Science Foundation Ireland

CONNECT research highlights – October 2020

Here are some recent high-impact publications from CONNECT researchers. Topics include providing network connectivity to drones, antenna design for mmWave , overcoming spectrum congestion, MAC protocols for Terahertz communications, a low-power optical frequency comb, a new thermoelectric material which could replace batteries in IoT sensors, power amplifier architectures for 5G, and reversible computing for acoustic communications.

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Title: Mobility in the sky: Performance and mobility analysis for cellular-connected UAVs
Authors: R. Amer, W. Saad, N. Marchetti
Journal: IEEE Transactions on Communications

What’s this paper about?
Cellular networks have not been built to be ‘sky-aware’. By default, the antennas on base stations tilt downwards. This creates a significant challenge for providing wireless connectivity to aerial drones.

Up until now, researchers have looked at solutions based on massive MIMO, mmWave and beamforming. In contrast, this paper presents results from a simulation model consisting of a network of clustered ground base stations that cooperatively serve a number of drones.

Previous work has focused largely on static (hovering) drones, while this paper also looks at mobile (moving) drones, allowing data to be gathered on handover issues.

What exactly have you discovered?
A clustered base station approach can improve the coverage probability of drones to 60% for an average of 2.5 collaborating base stations.

Speed noticeably degrades the coverage probability of mobile drones, and frequent up and down movements by mobile drones as they travel decreases the probability of connectivity.

 This paper includes the first rigorous mathematical analysis of connectivity transmission for both static and 3D mobile drones, and supplies a new 3D mobility model.

While the wireless connection between drones and base stations on the ground is much weaker than wireless connections between the base stations and user equipment on the ground, ground base stations may still offer connectivity to drones.

So what?
4G and 5G mobile networks will need to be reshaped to accommodate the connectivity needs of aerial drones. The realisation of the many applications of drones will depend on this.

Read the paper here (pdf).

For more information, please contact ramyr at tcd.ie
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Title: Near-Field Propagation Analysis for Vivaldi Antenna Design: Insight Into the Propagation Process for Optimizing the Directivity, Integrity of Signal Transmission, and Efficiency
Authors: Ha Hoang, Matthias John, Patrick McEvoy, Max J. Ammann
Journal: IEEE Antennas and Propagation Magazine

What is this paper about?
Analysing and visualising near field propagation in and around antennas by combining simulation and advanced signal processing.

What exactly have you discovered?
We have developed a method that can show what is going on inside an antenna in space-, time- and frequency-domain. This gives a new insight into how energy moves close to the antenna edges and the radiation/propagation process.

So what?
This will change how antennas are designed and optimized, in particular for the emerging mmWave antennas.

Read the paper here (pdf).

For more information, please contact max.ammann at dit.ie

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Title: Power efficient optical frequency comb generation using laser gain switching and dual-drive Mach-Zehnder modulator
Authors: Amol Delmade, Marko Krstić, Colm Browning, Jasna Crnjanski, Dejan Gvozdić, Liam Barry
Journal: Optics Express

What is this paper about?
Lasers are a key component in the transport of internet data around the globe via thousands of kilometers of optical cables laid under the sea. Multiple lasers and optical cables are required to carry this information, so the design of low power consuming lasers is essential for a low-cost, eco-friendly system. This paper is about developing a low-power optical source for deployment in such systems.

What exactly have you discovered?
We have created a low-power optical device which can perform the function of twelve lasers, resulting in significant cost and energy efficiency. Previous demonstrations by various groups required high amplitude (6 to 40 Volt) sinusoidal signals to expand the laser optical lines, while in this paper we demonstrated a technique that required only 1.5 Volt signals.

Apart from energy-efficiency, the use of this device can help to mitigate some transmission effects in the system – resulting in reduced requirements for digital signal processing.

So what?
The power-efficiency achieved with this technique makes a strong case for convincing operators to use this multiple optical line device rather than individual lasers as used in the current systems. This device can be used in almost all the optical systems, which require multiple lasers for their operation.

Read the paper here (pdf).

For more information, please contact amol.delmade2 at mail.dcu.ie

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Title: MAC protocols for Terahertz Communications: A Comprehensive Survey
Authors: Saim Ghafoor, Noureddine Boujnah, Mubashir Husain Rehmani, Alan Davy
Journal: IEEE Communications Surveys & Tutorials

What’s this paper about?
The Terahertz frequency band has the potential to provide internet speeds of terabits per second to achieve ultra-high throughput and ultra-low latency for future applications such as autonomous driving, and for data centre interconnections.

The Terahertz band, however, is useful only for short communication distance due to high path loss, and requires antenna directionality. As a result, the traditional Medium Access Control (MAC) protocols cannot be used directly.

New MAC protocols are required to efficiently utilize the spectrum resource and take advantage of huge bandwidth availability in the Terahertz band. This paper provides an extensive survey of MAC protocols for Terahertz communication networks with their requirements and design challenges for future applications.

What exactly have you discovered?
The Terahertz communication network is a new field where the research is so far mostly focused on the devices, channel, antenna, and physical layer aspects. Limited attention has been given to the MAC role and the challenges faced in achieving the fair resource allocation and high throughput requirement, especially for macro-scale networks.

This paper provides an extensive survey of Terhartz MAC protocols and explores the design issues and requirements for Terahertz MAC protocols.

The MAC protocols for different applications which require terabit per second links are also examined.

So what?
The paper highlights the design issues, requirements, and challenges, which need to be considered while designing efficient MAC protocols for these future applications.

This paper is a one-stop platform for researchers to get the insights into Terahertz MAC protocols, the challenges, and future directions, to advance the research in this field.

Read the paper here (pdf).

For more information, please contact sghafoor at tssg.org

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Title: Multi-Band Dual-Mode Doherty Power Amplifier Employing Phase Periodic Matching Network and Reciprocal Gate Bias for 5G Applications
Authors: Jingzhou Pang, Zhijiang Dai, Yue Li, Meng Li,  Anding Zhu
Journal: IEEE Transactions on Microwave Theory and Techniques

What’s this paper about?
The rapid development of modern wireless communication systems has been accompanied by a burst of new standards and frequency bands, which create strong demand for multi-band wireless transceivers. This demand will become more intense with 5G since not only the existing 4G bands must be covered but also many new frequency bands are added. As the most power-consuming element in wireless transmitters, power amplifiers (PA) thus face significant challenges in multi-band operation.

What exactly have you discovered?
We have developed a novel power amplifier architecture which can support multi-band/multi-mode operation. It is the first time that a six-band PA has been implemented, which accommodates high peak-to-average power ratio (PAPR) signals while maintaining enough bandwidth in every operation band. These breakthrough performances are achieved without increasing circuit complexity.

So what?
The proposed PA architecture provides a promising multi-band solution for broadband 5G/Beyond-5G wireless transmitters. The use of this technology is likely to significantly reduce the number of transmitters required for 5G systems and thus reduce the cost of 5G networks.

Read the paper here (pdf).

For more information, please contact anding.zhu at ucd.ie

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Title: Reversible Hardware for Acoustic Communications
Authors: Harun Siljak, Julien de Rosny, Mathias Fink
Journal: IEEE Communications Magazine

What’s this paper about?
Wave time reversal is a technique where the walls of a chamber have embedded microphones and speakers: as the sound produced by something in the room (e.g., a person speaking) reaches the microphones, it is recorded and played backwards through the speakers. An “echo” produced in that way causes the sound waves to reappear at the exact same place where they originated from (e.g., the person’s mouth!) This has multiple applications, but we’re interested in the communication side of it.

What exactly have you discovered?
We have discovered that the circuitry needed to perform signal processing for time reversal has a very natural interpretation in terms of quantum/reversible gates. This is the first paper that presents a solution for wireless communications signal processing using quantum gates and reversible computation.

So what?
Reversible computation offers lower power consumption and better scaling for the electronics of the future. It is related to quantum computing, which promises a paradigm shift in computing as we know it. Discoveries like ours prepare the technology of today for the world of tomorrow–so that communication doesn’t become a bottleneck, trailing behind computation.

Read the paper here (pdf).

For more information, please contact siljakh at tcd.ie

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Title: Strategies and Demonstration to Support Multiple Wireless Protocols with a Single RF Front-End
Authors: M. Mohamed, S. Handagala, J. Xu, M. Leeser, M. Onabajo
Journal: IEEE Wireless Communications

What’s this paper about?
With the increased number of IoT and other wireless devices, spectrum congestion has become a serious challenge especially in ISM frequency bands. In this paper, we present an approach that enables spectrum sharing between multiple wireless protocols using the same radio frequency front end. We support coexistence between WiFi, LTE and Zigbee protocols in 2.4 GHz spectrum,  using a state of the art Software Defined Radio (SDR) platform.

What exactly have you discovered?
The front-end flexibility of SDR platforms can be leveraged to support coexistence of multiple wireless protocols. It is possible to detect multiple protocols with a single RF front-end by using a specially designed, matched filter at the receiver, enabling spectral reuse in the same frequency band. We achieve this by resampling the matched filter coefficients of WiFi and Zigbee to a common sampling frequency which in our case is the LTE’s sampling frequency of 30.72 MHz.

The advantage of this method is that all protocols can be received and detected at a common sampling frequency regardless of their original sampling frequency. Subsequent processing such as demodulation and channel estimation are carried out based on the type of signal detected.

So what?
Using a single RF front-end for multiple wireless protocol detection eliminates the front-end complexity associated with continuous resampling of a signal. Such a method allows simplified receivers and spectral reuse which are major considerations in communication system design. The result is a testbench that can be used by others.  We are pursuing joint projects with Maynooth University that build on this research.

For more information, please contact me at ece.neu.edu

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Title: Enhanced thermoelectric properties of electrodeposited Cu-doped Te films
Authors: Swatchith Lal, Kafil M. Razeeb, Devendraprakash Gautam
Journal: ACS Applied Energy Materials

What is this paper about?
This paper introduces a new thermoelectric material, which can be used in micro-thermoelectric generators to efficiently convert waste heat into useful electricity. The electricity generated can be used to power sensors eliminating the use of batteries.

This paper reports the highest-ever reported power factor of a thin-film thermoelectric material prepared using electrodeposition. This material could be used in the mass production of micro thermoelectric devices that could generate high power outputs with a minimal footprint.

What exactly have you discovered?
We have discovered a better thermoelectric material capable of outperforming other thermoelectric materials when utilized at near room temperatures.

The material is synthesized using electrodeposition, which is one of the cost-effective techniques, thus lowering the overall cost of the devices.

When a certain percentage of copper is co-deposited along with tellurium to form coper telluride thin films, we observed the crystalline to the amorphous phase transition of the material resulting in enhanced thermoelectric properties of the material.

So what?
These results demonstrate that the electrodeposited copper telluride can be the new potential room-temperature thermoelectric material for micro-thermoelectric devices (both as a power generator and cooler for thermal management). These devices can be applied to convert any waste heat into useful electrical energy with ranges anywhere from industrial heat to human-body heat. This means that in future we can generate electricity using our own body heat and power different biomedical wireless sensors, which could be used to monitor our health to pave the way of future IoT devices.

Read the paper here (pdf).

For more information, please contact kafil.mahmood at tyndall.ie

CONNECT is the world leading Science Foundation Ireland Research Centre for Future Networks and Communications. CONNECT is funded under the Science Foundation Ireland Research Centres Programme and is co-funded under the European Regional Development Fund. We engage with over 35 companies including large multinationals, SMEs and start-ups. CONNECT brings together world-class expertise from ten Irish academic institutes to create a one-stop-shop for telecommunications research, development and innovation.


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