A Highly Secure IoT Firmware Update Mechanism Using Blockchain

Internet of Things (IoT) device security is one of the crucial topics in the field of information security. IoT devices are often protected securely through firmware update. Traditional update methods have their shortcomings, such as bandwidth limitation and being attackers’ easy targets. Although many scholars proposed a variety of methods that are based on the blockchain technology to update the firmware, there are still demerits existing in their schemes, including large storage space and centralized stored firmware. In summary, this research proposes a highly secure and efficient protection mechanism that is based on the blockchain technology to improve the above disadvantages. Therefore, this study can reduce the need of storage space and improve system security. The proposed system has good performance in some events, including firmware integrity, security of IoT device connection, system security, and device anonymity. Furthermore, we confirm the high security and practical feasibility of the proposed system by comparing with the existing methods.

Integrated Photonics Based High Speed Arbitrary Waveform Generation

High speed arbitrary waveform generator enabled by photonic digital to analog converter where the bandwidth limitation arising due to interconnect and device parasitics in its electronic counterparts is circumvented. Leveraging the silicon photonic integration technology for this purpose provides a potential high resolution, high bandwidth, and energy efficient solution for signal transmitters.

Integrated Photonics Based High Speed Arbitrary Waveform Generation

High speed arbitrary waveform generator enabled by photonic digital to analog converter where the bandwidth limitation arising due to interconnect and device parasitics in its electronic counterparts is circumvented. Leveraging the silicon photonic integration technology for this purpose provides a potential high resolution, high bandwidth, and energy efficient solution for signal transmitters.

Actively Controlled Frequency-Agile Fano-Resonant Metasurface for Broadband and Unity Modulation

The active control to the local resonant mode of metasurface is a promising route for improving the operation bandwidth limitation of metasurface. Here, we propose and experimentally demonstrated the active tunabilities in a frequency-agile Fano-resonant metasurface. The metasurface with a pair of asymmetric split ring resonators is integrated with double varactor diodes for active control of the sharp Fano resonance. It is found that the sharp Fano-type spectrum appears due to the near-field interferences between the collective electric and magnetic dipole modes. The physical insight is revealed through local field analysis, multipole decomposition and temporal coupled-mode theory. It is also found that the metasurface can be employed as a broadband and unity modulator. Hopefully, our results could inspire sophisticated electrically controlled photonic devices with novel functions.

Analysis of Distributed Wireless Sensor Systems with a Switched Quantizer

In this article, a switched quantizer is proposed to solve the bandwidth limitation application problem for distributed wireless sensor networks (WSNs). The proposed estimator based on switched quantitative event-triggered Kalman consensus filtering (KCF) algorithm is used to monitor the aircraft cabin environmental parameters when suffering packet loss and path loss issues during the communication process for WSN. The quantization error of the novel switched quantizer structure is bounded, and the corresponding stability theory for the quantitative estimation approach is proved. Compared with other methods, the simulation results for the introduced method verify that the environmental parameters can be estimated accurately and timely and reduce the burden of network communication bandwidth.

Transcending the gain bandwidth limitation in semiconductors for full-colour-tunable lasers

Developing semiconductors with wide tunable gain bandwidth have always been at the forefront of laser technologies. The variation in feedback resonators can provide a useful tool for producing a relatively wide range of discrete lasing wavelengths. However, the lasing wavelength range is limited by the fundamental gain bandwidth of the single semiconductor itself. Full-colour range lasing through gain bandwidth tuning remains a daunting challenge. Here we demonstrate the feasibility of dynamically tuning amplification/lasing wavelengths in the entire emission spectrum by leveraging on Förster resonance energy transfer (FRET)-assisted guest-host blends. The unprecedented tunability in amplification and lasing is governed by energy transfer process, which enables us to achieve wavelength-tunable semiconductor lasers spanning the full visible region of the electromagnetic spectrum. Our distributed feedback lasers cover almost all CIE colour gamut (94%), which is 170% more perceptible colours than standard Red Green Blue colour space. These insights can guide the versatile and convenient design of semiconductor materials transcending current gain bandwidth limitation, paving the way for next generation of optoelectronic devices.

QUIC transmission protocol: Test-bed design, implementation and experimental evaluation

With the ever increasing demand for higher speed internet connectivity that can fulfil the application continuous need for higher bandwidth Google being the pioneer in many web-based services has launched a new UDP-based protocol named quick UDP internet connections (QUIC), which aims at providing faster data delivery without requiring upgrades or modifications to the network infrastructure. The goal of this paper is to provide an overview about QUIC protocol, propose the design and implementation of a test-bed, that is used experimentally to evaluate QUIC protocol under different network conditions and scenarios. In particular, the performance advantage of QUIC in terms of delay and throughput are examined taking into account different network conditions that resemble the real internet environment. Two scenarios are proposed, the first one investigates the protocol performance under a controlled network environment, while the second one tests the protocol in a real uncontrolled network. To achieve that, a test-bed is proposed and implemented that emulates the network impairments encountered in real-network such as packet loss, bit errors, and bandwidth limitation in a controlled manner. After that, QUIC is tested in real operational wired and wireless networks. In both scenarios, QUIC outperforms TCP in terms of delay, which strengthens QUIC position for being a potential alternative to TCP.