Recent Progress on C-RAN Centralization and Cloudification
TL;DR: This paper presents the latest progress on cloud RAN (C-RAN) in the areas of centralization and virtualization and demonstrates the viability of various front-haul solutions, including common public radio interface compression, single fiber bidirection and wavelength-division multiplexing.
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.
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TL;DR: In this article, the authors survey the state-of-the-art in NFV and identify promising research directions in this area, and also overview key NFV projects, standardization efforts, early implementations, use cases, and commercial products.
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.
1,634 citations
TL;DR: In this paper, the authors explain how the first chapter of the massive MIMO research saga has come to an end, while the story has just begun, and outline five new massive antenna array related research directions.
556 citations
TL;DR: 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.
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.
459 citations
TL;DR: In this paper, the authors proposed a new framework for scalable cell-free massive MIMO systems by exploiting the dynamic cooperation cluster concept from the Network-MIMO literature and provided a novel algorithm for joint initial access, pilot assignment, and cluster formation.
Abstract: Imagine a coverage area with many wireless access points that cooperate to jointly serve the users, instead of creating autonomous cells. Such a cell-free network operation can potentially resolve many of the interference issues that appear in current cellular networks. This ambition was previously called Network MIMO (multiple-input multiple-output) and has recently reappeared under the name Cell-Free Massive MIMO. The main challenge is to achieve the benefits of cell-free operation in a practically feasible way, with computational complexity and fronthaul requirements that are scalable to large networks with many users. We propose a new framework for scalable Cell-Free Massive MIMO systems by exploiting the dynamic cooperation cluster concept from the Network MIMO literature. We provide a novel algorithm for joint initial access, pilot assignment, and cluster formation that is proved to be scalable. Moreover, we adapt the standard channel estimation, precoding, and combining methods to become scalable. A new uplink and downlink duality is proved and used to heuristically design the precoding vectors on the basis of the combining vectors. Interestingly, the proposed scalable precoding and combining outperform conventional maximum ratio (MR) processing and also performs closely to the best unscalable alternatives.
428 citations
TL;DR: In this article, the authors comprehensively survey the recent advances of C-RANs, including system architectures, key techniques, and open issues, and discuss the system architectures with different functional splits and the corresponding characteristics.
Abstract: As a promising paradigm to reduce both capital and operating expenditures, the cloud radio access network (C-RAN) has been shown to provide high spectral efficiency and energy efficiency. Motivated by its significant theoretical performance gains and potential advantages, C-RANs have been advocated by both the industry and research community. This paper comprehensively surveys the recent advances of C-RANs, including system architectures, key techniques, and open issues. The system architectures with different functional splits and the corresponding characteristics are comprehensively summarized and discussed. The state-of-the-art key techniques in C-RANs are classified as: the fronthaul compression, large-scale collaborative processing, and channel estimation in the physical layer; and the radio resource allocation and optimization in the upper layer. Additionally, given the extensiveness of the research area, open issues, and challenges are presented to spur future investigations, in which the involvement of edge cache, big data mining, social-aware device-to-device, cognitive radio, software defined network, and physical layer security for C-RANs are discussed, and the progress of testbed development and trial test is introduced as well.
364 citations
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TL;DR: The perspective of the 5G technologies with two major themes: green and soft is presented, showing that by rethinking the Shannon theorem and traditional cell-centric design, network capacity can be significantly increased while network power consumption is decreased.
Abstract: As the deployment and commercial operation of 4G systems are speeding up, technologists worldwide have begun searching for next generation wireless solutions to meet the anticipated demands in the 2020 era given the explosive growth of mobile Internet. This article presents our perspective of the 5G technologies with two major themes: green and soft. By rethinking the Shannon theorem and traditional cell-centric design, network capacity can be significantly increased while network power consumption is decreased. The feasibility of the combination of green and soft is investigated through five interconnected areas of research: energy efficiency and spectral efficiency co-design, no more cells, rethinking signaling/control, invisible base stations, and full duplex radio.
726 citations
"Recent Progress on C-RAN Centraliza..." refers background in this paper
...C-RAN is not only applicable for existing wireless networks but also an essential element for future 5G systems [1]....
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...In addition, system upgrades will become far more challenging when new technologies such as 5G are introduced into the multi-network environment [1]....
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24 Sep 2009
TL;DR: This paper presents some system level performance evaluation which shows that the CoMP-MU-MIMO transmission scheme can bring significant gains to both the average cell throughput and the cell edge user throughput.
Abstract: LTE-Advanced systems which based on orthogonal frequency division multiplexing (OFDM) can eliminate intra-cell interference but still can not mitigate inter-cell interference (ICI). Coordinated Multi-Point transmission/reception (CoMP) is one of the candidate techniques for LTE-Advanced systems to increase the average cell throughput and cell edge user throughput in the both uplink and downlink. Although CoMP naturally increases system complexity, it has potentially significant capacity and coverage benefits, making it worth a more detailed consideration. In this paper, we focus on the downlink CoMP-MU-MIMO transmission scheme and present some system level performance evaluation which shows that the CoMP-MU-MIMO transmission scheme can bring significant gains to both the average cell throughput and the cell edge user throughput.
61 citations
"Recent Progress on C-RAN Centraliza..." refers methods in this paper
...However, efficient CoMP algorithms such as Joint Transmission (JT) cannot achieve maximum performance gain with traditional X2 interface LTE architecture due to high latency and low bandwidth [3], [4]....
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