Table of Content

    25 June 2017, Volume 15 Issue S1
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    The whole issue of ZTE Communications June 2017, Vol. 15 No. S1
    2017, 15(S1):  0. 
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    Special Topic
    5G New Radio (NR): Standard and Technology
    Fa-Long Lu
    2017, 15(S1):  1-2. 
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    5G New Radio: Physical Layer Overview
    YUAN Yifei, WANG Xinhui
    2017, 15(S1):  3-10.  doi:10.3969/j.issn.1673-5188.2017.S1.001
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    This paper provides an overview of the physical layer of 5G new radio (NR) system. A general framework of 5G NR is first described, which glues together various key components, all of them helping to fulfill the requirements of three major deployment scenarios: enhanced mobile broadband (eMBB), ultra-reliable low latency communications (URLLC) and massive machine type communications (mMTC). Then, several key components of the 5G NR physical layer are discussed in more detail that include multiple access, channel coding, multiple antennas, frame structures, and initial access. The two-phase approach of NR is also discussed and the key technologies expected to be specified in Phase 1 and Phase 2 are listed.

    Enhanced OFDM for 5G RAN
    Zekeriyya Esat Ankaralı, Berker Peköz, Hüseyin Arslan
    2017, 15(S1):  11-20.  doi:10.3969/j.issn.1673-5188.2017.S1.002
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    Support of many different services, approximately 1000x increase of current data rates, ultra-low latency and energy/cost efficiency are among the expectations from the upcoming 5G standards. In order to meet these expectations, researchers investigate various potential technologies involving different network layers and discuss their tradeoffs for possible 5G scenarios. As one of the most critical components of communication systems, waveform design plays a vital role here to achieve the aforementioned goals. Basic features of the 5G waveform can be given in a nutshell as more flexibility, support of multiple access, the ability to co-exist with different waveforms, low latency and compatibility with promising future technologies such as massive MIMO and mmWave communications. Orthogonal frequency division multiplexing (OFDM) has been the dominant technology in many existing standards and is still considered as one of the favorites for broadband communications in 5G radio access network (RAN). Considering the current interest of industry and academia on enhancing OFDM, this paper drafts the merits and shortcomings of OFDM for 5G RAN scenarios and discusses the various approaches for its improvement. What is addressed in this paper includes not only enhancing the waveform characteristics, out of band leakage and peak to average power ratio in particular, but also methods to reduce the time and frequency redundancies of OFDM such as cyclic prefix and pilot signals. We present how the requirements of different 5G RAN scenarios reflect on waveform parameters, and explore the motivations behind designing frames that include multiple waveforms with different parameters, referred to as numerologies by the 3GPP community, as well as the problems that arise with such coexistence. In addition, recently proposed OFDM-based signaling schemes will also be discussed along with a brief comparison.

    An Overview of Non-Orthogonal Multiple Access
    Anass Benjebbour
    2017, 15(S1):  21-30.  doi:10.3969/j.issn.1673-5188.2017.S1.003
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    In recent years, non-orthogonal multiple access (NOMA) has attracted a lot of attention as a novel and promising power-domain user multiplexing scheme for Long-Term Evolution (LTE) enhancement and 5G. NOMA is able to contribute to the improvement of the tradeoff between system capacity and user fairness (i.e., cell-edge user experience). This improvement becomes in particular emphasized in a cellular system where the channel conditions vary significantly among users due to the near-far effect. In this article, we provide an overview of the concept, design and performance of NOMA. In addition, we review the potential benefits and issues of NOMA over orthogonal multiple access (OMA) such as orthogonal frequency division multiple access (OFDMA) adopted by LTE, and the status of 3GPP standardization related to NOMA.

    Uplink Multiple Access Schemes for 5G: A Survey
    YANG Shan, CHEN Peng, LIANG Lin, ZHU Jianchi, SHE Xiaoming
    2017, 15(S1):  31-40.  doi:10.3969/j.issn.1673-5188.2017.S1.004
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    In non-orthogonal multiple access (NMA) system, signal transmitter and receiver are jointly optimized, so that multiple layers of data from more than one user can be simultaneously delivered in the same resource. To meet the 5G requirements on the number of connections and spectral efficiency, uplink NMA is becoming an important candidate technology and has been extensively studied in 3GPP. A number of uplink NMA schemes from different industrial companies have been proposed in recent 3GPP meetings. In terms of their basic technique principles, this paper classifies these NMA schemes into three categories, namely: scrambling based NMA schemes, interleaving based NMA schemes, and spreading based NMA schemes. Moreover, the key characteristics of these schemes are summarized, and the detailed introduction of each scheme is provided according to the comprehensive survey of the latest progress in 3GPP 5G standardization work.

    Massive MIMO 5G Cellular Networks: mm-Wave vs. μ-Wave Frequencies
    Stefano Buzzi, Carmen D’Andrea
    2017, 15(S1):  41-49.  doi:10.3969/j.issn.1673-5188.2017.S1.005
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    Enhanced mobile broadband (eMBB) is one of the key use-cases for the development of the new standard 5G New Radio for the next generation of mobile wireless networks. Large-scale antenna arrays, a.k.a. massive multiple-input multiple-output (MIMO), the usage of carrier frequencies in the range 10-100 GHz, the so-called millimeter wave (mm-Wave) band, and the network densification with the introduction of small-sized cells are the three technologies that will permit implementing eMBB services and realizing the Gbit/s mobile wireless experience. This paper is focused on the massive MIMO technology. Initially conceived for conventional cellular frequencies in the sub-6 GHz range (μ-Wave), the massive MIMO concept has been then progressively extended to the case in which mm-Wave frequencies are used. However, due to different propagation mechanisms in urban scenarios, the resulting MIMO channel models at μ-Wave and mm-Wave are radically different. Six key basic differences are pinpointed in this paper, along with the implications that they have on the architecture and algorithms of the communication transceivers and on the attainable performance in terms of reliability and multiplexing capabilities.

    Novel MAC Layer Proposal for URLLC in Industrial Wireless Sensor Networks
    Mohsin Raza, Sajjad Hussain, Hoa Le-Minh, Nauman Aslam
    2017, 15(S1):  50-59.  doi:10.3969/j.issn.1673-5188.2017.S1.006
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    Ultra-reliable and low-latency communications (URLLC) has become a fundamental focus of future industrial wireless sensor networks (IWSNs). With the evolution of automation and process control in industrial environments, the need for increased reliability and reduced latencies in wireless communications is even pronounced. Furthermore, the 5G systems specifically target the URLLC in selected areas and industrial automation might turn into a suitable venue for future IWSNs, running 5G as a high speed inter-process linking technology. In this paper, a hybrid multi-channel scheme for performance and throughput enhancement of IWSNs is proposed. The scheme utilizes the multiple frequency channels to increase the overall throughput of the system along with the increase in reliability. A special purpose frequency channel is defined, which facilitates the failed communications by retransmissions where the retransmission slots are allocated according to the priority level of failed communications of different nodes. A scheduler is used to formulate priority based scheduling for retransmission in TDMA based communication slots of this channel. Furthermore, in carrier-sense multiple access with collision avoidance (CSMA/CA) based slots, a frequency polling is introduced to limit the collisions. Mathematical modelling for performance metrics is also presented. The performance of the proposed scheme is compared with that of IEEE802.15.4e, where the performance is evaluated on the basis of throughput, reliability and the number of nodes accommodated in a cluster. The proposed scheme offers a notable increase in the reliability and throughput over the existing IEEE802.15.4e Low Latency Deterministic Networks (LLDN) standard.

    Device-to-Device Based Cooperative Relaying for 5G Network: A Comparative Review
    JIANG Wei
    2017, 15(S1):  60-66.  doi:10.3969/j.issn.1673-5188.2017.S1.007
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    Due to the proliferation of mobile internet access, the cellular traffic is envisaged to experience a 1000-fold growth in the second decade of the 21st century. To meet such a huge traffic demand, the Fifth Generation (5G) network have to adopt new techniques to substantially increase spectral efficiency and reliability. At the base station side, available resources (power supply, equipment size, processing capability, etc.) are far more sufficient than that of the terminal side, which imposes a high challenge on the uplink transmission. The concept of cooperative communications opens a possibility of using multiple terminals to cooperatively achieve spatial diversity that is typically obtained by means of multiple antennas in the base station. The application of Device-to-Device (D2D) communications in the 3GPP LTE system further pushes the collaboration of terminals from the theory to the practice. The utilization of D2D-based cooperative relaying is promising in the era of 5G. In this paper, we comparatively study several cooperative multi-relay schemes, including the proposed opportunistic space-time coding, in the presence of imperfect channel state information. The numerical results reveal that the proposed scheme is the best cooperative solution until now from the perspective of multiplexing-diversity tradeoff.