Table of Content

    25 June 2018, Volume 16 Issue 2
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    The whole issue of ZTE Communications June 2018, Vol. 16 No. 2
    2018, 16(2):  0. 
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    Special Topic
    Ultra-Dense Networking Architectures and Technologies for 5G
    Victor C. M. Leung, ZHANG Haijun
    2018, 16(2):  1-2.  doi:10.3969/j.issn.1673-5188.2018.02.001
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    UAV Assisted Heterogeneous Wireless Networks: Potentials and Challenges
    LI Tongxin, SHENG Min, LYU Ruiling, LIU Junyu, LI Jiandong
    2018, 16(2):  3-8.  doi:10.3969/j.issn.1673-5188.2018.02.002
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    By fully exploiting the spatial resources, unmanned aerial vehicles (UAVs) are expected to serve as an efficient complementary to terrestrial wireless communication system to provide enhanced coverage and reliable connectivity to ground users. With the growing deployment of units such as small cell base stations (BSs), however, the incurred severe interference may hinder the potential benefits of the integration of UAVs. In this paper, we first discuss the intrinsic features and potential benefits of UAVs and introduce the architecture of multi-layer heterogeneous wireless network (MHetNet), in which traditional wireless network is assisted by UAVs. Then, an explicit discussion on the factors that limit the performance of MHetNet is presented, including the UAV topology, UAV density, and spectrum sharing of UAV and terrestrial networks. We use simulation results to investigate the performance of MHetNet in terms of spatial throughput (ST). It is shown that, together with the densities of UAV and terrestrial networks, the altitude of UAV is a limiting factor that should be optimized to improve the ST of MHetNet.

    Multi-QoS Guaranteed Resource Allocation for Multi-Services Based on Opportunity Costs
    JIN Yaqi, XU Xiaodong, TAO Xiaofeng
    2018, 16(2):  9-15.  doi:10.3969/j.issn.1673-5188.2018.02.003
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    To meet the booming development of diversified services and new applications in the future, the fifth-generation mobile communication system (5G) has arisen. Resources are increasingly scarce in the dynamic time-varying of 5G networks. Allocating resources effectively and ensuring quality of service (QoS) requirements of multi-services come to be a research focus. In this paper, we utilize effective capacity to build a utility function with multi-QoS metrics, including rate, delay bound and packet loss ratio. Taking advantage of opportunity cost (OC), we also propose a multi-QoS guaranteed resource allocation algorithm for multi-services to consider the future condition of system. In the algorithm, according to different business characteristics and the theory of OC, we propose different selection conditions for QoS users and best effort (BE) users to choose more reasonable resources. Finally, simulation results show that our proposed algorithm achieves superior system utility and relatively better fairness in multi-service scenarios.

    Energy-Efficient Wireless Backhaul Algorithm in Ultra-Dense Networks
    FENG Hong, LI Xi, ZHANG Heli, CHEN Shuying, JI Hong
    2018, 16(2):  16-22.  doi:10.3969/j.issn.1673-5188.2018.02.004
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    Ultra-dense networks (UDNs) are expected to be applied for the fifth generation wireless system (5G) to meet the requirements of very high throughput density and connections of a massive number of users. Considering the large amount of small base stations (SBSs), how to choose proper backhaul links is an important problem under investigation. In this paper, we propose a wireless backhaul algorithm to find an effective backhaul method for densely-deployed SBSs and to maximize energy efficiency of the system. We put forward adaptive backhaul methods of indirect and direct modes. The SBS can select the direct backhaul which connects to the macro base station (MBS) directly, or the indirect backhaul which selects an idle SBS as a relay based on the backhaul channel condition. The algorithm also allocates network resources, including the power of SBSs and system bandwidth, to solve the serious interference problem in UDN. Finally, the simulation results show that the proposed wireless backhaul algorithm has desired performance to achieve higher energy efficiency with required data rate.

    General Architecture of Centralized Unit and Distributed Unit for New Radio
    GAO Yin, HAN Jiren, LIU Zhuang, LIU Yang, HUANG He
    2018, 16(2):  23-31.  doi:10.3969/j.issn.1673-5188.2018.02.005
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    In new radio (NR) access technology, the radio access network (RAN) architecture is split into two kinds of entities, i.e., the centralized unit (CU) and the distributed unit (DU), to enhance the network flexibility. In this split architecture, one CU is able to control several DUs, which enables the function of base-band central control and remote service for users. In this paper, the general aspects of CU-DU split architecture are introduced, including the split method, interface functions (control plane functions and user plane functions), mobility scenarios and other CU-DU related issues. The simulations show the performance of Options 2 and 3 for CU-DU split.

    Two-Codebook-Based Cooperative Precoding for TDD-CoMP in 5G Ultra-Dense Networks
    GAO Tengshuang, CHEN Ying, HAO Peng, ZHANG Hongtao
    2018, 16(2):  32-36.  doi:10.3969/j.issn.1673-5188.2018.02.006
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    In ultra-dense networks (UDN), the local precoding scheme for time-division duplex coordinated multiple point transmission (TDD-CoMP) can have a good performance with no feedback by using reciprocity between uplink and downlink. However, if channel is time-varying, the channel difference would cause codeword mismatch between transmitter and receiver, which leads to performance degradation. In this paper, a linear interpolation method is proposed for TDD-CoMP system to estimate the uplink channel at the receiver, which would reduce the channel difference caused by time delay and decrease the probability of codeword mismatch between both sides. Moreover, to mitigate severe inter-cell interference and increase the coverage and throughput of cell-edge users in UDN, a two-codebook scheme is used to strengthen cooperation between base stations (BSs), which can outperform the global precoding scheme with less overhead. Simulations show that the proposed scheme can significantly improve the link performance compared to the global precoding scheme.

    Research Paper
    Markov Based Rate Adaption Approach for Live Streaming over HTTP/2
    XIE Lan, ZHANG Xinggong, HUANG Cheng, DONG Zhenjiang
    2018, 16(2):  37-41.  doi:10.3969/j.issn.1673-5188.2018.02.007
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    Dynamic adaptive streaming over HTTP (DASH) has been widely deployed. However, large latency in HTTP/1.1 cannot meet the requirements of live streaming. Data-pushing in HTTP/2 is emerging as a promising technology. For video live over HTTP/2, new challenges arise due to both low-delay and small buffer constraints. In this paper, we study the rate adaption problem over HTTP/2 with the aim to improve the quality of experience (QoE) of live streaming. To track the dynamic characteristics of the streaming system, a Markov-theoretical approach is employed. System variables are taken into account to describe the system state, by which the system transition probability is derived. Moreover, we design a dynamic reward function considering both the quality of user experience and dynamic system variables. Therefore, the rate adaption problem is formulated into a Markov decision based optimization problem and the best streaming policy is obtained. At last, the effectiveness of our proposed rate adaption scheme is demonstrated by numerous experiment results.

    SOPA: Source Routing Based Packet-Level Multi-Path Routing in Data Center Networks
    LI Dan, LIN Du, JIANG Changlin, Wang Lingqiang
    2018, 16(2):  42-54.  doi:10.3969/j.issn.1673-5188.2018.02.008
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    Many “rich-connected” topologies with multiple parallel paths between servers have been proposed for data center networks recently to provide high bisection bandwidth, but it remains challenging to fully utilize the high network capacity by appropriate multi-path routing algorithms. As flow-level path splitting may lead to traffic imbalance between paths due to flow size difference, packet-level path splitting attracts more attention lately, which spreads packets from flows into multiple available paths and significantly improves link utilizations. However, it may cause packet reordering, confusing the TCP congestion control algorithm and lowering the throughput of flows. In this paper, we design a novel packet-level multi-path routing scheme called SOPA, which leverages OpenFlow to perform packet-level path splitting in a round-robin fashion, and hence significantly mitigates the packet reordering problem and improves the network throughput. Moreover, SOPA leverages the topological feature of data center networks to encode a very small number of switches along the path into the packet header, resulting in very light overhead. Compared with random packet spraying (RPS), Hedera and equal-cost multi-path routing (ECMP), our simulations demonstrate that SOPA achieves 29.87%, 50.41% and 77.74% higher network throughput respectively under permutation workload, and reduces average data transfer completion time by 53.65%, 343.31% and 348.25% respectively under production workload.

    Open Source Initiatives for Big Data Governance and Security: A Survey
    HU Baiqing, WANG Wenjie, Chi Harold Liu
    2018, 16(2):  55-66.  doi:10.3969/j.issn.1673-5188.2018.02.009
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    With the rapid development of Internet technology, the volume of data has increased exponentially. As the large amounts of data are no longer easy to be managed and secured by the owners, big data security and privacy has become a hot issue. One of the most popular research fields for solving the data security and data privacy is within the scope of big data governance and security. In this paper, we introduce the basic concepts of data governance and security. Then, all the state-of-the-art open source frameworks for data governance and security, including Apache Falcon, Apache Atlas, Apache Ranger, Apache Sentry and Kerberos, are detailed and discussed with descriptions of their implementation principles and possible applications.