The 5th wireless communication (5G) techniques not only fulfil the requirement of 1, 000 times increase of internet traffic in the next decade, but also offer the underlying technologies to the entire industry and ecology for internet of everything. Compared to the existing mobile communication techniques, 5G techniques are more-widely applicable and the corresponding system design is more complicated. The resurgence of artificial intelligence (AI) techniques offers as an alternative option, which is possibly superior over traditional ideas and performance. Typical and potential research directions to which AI can make promising contributions need to be identified, evaluated, and investigated. To this end, this overview paper first combs through several promising research directions of AI for 5G, based on the understanding of the 5G key techniques. Also, the paper devotes itself in providing design paradigms including 5G network optimization, optimal resource allocation, 5G physical layer unified acceleration, end-to-end physical layer joint optimization, and so on.The 5G technology standards are in development, getting complete and mature [2,3]. In December 2017, 3G Partnership Project (3GPP) officially announced the new standards for 5G New Radio (NR) which include supports for 5G Non-Standalone architecture (NSA) and eMBB [4]. On June 14, 2018, 3GPP formally completed the Standalone (SA) version of the 5G NR standard, marking a long-awaited target date for 5G standardization [5]. These announced standards effectively set the stage to launch full-scale and cost-effective development of 5G networks. Compared to the current 4G networks, 5G NR: (1) enhances the MIMO systems with the massive MIMO technology; (2) makes completion to the time slot structure and resource block (RB) allocation of the orthogonal frequency-division multiplexing (OFDM), proposing a more flexible air interface; (3) will introduce the non-orthogonal multiple access (NOMA) to support the Internet of Things (IoT) in the near future; (4) follows the previous distributed antenna systems [6], splits the wireless functions into distributed units (DU) and central units (CU) and applies network virtualization and network slicing techniques based on cloud computing.Overall, 5G networks will tailor the provisioning mechanisms for more applications and services, hence is more challenging with the complicated configuration issues and evolving service requirements. Before 5G, researches of communication systems mainly aim at satisfactory data transmission rate and supportive mobility management. In the 5G era, the communication systems will gain the abilities to interact with the environment, and the targets are expanded to joint optimizations of ever-increasing numbers of key performance indicators (KPIs) including latency, reliability, connection density, user experience, etc [7]. Meanwhile, new features like the dynamic air interface, virtualised network and network slicing introduce complicated system design and optimization requirements as long as ...
Recently, the desired very high throughput of 5G wireless networks drives millimeter-wave (mm-wave) communication into practical applications. A phased array technique is required to increase the effective antenna aperture at mm-wave frequency. Integrated solutions of beamforming/beam steering are extremely attractive for practical implementations. After a discussion on the basic principles of radio beam steering, we review and explore the recent advanced integration techniques of silicon-based electronic integrated circuits (EICs), photonic integrated circuits (PICs), and antenna-on-chip (AoC). For EIC, the latest advanced designs of on-chip true time delay (TTD) are explored. Even with such advances, the fundamental loss of a silicon-based EIC still exists, which can be solved by advanced PIC solutions with ultra-broad bandwidth and low loss. Advanced PIC designs for mm-wave beam steering are then reviewed with emphasis on an optical TTD. Different from the mature silicon-based EIC, the photonic integration technology for PIC is still under development. In this paper, we review and explore the potential photonic integration platforms and discuss how a monolithic integration based on photonic membranes fits the photonic mm-wave beam steering application, especially for the ease of EIC and PIC integration on a single chip. To combine EIC, for its accurate and mature fabrication techniques, with PIC, for its ultra-broad bandwidth and low loss, a hierarchical mm-wave beam steering chip with large-array Manuscript delays realized in PIC and sub-array delays realized in EIC can be a future-proof solution. Moreover, the antenna units can be further integrated on such a chip using AoC techniques. Among the mentioned techniques, the integration trends on device and system levels are discussed extensively.Index Terms-5G, millimeter-wave, beam steering, true-timedelay, phase shifter, antenna-on-chip, photonic radio beam steering, broadband beamforming, phase control units. 0018-9197
Traffic accidents are often related to the driver’s driving behavior, which is mainly decided by his or her characters. In order to explore the correlation of traffic accident risk with driver characters, the age, driving experience, and driving style were statistically analyzed based on the China In-Depth Accident Study (CIDAS) database. Taking the number of casualties in the accident as evaluation indicators, the grey cluster analysis was used to classify the drivers into four accident risk ranks: low, medium to low, medium to high, and high. The results show that drivers aged 18–30 years are more likely to induce accidents; drivers with 6–10 years of driving experience have the highest risk to accidents, followed by drivers with 4-5 years of driving experience; and the driving style is also highly correlated with accident risk tendency.
We report mid-infrared Ge-on-Si waveguide based PIN diode modulators operating at wavelengths of 3.8 μm and 8 μm. Fabricated 1 mm-long electro-absorption devices exhibit a modulation depth of >35 dB with a 7 V forward bias at 3.8 μm, and a similar 1 mm-long Mach-Zehnder modulator has a V π •L of 0.47 V•cm. Driven by a 2.5 V pp RF signal, 60 MHz On-Off Keying modulation was demonstrated. Electro-absorption modulation at 8 μm was demonstrated preliminarily, with the device performance limited by large contact separation and high contact resistance.
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