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  • REVIEWS
    5G High Mobility Wireless Communications: Challenges and Solutions
    Pingzhi Fan, Jing Zhao, Chih-Lin I
    2016, 13(2z): 1-13.
    Abstract ( )   Knowledge map   Save
    The fifth generation (5G) network is expected to support significantly large amount of mobile data traffic and huge number of wireless connections, to achieve better spectrum- and energy-efficiency, as well as quality of service (QoS) in terms of delay, reliability and security. Furthermore, the 5G network shall also incorporate high mobility requirements as an integral part, providing satisfactory service to users travelling at a speed up to 500 km/h. This paper provides a survey of potential high mobility wireless communication (HMWC) techniques for 5G network. After discussing the typical requirements and challenges of HMWC, key techniques to cope with the challenges are reviewed, including transmission techniques under the fast time-varying channels, network architecture with mobility support, and mobility management. Finally, future research directions on 5G high mobility communications are given.
  • REVIEWS
    The Interdisciplinary Research of Big Data and Wireless Channel: A Cluster-Nuclei Based Channel Model
    Jianhua Zhang
    2016, 13(2z): 14-26.
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    Recently, internet stimulates the explosive progress of knowledge discovery in big volume data resource, to dig the valuable and hidden rules by computing. Simultaneously, the wireless channel measurement data reveals big volume feature, considering the massive antennas, huge bandwidth and versatile application scenarios. This article firstly presents a comprehensive survey of channel measurement and modeling research for mobile communication, especially for 5th Generation (5G) and beyond. Considering the big data research progress, then a cluster-nuclei based model is proposed, which takes advantages of both the stochastical model and deterministic model. The novel model has low complexity with the limited number of cluster-nuclei while the cluster-nuclei has the physical mapping to real propagation objects. Combining the channel properties variation principles with antenna size, frequency, mobility and scenario dug from the channel data, the proposed model can be expanded in versatile application to support future mobile research.
  • REVIEWS
    Big Wave of the Intelligent Connected Vehicles
    Yan Li, Yiqing Cao, Hong Qiu, Lu Gao, Zhimin Du, Shuping Chen
    2016, 13(2z): 27-41.
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    Internet of things is deemed as the one of the great revolution after the age of Industrial Revolution. With the development of the communication technology, more and more entities are connected to the communication network and become one of the elements in the network. Over recent decades, in the area of intelligent transportation, pedestrian and transport infrastructure are connected to the communication network to improve the driving safety and traffic efficiency which is known as the ICV (Intelligent Connected Vehicle). This paper summarizes the global ICV progresses in the past decades and the latest activities of ICV in China, and introduces various aspects regarding the recent development of the ICV, including industry development, spectrum and standard, at the same time.
  • REVIEWS
    5G Technology Requirements and Related Test Environments for Evaluation
    Xi Meng, Jian Li, Dong Zhou, Dacheng Yang
    2016, 13(2z): 42-51.
    Abstract ( )   Knowledge map   Save
    To meet the considerably increase of mobile data traffic and wireless communication connections around 2020, the 5th generation (5G) mobile network will necessarily consider more frequency bands, enabling technologies and diversified key performance indicators and test environments comparing with existing network, for example Long Term Evolution. More specifically, the obvious difference between 5G and previous wireless communication system are not only included eMBB(enhance mobile broadband) usage scenario, but also introduced mMTC(massive machine type communications) and URLLC(ultra-reliable and low latency communications) usage scenarios. Hence, in order to evaluate 5G related technologies, some novel test environments will be widely discussed, as well as, certain new key performance indicators will be drawn into 5G evaluation methodology for satisfied new requirements. We will discuss characteristic of these 4 candidate test environments, such as indoor isolated environment, high speed train environment; and the definition of 15 keys performance indicator will be explained and clarified, for example, Throughput, Network Energy Efficiency, Device Connection Density and so on. Furthermore, high-level assessment method of each test environment also will be initially considered. It is notable that an initial evaluation of indoor isolated environment also can be found, which the results show that there are 3 times average cell spectral efficiency than IMT-advanced’s in same test environment.
  • REVIEWS
    Analysis of Non-Orthogonal Multiple Access for 5G
    Yingmin Wang, Bin Ren, Shaohui Sun, Shaoli Kang, Xinwei Yue
    2016, 13(2z): 52-66.
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    The major challenge faced by the fifth generation (5G) mobile network is higher spectral efficiency and massive connectivity, i.e., the target spectrum efficiency is 3 times over 4G, and the target connection density is one million devices per square kilometer. These requirements are difficult to be satisfied with orthogonal multiple access (OMA) schemes. Non-orthogonal multiple access (NOMA) has thus been proposed as a promising candidate to address some of the challenges for 5G. In this paper, a comprehensive survey of different candidate NOMA schemes for 5G is presented, where the usage scenarios of 5G and the application requirements for NOMA are firstly discussed. A general framework of NOMA scheme is established and the features of typical NOMA schemes are analyzed and compared. We focus on the recent progress and challenge of NOMA in standardization of international telecommunication union (ITU), and 3rd generation partnership project (3GPP). In addition, prototype development and future research directions are also provided respectively.
  • REVIEWS
    Research and Development of Indoor Positioning
    Qi Liu, Jiahui Qiu, Yi Chen
    2016, 13(2z): 67-79.
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    Indoor positioning systems have been sufficiently researched to provide location information of persons and devices. This paper is focused on the current research and further development of indoor positioning. The standard evolution and industry development are summarized. There are various positioning systems according to the scenarios, cost and accuracy. However, there is a basic positioning system framework including information extraction, measurement and calculation. In particular, the detailed positioning technologies mainly including cellular positioning and Local Area Network (LAN) positioning are listed and compared to provide a reference for practical applications. Finally, we summarize the challenges of indoor positioning and give a 3-phase evolution route.
  • REVIEWS
    Neighbor-Aware Multiple Access Protocol for 5G mMTC Applications
    Yang Yang, Guannan Song, Wuxiong Zhang, Xiaohu Ge, Chengxiang Wang
    2016, 13(2z): 80-88.
    Abstract ( )   Knowledge map   Save
    In order to support massive Machine Type Communication (mMTC) applications in future Fifth Generation (5G) systems, a key technical challenge is to design a highly effective multiple access protocol for massive connection requests and huge traffic load from all kinds of smart devices, e.g. bike, watch, phone, ring, glasses, shoes, etc.. To solve this hard problem in distributed scenarios with massive competing devices, this paper proposes and evaluates a Neighbor-Aware Multiple Access (NAMA) protocol, which is scalable and adaptive to different connectivity size and traffic load. By exploiting acknowledgement signals broadcasted from the neighboring devices with successful packet transmissions, NAMA is able to turn itself from a contention-based random access protocol to become a contention-free deterministic access protocol with particular transmission schedules for all neighboring devices after a short transition period. The performance of NAMA is fully evaluated from random state to deterministic state through extensive computer simulations under different network sizes and Contention Window (CW) settings. Compared with traditional IEEE 802.11 Distributed Coordination Function (DCF), for a crowded network with 50 devices, NAMA can greatly improve system throughput and energy efficiency by more than 110% and 210%, respectively, while reducing average access delay by 53% in the deterministic state.
  • REVIEWS
    Mobile Edge Computing Towards 5G: Vision, Recent Progress, and Open Challenges
    Yifan Yu
    2016, 13(2z): 89-99.
    Abstract ( )   Knowledge map   Save
    Mobile Edge Computing (MEC) is an emerging technology in 5G era which enables the provision of the cloud and IT services within the close proximity of mobile subscribers. It allows the availability of the cloud servers inside or adjacent to the base station. The end-to-end latency perceived by the mobile user is therefore reduced with the MEC platform. The context-aware services are able to be served by the application developers by leveraging the real time radio access network information from MEC. The MEC additionally enables the compute intensive applications execution in the resource constraint devices with the collaborative computing involving the cloud servers. This paper presents the architectural description of the MEC platform as well as the key functionalities enabling the above features. The relevant state-of-the-art research efforts are then surveyed. The paper finally discusses and identifies the open research challenges of MEC.
    • ARTICLES
  • ARTICLES
    A New TDD Scheme and Interference-Aware Precoding for Device-to-Device Underlay Massive MIMO
    Xinxin Liu, Xueru Li, Yunzhou Li, Ming Zhao, Jing Wang
    2016, 13(2z): 100-108.
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    In device-to-device (D2D) underlay cellular networks with downlink spectrum sharing, massive MIMO seems promising as the large number of antennas at the base station (BS) can be utilized to suppress interference. However, the channel state information (CSI) from the BS to D2D receivers is required to obtain this advantage. In this paper, we first propose a novel time division duplex (TDD) scheme for D2D users to acquire this CSI, without additional pilot overhead. Moreover, we propose an interference-aware MMSE precoder utilizing the acquired CSI from the BS to not only cellular users but also D2D users to suppress the cellular-to-D2D interference. Simulation results show that our proposed TDD scheme and precoder can significantly improve the achievable sum spectral efficiency (SE) and D2D SE, compared to the classical MMSE precoder. Compared with the interference-aware ZF precoder, whose performance severely degrades for large user numbers, our proposed interference-aware MMSE precoder can always guarantees a high and stable performance in terms of achievable SE.
  • ARTICLES
    Hybrid CSI-RS Transmission Mechanism-Based 3D Beamforming Scheme for FDD Massive MIMO System
    Fangchao Zhang, Shaohui Sun, Qiubin Gao, Hui Li
    2016, 13(2z): 109-119.
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    Massive multiple-input multiple-output (MIMO) refers to the idea that equipping base station (BS) with a large number of antenna elements, and features the ability of three dimensional (3D) beamforming technique to enable improvement in system performance. The prior works on massive MIMO generally rely on a common assumption of the whole channel characteristics are perfectly known at both user equipment (UE) and BS, however, this is quite difficult to realize in practical frequency division duplexing (FDD) system since the channel state information reference signal (CSI-RS) overhead and CSI feedback overhead are proportional to the number of antenna elements. In this paper, two hybrid CSI-RS transmission mechanism-based 3D beamforming schemes are proposed in FDD massive MIMO system, in which non-beamformed CSI-RS configuration is utilized in conjunction with beamformed CSI-RS configuration. In the proposed schemes, an angle quantization-based vertical codebook and a DFT-based horizontal codebook are designed, respectively, and an eigenvalue decomposition-based precoding matrix indicator (PMI) selection algorithm is also proposed for CSI acquisition. Simulation results show that the proposed 3D beamforming schemes achieve significant improvement in system capacity without incurring excessive CSI-RS overhead.
  • ARTICLES
    Physical Layer Security of Multi-Hop Aided Downlink MIMO Heterogeneous Cellular Networks
    Xiaohui Qi, Kaizhi Huang, Zhihao Zhong, Xiaolei Kang, Zhou Zhong
    2016, 13(2z): 120-130.
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    This study investigates physical layer security in downlink multiple-input multiple-output (MIMO) multi-hop heterogeneous cellular networks (MHCNs), in which communication between mobile users and base stations (BSs) is established by a single or multiple hops, to address the problem of insufficient security performance of MIMO heterogeneous cellular networks. First, two-dimensional homogeneous Poisson point processes (HPPPs) are utilized to model the locations of K-tier BSs in MIMO MHCNs and receivers, including those of legitimate users and eavesdroppers. Second, based on the channel gain distribution and the statistics property of HPPP, the achievable ergodic rates of the main and eavesdropper channels in direct and ad hoc links are derived, respectively. Third, the secrecy coverage probability and the achievable ergodic secrecy throughput of downlink MIMO MHCNs are explored, and their expressions are derived. Lastly, the correctness of the theoretical derivation is verified through Monte Carlo simulations.
  • ARTICLES
    Joint Resource Allocation and Coordinated Com-putation Offloading for Fog Radio Access Networks
    Kai Liang, Liqiang Zhao, Xiaohui Zhao, Yong Wang, Shumao Ou
    2016, 13(2z): 131-139.
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    The cloud radio access network (C-RAN) and the fog computing have been recently proposed to tackle the dramatically increasing traffic demands and to provide better quality of service (QoS) to user equipment (UE). Considering the better computation capability of the cloud RAN (10 times larger than that of the fog RAN) and the lower transmission delay of the fog computing, we propose a joint resource allocation and coordinated computation offloading algorithm for the fog RAN (F-RAN), which takes the advantage of C-RAN and fog computing. Specifically, the F-RAN splits a computation task into the fog computing part and the cloud computing part. Based on the constraints of maximum transmission delay tolerance, fronthaul and backhaul capacity limits, we minimize the energy cost and obtain optimal computational resource allocation for multiple UE, transmission power allocation of each UE and the event splitting factor. Numerical results have been proposed with the comparison of existing methods.
  • ARTICLES
    A Novel Load Balancing Strategy of Software-Defined Cloud/Fog Networking in the Internet of Vehicles
    Xiuli He, Zhiyuan Ren, Chenhua Shi, Jian Fang
    2016, 13(2z): 140-149.
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    The Internet of Vehicles (IoV) has been widely researched in recent years, and cloud computing has been one of the key technologies in the IoV. Although cloud computing provides high performance compute, storage and networking services, the IoV still suffers with high processing latency, less mobility support and location awareness. In this paper, we integrate fog computing and software defined networking (SDN) to address those problems. Fog computing extends computing and storing to the edge of the network, which could decrease latency remarkably in addition to enable mobility support and location awareness. Meanwhile, SDN provides flexible centralized control and global knowledge to the network. In order to apply the software defined cloud/fog networking (SDCFN) architecture in the IoV effectively, we propose a novel SDN-based modified constrained optimization particle swarm optimization (MPSO-CO) algorithm which uses the reverse of the flight of mutation particles and linear decrease inertia weight to enhance the performance of constrained optimization particle swarm optimization (PSO-CO). The simulation results indicate that the SDN-based MPSO-CO algorithm could effectively decrease the latency and improve the quality of service (QoS) in the SDCFN architecture.
  • ARTICLES
    A Low-Interference Time-Domain N-Continuous OFDM Scheme
    Peng Wei, Lilin Dan, Yue Xiao, Xia Lei, Shaoqian Li
    2016, 13(2z): 150-158.
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    N-continuous orthogonal frequency division multiplexing (NC-OFDM) is an outstanding method to suppress sidelobe for baseband OFDM signals in future 5G wireless communications. However, the precoder of NC-OFDM usually causes severe interference and high complexity. To alleviate these problems, this paper proposes an improved time-domain N-continuous OFDM (TD-NC-OFDM) by optimizing the smooth signal, which is the linear combination of rectangularly pulsed OFDM basis signals truncated by a smooth window. Furthermore, we show that the proposed scheme is with lower transceiver complexity and notable performance gain in signal-to-interference-plus-noise ratio (SINR). Lastly, simulation results show that the proposed low-interference TD-NC-OFDM can achieve similar sidelobe suppression performance, with negligible bit-error rate (BER) degradation, compared to conventional NC-OFDM.
  • ARTICLES
    Pattern Matrix Design of PDMA for 5G UL Applications
    Bin Ren, Yingmin Wang, Xiaoming Dai, Kai Niu, Wanwei Tang
    2016, 13(2z): 159-173.
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    Pattern division multiple access (PDMA), which is a novel non-orthogonal multiple access (NOMA), has been proposed to address the challenges of massive connectivity and higher spectral efficiency for fifth generation (5G) mobile network. The performance of PDMA mainly depends on the design of PDMA pattern matrix. In this paper, pattern matrix design of PDMA for 5G uplink (UL) applications in massive machine type communication (mMTC) and enhanced mobile broadband (eMBB) deployment scenarios are studied. The design criteria and examples for application in UL mMTC and UL eMBB are investigated. The performance of the PDMA pattern matrix is analyzed with the discrete constellation constrained capacity (CC-Capacity), and verified by Monte Carlo simulation. The simulation results show that the preferred PDMA pattern matrix can achieve good performance with different overloading factors (OF).
  • ARTICLES
    Mobile Edge Computing and Field Trial Results for 5G Low Latency Scenario
    Jianmin Zhang, Weiliang Xie, Fengyi Yang, Qi Bi
    2016, 13(2z): 174-182.
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    Through enabling the IT and cloud computation capacities at Radio Access Network (RAN), Mobile Edge Computing (MEC) makes it possible to deploy and provide services locally. Therefore, MEC becomes the potential technology to satisfy the requirements of 5G network to a certain extent, due to its functions of services localization, local breakout, caching, computation offloading, network context information exposure, etc. Especially, MEC can decrease the end-to-end latency dramatically through service localization and caching, which is key requirement of 5G low latency scenario. However, the performance of MEC still needs to be evaluated and verified for future deployment. Thus, the concept of MEC is introduced into 5G architecture and analyzed for different 5G scenarios in this paper. Secondly, the evaluation of MEC performance is conducted and analyzed in detail, especially for network end-to-end latency. In addition, some challenges of the MEC are also discussed for future deployment.
  • ARTICLES
    A Networking Solution on Uplink Channel of Co-Frequency and Co-Time System
    Bingli Jiao, Sanjun Liu, Yiming Lei, Meng Ma
    2016, 13(2z): 183-188.
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    Co-frequency and co-time full duplex (CCFD) is an attractive technology for the future wireless communication because of its high spectral efficiency. However, applications of CCFD to mobile network can suffer from strong base station to base station (B2B) interference. In this paper, the authors proposed a design that uses centralized base station (BS) transmit antenna and distributed BS receive antennas, each of which consists of an antennary to perform beamforming that can nullify the B2B interference. In addition, we proposed a combination algorithm that uses the zero forcing method to cascade the recursive least square (RLS) method for reducing the necessary number of the bits taken to the digital processor. This enables the faster convergence and, thus, allows the transmission of more information bits, compared to the conventional method, for mobile communication. The simulation results confirm this approach for practical application.