Chunfeng Cui

Bio: Chunfeng Cui is an academic researcher from China Mobile Research Institute. The author has contributed to research in topics: Virtualization & Cloud computing. The author has an hindex of 5, co-authored 6 publications receiving 379 citations. Previous affiliations of Chunfeng Cui include Beijing University of Posts and Telecommunications.

Recent Progress on C-RAN Centralization and Cloudification

Abstract: This paper presents the latest progress on cloud RAN (C-RAN) in the areas of centralization and virtualization. A C-RAN system centralizes the baseband processing resources into a pool and virtualizes soft base-band units on demand. The major challenges for C-RAN including front-haul and virtualization are analyzed with potential solutions proposed. Extensive field trials verify the viability of various front-haul solutions, including common public radio interface compression, single fiber bidirection and wavelength-division multiplexing. In addition, C-RANs facilitation of coordinated multipoint (CoMP) implementation is demonstrated with 50%-100% uplink CoMP gain observed in field trials. Finally, a test bed is established based on general purpose platform with assisted accelerators. It is demonstrated that this test bed can support multi-RAT, i.e., Time-Division Duplexing Long Term Evolution, Frequency-Division Duplexing Long Term Evolution, and Global System for Mobile Communications efficiently and presents similar performance to traditional systems.

Rethink fronthaul for soft RAN

Abstract: In this article we discuss the design of a new fronthaul interface for future 5G networks. The major shortcomings of current fronthaul solutions are first analyzed, and then a new fronthaul interface called next-generation fronthaul interface (NGFI) is proposed. The design principles for NGFI are presented, including decoupling the fronthaul bandwidth from the number of antennas, decoupling cell and user equipment processing, and focusing on high-performancegain collaborative technologies. NGFI aims to better support key 5G technologies, in particular cloud RAN, network functions virtualization, and large-scale antenna systems. NGFI claims the advantages of reduced bandwidth as well as improved transmission efficiency by exploiting the tidal wave effect on mobile network traffic. The transmission of NGFI is based on Ethernet to enjoy the benefits of flexibility and reliability. The major impact, challenges, and potential solutions of Ethernet-based fronthaul networks are also analyzed. Jitter, latency, and time and frequency synchronization are the major issues to overcome.

Artificial-Intelligence-Enabled Air Interface for 6G: Solutions, Challenges, and Standardization Impacts

Abstract: As 3GPP has completed Release 16 specifications and worldwide 5G commercialization is speeding up, global interest in 6G is starting to grow. An interesting and important question is: will the rapid progress in artificial intelligence (AI) eventually alleviate the tremendous efforts required for future standardization of 6G and beyond? In this article, the potential impacts of AI on the air interface design and standardization are investigated. The AI-enabled network architecture is first discussed. The higher layer, physical layer, and cross-layer design empowered by AI capability are further presented. Based on these designs, the future 6G and beyond are expected to enter into an AI era. For potential new use cases and more challenging requirements, the network is capable of automatic updating the air interface protocols, which may substantially reduce the standardization efforts and costs of wireless communication networks.

Achieving High Spectrum Efficiency on High Speed Train for 5G New Radio and Beyond

Abstract: Realizing high mobile data rates in high mobility scenarios has been an important yet challenging target for wireless communications. One typical scenario of such "double high" communications is the HST, which has been one of the most representative infrastructures in more and more countries, especially in China. However, the current SE in HST communications according to the measurements is far from satisfactory to meet the data rate demand generated by the intensive users on HSTs. To address this issue, potential technologies to improve the SE performance of HST communications under various CSI assumptions are presented in this article. Specifically, two open loop beamforming methods with the help of location information (i.e., the location based MIMO precoding and the location assisted MIMO precoder cycling) are first proposed, which are shown to be robust to HST channel variations. Then, we study closed loop beamforming strategies, where channel prediction is proposed to be the key to obtain the essential CSI (e.g., channel matrix or channel covariance) with a low overhead. As HSTs usually go through complicated environments, a big data aided adaptation mechanism between the investigated methods is further proposed. Numerical results demonstrate that the proposed approaches are capable of achieving over 10x SE performance than the current HST transmission strategies and worthy to be studied and discussed in the future 5G New Radio (NR) standardization. It is anticipated that communications with high data rates in high mobility scenarios will be well supported for HSTs in the 5G era.

Overview of cloud RAN

Abstract: Featuring centralized, collaborative, cloud and clean system, the cloud RAN (C-RAN) is deemed to be one of the most promising evolution trends towards future network. This paper provides an overview on the study progress of C-RAN, covering the major challenges, the potential solutions, the initial study results and the relevant activities in the industry and academia. There are two key challenges. One is the fiber consumption due to centralization feature and the other is the implementation of virtualization. While WDM is the most promising solution to address the fiber consumption with several successful trials by operators, for virtualization, there are still several challenges, including optimization on hypervisor, operating systems, management functions and I/O virtualization before realizing C-RAN cloudization.

Network Function Virtualization: State-of-the-Art and Research Challenges

Abstract: Network function virtualization (NFV) has drawn significant attention from both industry and academia as an important shift in telecommunication service provisioning. By decoupling network functions (NFs) from the physical devices on which they run, NFV has the potential to lead to significant reductions in operating expenses (OPEX) and capital expenses (CAPEX) and facilitate the deployment of new services with increased agility and faster time-to-value. The NFV paradigm is still in its infancy and there is a large spectrum of opportunities for the research community to develop new architectures, systems and applications, and to evaluate alternatives and trade-offs in developing technologies for its successful deployment. In this paper, after discussing NFV and its relationship with complementary fields of software defined networking (SDN) and cloud computing, we survey the state-of-the-art in NFV, and identify promising research directions in this area. We also overview key NFV projects, standardization efforts, early implementations, use cases, and commercial products.

Towards 6G wireless communication networks: vision, enabling technologies, and new paradigm shifts

Abstract: The fifth generation (5G) wireless communication networks are being deployed worldwide from 2020 and more capabilities are in the process of being standardized, such as mass connectivity, ultra-reliability, and guaranteed low latency. However, 5G will not meet all requirements of the future in 2030 and beyond, and sixth generation (6G) wireless communication networks are expected to provide global coverage, enhanced spectral/energy/cost efficiency, better intelligence level and security, etc. To meet these requirements, 6G networks will rely on new enabling technologies, i.e., air interface and transmission technologies and novel network architecture, such as waveform design, multiple access, channel coding schemes, multi-antenna technologies, network slicing, cell-free architecture, and cloud/fog/edge computing. Our vision on 6G is that it will have four new paradigm shifts. First, to satisfy the requirement of global coverage, 6G will not be limited to terrestrial communication networks, which will need to be complemented with non-terrestrial networks such as satellite and unmanned aerial vehicle (UAV) communication networks, thus achieving a space-air-ground-sea integrated communication network. Second, all spectra will be fully explored to further increase data rates and connection density, including the sub-6 GHz, millimeter wave (mmWave), terahertz (THz), and optical frequency bands. Third, facing the big datasets generated by the use of extremely heterogeneous networks, diverse communication scenarios, large numbers of antennas, wide bandwidths, and new service requirements, 6G networks will enable a new range of smart applications with the aid of artificial intelligence (AI) and big data technologies. Fourth, network security will have to be strengthened when developing 6G networks. This article provides a comprehensive survey of recent advances and future trends in these four aspects. Clearly, 6G with additional technical requirements beyond those of 5G will enable faster and further communications to the extent that the boundary between physical and cyber worlds disappears.

5G Backhaul Challenges and Emerging Research Directions: A Survey

Abstract: 5G is the next cellular generation and is expected to quench the growing thirst for taxing data rates and to enable the Internet of Things. Focused research and standardization work have been addressing the corresponding challenges from the radio perspective while employing advanced features, such as network densification, massive multiple-input-multiple-output antennae, coordinated multi-point processing, inter-cell interference mitigation techniques, carrier aggregation, and new spectrum exploration. Nevertheless, a new bottleneck has emerged: the backhaul. The ultra-dense and heavy traffic cells should be connected to the core network through the backhaul, often with extreme requirements in terms of capacity, latency, availability, energy, and cost efficiency. This pioneering survey explains the 5G backhaul paradigm, presents a critical analysis of legacy, cutting-edge solutions, and new trends in backhauling, and proposes a novel consolidated 5G backhaul framework. A new joint radio access and backhaul perspective is proposed for the evaluation of backhaul technologies which reinforces the belief that no single solution can solve the holistic 5G backhaul problem. This paper also reveals hidden advantages and shortcomings of backhaul solutions, which are not evident when backhaul technologies are inspected as an independent part of the 5G network. This survey is key in identifying essential catalysts that are believed to jointly pave the way to solving the beyond-2020 backhauling challenge. Lessons learned, unsolved challenges, and a new consolidated 5G backhaul vision are thus presented.

System architecture and key technologies for 5G heterogeneous cloud radio access networks

Abstract: Compared with fourth generation cellular systems, fifth generation wireless communication systems are anticipated to provide spectral and energy efficiency growth by a factor of at least 10, and the area throughput growth by a factor of at least 25. To achieve these goals, a H-CRAN is presented in this article as the advanced wireless access network paradigm, where cloud computing is used to fulfill the centralized large-scale cooperative processing for suppressing co-channel interferences. The state-of-the-art research achievements in the areas of system architecture and key technologies for H-CRANs are surveyed. Particularly, Node C as a new communication entity is defined to converge the existing ancestral base stations and act as the base band unit pool to manage all accessed remote radio heads. Also, the software-defined H-CRAN system architecture is presented to be compatible with software-defined networks. The principles, performance gains, and open issues of key technologies, including adaptive large-scale cooperative spatial signal processing, cooperative radio resource management, network function virtualization, and self-organization, are summarized. The major challenges in terms of fronthaul constrained resource allocation optimization and energy harvesting that may affect the promotion of H-CRANs are discussed as well.