Travel Report: Xiaoqiang Ma, China
Xiaoqiang Ma, a Doctoral student in Computing Science, received a Graduate International Research Travel Award to further his research in China. His report:
With the proliferation of such high performance mobile devices as smartphones and tablets, and the advances in cellular network technologies, data-intensive applications including Voice over IP (VoiP), video streaming, and instant file sharing become increasingly popular. As a result, mobile data traffic has been experiencing a phenomenal rise in the past decade, which almost doubled each year  and is expected to keep growing to 11.2 Exabytes per month by 2017, a 13-fold increase over 2012 .
Such ever increasing data traffic has put significant pressure on the infrastructure of the state-of-the-art cellular networks. There have been great efforts on the development and deployment of next generation wireless communication systems. Recently, Device-to-Device (D2D) communication underlaying cellular networks has been suggested as a new paradigm of great potentials toward supporting proximity-based applications (3]. With this new paradigm, the cellular BS-based and the direct D2D communications are coordinated to operate on the same licensed spectrum. Different resource allocation strategies can be applied to al locate the spectrum and to adjust the transmit power to optimize the overall system performance . Prof. Hongbo Jiang at Huazhong University of Science and Technology, China, has great experience in the research area of wireless and cellular networks. Hence, I visited his lab for collaboration from May to August 2013.
During the visit, we focused on a modern D2D underlay to cellular networks serving diverse types of applications. We jointly considered resource al location and power control with heterogeneous Quality of Service (QoS) requirements from the applications for selecting the best resource sharing mode. We closely analyzed two representative classes of applications, namely streaming-like and file-sharing-like, and develop optimized solutions for coordinating the cellular and D2D communications. We further extended our solution to accommodate more general application scenarios and systems of larger scales. Our solution enables with better resource utilization for different types of applications with less possibility of under- or over-provisioning. We submitted this work to IEEE Journal on Selected Areas in Communications, which is a top-tier journal in the area of communications.
I also collaborated with Liang Zhang and Prof. Dan Wang at The Hong Kong Polytechnic University as well as Prof. Hongbo Jiang on data collection with delay control in duty-cycle sensor networks during the visit. We proposed the Minimum slots Augmentation with Expected delay Bound (MAEB) problem, which proves to be NP-Hard. We further developed a basic scheme and an enhanced scheme to solve it. Simulation results demonstrate that the
proposed schemes can effectively bound the network delay with as much as 30% less augmentation slots, as compared with the state-of-the-art method . We submitted this work to IEEE INFOCOM '2014, a top-tier conference.
 "Cellular Data Traffic Keeps Doubling Every Year," http://arstechnica.com/business/2013/02/cellular-datatraffic-keeps-doubling-every-year/
 "Cisco Visual Networking Index: Global Mobile Data Traffic Forecast Update, 2012-2017,"
http://www.cisco.com/ en/US/ solutions/collateral/ns341/ns525/ns53 7/ns705/ns827/whitepaper_c11-520862.html/.
 P. Janis, C. Yu, K. Doppler, C.B. Ribeiro, C. Wijting, K. Hugl, 0. Tirkkonen and V. Koivunen, "Device-to-Device Communication Underlaying Cellular Communications Systems," Inti J. of Commun. Netw. Syst. Sci., vol. 2, no. 3, pp.169-178, 2009, doi: 10.4236/ijcns.2009.23019.
 C.-H. Yu, K. Doppler, C. B. Ribeiro, and 0. Tirkkonen, "Resource Sharing Optimization for Device-to-Device Communication Underlaying Cellular Networks," IEEE Trans. Commun., vol. 10, no. 8, pp. 2752-2763, Aug. 2011.
 Q. Cao, T. Abdelzaher, T. He, and J. Stankovic, "Towards Optimal Sleep Schedu ling in Sensor Networks for Rare Event Detection", in Proc. IEEE IPSN 'OS, Los Angeles, the USA, Apr. 25-27, 2005.