach the goal of 100 GBit/s will be use of higher bandwidth. Owing to the limitation in ba...

5G networks will target on smaller cells serving more and more mobile users. Especially on the base station side new technologies are needed circling as buzzwords like massive MIMO and elevation beamforming. In that context more precise channel models are required focusing on the elevation characteristic of the radio channel at the base station. In...