Table of Content

    25 December 2012, Volume 10 Issue 4
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    The whole issue of ZTE Communications December 2012, Vol. 10 No. 4
    2012, 10(4):  0. 
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    Special Topic
    Guest Editorial: Millimeter Wave Communication for Cellular and Cellular-802.11 Hybrid Networks
    Philip Pietraski and I-tai Lu
    2012, 10(4):  1-2. 
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    The demand for wireless data has been driving network capacity to double about every two years for the past 50 years, if not 100 years, and this has come to be known as Cooper’s Law. In recent years, this trend has accelerated as a greater proportion of the population adopts wireless devices with ever greater capabilities, including tablets that support HD video and other advanced capabilities. Many cellular operators have tried to adapt this trend by throttling data rates, backing away from all-you-can-eat data plans, and offloading to WiFi. Over the next decade, further increases in demand are expected, and this issue of ZTE Communications examines millimeter wave communications as one technology that may answer the call.

    Historically, the ever-growing demand for data capacity has been met by adding more spectrum and improving spectral efficiency, but spectrum reuse employing smaller cells has been by far the most popular means of adding network capacity. Deploying cells with ever greater density is a simple way of adding capacity to a network. Increasing the number of cells in the network increases the network capacity without increasing the capacity per cell. However, this approach becomes cost-prohibitive in part because it is expensive to roll out all these cells and provide them with a quality backhaul connection, for example, fiber. A less-expensive means of adding network capacity is needed in the long term.

    As cells become smaller and link distances have become shorter, an alternative to adding capacity and reducing deployment costs is to use much higher carrier frequencies. Shorter link distances, which come with smaller cells, combined with recent advances in millimeter wave transceivers and antennas opens the door for the use of millimeter wave spectrum in cellular systems. An obvious benefit to this is the availability of a huge amount of spectrum. The 60 GHz unlicensed band alone offers 5-9 GHz of bandwidth (the exact amount depends on country), and there are many other millimeter wave and terahertz bands that have potential. Another great benefit of millimeter wave carriers is that high-gain, highly directional, electrically steerable antennas can be very small and greatly reduce interference. The wide bandwidths and narrow steerable beams enable low-cost deployment based on a wireless backhaul.

    WirelessHD devices with 60 GHz phased array antennas are already on the market, and WiGig/802.11ad devices are on their way. ABI research predicts that by 2016 one third of all WiFi products will be tri-band (2.4/5/60 GHz). Although WiGig is intended to be an indoor, short-link technology (~10m), it may be an important standard used as a starting point for larger networks to use millimeter wave communications. Mass production of devices such as these will continue to drive costs down for millimeter wave radios and antennas that should extend to longer links.

    The 60 GHz unlicensed band is of particular interest because of the growing ecosystem being built around consumer electronics that support WirelessHD and WiGig. However, the fact that the band is unlicensed means that it is riskier for cellular service providers to adopt. Molecular oxygen absorption at 60 GHz creates further confusion as some argue that these losses limit link distance. Others argue that reduced interference is worth it. Below 60 GHz, the LMDS bands are of interest and are underutilized; however, they offer less total spectrum than the 60 GHz unlicensed band. Recent technological advances may soon enable communications well above 100 GHz and into the terahertz region above 300 GHz, where allocations have not yet been made by regulators, and even greater bandwidths could become available. Some agreement on a band will be needed in order to make good progress.

    Of course, there are also great challenges with millimeter wave systems. Although link distances in a line-of-sight environment might be easily closed with millimeter wave technology, the environment poses particular problems. Millimeter waves do not generally penetrate through buildings or diffract around them. Furthermore, humans are great blockers of millimeter waves and tend move around more than buildings. The problem of cost-effective routing around buildings and people will be one of the larger problems.

    In this special issue, we examine the role that millimeter wave communication could play in cellular and cellular hybrid networks in access and backhaul. The first paper provides an introduction to the potential use of millimeter waves in a large network context and provides a preliminary simulation study. The second paper provides an overview of the 802.11ad/WiGig MAC and PHY. The third paper provides an experimental study of human blocking of millimeter wave propagation. The fourth paper describes the design and measurements of a 60 GHz LTCC phased array antenna with integrated waveguide distribution network that could be suitable for backhaul applications. The fifth paper considers the use of MIMO techniques for millimeter wave in line-of-sight conditions.

    We are grateful to the authors who made contributions to this special issue and to the reviewers who spent their valuable time to provide valuable and constructive feedback. We hope that you find this special issue interesting and useful.

    We are grateful to the authors who made contributions to this special issue and to the reviewers who spent their valuable time to provide valuable and constructive feedback. We hope that you find this special issue interesting and useful.
    Millimeter Wave and Terahertz Communications: Feasibility and Challenges
    Phil Pietraski, David Britz, Arnab Roy, Ravi Pragada, and Gregg Charlton
    2012, 10(4):  3-12. 
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    In this paper, the challenges with and motivations for developing millimeter wave and terahertz communications are described. A high-level candidate architecture is presented, and use cases highlighting the potential applicability of high-frequency links are discussed. Mobility challenges at these higher frequencies are also discussed. Difficulties that arise as a result of high carrier frequencies and higher path loss can be overcome by practical, higher-gain antennas that have the added benefit of reducing intercell interference. Simulation methodology and results are given. The results show that millimeter wave coverage is possible in large, outdoor spaces, and only a reasonable number of base stations are needed. Network throughput can exceed 25 Gbit/s, and cell-edge user throughput can reach approximately 100 Mbit/s.
    WiGig and IEEE 802.11ad for Multi-Gigabyte-Per-Second WPAN and WLAN
    Sai Shankar N, Debashis Dash, Hassan El Madi, and Guru Gopalakrishnan
    2012, 10(4):  13-22. 
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    The Wireless Gigabit Alliance (WiGig) and IEEE 802.11ad are developing a multigigabit wireless personal and local area network (WPAN/ WLAN) specification in the 60 GHz millimeter wave band. Chipset manufacturers, original equipment manufacturers (OEMs), and telecom companies are also assisting in this development. 60 GHz millimeter wave transmission will scale the speed of WLANs and WPANs to 6.75 Gbit/s over distances less than 10 meters. This technology is the first of its kind and will eliminate the need for cable around personal computers, docking stations, and other consumer electronic devices. High-definition multimedia interface (HDMI), display port, USB 3.0, and peripheral component interconnect express (PCIe) 3.0 cables will all be eliminated. Fast downloads and uploads, wireless sync, and multi-gigabit-per-second WLANs will be possible over shorter distances. 60 GHz millimeter wave supports fast session transfer (FST) protocol, which makes it backward compatible with 5 GHz or 2.4 GHz WLAN so that end users experience the same range as in today’s WLANs. IEEE 802.11ad specifies the physical (PHY) sublayer and medium access control (MAC) sublayer of the protocol stack. The MAC protocol is based on time-division multiple access (TDMA), and the PHY layer uses single carrier (SC) and orthogonal frequency division multiplexing (OFDM) to simultaneously enable low-power, high-performance applications.
    Modeling Human Blockers in Millimeter Wave Radio Links
    Jonathan S. Lu, Daniel Steinbach, Patrick Cabrol, and Philip Pietraski
    2012, 10(4):  23-28. 
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    The loss from multiple human blockers is empirically and analytically investigated at millimeter wave frequencies. Humans are modeled as absorbing screens of infinite height with two knife-edges, while physical optics is used to compute the contribution from rays diffracting around them. This model is validated with blocking gain measurements of multiple human blocking configurations on an indoor link. The blocking gains predicted from physical optics have good agreement with measurements ranging from -50 dB to 2.7 dB, making the absorbing screen model suitable for real human blockers. Mean and standared deviation of prediction error are approximately -1.2 and 5 dB, respectively.
    60 GHz SIW Steerable Antenna Array in LTCC
    Bahram Sanadgol, Sybille Holzwarth, Peter Uhlig, Alberto Milano, and Rafi Popovich
    2012, 10(4):  29-32. 
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    In this paper, we present a 60 GHz substrate-integrated waveguide fed-steerable low-temperature cofired ceramics array. The antenna is suitable for transmitting and receiving on the 60 GHz wireless personal area network frequency band. The wireless system can be used for HDTV, high-data-rate networking up to 4.5 GBit/s, security and surveillance, and similar applications.
    Line-of-Sight MIMO for Next-Generation Microwave Transmission Systems
    Xianwei Gong, Zhifeng Yuan, Jun Xu, and Liujun Hu
    2012, 10(4):  33-38. 
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    Line-of-sight MIMO (LoS MIMO) is not applicable in scattering wireless transmission scenarios, but it may be applied in LoS microwave transmission scenarios if antenna spacing (within transmit and/or receive arrays) is suitable and there is one hop distance. LoS MIMO can improve channel capacity and performance of a transmission system. In this paper, we discuss factors affecting channel capacity and performance in LoS MIMO. We also discuss the feasibility LoS MIMO applications.
    Research Paper
    Terabit Superchannel Transmission: A Nyquist-WDM Approach
    Hung-Chang Chien, Jianjun Yu, Zhensheng Jia, and Ze Dong
    2012, 10(4):  39-44. 
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    In this work, we focus on enhancing the network reach in terabit superchannel transmission by using a noise-suppressed Nyquist wavelength division multiplexing (NS-N-WDM) technique for polarization multiplexing quadrature phase-shift keying (PM-QPSK) subchannels at different symbol-rate-to-subchannel-spacing ratios up to 1.28. For the first time, we experimentally compare the transmission reach of this emerging technique with that of no-guard-interval coherent optical orthogonal frequency-division multiplexing (NGI-CO-OFDM) on the same testbed. At BER of 2 × 10-3 and 100 Gbit/s per channel, an NGI-CO-OFDM terabit superchannel can transmit over a maximum of 3200 km SMF-28 with EDFA-only amplification, and an NS-N-WDM terabit superchannel can transmit over a maximum of 2800 km SMF-28 with EDFA-only amplification. Assuming different coding gain, 11 × 112 Gbit/s per channel with hard-decision (HD) forward-error correction (FEC) and 11 × 128 Gbit/s per channel NS-N-WDM transmission with soft-decision (SD) FEC can be achieved over a maximum of 2100 km and 2170 km, respectively. These are almost equal and were achieved using digital noise filtering and one-bit maximum likelihood sequence estimation (MLSE) at the receiver DSP. Characteristics including the back-to-back (BTB) curves, the ADC bandwidth requirement, and the tolerance to unequal subchannel power of an NS-N-WDM superchannel were also evaluated.
    Parallel Web Mining System Based on Cloud Platform
    Shengmei Luo, Qing He, Lixia Liu, Xiang Ao, Ning Li, and Fuzhen Zhuang
    2012, 10(4):  45-53. 
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    Traditional machine-learning algorithms are struggling to handle the exceedingly large amount of data being generated by the internet. In real-world applications, there is an urgent need for machine-learning algorithms to be able to handle large-scale, high-dimensional text data. Cloud computing involves the delivery of computing and storage as a service to a heterogeneous community of recipients. Recently, it has aroused much interest in industry and academia. Most previous works on cloud platforms only focus on the parallel algorithms for structured data. In this paper, we focus on the parallel implementation of web-mining algorithms and develop a parallel web-mining system that includes parallel web crawler; parallel text extract, transform and load (ETL) and modeling; and parallel text mining and application subsystems. The complete system enables variable real-world web-mining applications for mass data.
    Hierarchical Template Matching for Robust Visual Tracking with Severe Occlusions
    Lizuo Jin, Tirui Wu, Feng Liu, and Gang Zeng
    2012, 10(4):  54-59. 
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    To tackle the problem of severe occlusions in visual tracking, we propose a hierarchical template-matching method based on a layered appearance model. This model integrates holistic- and part-region matching in order to locate an object in a coarse-to-fine manner. Furthermore, in order to reduce ambiguity in object localization, only the discriminative parts of an object’s appearance template are chosen for similarity computing with respect to their cornerness measurements. The similarity between parts is computed in a layer-wise manner, and from this, occlusions can be evaluated. When the object is partly occluded, it can be located accurately by matching candidate regions with the appearance template. When it is completely occluded, its location can be predicted from its historical motion information using a Kalman filter. The proposed tracker is tested on several practical image sequences, and the experimental results show that it can consistently provide accurate object location for stable tracking, even for severe occlusions.
    Design and Implementation of ZTE Object Storage System
    Huabin Ruan, Xiaomeng Huang, and Yang Zhou
    2012, 10(4):  60-64. 
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    This paper introduces the basic concepts and features of an object storage system. It also introduces some related standards, specifications, and implementations for several existing systems. ZTE’s Object Storage System (ZTE OSS) was designed by Tsinghua University and ZTE Corporation and is designed to manage large amounts of data. ZTE OSS has a scalable architecture, some open source components, and an efficient key-value database. ZTE OSS is easy to scale and highly reliable. Experiments show that ZTE OSS performs well with mass data and heavy