Dr Justin Lipman is an Industry Associate Professor at the University of Technology Sydney and Director of the RF Communications Technologies (RFCT) Lab, where he leads industry engagement in RF technologies, Internet of Things, Tactile Internet, Software Defined Communication and Agriculture 4.0. He serves as committee member in Standards Australia contributing to International IoT & Digital Twin standardisation and is a Research Program Lead for the Food Agility Cooperative Research Center. He received his PhD Telecommunications and BE Computer Engineering from the University of Wollongong, Australia in 2003 and 1999 respectively. From 2004 to 2017, Dr. Lipman was based in Shanghai, China and held a number of senior management and technical leadership roles at Intel and Alcatel leading research and innovation, product architecture and IP generation. He is an IEEE Senior Member. His research interests are in all “things” adaptive, connected, distributed and ubiquitous. Address: Sydney, Australia
Ad hoc networks typically require a significant amount of routing and control information to be d... more Ad hoc networks typically require a significant amount of routing and control information to be distributed in a timely and reliable manner throughout the network, particularly in dynamic environments. As traffic levels increase and the network becomes more heavily congested, there is an increased probability that these critical packets are lost, resulting in obsolete control information being used to make important decisions. This would further compound the problem of network congestion and lead to a very rapid loss of connectivity and throughput. Given this, we argue the solutions to these problems should not rely on putting extra bandwidth on a radio interface. Instead, we should exploit the use of multiple radios to ensure the route can be firmly established. In this paper, we propose a multiradio solution which reserves one radio channel exclusively for routing. Our simulation results have demonstrated that using a separate radio for routing protocol would dramatically improve reliability in heavily loaded ad hoc wireless networks, thereby effectively alleviating the impact of network congestion.
Being incident and polarization angle insensitive are crucial characteristics of metamaterial per... more Being incident and polarization angle insensitive are crucial characteristics of metamaterial perfect absorbers due to the variety of incident signals. In the case of incident angles insensitivity, facing transverse electric (TE) and transverse magnetic (TM) waves affect the absorption ratio significantly. In this scientific report, a crescent shape resonator has been introduced that provides over 99% absorption ratio for all polarization angles, as well as 70% and 93% efficiencies for different incident angles up to $$\theta =80^{\circ }$$ θ = 80 ∘ for TE and TM polarized waves, respectively. Moreover, the insensitivity for TE and TM modes can be adjusted due to the semi-symmetric structure. By adjusting the structure parameters, the absorption ratio for TE and TM waves at $$\theta =80^{\circ }$$ θ = 80 ∘ has been increased to 83% and 97%, respectively. This structure has been designed to operate at 5 GHz spectrum to absorb undesired signals generated due to the growing adoption of...
Of collective behaviors in networks of coupled systems, synchronization is of central importance ... more Of collective behaviors in networks of coupled systems, synchronization is of central importance and an extensively studied area. This is due to the fact that it is essential for the proper functioning of a wide variety of natural and engineered systems. Traditionally, uniform coupling strength has been the default choice and the synchronizability measure has been employed for analysis and enhancement of synchronizability. The main drawback of optimizing the synchronizability measure is that it can reach the Pareto frontier but not necessarily a unique point on the Pareto frontier. Additionally, the shortcoming of uniform coupling strength is that it can reach Pareto frontier in specific topologies including edge-transitive graphs. To achieve a unique optimal answer on the Pareto frontier, this paper takes a different approach and addresses the synchronizability in networks of coupled dynamical systems with nonuniform coupling strength and optimizing the synchronizability via maximizing the minimum distance between the nonzero eigenvalues of the Laplacian and the acceptable boundaries for the stability of the system. Furthermore, two solution methods, namely the concave-convex fractional programming and the Semidefinite Programming (SDP) formulations of the problem have been provided. The proposed solution methods have been compared over different topologies and branches of an arbitrary network, where the SDP based approach has shown to be less restricted and more suitable for a wider range of topologies.
Current crowd density estimation technologies that leverage IR depth perception, video and image ... more Current crowd density estimation technologies that leverage IR depth perception, video and image processing or WiFi/BLE-based sniffing and probing have privacy and deployment issues. This paper presents a novel method for non-intrusive crowd density estimation that monitors variation in EM radiation within an environment. The human body's electrical and magnetic characteristics can be correlated with variations in available EM energy. This allows for the determination of the number of people within a room. Simulations conducted using Comsol to analyse and measure electromagnetic energy levels inside a room containing human bodies. Experimental analysis provides validation of the simulation results by showing 0.8 dBm drop on the average level of EM energy per person.
With rapidly growing adoption of wireless technologies, requirements for the design of a miniatur... more With rapidly growing adoption of wireless technologies, requirements for the design of a miniature wideband multi-resonators are increasing. In this study, a compact fractal-based metamaterial structure with lumped resistors is described. The structure of the authors proposed absorber is a combination of Sierpinski curve and Minkowski fractal. The new combination provides larger capacitance and inductance in the system enabling perfect absorption at lower frequencies. The final structure with dimensions of 20 × 20 × 1.6 mm 3 and an air gap of 12.5 mm provides three main resonances at frequencies of 2.1, 5.1, and 12.8 GHz with bandwidth (absorption ratio over 90%) of 840 MHz, 1.05 GHz, and 910 MHz, respectively.
Information dissemination (flooding) forms an integral part of routing protocols, network managem... more Information dissemination (flooding) forms an integral part of routing protocols, network management, service discovery and information collection. Given the broadcast nature of ad hoc network communications, information dissemination provides a challenging problem. In this paper we compare the performance of existing distributed ad hoc network flooding algorithms indentifying stengths and weaknesses inherent in each mechanism. Additionally we propose to apply the Minimum Spanning Tree (MST) algorithm in a distributed manner as the basis of an optimised ad hoc network flooding algorithm called Localised Minimum Spanning Tree Flooding (LMSTFlood). LMSTFlood provides significant reduction in duplicate packet reception, average transmission distance and energy consumed. Thus LMSTFlood limits the broadcast storm problem more effectively than existing optimised flooding mechanisms.
Efficient and scalable information dissemination is important in network management, packet routi... more Efficient and scalable information dissemination is important in network management, packet routing and auto configuration. Given the very nature of a mobile ad hoc network, this information dissemination provides a challenging problem. This paper introduces a new packet flooding mechanism for information dissemination in mobile ad hoc networks. Neighbor Aware Adapative Power (NAAP) flooding, attempts to reduce redundant broadcasts and power consumption during flooding with the aim of minimizing medium contention among neighboring nodes thereby allowing for increased channel utilization. We show that compared to blind flooding and a multipoint relay mechanism, NAAP in a non-mobile environment with increasing node density shows increased performance in the reduction of power consumption and received duplicate packets. At 300 nodes: NAAP consumes 84% less power than blind flooding and 29% less power than multipoint relaying; nodes using NAAP receive 89% less duplicate packets than blind flooding and 43% less duplicate packets than multipoint relaying.
Information dissemination (flooding) forms an integral part of routing protocols, network managem... more Information dissemination (flooding) forms an integral part of routing protocols, network management, service discovery and information collection (sensing). Given the broadcast nature of ad hoc network communications, information dissemination provides a challenging problem. This paper introduces Utility Based Flooding (UBF). UBF is a distributed optimised flooding mechanism for ad hoc networks that unlike existing optimised flooding algorithms is fully resource aware. Resource awareness is achieved by assigning a forwarding utility to neighouring nodes to determining the desirability of a neighbouring node in continuing a flood. UBF is particularly applicable to ad hoc network environments composed of heterogeneous nodes that may have varying characteristics and constraints. In this paper, UBF is compared to existing flooding mechanisms in a constrained environment. Nodes are assigned varying degrees of remaining battery power and user based constraints that limit a nodes benevolence based upon its remaining battery power. We show through simulation that UBF compared to Utility Based Multipoint Relay (UMPR) flooding, Multipoint Relay (MPR) flooding and Blind flooding significantly improves broadcast reachability over successive broadcasts, does not adversely affect performance and extends the lifetime of the network. UBF delivers packets to over 90% of nodes in the network for over 70 successive broadcasts. Blind flooding, UMPR and MPR are only able achieve 42, 39 and 23 successive broadcasts respectively.
Ad hoc networks typically require a significant amount of routing and control information to be d... more Ad hoc networks typically require a significant amount of routing and control information to be distributed in a timely and reliable manner throughout the network, particularly in dynamic environments. As traffic levels increase and the network becomes more heavily congested, there is an increased probability that these critical packets are lost, resulting in obsolete control information being used to make important decisions. This would further compound the problem of network congestion and lead to a very rapid loss of connectivity and throughput. Given this, we argue the solutions to these problems should not rely on putting extra bandwidth on a radio interface. Instead, we should exploit the use of multiple radios to ensure the route can be firmly established. In this paper, we propose a multiradio solution which reserves one radio channel exclusively for routing. Our simulation results have demonstrated that using a separate radio for routing protocol would dramatically improve reliability in heavily loaded ad hoc wireless networks, thereby effectively alleviating the impact of network congestion.
Being incident and polarization angle insensitive are crucial characteristics of metamaterial per... more Being incident and polarization angle insensitive are crucial characteristics of metamaterial perfect absorbers due to the variety of incident signals. In the case of incident angles insensitivity, facing transverse electric (TE) and transverse magnetic (TM) waves affect the absorption ratio significantly. In this scientific report, a crescent shape resonator has been introduced that provides over 99% absorption ratio for all polarization angles, as well as 70% and 93% efficiencies for different incident angles up to $$\theta =80^{\circ }$$ θ = 80 ∘ for TE and TM polarized waves, respectively. Moreover, the insensitivity for TE and TM modes can be adjusted due to the semi-symmetric structure. By adjusting the structure parameters, the absorption ratio for TE and TM waves at $$\theta =80^{\circ }$$ θ = 80 ∘ has been increased to 83% and 97%, respectively. This structure has been designed to operate at 5 GHz spectrum to absorb undesired signals generated due to the growing adoption of...
Of collective behaviors in networks of coupled systems, synchronization is of central importance ... more Of collective behaviors in networks of coupled systems, synchronization is of central importance and an extensively studied area. This is due to the fact that it is essential for the proper functioning of a wide variety of natural and engineered systems. Traditionally, uniform coupling strength has been the default choice and the synchronizability measure has been employed for analysis and enhancement of synchronizability. The main drawback of optimizing the synchronizability measure is that it can reach the Pareto frontier but not necessarily a unique point on the Pareto frontier. Additionally, the shortcoming of uniform coupling strength is that it can reach Pareto frontier in specific topologies including edge-transitive graphs. To achieve a unique optimal answer on the Pareto frontier, this paper takes a different approach and addresses the synchronizability in networks of coupled dynamical systems with nonuniform coupling strength and optimizing the synchronizability via maximizing the minimum distance between the nonzero eigenvalues of the Laplacian and the acceptable boundaries for the stability of the system. Furthermore, two solution methods, namely the concave-convex fractional programming and the Semidefinite Programming (SDP) formulations of the problem have been provided. The proposed solution methods have been compared over different topologies and branches of an arbitrary network, where the SDP based approach has shown to be less restricted and more suitable for a wider range of topologies.
Current crowd density estimation technologies that leverage IR depth perception, video and image ... more Current crowd density estimation technologies that leverage IR depth perception, video and image processing or WiFi/BLE-based sniffing and probing have privacy and deployment issues. This paper presents a novel method for non-intrusive crowd density estimation that monitors variation in EM radiation within an environment. The human body's electrical and magnetic characteristics can be correlated with variations in available EM energy. This allows for the determination of the number of people within a room. Simulations conducted using Comsol to analyse and measure electromagnetic energy levels inside a room containing human bodies. Experimental analysis provides validation of the simulation results by showing 0.8 dBm drop on the average level of EM energy per person.
With rapidly growing adoption of wireless technologies, requirements for the design of a miniatur... more With rapidly growing adoption of wireless technologies, requirements for the design of a miniature wideband multi-resonators are increasing. In this study, a compact fractal-based metamaterial structure with lumped resistors is described. The structure of the authors proposed absorber is a combination of Sierpinski curve and Minkowski fractal. The new combination provides larger capacitance and inductance in the system enabling perfect absorption at lower frequencies. The final structure with dimensions of 20 × 20 × 1.6 mm 3 and an air gap of 12.5 mm provides three main resonances at frequencies of 2.1, 5.1, and 12.8 GHz with bandwidth (absorption ratio over 90%) of 840 MHz, 1.05 GHz, and 910 MHz, respectively.
Information dissemination (flooding) forms an integral part of routing protocols, network managem... more Information dissemination (flooding) forms an integral part of routing protocols, network management, service discovery and information collection. Given the broadcast nature of ad hoc network communications, information dissemination provides a challenging problem. In this paper we compare the performance of existing distributed ad hoc network flooding algorithms indentifying stengths and weaknesses inherent in each mechanism. Additionally we propose to apply the Minimum Spanning Tree (MST) algorithm in a distributed manner as the basis of an optimised ad hoc network flooding algorithm called Localised Minimum Spanning Tree Flooding (LMSTFlood). LMSTFlood provides significant reduction in duplicate packet reception, average transmission distance and energy consumed. Thus LMSTFlood limits the broadcast storm problem more effectively than existing optimised flooding mechanisms.
Efficient and scalable information dissemination is important in network management, packet routi... more Efficient and scalable information dissemination is important in network management, packet routing and auto configuration. Given the very nature of a mobile ad hoc network, this information dissemination provides a challenging problem. This paper introduces a new packet flooding mechanism for information dissemination in mobile ad hoc networks. Neighbor Aware Adapative Power (NAAP) flooding, attempts to reduce redundant broadcasts and power consumption during flooding with the aim of minimizing medium contention among neighboring nodes thereby allowing for increased channel utilization. We show that compared to blind flooding and a multipoint relay mechanism, NAAP in a non-mobile environment with increasing node density shows increased performance in the reduction of power consumption and received duplicate packets. At 300 nodes: NAAP consumes 84% less power than blind flooding and 29% less power than multipoint relaying; nodes using NAAP receive 89% less duplicate packets than blind flooding and 43% less duplicate packets than multipoint relaying.
Information dissemination (flooding) forms an integral part of routing protocols, network managem... more Information dissemination (flooding) forms an integral part of routing protocols, network management, service discovery and information collection (sensing). Given the broadcast nature of ad hoc network communications, information dissemination provides a challenging problem. This paper introduces Utility Based Flooding (UBF). UBF is a distributed optimised flooding mechanism for ad hoc networks that unlike existing optimised flooding algorithms is fully resource aware. Resource awareness is achieved by assigning a forwarding utility to neighouring nodes to determining the desirability of a neighbouring node in continuing a flood. UBF is particularly applicable to ad hoc network environments composed of heterogeneous nodes that may have varying characteristics and constraints. In this paper, UBF is compared to existing flooding mechanisms in a constrained environment. Nodes are assigned varying degrees of remaining battery power and user based constraints that limit a nodes benevolence based upon its remaining battery power. We show through simulation that UBF compared to Utility Based Multipoint Relay (UMPR) flooding, Multipoint Relay (MPR) flooding and Blind flooding significantly improves broadcast reachability over successive broadcasts, does not adversely affect performance and extends the lifetime of the network. UBF delivers packets to over 90% of nodes in the network for over 70 successive broadcasts. Blind flooding, UMPR and MPR are only able achieve 42, 39 and 23 successive broadcasts respectively.
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Papers by Justin Lipman