应哈工大电信学院韩帅副教授、孟维晓教授邀请，在国家外国专家局高端外国专家项目(文教类) 资助下，在IEEE ComSoc Harbin Chapter和IEEE VTS Harbin Chapter的联合支持下，无线通信领域国际知名学者、不列颠哥伦比亚大学Julian Zhishen Cheng教授将于2019年5月13日—2019年5月18日来哈尔滨工业大学访问讲学。
讲学题目1：When Free-Space Optical Communications Meets Unmanned Aerial Vehicles
讲学时间：2019年5月14日下午1:30-3:00
讲学地点：哈工大科学园2A栋1011会议室
讲座人：Julian Zhishen Cheng
Abstract: The fifth-generation (5G) wireless network is expected to leap ahead of current wireless technologies by offering a variety of remarkable services, and it will pave the way for new types of data-hungry applications. To reach this milestone, it is necessary to enhance the network capacity through an ultra-dense deployment of low-power and low-cost remote radio heads (RRHs). However, due to the RF spectrum scarcity, the data explosion challenge triggered by such data-rate-hungry services cannot be well addressed by using RF-based networks alone. Optical fibers have so far been considered as a high capacity solution for establishing front-haul links while network operators have to seek municipal approval for digging up a street to lay its cable. However, because of cell densification as well as the wide deployment of RRHs in 5G, the number of existing fiber links used for a front-haul connection is limited. To cope with these challenges, the idea of employing free space optical (FSO) communication has been recently proposed for establishing back-haul and front-haul links as an alternative easy-to-deploy solution to traditional optical fiber communication. Indeed, recent advances in small-scale unmanned aerial vehicles (UAVs) has opened up new horizons for establishing UAV-FSO links. In this talk, a state-of-the-art literature review on UAV-based FSO communications is provided. Moreover, the technical challenges of establishing UAV-based FSO links as well as the proposed solution to confront such challenges are expressed in details.
讲学题目2：80 Years of Research on Sum of Lognormal Random Variables: Recent Breakthroughs and Applications in Wireless Communications
讲学时间：2019年5月14日下午3:15-4:45
讲学地点：哈工大科学园2A栋1011会议室
讲座人：Julian Zhishen Cheng
Abstract: The distribution for the sum of lognormal random variables finds applications in many science and engineering disciplines, and it is particularly important for wireless communication engineers. However, the distribution for the simplistic sum of independent lognormal random variables is analytically intractable, and it is more so for a sum of correlated lognormal random variables with non-identical parameters. In 1934, Wilkinson from Bell Telephone Labs first studied this problem in an unpublished work. Since then, various approximations have been proposed in the literature. All these approximations fail to accurately quantify the left tail (or right tail) behavior of the distribution function of a sum of lognormal random variables. In this talk, in the context of diversity receptions over lognormal fading channels, we first present that the left tail distribution of the sum of independent lognormal random variables can be accurately represented by a Marcum Q-function. The proposed analytical result outperforms all existing well-known sum of lognormal approximations. Using a different approach, we then extend the problem to a sum of correlated and non-identically lognormal random variables, and show that its left-tail distribution can again be represented by another Marcum Q-function. Our study reveals a number of new and surprising engineering insights into the transmission characteristics over the lognormal fading channels. For example, for the dual-branch case, we show that the outage performance of negatively correlated lognormal channels is better than that of independent lognormal channels. We also show that under certain parameter conditions, one of the two lognormal channels can contribute no performance gain to the diversity reception systems. This implies that one link can be discarded without causing asymptotic performance loss. These new findings can guide the communication engineers to design better systems for transmission over the lognormal fading channels.
讲学题目3：Multiple Scattering Models for Scattering Based Optical Wireless Communication
讲学时间：2019年5月16日上午9:00-10:30
讲学地点：哈工大科学园2A栋1011会议室
讲座人：Julian Zhishen Cheng
Abstract: Scattering based optical wireless communications, e.g., ultraviolet communication and underwater optical communication, have attracted increasing attention for their valuable military and civil implementations. Multiple scattering effects have to be considered in accurate channel path loss and impulse response estimations. By now, the Monte-Carlo method based channel models are used for modeling the multiple scattering channel in both ultraviolet communication and underwater optical communication. This presentation focuses on a special Monte-Carlo model: the Monte-Carlo integration (MCI) model. We proved the feasibility of obtaining system impulse response function by MCI model for the first time. After analyzing the convergence performance of the MCI model, we proposed an improved MCI model based on the partial importance sampling method (MCI-PIS model). Numerical simulation for the computation efficiency of different Monte-Carlo models suggests that for a three-order scattering case, the computation efficiency of the MCI-PIS model is about 12 times of the original Monte-Carlo integration model based on uniform sampling (MCI-US model) and 5.6 times of the widely used Monte-Carlo simulation (MCS) model for ultraviolet communication, and 10.6 times and 2.12 times of those for the underwater optical communication. The numerical results also suggest that the computation efficiency of the MCI-PIS model can be higher in a higher scattering order communication compared to the MCS model. We provided a new optimizing direction for the improvement of Monte-Carlo channel models for the scattering based optical communications
讲学题目4：How to Write an IEEE Style Paper and Get it Published?
讲学时间：2019年5月16日上午10:30-12:00
讲学地点：哈工大科学园2A栋1011会议室
讲座人：Julian Zhishen Cheng
Abstract: Institute of Electrical and Electronics Engineers (IEEE) is world’s largest professional association which is best known, among other engineering disciplines, for its high quality flagship journal and conference publications. For electrical engineering graduate students and researchers, it is increasingly important to publish their research findings in core IEEE journals and conferences. However, most top IEEE journals and conferences typically have acceptance rate at 35% or much less, and it is also rare that a manuscript receives an outright acceptance. In this talk, I will introduce basic elements of an IEEE style paper, and offer some personal tips and strategies on how to improve the odds of acceptance. The goal of this presentation is to provide the proper guidance to the beginning graduate students so that, with some practice, they can write an IEEE style paper with high confidence. These graduate students can then focus more on the technical contributions of their work.
Biography:
Julian Cheng received his B. Eng. degree in electrical engineering from University of Victoria, Victoria, BC, Canada, M.Sc. (Eng.) degree in Mathematics and Engineering from Queen’s University, Kingston, ON, Ph.D. degree in electrical engineering from University of Alberta, Edmonton, AB, Canada. He is currently a Full Professor in the School of Engineering, Faculty of Applied Science, at The University of British Columbia, Okanagan campus in Kelowna, BC, Canada. His current research interests include wireless communication theory, wireless networks, optical wireless communications, and quantum communications. Dr. Cheng has served as a member of technical program committee for many IEEE conferences and workshops. He co-chaired the 12th Canadian Workshop on Information Theory (CWIT 2011) in Kelowna, Canada. In 2012, he chaired the 2012 Wireless Communications in Banff, Canada. Dr. Cheng also chaired the sixth IEEE Optical Wireless Communications Symposium at the 2015 IEEE Global Communications Conference. He now volunteers as an Area Editor for IEEE Transactions on Communications. In the past, he served as an Associate Editor for IEEE Transactions on Communications, IEEE Transactions on Wireless Communications, IEEE Communications Letters, and IEEE Access, and was a past Guest Editor for a special issue of IEEE Journal on Selected Areas in Communications on optical wireless communications. Currently, he serves as the President of the Canadian Society of Information Theory as well as the Secretary of IEEE Radio Communication Technical Committee within the IEEE Communication Society.
