Qianru Li

BIO


I am Qianru Li, pursuing Computer Science Ph.D. at UCLA. I am supervised by Prof. Songwu Lu. Before that, I received Bachelor of Science in Computer Science from Shanghai Jiao Tong University in 2016.

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PUBLICATION


Supporting Mobile VR in LTE Networks: How Close Are We? SIGMETRICS'18

Zhaowei Tan, Yuanjie Li, Qianru Li, Zhehui Zhang, Zhehan Li, Songwu Lu
The 44th ACM Annual Conference of Special Interest Group on Measurement and Evaluation (SIGMETRICS'18)

Mobile virtual reality (VR) headsets (e.g., Google Cardboard and Samsung Gear VR) seek to offer “anytime, anywhere” panorama, immerse 3D experiences for users. In this work, we study the viability of supporting mobile VR over operational 4G LTE networks, where the device provides pose information to the edge servers to offload graphical processing. We find that, contrary to common perceptions, wireless bandwidth is not the latency bottleneck for medium-quality VR. Instead, the signaling operations, which facilitate wireless data delivery, constitute a bulk portion of the latency. We report findings that challenge five common beliefs on VR network latency in LTE under both static and mobile scenarios, and quantify their impact. We design LTE-VR, a client-side solution to medium-quality VR over LTE. LTE-VR leverages cross-layer design and rich side channel information to reduce various latency sources in the signaling operations. Our prototype evaluation has confirmed its viability in 4G LTE. We discuss its applicability to the upcoming 5G.

@inproceedings {tan2018vr, author = {Zhaowei Tan and Yuanjie Li and Qianru Li and Zhehui Zhang and Zhehan Li and Songwu Lu}, title = {Enabling Mobile VR in LTE Networks: How Close Are We?}, booktitle = {The 44th ACM Annual Conference of Special Interest Group on Measurement and Evaluation (SIGMETRICS'18)}, year = {2018}, month = Jun, address = {Irvine, California, USA}}

Resolving Policy Conflicts in Multi-Carrier Cellular Access MobiCom'18

Zengwen Yuan, Qianru Li, Yuanjie Li, Songwu Lu, Chunyi Peng, George Varghese
The 24th Annual International Conference on Mobile Computing and Networking (ACM MobiCom'18)

Multi-carrier access dynamically selects a preferred cellular carrier, by leveraging the availability and diversity of multiple carrier networks at a location. It offers an alternative solution to the dominant single-carrier practice, and shows early signs of success through the operational Project Fi by Google. In this paper, we study an important, yet largely unexplored problem of inter-carrier switch for multi-carrier access. We show that policy con icts may arise between the inter- and intra-carrier levels, resulting in oscillations among carriers in the worst case, akin to BGP looping. We derive the conditions under which such oscillations occur for three categories of popular policy, and validate them with Project Fi whenever possible. We provide practical guidelines that ensure loop-freedom and assess them via trace-driven emulations.

@inproceedings {yuan2018resolving, author = {Zengwen Yuan and Qianru Li and Yuanjie Li and Songwu Lu and Chunyi Peng and George Varghese}, title = {Resolving Policy Conflicts in Multi-Carrier Cellular Access}, booktitle = {The 24th ACM Annual International Conference on Mobile Computing and Networking (MobiCom'18)}, year = {2018}, month = Oct, address = {New Delhi, India}}

SOFTWARE & PROJECT


MobileInsight: In-phone mobile network analytics
My contribution:
  • Support control-plane monitoring (RRC/NAS) on MediaTek chipsets.
  • Build analyzers to extract performance metrics on data plane (PDCP/RLC/MAC/PHY).
  • EXPERIENCE


    Software Engineering Intern @ Google, Seattle

    Jun 2019 - Sept 2019

    Design and evaluate approaches to mitigate latency for Google Stadia on Wi-Fi.

    Software Engineering Intern @ Uber, Palo Alto

    Jun 2018 - Sept 2018

    Develop network event collecting tools for Android. Analyze impact of LTE behavior on ride-sharing traffic.

    TEACHING


    CS M51A Logic Design of Digital Systems, 2019
    CS 32 Introduction to Computer Science II, 2019
    CS 117 Computer Neworks: Physical Layer, 2018

    ABOUT ME


  • I was born and grown up in Shijiazhuang, China. Call it "Rock Hometown" if you'd like an English name.
  • I enjoy teaching, if debugging for students doesn't count.
  • Avicii will never come back. But we love him always.
  • Most of the time, Yoga is a good escape from tiring work. At other times, just bring about pain, literally.
  • I'm learning how to play the guitar. Research is hard, while playing Hallelujah is hell.