In the next generation flexible and dynamic optical network, operators need more intelligent network management. One fundamental requests of such smart network management is to acquire the network status accurately and timely. On the other hand, coherent detection converts the complete information of optical field into electrical digital domain, so that the powerful digital signal processing (DSP) provides large room for performance monitor.
In this talk, we review various monitor technologies and discuss challenges for future. In coherent detection, the DSP compensates various impairments, such as chromatic dispersion, polarization mixing, optical filtering, transceiver imperfections, frequency offset. Based on such compensation function, DSP also knows the impairment itself and could provide the monitor function. With carefully designed training sequence, DSP could monitor optical signal to noise ratio with high nonlinear tolerance. The WDM channel spacing and linear crosstalk could also be monitored. Machine learning is another powerful tool for monitoring, in particular for the complicated task, such as nonlinear distortion monitoring. At transmitter side, DSP could stamp a label on the light, so that the lightpath could be identified in the network.

Zhenning Tao is one of the pioneers in coherent detection and digital signal proccing for optical communication. He leads a research group in Fujitsu R&D center to explore the next generation technology of Fujitsu optical transmission.
He and the group proposed various DSP algorithms for optical communication, including the perturbation based nonlinear compensation in coherent detection. The novel algorithm significantly reduces the computation complexity and was used in the world first nonlinear compensation product. He and his colleague got the 65th Award of Electrical Science and Engineering in 2017, Japan owing to commercialization of nonlinear compensation. His current research interests includes DSP in optical communication, transceiver technology and monitor technology for next generation optical network.
Zhenning Tao has published more than 200 papers in letters, journals and conferences. He holds a doctor degree in communication and information system from Peking University. He is the visiting professor of Beijing University of Posts and Telecommunications.

The optical single-sideband (SSB) technique has attracted considerable interest due to its capability to overcome the frequency-dependent power fading induced by fiber chromatic dispersion. It also doubles the spectral efficiency, compared to double-sideband transmission systems. One of the key system parameters of optical SSB transmission system is the carrier-to-signal-power ratio (CSPR). It is crucial to optimize this parameter in every system since a large CSPR degrades the receiver sensitivity, whereas a low CSPR makes the optical SSB system suffer from the signal-signal beat interference, nonlinear distortions inherent in the direct detection of optical SSB signal. However, it is not always straightforward and easy to measure the CSPR accurately since the optical carrier is located just next to the information-bearing signal, in most cases, without any frequency gap in the spectrum.
In this talk, we review the CSPR measurement techniques for optical SSB signals. The focus will be placed on our recent work on the time-domain CSPR measurement techniques. We present the experimental evaluation of our proposed techniques by comparing them with the conventional frequency-domain techniques using the optical spectrum analyzer.

Tianwai Bo received the B.Eng. degree from Jilin University, China, in 2012 and Ph. D. degree in the area of optical communications from The Chinese University of Hong Kong, Hong Kong, in 2016. Then, he joined KAIST in 2016 as a Postdoctoral Research Fellow. From 2019, he is a Research Assistant Professor at the same institute. His current research interests include short-/medium-reach communication, optical performance monitoring, and digital signal processing for optical communication.

We will discuss encryption schemes based on a 7-D Hyperchaotic System as well as a real-valued chaotic orthogonal matrix transform so as to improve the physical layer security in orthogonal frequency division multiplexing passive optical networks (OFDM-PONs).

Prof. C. K. Chan received his B.Eng., M.Phil. and Ph.D. degrees from the Chinese University of Hong Kong, all in Information Engineering. Upon graduation, he joined the Department of Electronic Engineering at the City University of Hong Kong as a Research Assistant Professor. At both universities, he worked on high-speed all-optical tunable channel multi-access networks and surveillance techniques for fault identification in various kinds of optical network elements. Later, he joined Bell Laboratories, Lucent Technologies, Holmdel, NJ, as a Member of Technical Staff where he worked on an optical packet switch fabric with terabit-per-second capacity. Then, he served as Senior Optical System Engineer at Jedai Broadband Networks, Inc. in NJ, USA where he worked on the design of optical access networks and optical-wireless systems. In August 2001, he joined Department of Information Engineering at the Chinese University of Hong Kong and now serves as a Professor as well as the Chairman of the Department. He has served as members of the Technical Program Committees of many international conferences, including OFC, OECC, ICCCAS, Photonic in Switching, APOC, ICOCN, COIN, ICCS, ICCC, ICCT, PGC, ChinaCom, ICAIT, IPOC, etc. He was an Associate Editor for OSA Journal of Optical Networking and IEEE/OSA Journal of Optical Communications and Networking. He served as the Chairman for IEEE Photonics Society Hong Kong Chapter during 2012-2013. Dr. Chan has published more than 200 technical papers in refereed international journals and conferences, two book chapters on passive optical networks and one edited book on optical performance monitoring. He holds two issued US patents. His research interests include enabling technologies for optical metro/access networks, high-speed optical signal processing techniques, optical performance monitoring and optical network design.

In great efforts to explore high capacity information transmission capability over visible light spectrum, technologies mainly including advanced modulation formats, different solid-state lighting sources and channel equalizations are involved in enabling several Gigabit of the transmission rate over up to meters. However, in pushing visible light communication (VLC) into actual indoor application, lots of considerations should be put in the first place. Those issues include low complexity modulation, only conventional white light LED bulbs as lighting device for the reason of its wide deployment, and moderate equalization in the receiver for the sake of keep Eco system philosophy, etc. It should be pointed out that indoor VLC is in a mobile networking, which can neither be under the strict line-of-sight (LOS) calibration nor lack of the functionality of anti-blocking and anti-shadowing. In such a cooperating system with dual lighting and communication system, multi-Lamps with plenty of non-line-of-sight (NLOS) transmission components are of great importance to alter the rule of thumb in lighting structure design procedure. This talk will be focus on the lighting infrastructure design considering full converge of VLC across a room with as little dead zone as possible. The exploration mainly reveals how to keep the signal-to-noise ratio (SNR) flatten/maximized and inter-symbol interference minimized, under the condition of energy saving lighting infrastructure design fulfilling international office lighting standardization first. Such an infrastructure design should be dynamical which always be ready to be adapt indoor VLC connections along with time-varying environment changes.

JIAN CHEN received the B.S., M.S., and Ph. D. degrees in electronic engineering from Southeast University in 1988, 1990, and 1994, respectively. From 1999 to 2001, he was with the Department of Electrical Engineering of the Korea Advanced Institute of Science and Technology (KAIST), Daejeon, Korea. In 2002, he was with the Institute for Communication Research of National University of Singapore (NUS) as member of technical staff. From 2003, he joined the Communications & Devices Division of the Institute of Infocomm Research (I2R) as a research scientist, Singapore. From 2010 up to now, He is appointed as a full professor in NUPT. He has been engaged in research on optical fiber communication systems and optical access networks for almost 30 years, and in pioneering works in VLC research and development since 2005. His current interests are focusing on visible light communication (VLC) and digital signal processing in coherent optical communications.

In order to further increase the capacity of wireless communication, co-frequency co-time full duplex (CCFD) technique is proposed for 5G system. Because the key challenge of CCFD is self-interference cancellation (SIC), we focus on the realizing of wideband and high carrier frequency SIC by using microwave photonics techniques. In our work, we have proposed a novel optimized SIC method based on integrated dual-parallel Mach Zehnder modulator (DP-MZM). Moreover, in order to process RF signals with high carrier frequency and realize down conversion, a self-polarization stabilizing optoelectronics oscillator (OEO) is integrated to the SIC system, and a microwave photonics down convertor is realized simultaneously. Thus, a microwave photonics RF processing setup with LO generation, down conversion, and self-interference cancellation is realized and integrated into one DP-MZM. In our experiment, 35 dB SIC ratio for single-tone and wideband OFDM signal is observed in 2.4 GHz center frequency. Meanwhile 5×20 MHz LTE-A signal with central-frequency of 12.6 GHz is down-converted to 2.6 GHz, and about 28 dB cancellation ratio is achieved experimentally. Moreover, the phase noise of -108.66 dBc/Hz at 10 kHz away from the carrier (10 GHz) is achieved. These researches provide a solution for integrated microwave photonics RF front-end and promote the using of microwave photonics technique in CCFD wireless communication for 5G and future system.

Lei Deng, professor in school of optical and electronic information, Huazhong University of Science and Technology. His research interests include high-speed fiber communications and fiber wireless communications with high performance optoelectronic integrated chip, advanced modulation formats and radio over fiber technologies. He is now undertaking and participating many national projects, such as National 863 Advanced Technology Foundation Project of China, National Nature Science Foundation Program of China, and Fundamental Research Funds for the Central Universities’ HUST. He was able to publish more than 80 journal and conference papers, of which more than 40 journal papers have been indexed by SCI. All the published papers have been cited more than 900 times, and the H-factor is 14.

Time synchronization technologies enable accurate resource and control coordination in distributed systems and begin to show great potential in optical networking and related areas. Low-cost and precise network time synchronization may play a critical role in future access/metro/regional infrastructure, intra-datacenter networking, cloud/edge computing, optical network status/performance monitoring, optical network security, network operation automation, etc. This talk will share our knowledge of the latest progress in the development of network time synchronization. Also, our high-precision network time synchronization prototype system, as well as some of its preliminary application results in optical networking will be presented.

Prof. Dr. Nan Hua received his B.S. and Ph.D. degrees in electronic engineering from Tsinghua University, Beijing, China, in 2003 and 2009, respectively. He is now an associate professor with the Department of Electronic Engineering at Tsinghua University. He has authored or coauthored more than 100 publications and is the holder of more than 20 issued patents. His current research interests include the control and management of optical networks, all-optical switching technologies, enabling technologies for multi-domain heterogeneous networks, datacenter optical networks, satellite networks, time synchronization networks, network automation, etc. He is a member of the IEEE and OSA.

In this paper, we firstly reviewed our recent research on advanced modulation formats including PAM, bit-loading DMT, DFT-spread DMT for beyond 100G datacenter optical interconnect. And then we will demonstrate and discuss possible schemes for future 400G and 800G optical datacenter optical interconnects.

Fan Li, Associate Professor, Sun Yat-Sen University. He obtained the Ph.D. degree in information and communication engineering from Hunan University, Changsha, China, in 2014. From 2012 to 2014, he worked as a visiting scholar in Georgia Institute of Technology under the supervision of Professor Gee-Kung Chang. After that, he worked as a research engineer in optical transmission labs in ZTE TX, New Jersey for two years. His research interests include Datacenter optical interconnects, Fiber wireless integration, Direct-detection and coherent transmission systems, Optical OFDM.

With the flourish of high-speed internet access, high resolution multi-media entertainment with virtual reality and machine-to-machine communications, the global mobile data traffic in the 5G era will grow exponentially. As the key component of centralized radio access network, mobile fronthaul (MFH) faces great challenges such as demands of higher capacity, higher bandwidth efficiency, lower latency, and lower cost. To address these issues, both digital and analog radio-over-fiber based MFH architectures have been widely investigated, due to the excellent immunity to nonlinear distortions and high bandwidth efficiency, respectively. However, the digital MFH has the drawback of relatively low bandwidth efficiency; analog MFH suffers from high sensitivity to nonlinear distortions and the relatively high implementation complexity, which are the key issues in 5G MFH.
To resolve the key problems above, we propose and experimentally demonstrate the digital MFH architecture employing high order delta-sigma modulator with PAM-4 format, differential pulse coding modulation with employing noise shaping, enhanced noise shaping based pulse code modulation, and discrete cosine transform combined with multi-band quantization, respectively. Besides this, the analog MFH architecture employing digital code-division multiplexing (CDM) channel aggregation is firstly proposed. Synchronous transmission of both the I/Q waveforms of wireless signals and the control words used for the purpose of control and management using the CDM approach is also presented and proof-of concept experiments are carried out. Finally, a code reservation technique is proposed to reduce the peak-to-average power ratio (PAPR) of CDM based channel aggregation for analog MFH.

Haibo Li is currently a research engineer in the State Key Laboratory of Optical Communication Technology and Network, China Information Communication Technologies Group Corporation. He received the B.S. degree in the Institute of Mathematics and Statistics from Huazhong University of Science and Technology in 2009, M.S. degree in department of Electronics and Information Technology from Huazhong University of Science and Technology in 2012, and Ph.D. degree in Wuhan National Laboratory for Optoelectronics & School of Optical and Electronic Information, Huazhong University of Science and Technology in 2018. His current research interests include high speed optical access networks, mobile fronthaul, radio-over-fiber technology, passive optical networks, advanced modulation technology, real-time optical communication, coherent optical communication, and long distance transmission.

In recent years, artificial intelligence (AI) is becoming increasingly important and many countries have taken it as the future research focus in the next few years. In the field of operation, administration and maintenance (OAM) of optical networks, AI also has a significant guiding and application value. It can decrease the complexity and improve the implementation efficient of the OAM of optical networks, and helps to optical network optimization design. AI is a collective name, covering a variety of individual technologies such as decision tree, association rules, support vector machine (SVM), artificial neural networks (ANN), Bayesian networks, genetic algorithms, etc. In the presentation, the speaker will first give a brief introduction to the above technologies. Then, he focuses on the application of artificial intelligence in performance monitoring of optical networks. The problem of optical signal-to-noise ratio (OSNR) prediction and availability prediction for light-paths and light-trees will be elaborated in detail.

Dr. Xin Li is currently a Lecturer at Beijing University of Posts and Telecommunications. He received the Ph.D. degree in communication and information system from Beijing University of Posts and Telecommunications in 2014. From Jul. 2015 to Jul. 2017, he did postdoctoral research in Beijing University of Posts and Telecommunications. He has been actively undertaking several national projects, published more than 50 journals and conferences, and applied for more than 20 patents. He was awarded the Best Achievement Award by State Key Laboratory of Information Photonics and Optical Communications in 2018. His current research interests include the networks designing and planning, routing algorithms and performance analysis, software-defined optical networking, artificial intelligence, network survivability, photonic firewall, etc.

Mobile edge computing (MEC) is a promising solution to meet the latency requirement for delay-sensitive services in a 5G radio access network (RAN). Its key idea is to deploy computing and storage capacities at the edge of the RAN to quickly provision content and processing capacities as required by users. Efficient content caching and delivery are key issues to ensure the success of this technique. This paper proposes a zone-based cooperative content caching and delivery scheme for a RAN supporting MEC (MEC-RAN), where the RAN is modelled as a zone and is further sub-divided into multiple sub-zones. Content items are cooperatively cached and delivered among multiple sub-zones. The caching problem is formulated as a mixed integer linear programming (MILP) model. We also develop a heuristic cooperative content caching strategy (MixCo) to decide the content items to be cached in each MEC server. This novel strategy divides the storage space in each MEC server into two parts. The first part caches locally popular contents and the second is used to cooperatively cache zone-wide popular items. We study the proposed scheme both through simulations and implementation on a testbed that consists of a subnetwork on our campus and a commercial cloud service from Ali-Cloud. Both of these show that the proposed zone-based scheme performs better than other typical caching strategies in terms of average content delivery latency and balanced loading of the MEC servers.

Gangxiang Shen received his B.Eng. degree from Zhejiang University, China; his M.Sc. degree from Nanyang Technological University, Singapore; and his Ph.D. degree from the University of Alberta, Canada, in January 2006. He is a Distinguished Professor with the School of Electronic and Information Engineering of Soochow University in China. Before he joined Soochow University, he was a Lead Engineer with Ciena, Linthicum, Maryland. He was also an Australian ARC Postdoctoral Fellow with University of Melbourne. His research interests include integrated optical and wireless networks, spectrum efficient optical networks, and green optical networks. He has authored and co-authored more than 150 peer-reviewed technical papers, among which one of the papers received the highest citations among all the papers published in IEEE/OSA JOCN. He was a Lead Guest Editor of IEEE JSAC Special Issue on “Next-Generation Spectrum-Efficient and Elastic Optical Transport Networks,” and a Guest Editor of IEEE JSAC Special Issue on “Energy-Efficiency in Optical Networks.” He is an associated editor of IEEE/OSA JOCN, and an editorial board member of Optical Switching and Networking and Photonic Network Communications. He has served as TCP chairs for various international conference in the area of optical networking, including general TPC co-chair of ACP 2018 and symposium lead chair of GLOBECOM 2017. He received the Young Researcher New Star Scientist Award in the “2010 Scopus Young Researcher Award Scheme” in China. He was a recipient of the Izaak Walton Killam Memorial Award from the University of Alberta and the Canadian NSERC Industrial R&D Fellowship. He is a “Highly Cited Chinese Research Scholar” selected by Elsevier (from 2014 to 2017) and an “Excellent Young Research Scholar” sponsored by NSFC. He was a Secretary for the IEEE Fiber-Wireless (FiWi) Integration Sub-Technical Committee. He is serving as a member of IEEE ComSoc Strategic Planning Standing Committee and an IEEE ComSoc Distinguished Lecturer (2018-2019).

Optical wireless technologies have been widely studied in short-range indoor applications to provide high-speed wireless communications in personal working and living spaces and to meet the rapidly growing bandwidth demand of end users. In previous studies, we have demonstrated over 10 Gb/s data rate using the near-infrared indoor optical wireless communication technology, by combining limited mobility with user localizations. However, the system has two major limitations: firstly, since the direct line-of-sight (LOS) is used for high-speed optical wireless data transmission, the system is vulnerable to physical shadowing and blocking; and secondly, the mobility can be provided is limited since the maximum transmission power is constrained by safety regulations. To overcome these issues, we proposed and investigate the use of spatial diversity principle, where multiple transmitters are used for near-infrared optical wireless communications simultaneously. Robust indoor optical wireless communications with data rate of 10 Gb/s are experimentally demonstrated. Both the space-time-block code (STBC) and the repetition code (RC) based schemes are studied, and results show that the RC scheme is capable of achieving better bit-error-rate (BER) results. Results also show that the spatial diversity schemes require precise synchronization to achieve the benefit, which is challenging in high-speed wireless communications. To overcome this issue, we further propose and demonstrate a delay-tolerant optical wireless communication system with spatial diversity, which is achieve by using orthogonal spatial filters. Experimental results show that there is no BER degradation even with up to 10 symbol delays.

Dr Ke Wang receives his B.Sc. degree from Huazhong University of Science and Technology, and the PhD degree from The University of Melbourne, Australia, in 2014. He is currently an Australian Research Council (ARC) DECRA Fellow and a Senior Lecturer at the School of Engineering, Royal Melbourne Institute of Technology (RMIT University). Before joining RMIT, Dr Wang was an Assistant Professor at Stanford University, USA. Dr Wang’s major research areas include high-speed wireless communications, optical wireless technologies, optical interconnects, quasi-passive optical nodes, and silicon photonic integrations. He has published over 115 papers, including over 20 invited papers. Dr Wang is an Assessor for ARC, and is also the Academic Mentor of the OSA RMIT Branch. Dr Wang has received numerous prestigious awards for his research excellence, including the Victoria Fellowship, the AIPS Young Tall Poppy Science Award, the Fresh Science Award, and the Marconi Society Paul Baran Young Scholar Award.

Based on the fundamental laws of quantum physics, quantum key distribution (QKD) promises to achieve the unconditional security in communication without making assumptions on the computational power of the potential eavesdropper. Single-photon QKD is one of the most in-depth and hottest research directions, and some companies even have launched related commercial products. The presentation will introduce the motivation and the current state of the art of experimental works in single-photon QKD. In particular, the concepts of single-photon QKD together with its assumption, security and limitations are discussed. After presentation of some practical QKD systems and field QKD networks, the latest developments in measurement-device-independent QKD, round-robin differential phase shift QKD, and twin-field QKD are introduced.

Shuang Wang, received the Ph.D. degrees in optics from the University of Science and Technology of China in 2011. In the same year, he joined and CAS Key Laboratory of Quantum Information, University of Science and Technology of China, and became a professor in 2017. His current research interest is quantum key distribution (QKD) or quantum cryptography, including the security and systems of QKD, QKD network, quantum random number generator, and single photon detector.

The emerging 5G network will bring a huge amount of network traffic with big variations to optical transport networks. Software-defined optical networks and network function virtualization share a vision for future programmable, disaggregated, and dynamic optical networks. Programmable optical hardware with a reduced link margin improved the hardware utilization by introducing flexible network functions. Therefore, future optical networks will be more dynamic in network functions and network services, with high-frequency network reconfigurations. To configure network dynamically, real-time network abstractions are required for both current links and available-for-deploy links. The former abstraction guarantees the established links not be interfered by the newly established link while the latter abstraction provides information for network optimizations. In this talk, we use machine-learning technologies to process the collected monitoring data in a field-trial testbed to abstract performances of multiple optical channels. Based on the abstract information, a new channel can be established with maximum performance and minimized interferences on the current signals. We demonstrated the dynamic network abstraction over a 560-km field-trial testbed for 8 dynamic optical channels.

Dr Shuangyi Yan is a lecturer in High Performance Networks group at the department of Electrical & Electronic Engineering, University of Bristol. He received the B.E degree in information engineering from Tianjin University, Tianjin, China in 2004. In 2009, he got the PhD degree in optical engineering from Xi’an Institute of Optics and Precision Mechanics, CAS, Xi’an, China. From 2011 to 2013, he worked on the spectra-efficient long-haul transmission system and low-cost short-range transmission system in Photonics Research Centre, Dept. EIE of the Hong Kong Polytechnic University, Hong Kong. In July 2013, he joined the High Performance Networks Group at University of Bristol. His research interests include multi-dimensional programmable optical networks, multi-layer network analytics for network optimization, and next generation data center networks. He is the author or co-author of over 60 publications, of which consist several post deadline papers in optical communication related top-level conferences.

After 100-Gb/s coherent transponder is commercialized, wavelength-division-multiplexing (WDM) technique enables 8-Tb/s total capacity of single mode fiber in core-network. Bandwidth demand of various internet services drives network capacity improvement continuously. Single channel speed has increased from 100-Gb/s to 400-Gb/s and beyond, while commercial system capacity have reached 19.2 Tb/s, which is expected to increase to 100-Tb/s in future. However, as the capacity is improved in terms of higher order modulation, the transmission distance is reduced. Thus, advanced modulation technologies, such as constellation shaping and spectrum shaping, are used to extend transmission distance in different ways. Moreover, additional available band of optical fiber can increase system capacity further. Nevertheless, it is required to carefully handle fiber nonlinearity in high density WDM system, which becomes significant as channel number increases. Nonlinear effect mitigation and compensation play a key role of capacity improvement, after the linear performance has been closed to Shannon limit. In addition, low-loss large-effective-area fiber is proposed to be an effective solution for next generation high capacity transmission system which brings the benefits of OSNR improvement and nonlinearity mitigation.

Dr. Yu Yi got Ph.D degree from National University of Singapore in 2015, and joined network technology research department in Huawei Technologies from 2015. His research work is focused on high capacity transmission system and oDSP. He published more than 30 Academic papers and 6 patents in related area.

With the development of hardware facilities and parallel computation, machine learning (ML) has once again received widespread attention and been introduced into nonlinearity mitigation, optical performance monitor and optical network, etc. The operating mechanism of most ML based equalizers is nonlinear classification, which generates a nonlinear classification boundary through supervised or unsupervised training, e.g. the clustering, deep neural network (DNN) , statistical learning algorithm. There is also growing interest in deep learning to realize different parameters’ monitoring and overcome the bottleneck of monitoring when different impairments are physically inseparable in traditional OPM.
We review our recent work on the application of machine learning in optical fiber communication, especially the nonlinear equalization and optical performance monitoring, including OSNR and chromatic dispersion. We use different neural network (NN) equalization schemes to mitigate the fiber nonlinearity. The BER can be reduced by half. We propose to use transfer learning for ONSR monitoring. The root mean squared error (RMSE) of OSNR estimation can be less than 0.1 dB.

Jing Zhang, received the B.S. and Ph.D. degree in optical engineering from the University of Electronic Science and Technology of China, Chengdu, China, in 2013. She has been with the University of Electronic Science and Technology of China since 2007, where she is currently an Associate Professor. From 2015to 2016, she was a Visiting Research Scholar with the Department of Electrical and Computer Engineering, National University of Singapore, Singapore. Her current research interests include optical fiber communication and network, digital signal processing at the transceiver, nonlinear equalization with machine learning.

Offset quadrature amplitude modulation orthogonal frequency division multiplexing (offset-QAM OFDM) can eliminate the cyclic prefix required in OFDM for channel compensation. However, conventional compensation schemes in offset-QAM OFDM are only applicable to cases where dispersion-induced delay difference between subcarriers is much smaller than the OFDM symbol period. In this talk, we will analyze the fundamental mechanism limiting the dispersion tolerance of offset-QAM OFDM, and show that the orthogonality between the signal and the intrinsic imaginary interference (IMI) can be maintained even when any subcarrier has any time delay, provided that the phase difference between subcarriers satisfies a certain condition and the sampling phase of each subcarrier is recovered. Based on the analysis, we propose several channel compensation schemes to enhance the dispersion tolerance beyond the point where the maximal delay difference between subcarriers is comparable to or larger than the OFDM symbol period. Simulations and experiments are performed to verify the effectiveness of the proposed schemes. We also compare offset-QAM OFDM based on the proposed schemes and conventional OFDM, and show that offset-QAM OFDM gives better transmission performance than conventional OFDM.

Jian Zhao received the B.Eng. degree from the University of Science and Technology of China in 2002, and the M.Phil. and Ph.D. degrees from the Chinese University of Hong Kong in 2004 and 2007, respectively. In August 2007, he joined Tyndall National Institute, where he established an independent team in 2012. In 2018, he joined the South China University of Technology (SCUT) as a full professor, under the support of the “1000 Youth Talent Program”. At Tyndall, he captured €2.4 million funding as the principal investigator from Science Foundation Ireland (SFI), European Commission, Industry, and Enterprise Ireland. He was also the Co-PI of two Hong Kong RGC projects. He was the recipient of SFI Career Development Award, Starting Investigator Research Award, and Technology Innovation and Development Award. The team he led was the EMEA finalist in Alcatel-Lucent Innovation Competition. Prof. Zhao has published 130+ technical papers (18 invited) in peer-reviewed international journals and conferences. His current research interests include optical OFDM, advanced modulation and detection schemes, fiber nonlinearity mitigation, and visible light communications. Prof. Zhao served in 10+ international conferences as a TPC member, and is a reviewer for Funding for Scientific Research Belgium, HK RGC, and various journals including Nature Communications, Optics Express, Journal of Lightwave Technology (a top reviewer of 2015 and 2016), etc.

In 5G/IoT and beyond, the larger traffic volume, higher connection density and/or more stringent requirement on latency will put heavy burden on the radio access networks including their edge -- fronthaul. In this talk, we will introduce some recent progress of "overloading" techniques based on digital signal processing to improve fronthaul utilization with low latency. The technical principles and hardware implementation aspects will be discussed.
This work was partially supported by the R&D contract (FY2017~2020) “Wired-and-Wireless Converged Radio Access Network for Massive IoT Traffic” for radio resource enhancement by the Ministry of Internal Affairs and Communications, Japan.

Paikun Zhu received Ph.D. degree in 2017 from Peking University, China. Since 2017 he has been a project assistant professor at GPI, Japan, collaborating with NICT, Japan. He has co-authored over 60 IEEE/OSA publications. He has served as a journal reviewer of Optics Express, IEEE Photonics Technology Letters, etc. He is a recipient of 2016 SPIE Optics & Photonics Education Scholarship. His current research interests include fiber-wireless converged system, signal processing and optical networks.