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Introduction
Kin-Fai Tong currently works at the School of Science and Technology in Hong Kong Metropolitan University . Kin-Fai does research in Antenna Engineering, Wireless Communications and Engineering Education. His current project is 'High Performance Fluid Antennas Design; Surface Wave Communications Systems'.
Current institution
Current position
- Chair Professor of Antennas and Applied Electromagnetics
Additional affiliations
August 2000 - December 2004
June 1998 - August 2000
January 2005 - present
Education
July 1993 - June 1997
Publications
Publications (250)
In-band full-duplex (IBFD) systems are expected to double the spectral efficiency compared to half-duplex systems, provided that loopback self-interference (SI) can be effectively suppressed. The inherent interference mitigation capabilities of the emerging fluid antenna system (FAS) technology make it a promising candidate for addressing the SI ch...
Fluid Antenna Systems (FASs) have recently emerged as a promising solution to address the demanding performance indicators (KPIs) and scalability challenges of future 6G mobile communications. By enabling agile control over both radiating position and antenna shape, FAS can significantly improve diversity gain and reduce outage probability through...
Fluid antenna system (FAS) is an emerging technology that uses the new form of shape- and position-reconfigurable antennas to empower the physical layer for wireless communications. Prior studies on FAS were however limited to narrowband channels. Motivated by this, this paper addresses the integration of FAS in the fifth generation (5G) orthogonal...
Magneto-electric dipole (ME-dipole) antennas offer several advantages, including wide impedance bandwidth, stable high gain, unidirectional radiation, and low back-lobe radiation patterns, making them suitable for modern wireless communication systems. However, the thickness of conventional ME-dipole antennas is typically about a quarter wavelength...
Interference and scattering, often deemed undesirable, are inevitable in wireless communications, especially when the current mobile networks and upcoming sixth generation (6G) have turned into ultra-dense networks. Current approaches relying on multiple-input multiple-output (MIMO) combined with artificial-intelligence-aided (AI) signal processing...
Fluid antenna multiple access (FAMA) is a concept capable of massive connectivity on the same physical channel without the need of precoding or interference cancellation, by exploiting a super‐high dimensional received signal in the spatial domain from fluid antenna system (FAS). This letter investigates the use of 5G New Radio (NR) Modulation Codi...
Fluid antennas present a relatively new idea for harnessing the fading and interference issues in multiple user wireless systems, such as 6G. Here, we systematically compare their unique radiation beam forming mechanism to the existing multiple-antenna systems in a wireless system. Subsequently, a unified mathematical model for fluid antennas is de...
Enabled by the emerging fluid antenna system (FAS) technology, fast fluid antenna multiple access (FAMA) provides a massive connectivity scheme which is able to serve on the same physical channel hundreds of users, without the need of precoding nor interference cancellation at each user. This is, however, only possible if we know the antenna positi...
This letter presents a novel scheme to construct multiple wireless channels for multi-user over-the-air (OTA) testing in a limited zone without physical separation. The system model of the two devices under test (DUTs) OTA testing is provided, according to which the pre-compensation matrix is proposed to mitigate the crosstalk between the two DUTs....
Fluid antennas present a relatively new idea for harnessing the fading and interference issues in multiple user wireless systems, such as 6G. Here, we systematically compare their unique radiation beam forming mechanism to the existing multiple- antenna systems in a wireless system. Subsequently, a unified mathematical model for fluid antennas is d...
A magneto-electric dipole implemented using substrate integrated blocks (SIBs) is proposed for broadband dual-polarized array application. Facilitated by the SIB-based design approach, an interlaced arrangement of the perpendicular feeding probes is developed for dual-polarization excitation. While maintaining the wideband feature and single-layere...
This paper investigates the performance of a single-user fluid antenna system (FAS), by exploiting a class of elliptical copulas to describe the dependence structure amongst the fluid antenna positions (ports). By expressing the well-known Jakes’ model in terms of the Gaussian copula, we consider two cases: (i) the general case, i.e., any arbitrary...
Integrated sensing and communication (ISAC) is poised to be a cornerstone in advancing wireless networks, encompassing 5G and future generations. This visionary technology melds the realms of sensing and communication, optimizing the utilization of wireless resources while fostering a symbiotic relationship between the two functionalities. Under IS...
Fluid antenna system (FAS) is a new flexible antenna technology that offers a new approach to multiple access, referred to as fluid antenna multiple access (FAMA). The performance of FAMA has been investigated but previous results were based on simplified spatial correlation models. In this paper, we will revisit FAMA for the two-user case and stud...
In this letter, we study the performance of content caching in a heterogeneous cellular network (HetNet) consisting of fluid antenna system (FAS)-equipped mobile users (MUs) and single fixed-antenna small base stations (SBSs), distributed according to an independent homogeneous Poisson point processes (HPPP). It is assumed that the most popular con...
The advent of the sixth-generation (6G) networks presents another round of revolution for the mobile communication landscape, promising an immersive experience, robust reliability, minimal latency, extreme connectivity, ubiquitous coverage, and capabilities beyond communication, including intelligence and sensing. To achieve these ambitious goals,...
Fluid Antenna Systems (FASs) have recently been proposed for enhancing the performance of wireless communication. Previous antenna designs to meet the requirements of FAS have been based on mechanically movable or liquid antennas and therefore have limited reconfiguration speeds. In this paper, we propose a design for a pixel-based reconfigurable a...
While multiple-input multiple-output (MIMO) technologies continue to advance, concerns arise as to how MIMO can remain scalable if more users are to be accommodated with an increasing number of antennas at the base station (BS) in the upcoming sixth generation (6G). Recently, the concept of fluid antenna system (FAS) has emerged, which promotes pos...
This paper introduces a novel reconfigurable technique for partitioning the propagation of surface waves by utilizing a T-shaped structure and pathways established through the introduction of fluid metal or metal pins into evenly spaced cylindrical cavities within a porous surface wave platform. Notably, the co-printing of metal and dielectric mate...
Surface wave-assisted wireless communication systems have recently emerged as a promising complementary solution for creating a smart radio environment, particularly in the context of beyond-fifth generation (5G) and sixth generation (6G) networks. Unlike traditional approaches that rely solely on space waves or use passive elements on a large surf...
Surface wave communication (SWC) is an emerging technology garnering significant interest for its diverse potential applications in communications. However, accurately computing electromagnetic field strength, which is related to the path loss, in reconfigurable surface structures, particularly for long-distance transmission, presents an ongoing ch...
Fluid Antenna Systems (FASs) have recently been proposed for enhancing the performance of wireless communication. FAS have previously exploited mechanical movement or liquids to perform the required adaptation to the wireless environment. Due to the mechanical or liquids approach, these systems have limited switching speeds that prevents their use...
Reconfigurable intelligent surface (RIS) as a smart reflector is revolutionizing research for next-generation wireless communications. In contrast to this is a concept of using RIS as an efficient propagation medium for superiorly low path loss characteristics and excellent flexibility. Motivated by the recent porous surface architecture that facil...
The advent of the sixth-generation (6G) networks presents another round of revolution for the mobile communication landscape, promising an immersive experience, robust reliability, minimal latency, extreme connectivity, ubiquitous coverage, and capabilities beyond communication, including intelligence and sensing. To achieve these ambitious goals,...
Multiple access can be realized by utilizing the spatial moments of deep fades, using fluid antennas. The interference immunity for fluid antenna multiple access (FAMA), nevertheless, comes with the requirement of a large number of ports at each user. To alleviate this, we study the synergy between opportunistic scheduling and FAMA. A large pool of...
In this letter, we study the performance of a single-user fluid antenna system (FAS) under arbitrary fading distributions, in which the fading channel coefficients over the ports are correlated. We adopt copula theory to model the structure of dependency between fading coefficients. Specifically, we first derive an exact closed-from expression for...
A wideband via-free magneto-electric (ME) dipole antenna is conceived for millimeter wave band applications. Herein, the electric dipole patch and a half-wavelength radiating slot are excited in phase on the patch layer by a substrate integrated coaxial line (SICL) to fulfill the complementary conditions as a ME dipole. The proposed antenna omits t...
This paper introduces a novel reconfigurable technique for partitioning surface waves by utilizing a T-shaped structure and pathways established through the introduction of fluid metal or metal pins into evenly spaced cylindrical cavities within a porous surface wave platform. Notably, the co-printing of metal and dielectric materials via 3D printi...
The promising performance of fluid antenna systems (FAS) relies on activating the optimal port to access the spatial opportunity for favourable channel conditions for wireless communications. This nevertheless can imply enormous overheads in channel estimation and signal reception as the resolution of fluid antenna could be arbitrarily high. There...
With research efforts gearing up to build the sixth-generation (6G) mobile communications, it is only logical to seek new mobile technologies that can provide the next generational leap for much better performance under harsher environments. To this end, one interesting concept is fluid antenna system (FAS) which utilizes flexible antenna architect...
Reconfigurable intelligent surface (RIS) has recently emerged as a promising technology to extend the coverage of a base station (BS) in wireless communication networks. However, the adoption of RIS comes with the challenges of highly complex joint optimization of the multiple-input multiple-output (MIMO) precoding matrix at the BS and the phase sh...
Fluid antenna system (FAS) facilitating a position-switchable antenna, enables a mobile receiver to exploit the deep fade opportunity of its interference for multiple access. Slow fluid antenna multiple access (
s
-FAMA) is such an emerging proposal that lets multiple users share the same time-frequency channel while each user adopts a fluid anten...
Recent researches have revealed that fluid antenna, a new position-switchable antenna technology, can make use of the spatial moments of deep fades of the interference signal occurred naturally due to multipath for multiple access. In this letter, this phenomenon is exploited in a physical layer security setup where a base station (BS) transmits an...
In this letter, we study the performance of a single-user fluid antenna system (FAS) under arbitrary fading distributions, in which the fading channel coefficients over the ports are correlated. We adopt copula theory to model the structure of dependency between fading coefficients. Specifically, we first derive an exact closed-from expression for...
Fluid antennas offer a novel way to achieve massive connectivity by enabling each user to find a ‘port’ in space where the instantaneous interference undergoes a deep null for multiple access. While this unprecedented capability permits hundreds of users to share the same radio channel, each user needs to switch its best port on a symbol-by-symbol...
Reconfigurable intelligent surface (RIS) as a smart reflector is revolutionizing research for next-generation wireless communications. Complementing this is a concept of using RIS as an efficient propagation medium for potentially superior path loss characteristics. Motivated by a recent porous surface architecture that facilitates reconfigurable p...
Multiple-input multiple-output (MIMO) system has been the defining mobile communications technology in recent generations. With the ever-increasing demands looming towards 6G, we are in need of additional degrees of freedom that deliver further gains beyond MIMO. To this goal, fluid antenna system (FAS) has emerged as a new way to obtain spatial di...
Using reconfigurable fluid antennas, it is possible to have a software‐controlled position‐tuneable antenna to realize spatial diversity and multiplexing gains that are previously only possible using multiple antennas. Recent results illustrated that fast fluid antenna multiple access (f‐FAMA) which always tunes the antenna to the position for maxi...
In this paper, we proposed a new wideband circularly polarized cross-fed magneto-electric dipole antenna. Different from conventional cross-dipole or magneto-electric dipole antennas, the proposed simple geometry realizes a pair of complementary magnetic dipole modes by utilizing the two open slots formed between the four cross-fed microstrip patch...
The increasing interest of fluid antenna systems is reinforced by an unprecedented way of achieving multiple access, by exploiting moments of deep fades in space. This phenomenon, referred to as fluid antenna multiple access (FAMA), allows the fluid antenna at each user to be switched to a location in space (i.e., port) where the sum-interference p...
To enable innovative applications and services, both industry and academia are exploring new technologies for sixth generation (6G) communications. One of the promising candidates is fluid antenna system (FAS). Unlike existing systems, FAS is a novel communication technology where its antenna can freely change its position and shape within a given...
Multiple-input multiple-output (MIMO) system has been the defining mobile communications technology in recent generations. With the ever-increasing demands looming towards the sixth generation (6G), we are in need of additional degrees of freedom that deliver further gains beyond MIMO. To this goal, fluid antenna system (FAS) has emerged as a new w...
Fluid antenna system (FAS) has recently emerged as a promising candidate for the sixth generation (6G) wireless networks. Unlike traditional antenna systems (TASs), FAS is a new wireless communication system where the so-called ‘fluid’ antenna (FA) can finely change its position within a given area. This unique ability allows FAS to harness additio...
This paper aims to present a simple multiple access scheme for massive connectivity that enables a large number of mobile user equipments (UEs) to occupy the same time-frequency channel without the need of precoding and power control at the base station (BS) and interference cancellation at each UE. The proposed approach does not even require the U...
This letter investigates the application of the emerging fluid antenna (FA) technology in multiuser communication systems when side information (SI) is known at the transmitters. We consider a
K
-user dirty multiple access channel (DMAC) with non-causally known SI at the transmitters, where
K
users send independent messages to a common receiver...
To enable innovative applications and services, both industry and academia are exploring new technologies for sixth generation (6G) communications. One of the promising candidates is fluid antenna system (FAS). Unlike existing systems, FAS is a novel communication technology where its antenna can freely change its position and shape within a given...
Liquid-based antennas promise to overcome crucial limitations of traditional solid-based ones. Here, we describe different liquid antenna technologies that can be used to build arrays with the unprecedented flexibility and adaptivity needed to enable an evolution in wireless communications. We focus on two approaches that use either metallic or non...
Reconfigurable surfaces facilitating energy-efficient, intelligent surface wave propagation have recently emerged as a technology that finds applications in many-core systems and 6G wireless communications. In this paper, we consider the porosity-based reconfigurable surface where there are cavities that can be filled on-demand with fluid metal suc...
Fluid antenna multiple access (FAMA) is a new way of accommodating a large number of users on a single channel for massive connectivity, with slow FAMA (s-FAMA) being the practical version for achieving this. The impressive performance is understood to be achievable if the users have independent Rayleigh fading envelopes. With mobile networks vampi...
In this paper, an antenna design that combines surface wave and fluidic reconflgurable techniques was presented. The antenna operates in a wide frequency range from 23 to 38 GHz, which covers the Very High 5G Frequency band in the US, Europe, China, Japan, and Korea. In this design, only one RF input port is needed to achieve diversity when compare...
In this paper, we present an antenna design for millimeter wave 5G applications. The proposed antenna has a wide working frequency range from 23.5 GHz to 36.5 GHz. This can cover the millimeter wave 5G frequency band in most countries. The design is simple and will mitigate the difficulty when implementing in a wireless system with reconfigurable c...
This work presents a surface wave antenna metallic cell pattern prediction method which can be generated based on the required far-field radiation pattern by the mean of applying Wasserstein generative adversarial network (WGAN) and bi-directional gated recurrent unit (Bi-GRU) neural network models. The predicted metallic cell pattern has been 3D-m...
Fluid antenna has emerged as a new antenna technology that enables software-controllable position reconfigurability for great diversity and multiplexing benefits. The performance of fluid antenna systems has recently been studied for single and multiuser environments adopting a generalized spatial correlation model that accounts for the channel cor...
Due to the exceedingly high integration density of VLSI circuits and the resulting high power density, thermal integrity became a major challenge. One way to tackle this problem is Dark silicon. Dark silicon is the amount of circuitry in a chip that is forced to switch off to insure thermal integrity of the system and prevent permanent thermal-rela...
Reconfigurable surfaces facilitating energy-efficient, intelligent surface wave propagation have recently emerged as a technology that finds applications in many-core systems and 6G wireless communications. In this paper, we consider the porosity-based reconfigurable surface where there are cavities that can be filled on-demand with fluid metal suc...
With massive deployment, multiple-input-multiple-output (MIMO) systems continue to take mobile communications to new heights, but the ever-increasing demands mean that there is a need to look beyond MIMO and pursue the next disruptive wireless technologies. Reconfigurable intelligent surface (RIS) is widely considered a key candidate technology blo...
Fluid antenna system promises to obtain enormous diversity in the small space of a mobile device by switching the position of the radiating element to the most desirable position from a large number of prescribed locations of the given space. Previous researches have revealed the promising performance of fluid antenna systems if the position with t...
The emerging fluid antenna technology enables a high-density positionswitchable antenna in a small space to obtain enormous performance gains for wireless communications. To understand the theoretical performance of fluid antenna systems, it is important to account for the strong spatial correlation over the different positions (referred to as ‘por...
![Fig. 1. Various dark silicon patterns [25].](profile/Ammar-Karkar/publication/359502124/figure/fig1/AS:1177617139015681@1657777213518/arious-dark-silicon-patterns-25_Q320.jpg)
Due to the exceedingly high integration density of VLSI circuits and the resulting high power density, thermal integrity became a major challenge. One way to tackle this problem is Dark silicon. Dark silicon is the amount of circuitry in a chip that is forced to switch off to insure thermal integrity of the system and prevents permanent thermal-rel...
While 5G is tasked to transform our lives for the better over the next 10 years, next-generation mobile communications, a.k.a. 6G, will undoubtedly demand even higher energy and spectral efficiencies capable of providing myriads of new services and experience to users everywhere they go. Although our technologies do evolve from one generation to th...
Surface wave inherently has less propagation loss as it adheres to the surface and minimizes unwanted dissipation in space. Recently, they find applications in network-on-chip (NoC) communications and intelligent surface aided mobile networked communications. This paper puts forward a reconfigurable surface wave platform (RSWP) that utilizes liquid...
Fluid antenna system promises to obtain enormous diversity in the small space of a mobile device by switching the position of the radiating element to the most desirable position from a large number of prescribed locations of the given space. Previous researches have revealed the promising performance of fluid antenna systems if the position with t...
Massive connectivity over wireless channels relies on aggressive spectrum sharing techniques. Conventionally, this may be achieved by sophisticated signal processing and optimization of applying multiple antennas and/or complex multiuser decoding at each user terminal (UT). Different from previous methods, this letter proposes a radical approach fo...
Fluid antenna system represents an emerging technology that enables an antenna to switch its physical location in a predefined space. This paper explores the potential of using a single fluid antenna at each mobile user for multiple access, which we refer to it as fluid antenna multiple access (FAMA). FAMA exploits spatial moments of deep fade suff...
As an attempt to develop a reconfigurable surface architecture that can use liquid metal such as Galinstan to shape surface channels on demand, this paper considers a punctured surface where cavities are evenly distributed and can be filled with liquid metal potentially via digitally controlled pumps. In this paper, we look at the benefits of such...
This work presents a surface wave antenna metallic pattern prediction from electric field in near-field by applying Bidirectional Gated Recurrent Unit neural network prediction model. The metallic pattern of the proposed antenna has been predicted by using Bi-GRU neural network model with prediction accuracy 100% at 34.5GHz. Different uniform mark-...
As an attempt to develop a reconfigurable surface architecture that can use liquid metal such as Galinstan to shape surface channels on demand, this paper considers a punctured surface where cavities are evenly distributed and can be filled with liquid metal potentially via digitally controlled pumps. In this paper, we look at the benefits of such...
Surface wave inherently has less propagation loss as it adheres to the surface and minimizes unwanted dissipation in space. Recently, they find applications in network-on-chip (NoC) communications and intelligent surface aided mobile networked communications. This paper puts forward a reconfigurable surface wave platform (RSWP) that utilizes liquid...
IEEE Complementary to traditional approaches that focus on transceiver design for bringing the best out of unstable, lossy fading channels, one radical development in wireless communications that has recently emerged is to pursue a smart radio environment by using software-defined materials or programmable metasurfaces for establishing favorable pr...
A millimeter-wave low-profile magneto-electric(ME) dipole antenna is presented in this paper. The proposed ME dipole antenna is designed on two pieces of substrate with different materials and fed by aperture-coupled technique. Unlike the previously reported ME dipole antennas, there is no vertical-cavity serving as a magnetic dipole in this design...
Local warming of human tissue causes vasodilation and therefore blood volume to increase. Such thermal blood volume response allows the assessment of microcirculation in tissue, providing clinically important information. The deep warming is provided by a novel microwave applicator, which has a annular-ring microstrip patch operating at 2450 MHz wi...
This work presents our preliminary work on an electric field (E-field) prediction technique and near-field tofar-field transformation of a surface wave antenna with a cosecant-squared pattern for a millimeter-wave FMCW vertical-looking radar system. Fourier and Gaussian fitting models were used to predict the magnitude and phase of E-field on the a...
Over the past twenty years, multiple antenna technologies have appeared in many different forms, most notably as multiple-input multiple-output (MIMO), that have transformed wireless communications for extraordinary diversity and multiplexing gains. The various MIMO technologies have been based on placing a number of antennas at some fixed location...
We are organizing a special section of IEEE Open Journal of Antennas and Propagation (OJAP). The title is Advanced Antenna Technologies for 5G Internet-of-Things Applications. Please refer to the brochure and submit your research in this emerging journal in IEEE AP-Society.
Since its inception, multiple-input multiple-output (MIMO) has become a magical technology that continues to break new grounds and deliver the needed upgrades in mobile communications. The emerging 5G systems are also being labelled by many as the massive MIMO generation. This somewhat oversimplified view is perhaps a reflection of the great impact...
Fluid antenna represents a concept where a position-flexible antenna can switch its location freely within a given space. Recently, it has been demonstrated that even with a tiny space, a single-antenna fluid antenna system (FAS) can outperform an
$L$
-antenna maximum ratio combining (MRC) system in terms of outage probability if the number of lo...
Fluid antenna is a novel technology that can make an antenna appear instantly at one of N preset locations in a predefined space. An important application is to adopt fluid antenna in a small space of mobile device for obtaining the tremendous diversity hidden in the small space. Previous results have revealed that a single-antenna fluid antenna sy...
Complementary to traditional approaches that focus on transceiver design for bringing the best out of unstable, lossy fading channels, one radical development in wireless communications that has recently emerged is to pursue a smart radio environment by using software-defined materials or programmable metasurfaces for establishing favourable propag...
Fluid antenna represents a concept where a mechanically flexible antenna can switch its location freely within a given space. Recently, it has been reported that even with a tiny space, a single-antenna fluid antenna system (FAS) can outperform an L-antenna maximum ratio combining (MRC) system in terms of outage probability if the number of locatio...
