Practical Mobile Edge Computing: in the case of Augmented and Virtual Reality

The Hong Kong University of Science and Technology
Department of Computer Science and Engineering


PhD Thesis Defence


Title: "Practical Mobile Edge Computing: in the case of Augmented and 
Virtual Reality"

By

Mr. Wenxiao ZHANG


Abstract

Smartphone is now a necessity of people's daily life, and we are enjoying
various services on it with numerous mobile applications. However, the
resource and communication limitations of a single mobile device make it
insufficient in satisfying the real-time and interactive constraints of
some computation intensive applications, such as mobile Augmented Reality
(AR) and mobile Virtual Reality (VR). To bridge the gap, we utilize the
processing power of edge servers via task offloading and build practical
mobile systems which significantly outperforms state-of-the-art mobile
systems in terms of latency, scalability, quality of experience (QoE), and
many other aspects.

In the case of mobile Augmented Reality, large-scale object recognition is
an essential but time consuming task. To offload the object recognition
task and enhance the system performance, we explore how the GPU and the
multi-core architecture on the edge servers would accelerate the
large-scale object recognition process. With the carefully designed
offloading pipeline and edge acceleration, we are able to finish the whole
AR pipeline within one camera frame interval while maintaining high
recognition accuracy with large-scale datasets.

Despite the performance concerns on the mobile devices, edge servers are
also faced with scalability issue, as too many concurrent offloading
requests would exhaust the processing capacity of the edge and result in
delayed execution with tasks queuing on the edge. To address this issue,
we propose a two-tier caching architecture for mobile AR: 1) when there is
enough processing capacity remaining on the edge, the mobile client would
offload the recognition task to achieve the best performance, and 2) when
the edge is heavily occupied, the mobile client would derive its own
result based on the previous recognition result from nearby device's
cache, which is based on the fact that users in vicinity have a high
chance of querying the same physical objects. This two-tier caching
architecture not only guarantees the system performance when serving
massive concurrent users, but also enables innovative features such as
multi-player AR.

In the case of mobile Virtual Reality, existing 360 degree video streaming
systems are suffering from insufficient pixel density, as the video
resolution falling within the user's field of view (FoV) is relatively
low. We utilize the edge server for ultra-high resolution video
transcoding and implement a system which streams tile-based viewport
adaptive 360 degree videos onto the mobile client. With this edge proxy,
we successfully achieve 16K 360 degree video streaming onto off-the-shelf
smartphones, achieving high frame quality and fluent playback without
overwhelming the processing capacity of the smartphones.


Date:			Wednesday, 24 July 2019

Time:			2:00pm - 4:00pm

Venue:			Room 3494
 			Lifts 25/26

Chairman:		Prof. Zhihong Guo (CHEM)

Committee Members:	Prof. Pan Hui (Supervisor)
 			Prof. Gary Chan
 			Prof. Qifeng Chen
 			Prof. Danny Tsang (ECE)
 			Prof. Jiannong Cao (PolyU)


**** ALL are Welcome ****