Filtyp
The non line-of-sight (NLOS) scenario in urban intersections is critical in terms of traffic safety—a scenario where Vehicle-to-Vehicle (V2V) communication really can make a difference by enabling communication and detection of vehicles around building corners. A few NLOS V2V channel models exist in the literature but they all have some form of limitation, and therefore further research is need. I
Connected autonomous vehicles and industry 4.0 productions scenarios require ultra-reliable low-latency communication links. The varying positions of transmitter, reflecting objects and receiver cause a non-stationary time- and frequency-selective fading process. In this paper, we present the necessary hardware architecture and signal processing algorithms for a real-time geometry-based channel em
In this paper, we consider a wireless communication system where a large intelligent surface (LIS) is deployed comprising a number of small and distributed LIS-Units. Each LIS-Unit has a separate signal process unit (SPU) and is connected to a central process unit (CPU) that coordinates the behaviors of all the LIS-Units. With such a LIS system, we consider the user assignments both for sum-rate a
Time-dependent ensemble averages, i.e., trajectory-based averages of some observable, are of importance in many fields of science. A crucial objective when interpreting such data is to fit these averages (for instance, squared displacements) with a function and extract parameters (such as diffusion constants). A commonly overlooked challenge in such function fitting procedures is that fluctuations
A scheme for exploiting cooperation in satellite receivers is proposed. The cooperation takes place through a capacity-constrained link, and we assume that a relay node quantizes its received signal and sends it to the destination node. We demonstrate its effectiveness with three different schemes on satellite channels with high-order APSK modulations. The first two schemes employ equidistant quan
Today's test methods used for verifying the performance and robustness of automotive applications using wireless communication are often based on fieldtrails, which are time consuming, costly, and not repeatable. Therefore, there is an urgent need for new verification methods that can be performed in lab environment, where the realistic radio propagation environment can be emulated. The telecom in
The focus of this thesis is on proposing and analyzing a powerful class of codes on graphs---with trellis constraints---that can simultaneously approach capacity and achieve very low error floor. In particular, we propose the concept of spatial coupling for turbo-like code (SC-TC) ensembles and investigate the impact of coupling on the performance of these codes. The main elements of this study ca
Generalized low-density parity-check (GLDPC) codes are a class of LDPC codes in which the standard single parity check (SPC) constraints are replaced by more general constraints, viz., constraints defined by a linear block code. These stronger constraints typically result in improved error floor performance, due to better minimum distance and trapping set properties, at a cost of some increased de
Algorithms for Massive MIMO uplink detection typically rely on a centralized approach, by which baseband data from all antennas modules are routed to a central node in order to be processed. In case of Massive MIMO, where hundreds or thousands of antennas are expected in the base-station, this architecture leads to a bottleneck, with critical limitations in terms of interconnection bandwidth requi
In this paper, we show how each independent spatial mode of a circular array can be individually encoded and collimated to yield high ergodic spectral sum efficiency of an uplink mobile communication system. We show that every mode generated with the help of Rotman Lens is orthogonal to every other mode. This reduces the spatial cross-coupling and thereby enhances data throughput.We also show that
It is well established that the utilization of unused millimeter-wave (mmWave) spectrum is inevitable due to unavailability of required bandwidth in the conventional RF band to support the high data demands of 5G. Large antenna arrays with beamforming capabilities are required to compensate for the high path loss at mmWave frequencies. We are at the verge of a massive mmWave radio front-end deploy
This paper presents the light-scattering properties of atmospheric aerosol particles measured over the past decade at 28 ACTRIS observatories, which are located mainly in Europe. The data include particle light scattering (σsp) and hemispheric backscattering (σbsp) coefficients, scattering Ångström exponent (SAE), backscatter fraction (BF) and asymmetry parameter (g). An increasing gradient of σsp
Massive MIMO (MaMIMO) is a key technology for 5G wireless communication, enabling large increase in both spectral and energy efficiency at the same time. Before it can be deployed, it is important to find efficient implementation strategies. Because of the many antennas, an essential part of decreasing complexity, and further improving energy efficiency, is optimization of the digital signal proce
In this paper, we consider positioning with observed-time-difference-of-arrival (OTDOA) for a device deployed in long-term-evolution (LTE) based narrow-band Internet-of-things (NB-IoT) systems. We propose an iterative expectation- maximization based successive interference cancellation (EM-SIC) algorithm to jointly consider estimations of residual frequency- offset (FO), fading-channel taps and ti
Timely loss-of-contact detection between devices in pervasive systems using mobile networks is an important aspect for both functionality and user experience. Traditional schemes where time-to-live is defined by the service provider are not adequate in mobile networks where communication failures are frequent. On the other hand, schemes using keep-alive messaging tend to increase the communication
In this paper, we consider precoder design for multiuser multiple-input-multiple-output (MIMO) Gaussian broadcast (BC) channels and propose a generalized zero-forcing (GZF) precoder based on successive dirty-paper coding (DPC), i.e., the GZF-DP precoder. The GZF-DP precoder is an extension of the GZF-DP precoder designed earlier for multi-input-single-output broadcast (MISO-BC) channels, and also
Despite of having no explicit shape model, multi-atlas approaches to image segmentation have proved to be a top-performer for several diverse datasets and imaging modalities. In this paper, we show how one can directly incorporate shape regularization into the multi-atlas framework. Unlike traditional methods, our proposed approach does not rely on label fusion on the voxel level. Instead, each re
We consider the potential for positioning with a system where antenna arrays are deployed as a large intelligent surface (LIS). We derive Fisher-informations and Cram\'{e}r-Rao lower bounds (CRLB) in closed-form for terminals along the central perpendicular line (CPL) of the LIS for all three Cartesian dimensions. For terminals at positions other than the CPL, closed-form expressions for the Fishe
The concept of Channel Shortening (CS) is a well-known technique that has a rich history over 40 years. CS transfers linear vector channels such as multi-input multi-output (MIMO) and intersymbol interference (ISI) channels into ``shortened'' versions, for the purpose of reducing demodulation-complexity and improving data-transmission performance. The original CS idea can trace back to the minimum
