Ring-VCO (Voltage controlled oscillator)-based ADCs are suitable for the data acquisition in embedded sensors which are at the core of AI enabled IoT (Internet of Things) devices. Fundamentally, the ring-VCO can generate digital code by counting frequency from its voltage-controlled oscillation. However, the ring-VCO has some issues related to non-linearity and power dissipation due to the voltage-to-frequency (V-to-F) tuning characteristics. Particularly, for low power operation with low voltage supply, the linearity further degrades. This paper presents a complementary bias voltage control approach to attain a linear V-to-F characteristics with low-power dissipation. The novel voltage-to-current (V-to-I) conversion provides the linear bias current source and sink matching for current-starved inverter-based delay elements. Furthermore, the proposed circuit can be extended to optimize nonlinearity error by selecting an optimal transistor size. Simulation results with a 0.5V power supply circuit designed in TSMC 180nm CMOS technology shows that maximum nonlinearity error is below 0.24% for 4-stage and below 0.49% for 8-stage ring-VCO.

The derivation of the 7-point Winograd fast Fourier transform (FFT) requires complex steps such as using the Rader prime algorithm to turn an N-point discrete Fourier transform (DFT) into an (N − 1)-point convolution and then using the Chinese remainder theorem for polynomials to find the set of remainders. In this paper, we describe a simpler method for deriving the 7-point Winograd FFT using the diagonalized identical equations of 3 by 3 circulant and quasi-circulant matrices. These diagonalized identical equations of 3 by 3 matrices are not found in the literature and are newly derived.

This paper proposes a caching data protection scheme that uses blockchains and hashchains for unmanned aerial vehicle (UAV)-assisted information-centric wireless sensor networks in smart-city applications as a case study. In the consensus scheme of the proposed scheme, a new block is verified according to voting by validators without exhaustive mining computations. Therefore, the proposed scheme is suitable for resource-limited wireless and mobile devices. With the scheme, UAVs work as validators as well as data collectors, and the overhead of transaction-fee management can be eliminated. Validators are responsible for block verifications; thus, the proposed scheme maintains the consensus by detecting and removing validators that vote incorrectly by using hashchain-based signatures. Simulations were conducted to evaluate the proposed scheme, and the results revealed the requirements for implementing it in smart-city applications and its robustness, feasibility, and effectiveness.

In this session, we explain that Heaviside reformulated the Maxwell equations and showed by the vector analysis method that the direction of a flow of power of electromagnetic waves is given by the Poynting vector. Therefore, it was shown that the direction of the flow is perpendicular to the electric and magnetic flux lines. Namely, the direction of the interaction of electromagnetic waves is different from and perpendicular to the directions of the flux lines. Therefore, we examine the arrangement of the electric and magnetic fields of electromagnetic waves. As a result, it is shown that the arrangement of the electric and magnetic fields that form in coaxial transmission lines is highly effective for the transfer and work of electromagnetic waves.