Andreas F. Molisch's research while affiliated with King Abdulaziz City for Science and Technology and other places

Publications (827)

Preprint
Full-text available
Indoor localization is a challenging task. There is no robust and almost-universal approach, in contrast to outdoor environments where GPS is dominant. Recently, machine learning (ML) has emerged as the most promising approach for achieving accurate indoor localization, yet its main challenge is the requirement for large datasets to train the neura...
Preprint
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Pathloss prediction is an essential component of wireless network planning. While ray-tracing based methods have been successfully used for many years, they require significant computational effort that may become prohibitive with the increased network densification and/or use of higher frequencies in 5G/B5G (beyond 5 G) systems. In this paper, we...
Preprint
Full-text available
In recent years, terahertz (THz) systems have become an increasingly popular area of research thanks to their unique properties such as extremely high data rates towards Tb/s, submillimeter localization accuracy, high resolution remote sensing of materials, and remarkable advances in photonics and electronics technologies. This article traces the p...
Article
Full-text available
Structured electromagnetic (EM) waves carrying orbital angular momentum (OAM) have been explored in various frequency regimes to enhance the data capacity of communication systems by multiplexing multiple co-propagating orthogonal OAM beams (i.e., mode-division multiplexing (MDM)). Terahertz (THz) communications in free space have gained interest a...
Preprint
Full-text available
Terahertz (THz) communication signals are susceptible to severe degradation because of the molecular interaction with the atmosphere in the form of subsequent absorption and re-radiation. Recently, reconfigurable intelligent surface (RIS) has emerged as a potential technology to assist in THz communications by boosting signal power or providing vir...
Article
Full-text available
Terahertz (0.1-10 THz) communications are envisioned as a key technology for sixth generation (6G) wireless systems. The study of underlying THz wireless propagation channels provides the foundations for the development of reliable THz communication systems and their applications. This article provides a comprehensive overview of the study of THz w...
Article
Many wireless networks, including 5G NR (New Radio) and future beyond 5G cellular systems, are expected to operate on multiple frequency bands. This paper considers the band assignment (BA) problem in dual-band systems, where the basestation (BS) chooses one of the two available frequency bands (centimeter-wave and millimeter-wave bands) to communi...
Article
Full-text available
The channel capacity of terahertz (THz) wireless communications can be increased by multiplexing multiple orthogonal data-carrying orbital-angular-momentum (OAM) beams. In THz links using OAM multiplexing (e.g., Laguerre-Gaussian LGℓ,p beams with p = 0), the system performance might degrade due to limited receiver aperture size and multipath effect...
Article
Vehicle-to-vehicle (V2V) wireless communication systems are fundamental in many intelligent transportation applications, e.g., traffic load control, driverless vehicle, and collision avoidance. Hence, developing appropriate V2V communication systems and standardization require realistic V2V propagation channel models. However, most existing V2V cha...
Article
Throughput-Outage scaling laws for single-hop cache-aided device-to-device (D2D) communications have been extensively investigated under the assumption of the protocol model. However, the corresponding performance under physical models has not been explored; in particular it remains unclear whether link-level power control and scheduling can improv...
Article
The 5G mmWave Channel Model Alliance was formed to take a longer view by addressing issues related to measurement and modeling that impede progress in standards development and hardware optimization. There is a strong link between the modeling and measurement communities. The extent to which the sounder captures the channel’s features will depend o...
Article
The purpose of any propagation channel model is to represent the essential physical propagation effects that influence system design and performance, without getting swamped by irrelevant details. Thus, while the propagation channel itself is independent of any system that operates in it, channel models do depend on the system. The focus of this pa...
Article
When designing a wireless communication system, it is essential to have a channel model that can quickly and accurately generate channel impulse response needed for system simulations. Deterministic models such as ray-tracing offer an accurate model of the propagation environment, but their high computational complexity prohibits the intensive link...
Article
The parameters of channel models are traditionally determined using measurements. Thus, it is critical to understand the connection between channel measurements and channel models. This will address two important questions: (1) How to use the channel measurements in estimating model parameters? Or how to fit the models to the measurements? And (2)...
Article
Channel sounder verification ensures that participants measure and report channel characteristics that are due to the environment as opposed to measurement artifacts arising from the use of a suboptimal configuration, from nonidealities in the sounder hardware, or from errors in analysis and/or postprocessing. The participants in the 5G mmWave Chan...
Article
This book offers comprehensive, practical guidance on RF propagation channel characterization at mmWave and sub-terahertz frequencies, with an overview of both measurement systems and current and future channel models. It introduces the key concepts required for performing accurate mmWave channel measurements, including channel sounder architecture...
Article
Frequencies from 100 GHz to 3 THz are promising bands for the next generation of wireless communication systems because of the wide swaths of unused and unexplored spectrum. Terahertz wireless communications have two key advantages that can be combined to achieve very high data rates. First, the usable frequency band around each frequency is much l...
Article
This book offers comprehensive, practical guidance on RF propagation channel characterization at mmWave and sub-terahertz frequencies, with an overview of both measurement systems and current and future channel models. It introduces the key concepts required for performing accurate mmWave channel measurements, including channel sounder architecture...
Article
This book offers comprehensive, practical guidance on RF propagation channel characterization at mmWave and sub-terahertz frequencies, with an overview of both measurement systems and current and future channel models. It introduces the key concepts required for performing accurate mmWave channel measurements, including channel sounder architecture...
Article
Human blockage causes temporal variations to radio channels when a mobile device is in motion and some plane waves constituting the radio channels are blocked by a human body. Even when two sides of communications are static, moving human bodies often shadow some plane waves, leading to time-varying radio channel responses. Shadowing of plane waves...
Article
Device-to-device (D2D) radio channels have fundamentally different properties compared to those of conventional cellular (device-to-infrastructure, D2I) channels. The main reason for this is that most often both the receive antenna and the transmit antenna are located at low heights, and hence there is more interaction with objects in the close nei...
Article
Structured electromagnetic (EM) waves have been explored in various frequency regimes to enhance the capacity of communication systems by multiplexing multiple co-propagating beams with mutually orthogonal spatial modal structures (i.e., mode-division multiplexing). Such structured EM waves include beams carrying orbital angular momentum (OAM). An...
Article
Full-text available
Design and performance assessment of THz communications systems, which will form an essential part of 6G, require an understanding of the propagation channels the systems will operate in. This paper presents investigations of the channel characteristics in various scenarios at 145 GHz, which is the band currently envisioned for the first round of d...
Article
To provide higher data rates, as well as better coverage, cost efficiency, security, adaptability, and scalability, the 5G and beyond 5G networks are developed with various artificial intelligence (AI) techniques. In this two-part article, we investigate the application of AI and, in particular, machine learning (ML) to the study of wireless propag...
Article
This two-part paper investigates the application of artificial intelligence (AI) and, in particular, machine learning (ML) to the study of wireless propagation channels. In Part I of this article, we introduced AI and ML and provided a comprehensive survey on ML-enabled channel characterization and antenna-channel optimization, and in this part (Pa...
Preprint
Distributed computing (cloud) networks, e.g., mobile edge computing (MEC), are playing an increasingly important role in the efficient hosting, running, and delivery of real-time stream-processing applications such as industrial automation, immersive video, and augmented reality. While such applications require timely processing of real-time stream...
Preprint
The timely delivery of resource-intensive and latency-sensitive services (e.g., industrial automation, augmented reality) over distributed computing networks (e.g., mobile edge computing) is drawing increasing attention. Motivated by the insufficiency of average delay performance guarantees provided by existing studies, we focus on the critical goa...
Preprint
Next-generation distributed computing networks (e.g., edge and fog computing) enable the efficient delivery of delay-sensitive, compute-intensive applications by facilitating access to computation resources in close proximity to end users. Many of these applications (e.g., augmented/virtual reality) are also data-intensive: in addition to user-spec...
Article
The ability to multiplex multiple structured beams for sub-terahertz (sub-THz) wireless communications has been recently explored. The spatial orthogonality of structured beams enables mode-division multiplexing (MDM). In an MDM system, multiple data-carrying beams are transmitted and received simultaneously through a single aperture pair with low...
Preprint
We are entering a rapidly unfolding future driven by the delivery of real-time computation services, such as industrial automation and augmented reality, collectively referred to as AgI services, over highly distributed cloud/edge computing networks. The interaction intensive nature of AgI services is accelerating the need for networking solutions...
Preprint
Emerging Metaverse applications, designed to deliver highly interactive and immersive experiences that seamlessly blend physical reality and digital virtuality, are accelerating the need for distributed compute platforms with unprecedented storage, computation, and communication requirements. To this end, the integrated evolution of next-generation...
Conference Paper
Multi-path components (MPCs) in wireless channels generally occur in clusters, i.e., groups of MPCs that have similar delay/angle characteristics. However, when those clusters are widely separated and have significantly different power, high-resolution parameter extraction (HRPE) algorithms based on serial interference cancellation, such as CLEAN,...
Preprint
Emerging distributed cloud architectures, e.g., fog and mobile edge computing, are playing an increasingly important role in the efficient delivery of real-time stream-processing applications such as augmented reality, multiplayer gaming, and industrial automation. While such applications require processed streams to be shared and simultaneously co...
Preprint
The worlds of computing, communication, and storage have for a long time been treated separately, and even the recent trends of cloud computing, distributed computing, and mobile edge computing have not fundamentally changed the role of networks, still designed to move data between end users and pre-determined computation nodes, without true optimi...
Article
Full-text available
THz band communication has the potential to meet the high data rate demands of many current and future applications. However, before these networks are realized, extensive channel measurements are needed in order to characterize the wireless channel at these frequencies, in order to inform system design and deployment. In the current paper, we pres...
Article
We experimentally demonstrate a THz integrated circuit with a pixel-array-based orbital-angular-momentum (OAM) mode converter for the generation and multiplexing of multiple data-carrying OAM beams. The integrated device consists of (i) two coupling spikes, which serve as inputs and can couple THz signals from hollow metallic waveguides to the devi...
Article
Performance assessment and optimization for networks jointly performing caching, computing, and communication (3C) has recently drawn significant attention because many emerging applications require 3C functionality. However, studies in the literature mostly focus on the particular algorithms and setups of such networks, while their theoretical und...
Article
We are entering a rapidly unfolding future driven by the delivery of real-time computation services, such as industrial automation and augmented reality, collectively referred to as augmented information (AgI) services, over highly distributed cloud/edge computing networks. The interaction intensive nature of AgI services is accelerating the need f...
Article
Full-text available
Cell-free massive multiple-input multiple-output (CF-mMIMO) systems are expected to provide faster and more robust connections to user equipments by cooperation of a massive number of distributed access points (APs), and to be one of the key technologies for beyond 5G (B5G). CF-mMIMO systems with multiple-antenna APs have been investigated from var...
Article
Full-text available
Hybrid beamforming is an attractive solution to build cost-effective and energy-efficient transceivers for millimeter-wave and terahertz systems. However, conventional hybrid beamforming techniques rely on analog components that generate a frequency flat response such as phase-shifters and switches, which limits the flexibility of the achievable be...
Article
Full-text available
In recent years wireless propagation channel research has paid considerable attention to dense multipath, which is an indispensable part of propagation channels and may significantly contribute to the received power in variety of environments and frequency bands. Mathematical representation of dense multipath is different from that of specular comp...
Conference Paper
We design and fabricate a pixel-array-based THz integrated circuit for the generation and multiplexing of multiple OAM beams. We experimentally demonstrate a 20-Gbit/s QPSK free-space THz link at 0.317 THz by multiplexing OAM +1 and –1 using the integrated circuit.
Conference Paper
Next-generation wireless communication systems need to provide extremely high data rates that can enable upcoming applications. To obtain the large contiguous bandwidth required for providing such high data rates, usage of the spectrum above 100 GHz is envisioned. In order to determine the maximum data rate available in these bands, it is necessary...
Article
This paper proposes a deep reinforcement learning-based video streaming scheme for mobility-aware vehicular networks, e.g., vehicles on the highway. We consider infrastructure-assisted and mmWave-based scenarios in which the macro base station (MBS) cannot directly provide the streaming service to vehicles due to the short range of mmWave beams so...
Preprint
Full-text available
The THz band (0.1-10 THz) has attracted considerable attention for next-generation wireless communications, due to the large amount of available bandwidth that may be key to meet the rapidly increasing data rate requirements. Before deploying a system in this band, a detailed wireless channel analysis is required as the basis for proper design and...
Preprint
Full-text available
Adaptation of a wireless system to the polarization state of the propagation channel can improve reliability and throughput. This paper in particular considers polarization reconfigurable multiple input multiple output (PR-MIMO) systems, where both transmitter and receiver can change the (linear) polarization orientation at each element of their an...
Preprint
Full-text available
To provide higher data rates, as well as better coverage, cost efficiency, security, adaptability, and scalability, the 5G and beyond 5G networks are developed with various artificial intelligence techniques. In this two-part paper, we investigate the application of artificial intelligence (AI) and in particular machine learning (ML) to the study o...
Preprint
Full-text available
This two-part paper investigates the application of artificial intelligence (AI) and in particular machine learning (ML) to the study of wireless propagation channels. In Part I, we introduced AI and ML as well as provided a comprehensive survey on ML enabled channel characterization and antenna-channel optimization, and in this part (Part II) we r...
Preprint
This paper, containing the detailed derivations and proofs for the asymptotic analysis of the delay-outage tradeoff of noise-limited wireless edge networks with joint caching, computing, and communication, serves as the supplemental file for some peer-reviewed conference and journal papers.
Preprint
Terahertz (THz) communications are envisioned as a key technology for sixth generation (6G) wireless systems. The study of underlying THz wireless propagation channels provides the foundations for the development of reliable THz communication systems and their applications. This article provides a comprehensive overview of the study of THz wireless...
Preprint
Full-text available
Cell-free massive MIMO (CF-mMIMO) provides wireless connectivity for a large number of user equipments (UEs) using access points (APs) distributed across a wide area with high spectral efficiency (SE). The energy efficiency (EE) of the uplink is determined by (i) the transmit power control (TPC) algorithms, (ii) the numbers, configurations, and loc...
Preprint
Full-text available
Vehicle-to-vehicle (V2V) wireless communication systems are fundamental in many intelligent transportation applications, e.g., traffic load control, driverless vehicle, and collision avoidance. Hence, developing appropriate V2V communication systems and standardization require realistic V2V propagation channel models. However, most existing V2V cha...
Chapter
This article provides an overview of measurements and models of millimeter-wave (mmWave) propagation channels. After a review of the frequency dependence of propagation phenomena and the definition of parameters of interest, we then discuss the different methods for measuring mmWave channels both indoors and outdoors. Then follows an overview of th...
Article
Line-of-sight (LOS) probability is a key component of system-level simulations that are required for creating new standards and recommendations for wireless systems. In particular for millimeter-wave systems, an unobstructed view between the base station at an elevation and an user at ground level is important to ensure high-throughput service. Whi...
Preprint
This paper proposes a deep reinforcement learning-based video streaming scheme for mobility-aware vehicular networks, e.g., vehicles on the highway. We consider infrastructure-assisted and mmWave-based scenarios in which the macro base station (MBS) cannot directly provide the streaming service to vehicles due to the short range of mmWave beams so...
Preprint
Full-text available
Cell-free massive multiple-input multiple-output (CF mMIMO) systems are expected to provide faster and more robust connections to user equipments (UEs) by cooperation of a massive number of distributed access points, and to be one of the key technologies for beyond 5G (B5G). In B5G, energy efficiency (EE) is one of the most important key indicators...
Conference Paper
Full-text available
Cell-free massive MIMO (CF-mMIMO) is expected to provide reliable wireless services for a large number of user equipments (UEs) using access points (APs) distributed across a wide area. When the UEs are battery-powered, uplink energy efficiency (EE) becomes an important performance metric for CF-mMIMO systems. Therefore, if the "target" spectral ef...
Preprint
Full-text available
THz band is envisioned to be used in 6G systems to meet the ever-increasing demand for data rate. However, before an eventual system design and deployment can proceed, detailed channel sounding measurements are required to understand key channel characteristics. In this paper, we present a first extensive set of channel measurements for urban outdo...