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Unifying eigen-mode MIMO transmission

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Science in China(Series F) 2009年第12期52卷 2269-2278页

作者： GAO XiQi YOU XiaoHu JIANG Bin WANG WenJin JIN Shi National mobile communications research Laboratory Southeast University Nanjing 210096 China

Multiple-input multiple-output （MIMO） technique plays a key role in improving the spectrum and power efficiency in future mobile communication systems. Exploiting a unified MIMO transmission scheme that can adapt with various channel conditions is well motivated both in theory and practical applications. An eigen-mode based closed-loop MIMO transmission over frequency selective fading MIMO channels, which considers receive correlation, transmit correlation and line of sight （LOS） components, is investigated by maximizing the upper bound of channel capacity under the assumption that the channel is partially known at the transmitter and perfectly known at the receiver. Based on the eigen-mode transmission, several key techniques including linear precoding, stream selection, virtual spatial hopping and online capacity estimation are proposed, and a unified MIMO transmission scheme is established. Both computer simulation and field test results show that the proposed scheme can significantly improve the spectral efficiency and link reliability under various channel conditions.

关键词： MIMO eigen-mode closed-loop MIMO transmission

When It Strikes,Are We Ready?Lessons Identified at the 7th Planetary Defense Conference in Preparing for a Near-Earth Object Impact Scenario

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International Journal of Disaster Risk Science 2022年第1期13卷 151-159页

作者： Shirish Ravan Tom De Groeve Lara Mani Einar Bjorgo Richard Moissl Jose Miguel Roncero Katherine Rowan David Schuld Leviticus A.Lewis Romana Kofler United Nations Office for Outer Space Affairs(UNOOSA) United Nations1220 ViennaAustria European Commission Joint research Centre 21027 IspraItaly Centre for the Study of Existential Risk University of CambridgeCambridge CB21SBUK division for Satellite Analysis United Nations Institute for Training and Research(UNITAR)1202 GenevaSwitzerland European Space Agency/European Space research and Technology Centre(ESA/ESTEC) 2201 AZ NoordwijkThe Netherlands Security and Situational Awareness Unit European Commission's Directorate-General for European Civil Protection and Humanitarian Aid Operations1049 BrusselsBelgium Department of communication George Mason UniversityFairfaxVA 22030USA Hagerty Consulting EvanstonIL 60201USA Response Operations division Federal Emergency Management AgencyWashingtonDC 20024USA

Near-Earth object(NEO)impact is one of the examples of high impact and low probability(HILP)event,same as the Covid-19 pandemic the world faces since the beginning of *** 7 th Planetary Defense Conference held by the International Academy of Astronautics(IAA)in April 2021 included an exercise on a hypothetical NEO impact event,allowing the planetary defense community to discuss potential *** the span of the 4-day conference this exercise connected disaster response and management professionals to participate in a series of panels,providing feedback and perspective on the unfolding crisis *** hypothetical but realistic asteroid threat scenario illustrated how such a short-warning threat might *** scenario utilized during the conference indicates a need to prepare now for what might come in the future,because even with advance notice,preparation time might be *** scenario chose Europe for the impact,which may likely cope with such a disaster,through the Union Civil Protection Mechanism(UCPM)and other solidarity and support mechanisms within the European Union(EU),as well as with potential support from international *** short article raises concern about other areas in the world on how they may access NEO impact information and cope with such *** also provides an idea on vast scale of such disaster vis-a-vis the current capacity of response systems to cope with a larger event in Europe or *** scenario showed that planetary defense is a global *** engagement of the planetary defense and disaster response communities is essential in order to keep the world safe from potential disasters caused by NEO impacts.

关键词： Asteroid threats Disaster risk reduction Planetary defense Risk management and prevention

Phase Noise Pre-correction Scheme for SC-FDMA Signals in LTE-Uplink

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Chinese Journal of Electronics 2017年第3期26卷 634-639页

作者： XU Zijie REN Guangliang ZHANG Yang State Key Laboratory of Integrated Service Networks Xidian University National mobile communications research Laboratory Southeast University

This paper proposes a novel carrier Phase noise(PN)pre-correction scheme with an adaptive PN prediction algorithm for Single-carrier Frequency-division multiple-access(SC-FDMA)systems to alleviate degradation due to the *** proposed PN prediction algorithm is a modified polynomial fitting algorithm which is based on receding horizon *** parameters of the prediction model are optimized by using the algorithm on PN samples of the local oscillator signal in a training *** using the optimized prediction model parameters and the latest PN samples,we can predict future PN *** these predicted PN samples are put into our proposed PN pre-correction scheme and the SC-FDMA symbols at the transmitter are *** to the absence of the radio frequency delay device,the proposed scheme has a low hardware *** results show that our proposed scheme can greatly reduce the effect of the PN on the transmitted SC-FDMA signal.

关键词： Phase noise(PN) Single-carrier Frequency-division multiple access(SC-FDMA) Prediction algorithm

Potential key technologies for 6G mobile communications

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Science China(Information Sciences) 2020年第8期63卷 217-235页

作者： Yifei YUAN Yajun ZHAO Baiqing ZONG Sergio PAROLARI China mobile ZTE Corporation

The standard development of 5G wireless communication culminated between 2017 and 2019,followed by the worldwide deployment of 5G networks, which is expected to result in very high data rate for enhanced mobile broadband, support ultrareliable and low-latency services and accommodate massive number of connections. research attention is shifting to future generation of wireless communications, for instance, beyond 5G or 6G. Unlike previous studies, which discussed the use cases, deployment scenarios,or new network architectures of 6G in depth, this paper focuses on a few potential technologies for 6G wireless communications, all of which represent certain fundamental breakthrough at the physical layer —technical hardcore of any new generation of wireless communications. Some of them, such as holographic radio, terahertz communication, large intelligent surface, and orbital angular momentum, are of revolutionary nature and many related studies are still at their scientific exploration stage. Several technical areas, such as advanced channel coding/modulation, visible light communication, and advanced duplex, while having been studied, may find more opportunities in 6 G.

关键词： 6G holographic radio terahertz large intelligent surface orbital angular momentum advanced channel coding modulation visible light communication

Capacity and Flexibility Improvement of Traffic Aggregation for Fixed 5G:Key Enabling Technologies,Challenges and Trends

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China communications 2022年第12期19卷 1-13页

作者： Jing Zhang Tianhai Chang Zhuqiang Zhong Xianqing Jin Shaohua Hu Taowei Jin Jiahao Zhou Mingyue Zhu Yi Yu Jianming Tang Liangchuan Li Kun Qiu School of communication and Information Engineering University of Electronic Science and Technology of ChinaChengduSichuan 611731China Optical research Dept Huawei Technologies518129ShenzhenChina School of Electronic Engineering Bangor UniversityBangorLL571UTUK

As the emergence of various highbandwidth services and the requirements to support 5G/Wi-Fi 6 wireless networks,the next generation fixed networks,i.e.F5G,are expected to be realized in the 5G era.F5G is endowed with new characteristics,including ultra-high bandwidth,all-optical connections and optimal service *** the prospect of optical-to-everywhere,optical technologies are used for mobile front-haul,mid-haul,and *** access networks would play an important role in F5G to support radio access network and fixed access ***-latency PON is a key for cost effective-haul traffic *** terms of signal transmission,intensity modulation directdetection(IM-DD)is a promising scheme due to its simple *** fundamental challenge associated with direct-detection is the disappearance of the transmitted signal’s *** access network,the flexibility and low latency are the two key factors affecting service *** this article,we review the evolution of PONs and the challenges of current PONs in *** analyze key enabling digital signal processing(DSP)techniques,including detection linearization for direct-detection and simplified coherent detection,adaptive equalizers,digital filer enabled flexible access network and low-latency inter-ONU ***,we discuss the developing trends of future optical access networks.

关键词： optical fiber communication flexible access network optical field recovery inter-ONU communication

HF communications: Past, Present, and future

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China communications 2018年第9期15卷 1-9页

作者： Jinlong Wang Guoru Ding Haichao Wang College of communications Engineering Army Engineering University of PLA National mobile communications research Laboratory Southeast University

High frequency(HF) communication, commonly covering frequency range between 3 and 30 MHz, is an important wireless communication paradigm to offer over-thehorizon or even global communications with ranges up to thousands of kilometers via skywave propagation with ionospheric refraction. It has widespread applications in fields such as emergency communications in disaster areas, remote communications with aircrafts or ships and non-light-of-the-sight military operations. This tutorial article overviews the history of HF communication, demystifies the recent advances, and provides a preview of the next few years, which the authors believe will see fruitful outputs towards wideband, intelligent and integrated HF communications. Specifically, we first present brief preliminaries on the unique features of HF communications to facilitate general readers in the communication community. Then, we provide a historical review to show the technical evolution on the three generations of HF communication systems. Further, we highlight the key challenges and research directions. We hope that this article will stimulate more interests in addressing the technical challenges on the research and development of future HF radio communication systems.

关键词：无线通讯 HF 技术进化通讯系统频率范围应用程序紧急情况高频率

A CODE DESIGN CRITERIA FOR NOT FULLY CONNECTED CHANNEL

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Journal of Electronics(China) 2006年第2期23卷 193-196页

作者： Xiao Haiyong Bi Guangguo Zhang Peng Jin Xiufeng National mobile communication research Lab Southeast University Nanjing 216096 China

There are parallel channels which are not fully connected in practice, such as Frequency division Multiplex (FDM or Orthogonal FDM) systems. Conventional space-time codes can be used for such parallel channels but not the optimal. Based on the derivation of PEP expression for codes transmitted on parallel block fading channels, criteria of codes design for not fully connected channels are proposed and are compared with Tarokh's criteria for fully connected channel. New codes for such channels are provided by systematical and exhaustive search. Simulation results show that these codes offer better performance on parallel FDM channels than other known codes.

关键词：块衰退信道平行信道空间时间代码正交平分复用系统

Does Amplify-and-Forward Cooperative Relay Improve OFDM/OFDMA Ergodic Capacity？

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China communications 2014年第2期11卷 83-89页

作者： HUANGFU Wei ZHANG Zhongshan ZHANG Dandan LONG Keping School of Computer and communication Engineering Beijing Engineering and Technology Center for Convergence Networks andUbiquitous Services University of Science and Technology Beijing (USTB) No. 30Xueyuan Road Haidian District Beijing China 100083 National mobile communications research Laboratory Southeast University Nanjing China 210096

The ergodic information rate for Orthogonal Frequency-division Multiplexing/ Orthogonal Frequency-division Multiple Access with amplify-and-forward(AF)relaying systems in the presence of frequency offsets is *** previous work,per-subcarrier adaptive power allocation is performed on each relay to optimize the system ergodic information *** a given frequency offset and total number of relays M,the AF ergodic information rate is proven to be a monotonically increasing function of a(the ratio of the power allocated to the source node and the total transmit power),implying that the maximum ergodic information rate can be obtained at α=1(i.e.,there is no cooperative relay).Furthermore,the proof of "cooperative relays cannot improve the AF ergodic information rate in a quasi-static wireless channel" is also provided in this letter.

关键词：中继系统 OFDMA 遍历放大转发正交频分复用信息速率协同

Sort-based relay selection algorithm for decode-and-forward relay system

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Science China(Information Sciences) 2013年第2期56卷 41-48页

作者： XIE Gang LIU YuanAn GAO JinChun LI XingZheng Beijing Key Laboratory of Network System Architecture and Convergence Beijing University of Posts and Telecommunications School of Electronic Engineering Beijing University of Posts and Telecommunications division of research China Mobile Group Design Institute Co.

In this paper, a sort-based relay selection algorithm is proposed for decode-and-forward wireless relay systems. The proposed algorithm can reduce computational complexity and system overhead in the relay selection for practical decode-and-forward wireless relay systems with multiple sources and multiple relays. This would be a very important improvement. Firstly, the sufficient and necessary conditions for a relay to be feasible to a source are derived. By adopting relay transmission via its feasible relay, the source can improve channel capacity compared to direct transmission. Then, a sort-based relay selection algorithm is proposed based on the sufficient and necessary conditions. In the proposed algorithm, each relay makes decision on its feasibility individually, but the final source-relay paring decision is made in a centralized manner. Simulation results show that the proposed algorithm can provide considerable system performance improvement over the existing algorithm. Especially at low signal-to-noise (SNR) region, the performance of the proposed algorithm almost reaches the optimal one.

关键词： relay selection decode-and-forward relay cooperative communication wireless relay system