As an integral part of V2G networks, EVs receive electricity from not only the grid but also other EVs and may frequently feed the power back to the grid. Payment records in V2G networks are useful for extracting user behaviors and facilitating decision-making for optimized power supply, scheduling, pricing, and consumption. Sharing payment and user information, however, raises serious privacy concerns in addition to the existing challenge of secure and reliable transaction processing. In this article, we propose a blockchain-based privacy preserving payment mechanism for V2G networks, which enables data sharing while securing sensitive user information. The mechanism introduces a registration and data maintenance process that is based on a blockchain technique, which ensures the anonymity of user payment data while enabling payment auditing by privileged users. Our design is implemented based on Hyperledger to carefully evaluate its feasibility and effectiveness.

A Blockchain-Based Privacy-Preserving Payment Mechanism for Vehicle-to-Grid Networks

Synthetic aperture is a method used to improve radar resolution in azimuth or in the direction of the velocity vector of platform. This resolution is comparable with the one that is obtained by a very large physical antenna. This chapter focuses on the optimal aspect of the synthetic aperture processing and its uses in air-borne and space-borne imaging radar applications. The synthetic aperture effect is obtained by displacement of the platform or target. Focused synthetic aperture processing takes into account the variation of target angular position with radar velocity during illumination. The received signal is expressed in relation to the transmitted signal and target range. Unfocused synthetic aperture processing is performed by a simple spectral analysis that is matched to targets located at infinity. The processing of unfocused synthetic aperture is optimum when illumination time is very short. If the illumination time is sufficiently long, the received signal is linearly frequency modulated. Target illumination time depends on antenna aperture, platform velocity, and the distance between the radar and the target. A pulse waveform of low repetition frequency is generally used in synthetic aperture radar (SAR). The time and Doppler ambiguities are related to the value of the repetition period.

15 – synthetic aperture radar

While millimeter-wave (mm-wave) communication can provide abundant spectrum and support high data rate for future 5G systems, its coverage capability in urban environments is a critical issue due to the severe penetration loss. In this letter, we propose a simple scheme to enhance the coverage area of a cell centered with an mm-wave base station. This key idea is to employ multiple passive-reflectors to reflect the mm-wave to the non-line-of-sight (NLOS) regions with low received power levels. In order to improve the received power, a design method for the passive-reflector is discussed intensively. Numerical experiment for an outdoor urban environment is presented. The numerical results show that, with the proposed scheme, the coverage radius of an mm-wave cell can be remarkably increased. This indicates that our scheme is an attractive option to alleviate the mm-wave coverage problem for future 5G systems.

An Effective Coverage Scheme With Passive-Reflectors for Urban Millimeter-Wave Communication

This paper investigates the utilization of satellite broadcast signals such as DVB-S and DVB-S2 as illuminator of opportunity for passive radar imaging techniques like SAR or ISAR. It includes an analysis of the key elements of the structure of the DVB-S2 signal and their implications for SAR/ISAR signal processing, with particular emphasis on the interference properties due to the presence of multiple illuminating satellites. Moreover, first real world DVB-S based radar images are presented using a newly developed passive radar system.

Passive radar imaging using DVB-S2

Sparse recovery techniques find applications in many areas. Real-time implementation of such techniques has been recently an important area for research. In this paper, we propose computationally efficient techniques based on dichotomous coordinate descent (DCD) iterations for recovery of sparse complex-valued signals. We first consider $\ell _{2} \ell _{1}$ optimization that can incorporate a priori information on the solution in the form of a weight vector. We propose a DCD-based algorithm for $\ell _{2} \ell _{1}$ optimization with a fixed $\ell _{1}$ regularization, and then efficiently incorporate it in reweighting iterations using a warm start at each iteration. We then exploit homotopy by sampling the regularization parameter and arrive at an algorithm that, in each homotopy iteration, performs the $\ell _{2} \ell _{1}$ optimization on the current support with a fixed regularization parameter and then updates the support by adding/removing elements. We propose efficient rules for adding and removing the elements. The performance of the homotopy algorithm is further improved with the reweighting. We then propose an algorithm for $\ell _{2} \ell _{0}$ optimization that exploits homotopy for the $\ell _{0}$ regularization; it alternates between the least-squares (LSs) optimization on the support and the support update, for which we also propose an efficient rule. The algorithm complexity is reduced when DCD iterations with a warm start are used for the LS optimization, and, as most of the DCD operations are additions and bit-shifts, it is especially suited to real-time implementation. The proposed algorithms are investigated in channel estimation scenarios and compared with known sparse recovery techniques, such as the matching pursuit (MP) and YALL1 algorithms. The numerical examples show that the proposed techniques achieve a mean-squared error smaller than that of the YALL1 algorithm and complexity comparable to that of the MP algorithm.

Low-Complexity DCD-Based Sparse Recovery Algorithms

In passive radar which exploits opportunity source as the illuminator, the presence of direct signal and clutter echoes in surveillance channel is demonstrated strongly affecting the detection performance. In this paper, based on the well-known CLEAN approach which iteratively removes strong signal and detects targets, an effective CLEAN algorithm is derived for interference cancellation. The new technique adopts the method of orthogonal subspace projection and is more robust even under the following cases: (i) The arrival time of interference signals may be fractional sampling interval after sampling; (ii) The Doppler-delay estimation of interference may be inaccuracy; (iii) The echoes from continuous scattering targets may be Dopplerdelay spread. The approach is shown to be effective through simulation results which considers digital video broadcasting satellites (DVB-S) as the illuminator.

An effective CLEAN algorithm for interference cancellation and weak target detection in passive radar

This paper presents a study to demonstrate the feasibility of using digital video broadcasting-satellite (DVB-S) signal for passive radar The study concentrates on the analysis of DVB-S signal properties, mainly including its spectrum, resolution capability, ambiguity function, and analysis of direct path signal-to-noise ratio (SNR) Since DVB-S signal has a higher range resolution due to its wide bandwidth and wider coverage area, it turns out to be more competitive than other passive radar signals Finally, results based on field measurements provide some useful references about the performance and potential capability of using DVB-S signal for passive radar applications

Analysis of the properties of DVB-S signal for passive radar application

Electric vehicle is the automobile that powered by electrical energy stored in batteries. Due to the frequent recharging, vehicles need to be connected to the recharging infrastructure while they are parked. This may disclose drivers’ privacy, such as their location that drivers may want to keep secret. In this paper, we propose a scheme to enhance the privacy of the drivers using anonymous credential technique and Trusted Platform Module(TPM). We use anonymous credential technique to achieve the anonymity of vehicles such that drivers can anonymously and unlinkably recharge their vehicles. We add some attributes to the credential such as the type of the battery in the vehicle in case that the prices of different batteries are different. We use TPM to omit a blacklist such that the company that offer the recharging service(Energy Provider Company, EPC) does not need to conduct a double spending detection.

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An anonymous payment system to protect the privacy of electric vehicles

This paper investigates the passive radar detection system which exploits advanced broadcasting system-satellite (ABS-S) as opportunity illuminator Firstly, the signal model is established and our ABS-S passive radar system architecture is presented Then a low complexity and efficient cancellation method named a batch version of sequential cancellation algorithm (SCA-B) is proposed in signal processing scheme, in order to reduce the computational burden of direct path interference (DPI) suppression caused by a long integration time which can be used to solve the problem of low target echo signal-to-noise ratio (SNR) of passive radar Finally, the results of the detection of typical buildings using ABS-S passive radar both confirm the effectiveness of the proposed DPI suppression method and the feasibility of passive detection using ABS-S signal

Passive radar detection based on advanced broadcasting system-satellite

Passive radars using illuminators of opportunity have attracted much attention in recent years. This paper presents a study to demonstrate the feasibility of using Advanced Broadcasting System-Satellite (ABS-S) signals for passive radar. The study includes system link budget, the design and implementation of an ABS-S based passive radar demonstrator, and the field measurements. The measurement results have proven the feasibility of the ABS-S based passive radar systems for target detection.

Chang Chen

Papers

An effective CLEAN algorithm for interference cancellation and weak target detection in passive radar

Analysis of the properties of DVB-S signal for passive radar application

An anonymous payment system to protect the privacy of electric vehicles

Passive radar detection based on advanced broadcasting system-satellite

Design and implementation of an experimental ABS-S based passive radar