Piet Demeester

Ghent University | UGhent · Department of Information Technology

Cell-free massive multiple-input multiple-output (MIMO) has attracted wide attention as wireless spectral efficiency has become a 6G key performance indicator. The distributed scheme improves the spectral efficiency and user fairness, but the fronthaul network must evolve to enable it. This work demonstrates a fronthaul network for distributed ante...

We demonstrate a highly-scalable distributed antenna system enabled by real-time bit-interleaved sigma-delta-over-fiber links. By (time-)interleaving multiple sigma-delta modulated in-phase and quadrature pairs into one bitstream for each fiber, the optical bit-rate efficiency is improved while the remote radio unit complexity remains sufficiently...

We present a low-power all-digital radio-over-fiber (RoF) transmitter for the 28 GHz band using sigma-delta modulation. Using a parallel electro-absorption modulator (EAM) structure, the radio signal upconversion is split between the electrical and the optical domains. This halves the maximum bandwidth requirement of the driver circuit with respect...

Silicon photonics is a key-enabling technology lever-aging decades of effort and infrastructure of the microelectronics CMOS industry resulting in high yield, low cost and potential high volume manufacturing. Furthermore, due to the high index contrast of the platform, very compact, high-complexity photonic integrated circuits can be devised. To be...

Exploring mmWave frequencies and adopting small-cell architectures are two key enablers for increased wireless data rates. To make these evolutions economically viable, centralized architectures based on radio-over-fiber (RoF) are devised. To reduce the complexity of the cellular network even further, RF-over-Fiber transmission schemes are adopted...

We will demonstrate a 2x2 distributed multi-user MIMO transmission using sigma-delta-over-fiber targeting 5G downlink. OFDM signals, sigma-delta modulated and digitally up-converted to 3.5GHz on FPGA, are transmitted over 100-m multi-mode fibers at 850nm using a commercial QSFP-100G-SR4 and wirelessly using in-house developed antennas.

With Radio-Over-Fiber becoming an established technology for the next generation mobile communication networks, interest in integrated microwave photonic circuits is rapidly increasing. Especially photonic frequency converters receive quite some attention as they offer a very large bandwidth and high isolation. In this work, a flexible, integrated...

An advanced transmit remote opto-antenna unit is proposed that accomplishes impedance matching between a photodetector and a low-profile antenna in a specified frequency bandwidth, without requiring an area-consuming matching network. This results in a highly compact design, which also avoids the losses and spurious radiation by such an electricall...

This paper presents a numerical approach for massive MIMO human exposure assessment. It combines Ray-Tracing for estimation of the wireless channel and the Finite-Difference Time-Domain method to simulate the exposure of a realistic human phantom. We apply it to estimate the exposure in a model of an industrial indoor environment with a single mass...

We present the first real-time 100-GS/s FPGA-based sigma-delta modulator to enable all-digital radio-over-fiber transmission in the 22.75-27.5GHz band. 4.68Gb/s (2.34Gb/s) 64-QAM is transported over 10-km SSMF at 1562nm with 6.46% (4.73%) EVM.

We demonstrate a very low-cost low-power solution for a short-reach optical-wireless downlink consisting of sigma-delta radio-over-fiber and a fully passive opto-antenna. An FPGA-based prototype, performing sigma-delta modulation at 7-GS/s and covering a wide frequency band from 3.3 to 3.7 GHz, achieves 218.75 MBd 64-QAM over 200 m OM4 multi-mode f...

A 4-lane proof-of-concept real-time sigma-delta-over-fiber system targeting 5G C-RAN downlink is demonstrated using off-the-shelf components. Per lane, an EVM of 2.67% is achieved for a 3.5 Gbps 256-QAM signal modulated at 3.5 GHz over 20-km single-mode fiber at 1310 nm.

In-band full-duplex (FD) wireless communication allows the simultaneous transmission and reception of data at the same frequency band, effectively doubling the spectral efficiency and data rate while reducing the latency. Previously published designs mostly target the self-interference (SI) cancellation in conventional wireless systems. In this pap...

In this article, we study human electromagnetic exposure to the radiation of an ultra dense network of nodes integrated in a floor denoted as ATTO-cell floor, or ATTO-floor. ATTO-cells are a prospective 5 G wireless networking technology, in which humans are exposed by several interfering sources. To numerically estimate this exposure we propose a...

A new high-speed delta-sigma modulator (DSM) topology is proposed by cascading a bit reduction process with a multi-stage noise shaping MASH-1-1 DSM. This process converts the two-bit output sequence of the MASH-1-1 DSM to a single-bit sequence, merely compromising the DSM noise-shaping performance. Furthermore, the high clock frequency requirement...

A novel remote antenna unit, intended for application in the downlink of an analog radio frequency over fiber system, is proposed, whose radiated power originates entirely from the optical signal supplied by a single multi-mode fiber. By operating the photodetector of the optical receiver at zero bias voltage, while omitting typical active componen...

In an Internet of Things environment, where multiple mobile devices are brought together, it is not always possible to serve all these devices simultaneously. We developed an intelligent Time Division Multiple Access (TDMA) scheduler which allows to plan the individual packets of the different streams in such a way that everyone can be served by ta...

This paper describes improvements in a Farrow structured variable fractional delay (FD) Lagrange filter for all-pass FD interpolation. The main idea is to integrate the truncated sinc into the Farrow structure of a Lagrange filter, in order that a superior FD approximation in the least-square sense can be achieved. Its primary advantages are the lo...

This article describes a method for increasing the sampling rate of efficient polyphase arbitrary resampling FIR filters. An FPGA proof of concept prototype of this architecture has been implemented in a Xilinx Kintex-7 FPGA which is able to convert the sampling rate of a signal from 500 MHz to 600 MHz. This article compares this new architecture w...

Network virtualization and softwarizing network functions are trends aiming at higher network efficiency, cost reduction and agility. They are driven by the evolution in Software Defined Networking (SDN) and Network Function Virtualization (NFV). This shows that software will play an increasingly important role within telecommunication services, wh...

Due to ever-increasing throughput demands, the lookup in conventional IP routers based on longest prefix matching is becoming a bottleneck. Additionally, the scalability of current routing protocols is limited by the size of the routing tables. Geometric greedy routing is an alternative to IP routing which replaces longest prefix matching with a si...

This paper combines the multi-product variant of the capacitated facility location problem with multicommodity flow routing. This problem shares many similarities with the digital content placement and retrieval problem when minimizing the cost of installing a set of servers for storing multiple sets of data objects (files) and connecting clients t...

ATTO targets wireless networking at fiber speed: 100 Gbps/m2 with latencies smaller than 10 $\mu$ s. To provide this tremendous wireless capacity, ultra-small floor-integrated cells are proposed. In this way, short-reach communication can be established, reducing the effect of interference and providing full frequency reuse in the wireless domain....

This paper shows how to estimate an extended polynomial matrix description of a non-linear MIMO system. Both linear and non-linear impulse responses are obtained by transmitting pseudo random binary sequence (PRBS) test-patterns and can be easily separated thanks to the shift-and-add property of PRBS. Further on, a method to equalize such non-linea...

With the continuously increasing demand of cost effective, broadband wireless access, radio-over-fiber (RoF) starts to gain more and more momentum. Various techniques already exist, using analog (ARoF) or digitized (DRoF) radio signals over fiber. Each with their own advantages and disadvantages. By transmitting a sigma delta modulated signal over...

This paper describes improvements in the Farrow structured variable fractional delay (FD) Lagrange interpolation. The main idea is to replace the first sub-filter of the Farrow structure by a sinc-interpolation filter of half a sample period to achieve a superior FD approximation in the vicinity of half a sample period. Its primary advantages over...

Background Recently, many standalone applications have been proposed to correct sequencing errors in Illumina data. The key idea is that downstream analysis tools such as de novo genome assemblers benefit from a reduced error rate in the input data. Surprisingly, a systematic validation of this assumption using state-of-the-art assembly methods is...

As the IoT continues to grow over the coming years, resource-constrained devices and networks will see an increase in traffic as everything is connected in an open Web of Things. The performance- and function-enhancing features are difficult to provide in resource-constrained environments, but will gain importance if the WoT is to be scaled up succ...

A wide range of social, technological and communication systems can be described as complex networks. Scale-free networks are one of the well known classes of complex networks in which nodes’ degrees follow a power-law distribution. The design of scalable, adaptive and resilient routing schemes in such networks is very challenging. In this article...

In the future, wireless radiofrequency (RF) telecommunications networks will provide users with gigabit-per-second data rates. Therefore, these networks are evolving toward hybrid networks, which will include commonly used macro- and microcells in combination with local ultra-high density access networks consisting of so-called attocells. The use o...

Nowadays deep neural networks are widely used to accurately classify input data. An interesting application area is the Internet of Things (IoT), where a massive amount of sensor data has to be classified. The processing power of the cloud is attractive, however the variable latency imposes a major drawback in situations where near real-time classi...

Home automation devices are becoming increasingly popular in the field of consumer electronics. Various appliances like thermostats, smoke detectors, intelligent lighting systems, etc., have appeared on the market to create a smart home. Vendors have the availability over multiple wireless technologies to connect their products to the smart home an...

Availability and implementation: The Cytoscape app for ISMAGS can be freely downloaded from the Cytoscape App store http://apps.cytoscape.org/apps/ismags Source code and documentation for ISMAGS are available at https://github.com/biointec/ismags Source code and documentation for the Cytoscape app are available at https://gitlab.psb.ugent.be/thpar...

In this letter, we propose a novel protocol, inter-burst segregation protocol (IBSP), which guarantees zero packet loss in packet-switched networks. The protocol is implemented and evaluated in network simulator-3 and in the data plane development kit (DPDK) implemented by INTEL. The results confirm that a packet-switched network can achieve zero p...

While smart cities have the potential to monitor and control the city in real-time through sensors and actuators, there is still an important road ahead to evolve from isolated smart city experiments to real large-scale deployments. Important research questions remain on how and which wireless technologies should be setup for connecting the city, h...

Sensors and actuators are becoming important components of Internet of Things (IoT) applications. Today, several approaches exist to facilitate communication of sensors and actuators in IoT applications. Most communications go through often proprietary gateways requiring availability of the gateway for each and every interaction between sensors and...

The Internet of Things (IoT) is expanding rapidly to new domains in which embedded devices play a key role and gradually outnumber traditionally-connected devices. These devices are often constrained in their resources and are thus unable to run standard Internet protocols. The Constrained Application Protocol (CoAP) is a new alternative standard p...

Background Third generation sequencing platforms produce longer reads with higher error rates than second generation technologies. While the improved read length can provide useful information for downstream analysis, underlying algorithms are challenged by the high error rate. Error correction methods in which accurate short reads are used to corr...

A high-performance, three-element substrate-integrated-waveguide (SIW) cavity-backed slot antenna array that covers the (5.15-5.85) GHz band is designed for integration inside or underneath the worktop of a desk, to set up a stable, high data-rate ultra-short-range 3 × 3 multiple-input multiple-output (MIMO) wireless communication link with a mobil...

Given a set of potential facilities (with individual opening cost and finite capacity) and a set of client demands, the capacitated Facility Location Problem (cFLP) consists in selecting a set of facilities to open and performing an assignment of demands to open facilities that minimize the sum of the facility opening cost, supplying cost and trans...

The growth of the size of the routing tables limits the scalability of the conventional IP routing. As scalable routing schemes for large-scale networks are highly demanded, this paper proposes and evaluates an efficient geometric routing scheme and related low-cost node design applicable to large-scale networks. The approach guarantees that greedy...

Many algorithms have been developed to infer the topology of gene regulatory networks from gene expression data. These methods typically produce a ranking of links between genes with associated confidence scores, after which a certain threshold is chosen to produce the inferred topology. However, the structural properties of the predicted network d...

In OpenFlow, a network as a whole can be controlled from one or more external entities (controllers) using in-band or out-of-band control networks. In this article, we propose in-band control, queuing, and failure recovery functionalities for OpenFlow. In addition, we report experimental studies and practical challenges for implementing these funct...

Substrate integrated waveguide (SIW) cavity-backed slot antenna topologies are promising candidates to adress the specific design challenges posed by the Internet of Things (IoT). In this contribution, we demonstrate their potential by discussing two designs on two different, application-specific, innovative substrate materials. First, a compact, u...

Increasing line rates beyond 56Gb/s is a big challenge for transceiver front-ends. We discuss recent developments towards 100Gb/s copper, +56Gb/s multi-channel single-mode VCSEL links and segmented MZM drivers for advanced modulation.

Real-Time Travel Information (RTTI) for rail commuters is still used inefficiently today and is rarely combined with other knowledge to come to a truly personalised and situation-aware multimodal travelling assistance. It is up to the travellers themselves to look for important info about their trip through static schedules or dedicated non-persona...

In OpenFlow, data and control plane are decoupled from switches or routers. While the data plane resides in the switches or routers, the control plane might be moved into one or more external servers (controllers). In this article, we propose verification mechanisms for the data plane functionality of switches. The latter consists of two parts: (1)...

In recent years, rising energy prices and increasing environmental concerns have boosted research in the so called green ICT and green networking research tracks, aimed at improving the energy efficiency of communications while still offering maximal functionality. In this article we explore a future scenario in which low power networking is no lon...

Spectacular advances in hardware and software technologies have resulted in powerful mobile devices, equipped with advanced processing, storage and network capabilities. Therefore, using resource-intensive applications has become a commodity in many contexts. However, the rapid evolution in hardware and software capabilities has not been paralleled...

SDN and NFV are two paradigms that introduce unseen flexibility in telecom networks. Where previously telecom services were provided by dedicated hardware and associated (vendor-specific) protocols, SDN enables to control telecom networks through specialized software running on controllers. NFV enables highly optimized packet-processing network fun...

As the Internet of Things continues to expand in the coming years, the need for services that span multiple IoT application domains will continue to increase in order to realize the efficiency gains promised by the IoT. Today, however, service developers looking to add value on top of existing IoT systems are faced with very heterogeneous devices a...

This paper proposes an optical distribution network (ODN) architecture for open access networks. The proposed scheme ensures co-existence of multiple business partners (BPs) e.g., service, network equipment, and infrastructure providers at different levels of the distribution network, along with physical-layer security. Further, physical-layer isol...

The rise of Software-Defined Networking (SDN) and Network Function Virtualization (NFV) introduce opportunities for service providers to reduce CAPEX/OPEX and to offer and quickly deploy novel network services. In particular, SDN and NFV enable the flexible composition of network functions, a generic service concept known as network service chainin...

It is envisioned that by the year 2020 the Internet will contain more than 50 billion devices, among which the majority of them will have constraints in terms of memory, processing power or energy. As a consequence, they are often unable to run current standard Internet protocols, requiring special, optimized protocols. A number of these protocols,...

Third generation sequencing platforms produce longer reads with higher error rates than second generation sequencing technologies. While the improved read length can provide useful information for downstream analysis, underlying algorithms are challenged by the high error rate. Error correction methods in which accurate short reads are used to corr...

Several dynamic bandwidth allocation (DBA) algorithms have been proposed for long-reach passive optical networks (LR-PONs). The gains in the current protocols, however, are incremental and limited to a specific range of loads. Using an analytical framework, we first examine the main sources of performance degradation specific to LR-PONs. From this,...

An ultra-wideband (UWB) substrate-integrated-waveguide (SIW) cavity-backed slot antenna covering the lower part of the 3.1–10.6 GHz block allocated to UWB transmission systems, being 3.1–3.6 GHz, is designed, constructed and validated. Owing to its planar topology, low profile and the use of cork substrate material, the proposed antenna may be inte...

Energy efficiency is of a vital significance in the design of next generation time and wavelength division multiplexed passive optical networks (TWDM-PONs). In this paper, we first review strategies to save energy in TWDM-PONs using the state-of-the-art dynamic bandwidth allocation (DBA) algorithms. The DBA algorithms should not only minimize energ...