Device-to-Device (D2D) communication has emerged as a promising technology for optimizing spectral efficiency in future cellular networks. D2D takes advantage of the proximity of communicating devices for efficient utilization of available resources, improving data rates, reducing latency, and increasing system capacity. The research community is actively investigating the D2D paradigm to realize its full potential and enable its smooth integration into the future cellular system architecture. Existing surveys on this paradigm largely focus on interference and resource management. We review recently proposed solutions in over explored and under explored areas in D2D. These solutions include protocols, algorithms, and architectures in D2D. Furthermore, we provide new insights on open issues in these areas. Finally, we discuss potential future research directions.

A Survey of Device-to-Device Communications: Research Issues and Challenges

With the development of wireless communication technology, the need for bandwidth is increasing continuously, and the growing need makes wireless spectrum resources more and more scarce. Cognitive radio (CR) has been identified as a promising solution for the spectrum scarcity, and its core idea is the dynamic spectrum access. It can dynamically utilize the idle spectrum without affecting the rights of primary users, so that multiple services or users can share a part of the spectrum, thus achieving the goal of avoiding the high cost of spectrum resetting and improving the utilization of spectrum resources. In order to meet the critical requirements of the fifth generation (5G) mobile network, especially the Wider-Coverage , Massive-Capacity , Massive-Connectivity , and Low-Latency four application scenarios, the spectrum range used in 5G will be further expanded into the full spectrum era, possibly from 1 GHz to 100 GHz. In this paper, we conduct a comprehensive survey of CR technology and focus on the current significant research progress in the full spectrum sharing towards the four scenarios. In addition, the key enabling technologies that may be closely related to the study of 5G in the near future are presented in terms of full-duplex spectrum sensing, spectrum-database based spectrum sensing, auction based spectrum allocation, carrier aggregation based spectrum access. Subsequently, other issues that play a positive role for the development research and practical application of CR, such as common control channel, energy harvesting, non-orthogonal multiple access, and CR based aeronautical communication are discussed. The comprehensive overview provided by this survey is expected to help researchers develop CR technology in the field of 5G further.

Full Spectrum Sharing in Cognitive Radio Networks Toward 5G: A Survey

Probabilistic Graphical Models

Smart metering systems generally referred to as the next-generation power measurement system, is considered as a revolutionary and evolutionary regime of existing power grids. More importantly, with integration of advanced computing and communication technologies, the smart meter (SM) is expected to greatly enhance efficiency and reliability of future power systems with renewable energy resources, as well as distributed intelligence and demand response. Different electrical energy metering standards are point of concern for power/energy measurements. As measurement standards are formed, systems built around them can become interoperable from a standards point of view but still have incompatible configurations or different maturity levels, or include non-standardized functions. Even in areas that are standardized, there are sometimes implementation decisions that can result in different measurement and security behavior. With this paper we make three contributions: firstly, we identify various 1-channel and 3-channel metrology integrated circuits (ICs), which are mandatory for the standard measurement of distributed and renewable electricity generation. Secondly, we describe harmonics effect on metrology, which impacts on reliability of widespread smart metering infrastructure. Finally, we develop and describe a comprehensive set of security issues for SMs. Specifically, we focus on reviewing and discussing smart metrology meter (SMM) applications (i.e. metrological functions and real-time monitoring functions), security requirements, network vulnerabilities, attack countermeasures, secure communication protocols required in smart grid (SG) architectures. This review will enable the researchers, public policy makers and stakeholders to open the mind to explore possible in an evolving energy domain as well as beyond this area.

Performance analysis of smart metering for smart grid: An overview

The 5th-generation mobile communication system (5G) has higher security requirements than previous systems. Accordingly, international standard organizations, operators, and equipment manufacturers are focusing extensively on 5G security technology. This paper analyzes the security requirements of 5G business applications, network architecture, the air interface, and user privacy. The development trends of 5G security architecture are summarized, with a focus on endogenous defense architecture, which represents a new trend in 5G security development. Several incremental 5G security technologies are reviewed, including physical layer security, lightweight encryption, network slice security, user privacy protection, and block chain technology applied to 5G.

Overview of 5G security technology

The study introduces the novel message authentication schemes for the smart meter system, where the symmetric cryptography-based physical layer-assisted message authentication (PLAA) scheme and the public key infrastructure- based PLAA scheme are introduced. The proposed schemes integrate the conventional message authentication schemes and the physical layer authentication mechanisms by taking advantage of temporal and spatial uniqueness in physical layer channel responses, aiming to achieve fast authentication while minimising the packet transmission overhead. The authors also verify their claims through extensive analysis and simulation via comparing with proposed PLAA scheme with traditional upper layer authentication schemes. The proposed novel schemes yield the lower time delay for authenticating each message, which can satisfy the requirement of the real-time control over the smart grid.

Physical layer assist authentication technique for smart meter system

Cognitive radio is one of the enabling technologies considered for the next generation communication systems for many mission-critical applications. In cognitive radio systems, cooperative spectrum sensing is one of the key techniques that can improve reliability and agility. In this paper, a framework that integrates quickest detection and belief propagation is applied to the cooperative spectrum sensing, where the primary user activities are heterogeneous in the space and dynamic in the time. The performance of the proposed scheme is analyzed mathematically. Using numerical simulations, detection performance measured by false alarm rate and average detection delay is obtained for different setups. The results show that the proposed scheme achieves better receiver operational curves than traditional detection method.

Belief Propagation and Quickest Detection-Based Cooperative Spectrum Sensing in Heterogeneous and Dynamic Environments

Cognitive radio is one of the enabling technologies considered for the next generation communications systems for many mission-critical applications, such as in the Joint Tactical Radio System (JTRS) program and the DARPA xG program. In cognitive radio systems, cooperative spectrum sensing is one of the key techniques that can improve the reliability and agility. In this study, a framework integrating quickest detection with belief propagation (BP) is applied to the scenario of temporally and spatially varying primary user activities. Using numerical simulations, system performance measured by false alarm (FA) rate, missed detection (MD) rate and average detection delay is obtained for different setups. The results show that the proposed scheme achieves better detection error rate and detection delay tradeoff.

Belief Propagation Based Spectrum Sensing Subject to Dynamic Primary User Activities: Phantom of Quickest Detection

LT codes are designed for the purpose of scalable and fault-tolerant distribution of data over wireless networks. This paper introduces the four design methods of LT codes degree distribution. Analyzing and comparison results of the short and long of LT code performance under the different channel probability are given, which show that in the case of large delete the probability, the original data packets can be recovered with high probability as long as the decoder receives a sufficient number of packets. The results of this paper will reference for system choose a different LT code parameters.

The Performance Analysis of LT Codes

In modern cognitive ratio systems, the spectrum is becoming increasingly crowded and expensive; thus spectrum sensing becomes more important than ever before. Traditional spectrum sensing assumes Gaussian noise (or of other given distributions) in general. However when secondary users (SUs) have no prior information about the measurement distributions, the spectrum sensing schemes assuming given distribution forms (even if the parameters are assumed to be unknown) no longer apply. In this paper we propose a universal quickest change detection scheme based on density ratio estimation for spectrum sensing by detecting the sudden change of spectrum (e.g., the emergence of primary user), where neither the pre- change nor post-change distribution (even the distribution forms) is known to SUs, thus achieving robustness to complex spectrum environment.

Yifan Wang

Papers

Physical layer assist authentication technique for smart meter system

Belief Propagation and Quickest Detection-Based Cooperative Spectrum Sensing in Heterogeneous and Dynamic Environments

Belief Propagation Based Spectrum Sensing Subject to Dynamic Primary User Activities: Phantom of Quickest Detection

The Performance Analysis of LT Codes

Universal Quickest Spectrum Sensing