A solar-blind multi-quantum well (MQW) structure wafer based on AlGaN materials is epitaxial growth by metal-organic chemical vapor deposition (MOCVD). The monolithically integrated photonic chips including light-emitting diodes (LEDs), waveguides, and photodetectors (PDs) are presented. The results of the finite-difference time-domain (FDTD) simulation confirm the strong light constraint of the waveguide designed with the triangular structure in the optical coupling region. Furthermore, in virtue of predominant ultraviolet transverse magnetic (TM) modes, the solar blind optical signal is more conducive to lateral transmission along the waveguide inside the integrated chip. The integrated PDs demonstrate sufficient photosensitivity to the optical signal from the integrated LEDs. When the LEDs are operated at 100 mA current, the photo-to-dark current ratio (PDCR) of the integrated PD is about seven orders of magnitude. The responsivity, specific detectivity, and external quantum efficiency of the integrated self-driven PD are 74.89 A/W, 4.22×10¹³ Jones, and 3.38×10⁴%, respectively. The stable on-chip optical information transmission capability of the monolithically integrated photonic chips confirms the great potential for application in large-scale on-chip optical communication in the future.

The exponential growth of using wireless devices in recent years has motivated the exploration of the millimeter-wave (mmWave) frequency spectrum for multi-gigabit wireless communications. Recent advances in antenna technology, radio-frequency complementary metal-oxide semi-conductor (RF CMOS) process and high-speed baseband signal processing algorithms have promised the feasibility of millimeter-wave wireless communications. The multi-gigabit-per-second data rate of millimeter-wave wireless communication systems is leading to applications in many important scenarios, such as wireless personal area networks (WPAN), wireless personal area networks (WLAN), back-haul for cellular systems. The frequency bands include 28 GHz, 38 GHz, 45 GHz, 60 GHz, E-BAND, and even beyond 100 GHz.

The special issue aims to present some major achievements of the research and development in multi-gigabit millimeter-wave wireless communications. It includes four technical contributions from leading researchers in mmWave communications. The first paper entitled “Substrate-Integrated Waveguide-Based Monopulse Slot Antenna Arrays for 60 GHz Applications”, co-authored by ZHU, XUE and LIAO, presents the substrate-integrated waveguide (SIW)-based monopulse slot antenna arrays for the application of 60 GHz monopulse tracking systems. The second paper entitled “Millimeter Wave and THz Propagation Channel Modeling for High-Data Rate Railway Connectivity — Status and Open Challenges” is co-authored by Kürner, GUAN, Molisch, AI, HE, LI, TIAN, DOU and ZHONG. In this paper, the authors provide elementary discussions on bandwidth requirements of high-data rate railway connectivity, and highlight the open challenges in terms of wave propagation, static channel, and dynamic channel.

Co-authored by XU, MENG, MA and YEO, the third paper entitled “State of the Art in Passive Bandpass Filter Solutions for 60-GHz Communications”, reviews the state-of-the-art filter designs for 60-GHz applications. Design methodology, design technology, key performance parameters, similarities and differences, advantages and drawbacks, and future trends are explored and studied. The last (but not least) paper “Low-Power High-Efficiency Multi-Gigabit 60 GHz Transceiver Systems Routing in Vehicular Environments” is co-authored by Byeon and Park. It proposes low-power high-efficiency multi-gigabit 60 GHz transceiver systems for short-range communications. The antenna-in-package module with the transceiver demonstrates mobile-to-display 1080p Full-HD video transmission over a distance of 60 cm.

We would like to thank all the authors for choosing this special issue to publish their new research results and insights, all the reviewers for their valuable review comments which help to improve the technical quality and presentation of this special issue, and the editorial official of ZTE Communications for all the support and help during the editorial process of this special issue. We are sure this special issue will again be quite informative and a pleasure for you to browse through and read in depth.

Managing largescale complex network infrastructures is challenging due to the huge number of heterogeneous network elements. The goal of this survey is to provide an overview of event mining techniques applied in the network management domain. Event mining includes a series of techniques for automatically and effectively discovering valuable knowledge from historical event/log data. We present three research challenges (i.e., event generation, root cause analysis, and failure prediction) for event mining in network management and introduce the corresponding solutions. Event generation (i.e., converting messages in log files into structured events) is the first step in many event mining applications. Automatic root cause analysis can locate the faulty elements/components without the help of experienced domain experts. Failure prediction in proactive fault management improves network reliability. The representative studies to address the three aforementioned challenges are reviewed and their main ideas are summarized in the survey. In addition, our survey shows that using event mining techniques can improve the network management efficiency and reduce the management cost.

The convergence of communication services becomes a focus in the industry along with the requirement for full-service operation and technical development. Service convergence includes two aspects: The convergence of the fixed and mobile networks; and the convergence of traditional communications and Internet services. This requires balancing the conflicts between the openness and operationability of terminal capability and network convergence. Unified authentication and authorization are the basis for service convergence in terms of operationability. Modular network and open terminal are technical solutions for the service convergence.

According to the basic functions and objectives of Cognitive Radio (CR ) systems, the cognition-based adaptive control mechanism is the generalization of the research contents and approaches of cognitive radio systems. Therefore, the mechanism is described by a cognition loop, which contains the following parts: environment, inner structure of intelligent systems, observation and action.