(1) Network Science, Inference and Cyber-Security

(2) Real-time Trading in Cloud Computing by Data Analytics

  • image The increasing digitalization in many aspects of life leads to a proliferation of data inventory. We focus on the mathematical principles underlying data analytics for web intelligence applications and to develop the software technologies. In [1], we design real-time bidding algorithms for variable cloud computation services using dynamic pricing in Amazon Web Services. The challenge is: What is the optimal price to bid for high-value and low-cost cloud computation? In [2,3], we analyze novel economic strategies to trade cloud resources and mobile data plans in a secondary market, and we are currently working on the data analytics software with a mobile operator in Hong Kong. The challenge is: How to intelligently match buyers and sellers to optimize digital services?

    [1] L. Zheng, C. Joe-Wong, C. W. Tan, M. Chiang and X. Wang, How to Bid the Cloud?, ACM SIGCOMM 2015.
    [2] L. Zheng, C. Joe-Wong, C. Brinton, C. W. Tan, S. Ha and M. Chiang, On the Viability of a Cloud Virtual Service Provider, ACM SIGMETRICS 2016.
    [3] L. Zheng, C. Joe-Wong, C. W. Tan, S. Ha and M. Chiang, Secondary Markets for Mobile Data: Feasibility and Benefits of Traded Data Plans, IEEE INFOCOM 2015.

(3) Network Optimization in Heterogeneous Wireless Networks

(4) Performance Evaluation: How good is our Internet Routing Protocol?

  • A fundamental question in Internet TCP/IP congestion control and routing is: “What is the cost of routing TCP flows over a single path or multiple routes?” The answer can guide the decision on whether to support multipath routing –an expensive operation– in the Internet. This is in fact an NP-hard problem [1]. We show that optimal routing can in fact be achieved using a randomized TCP/IP algorithm to load-balance a large portion of Internet traffic with only a small group of users sparsely routing over more than one path [2]. Our work in [1, 2] lend theoretical evidence that the current single-path routing, e.g., the OSPF Internet routing protocol, can be improvised to scale up for next-generation multipath routing. We are now studying new routing protcols in next-generation software-defined networks.

    [1] M. Wang, C. W. Tan, W. Xu and A. Tang, Cost of Not Splitting in Routing: Characterization and Estimation, IEEE/ACM Transactions on Networking, Vol. 19, No. 6, pp. 1849-1859, 2011.
    [2] Y. Bi, C. W. Tan and A. Tang, Network Utility Maximization with Path Cardinality Constraints, IEEE INFOCOM, 2016.

(5) Information Theory

  • Information-theoretic problems often possess surprisingly beautiful structures associated with optimization theory that shed insights to designing optimal systems. In [2], we discovered an intriguing zig-zag phenomenon in the Gaussian interference channel rate optimization problem when physical-layer innovation such as superposition coding is used to cancel interference. In [1], we discovered that linear programming can be used to automate the process of proving and disproving very large-scale information theory inequalities, which are traditionally difficult to prove by hand. We are currently working on the software automation (software forthcoming). We are also using this cloud software and linear programming to analyze some problems in probability theory and mathematics.

    [1] S. W. Ho, C. W. Tan and R. W. Yeung, Proving and Disproving Information Inequalities, Proc. of IEEE Symp. of Information Theory, 2014.
    [2] Y. Zhao, C. W. Tan, A. S. Avestimehr, S. N. Diggavi and G. J. Pottie, On the Maximum Achievable Sum-rate with Successive Decoding in Interference Channels, IEEE Transactions on Information Theory, Vol. 58, No. 6, pp. 3798-3820, 2012.

(6) Estimation and Detection

  • imageEstimation and detection theory in wireless communications is a branch of statistics and signal processing that deals with building robust and reliable transmissions based on measured and empirical data. A novel code diversity for space-time communication was proposed in [1] that uses the Alamouti signal as building blocks to create robust transmissions. The idea is to select the best code from a family of codes induced by a small number of feedback bits (link). In [2], we study new statistical methods for estimating the values of link parameters in fast fading channels.

    [1] C. W. Tan and A. R. Calderbank, Multiuser Detection of Alamouti Signals, IEEE Transactions on Communications, Vol. 57, No. 7, pp. 2080-2089, 2009.
    [2] S. Sorooshyari, C. W. Tan and H. V. Poor, On Maximum-Likelihood SINR Estimation of MPSK in a Multiuser Fading Channel, IEEE Transactions on Vehicular Technology, Vol. 59, No. 8, pp. 4175-4181, 2010.

(7) Power Network Optimization

(8) Energy Efficiency and Sustainable Information Technology