Research Projects in the Mobile Computing
and Networking (MCN) Lab
Guohong Cao
Department of Computer Science and Engineering
The Pennsylvania State University
http://www.cse.psu.edu/~gcao
Mobile Computing and Networking (MCN) Lab
• MCN lab conducts research in many areas of wireless
networks and mobile computing, emphasis on designing and
evaluating mobile systems, protocols, and applications.
– Current Projects: smartphones, wireless network security, data
dissemination/access in wireless P2P networks, vehicular networks,
wireless sensor networks, resource management in wireless networks.
– Support: NSF (CAREER, ITR, NeTS, NOSS, CT, CNS), Army
Research Office, NIH, DoD/Muri, DoD/DTRA, PDG/TTC and
member companies Cisco, Narus, Telcordia, IBM and 3ETI.
• Current students:
– 10 PhD students
– 1 PostDoc
– 3 visiting scholars
Alumni
• 15 PhDs
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Hao Zhu (8/2004), Qualcomm.
Liangzhong Yin (12/2004), Microsoft.
Wensheng Zhang (8/2005), Associate Professor, Iowa State University
Hui Song (8/2007), Assistant Professor, Frostburg State University
Jing Zhao (8/2008), Cisco Systems.
Min Shao (12/2008), Microsoft
Changlei Liu (5/2010), UMUC
Yang Zhang (2/2011), Palo Alto Networks.
Baojun Qiu (Co-chaired with J. Yen) 8/2011, eBay.
Bo Zhao (10/2011), AT&T.
Zhichao Zhu (2/2012), Nokia.
Qiang Zheng (5/2012), Google
Wei Gao (5/2012), Assistant Professor, University of Tennessee.
Qinghua Li (5/2013), Assistant Professor, University of Arkansas.
Yi Wang (5/2013), Google.
• 12 MS students went to various companies
• 5 visiting scholars
Outline
• Efficient Energy-Aware Web Access in Wireless
Networks
• Social-Aware Data Dissemination in Delay
Tolerant Networks
• Resilient and Efficient Data Access in Cognitive
Radio Networks
• Privacy-Aware Mobile Sensing
3
Web Browsing in 3G/4G Networks
• Smartphones in 3G/4G networks:
– Increasingly used to access the Internet
– Consume more power
• Cellular interface consumes lots of energy
– 30%-50% of total energy
• Current status:
– 3G/4G radio interface always on, timer control
– Radio resource is not released, reduce network
capacity
4
Characteristics of 3G Radio interface
T1 = 4 sec
T2 = 15 sec
Traffic Load of Opening Webpages
Radio interface is always on during data transmission
Reorder the Computation Sequence
• Reorganize the computation sequence of the web browser, so
that it first runs the computations that will generate new data
transmissions and retrieve these data from the web server.
– Then, the web browser can put the 3G radio interface into low power
state, and then run the remaining computations.
7
Reducing the Energy of FACH State
• After a webpage is downloaded, predict the user reading time
on the webpage
– This time > a threshold (delay vs. power): switch into low power state
– Prediction is based on Gradient Boosted Regression Trees (GBRT).
• Selected 10 features such as Data transmission time, webpage
data size, figure size, no. of downloaded objects, etc.
• Also consider user interest.
Evaluations
• The prototype:
– Android Phones
– T-Mobile 3G/UMTS network
• Implement the prototype and collect real traces
• Experimental results:
– Reduce power consumption:
– Reduce loading time:
– Increase network capacity: 19%
30%
17%
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Motivation
Power
Power
t
t
Power
t
Power
Power
Data transmission
Tail
t
t
Promotion
How to reduce tail energy and promotion delay?
Tail
Basic idea
Power
Power
t
t
Power
P2P
interface
t
Power
Proxy
Power
t
• Aggregation traffics on one node (proxy)
– How? An optimization problem.
• Forward via P2P (Bluetooth or WiFi direct)
t
Testbed Results
• Total energy saving rate: 30.4%
• Average delay reducing rate: 31%
Outline
• Efficient Energy-Aware Web Access in Wireless
Networks
• Social-Aware Data Dissemination in Delay
Tolerant Networks
• Resilient and Efficient Data Access in Cognitive
Radio Networks
• Privacy-Aware Mobile Sensing
13
Data Dissemination in DTNs
• Lack of infrastructure support in disaster recovery,
battlefield, environmental monitoring, etc.
• Mobile devices can form mobile opportunistic
networks or Disruption Tolerant Networks (DTN).
• General methodology: Carry-and-forward
• The key issue is to select which node (relay) to
forward the data.
Japan tsunami 2010
Social-Aware Data Dissemination
• Exploiting social relations among mobile nodes
for relay selections
– Stable long-term characteristics compared to node
mobility
– Centrality (Degree or betweenness), which shows the
importance of some nodes to help communications
among other nodes.
• High centrality nodes can be used as relay nodes.
– Community, i.e., nodes have common acquaintances
have higher probabilities to know each other.
• data can reach the destination easier if it reaches someone in
the same social community as the destination.
Our Results
• Social interest: User-Centric Data Dissemination in
Disruption Tolerant Networks (infocom’11)
• Social Contact Patterns: On Exploiting Social Contact
Patterns for Data Forwarding in Delay Tolerant Networks
(icnp’10, TMC’13)
• Social selfishness: Routing in socially selfish disruption
tolerant networks (infocom’10, Adhoc’12)
• Social-aware caching: Supporting Cooperative Caching in
Disruption Tolerant Networks (icdcs’11, icdcs’12, TMC’13)
• Social relationship: Social-Aware Data Diffusion in Delay
Tolerant MANETs (book chapter’12)
• Social-aware multicast: Social-aware Multicast in
Disruption Tolerant Networks (Mobihoc’09, ToN’12)
Social Interest
• System development: recording users’ interests
– Data access via Samsung Nexus S smartphones
– Categorized web news from CNN
• Application scenarios
– Public commute systems: bus, subway
– Public event sites: stadium, shopping mall
– Disaster recovery
webpage
XML format
Android
phone display
Social Interest
• User interests: dynamically updated by users’ activities
• System execution
– 30 users at Penn State, 5-month period
– 11 categories, 306,914 transceived, 40, 872 read by users
A
Contact
C
B
Social Contact
• System development
 802.15.4/ZigBee compliant
 10kB RAM, 250kbps data rate
 TinyOS 2.0
– Testbed: TelosB sensors
– Deployment: 1000+ sensors distributed to high school students
• Heterogeneity of centrality, community, high cluster coefficient
• Flu immunization
B
A
C
Outline
• Efficient Energy-Aware Web Access in Wireless
Networks
• Social-Aware Data Dissemination in Delay
Tolerant Networks
• Resilient and Efficient Data Access in Cognitive
Radio Networks
• Privacy-Aware Mobile Sensing
20
Emergence of Cognitive Radio
• Unlicensed use of licensed spectrum is approved by
government agencies
– Cognitive radio – dynamically configure the operating
spectrum
Cognitive Radio Networks
 Dynamic spectrum access
Must avoid interference with primary users (licensed users)
 With infrastructure / without infrastructure (ad-hoc)

Our Work
Data Caching
• No
caching
• Caching
(delay is statistically
bounded)
Outline
• Efficient Energy-Aware Web Access in Wireless
Networks
• Social-Aware Data Dissemination in Delay
Tolerant Networks
• Resilient and Efficient Data Access in Cognitive
Radio Networks
• Privacy-Aware Mobile Sensing
26
Proliferation of Mobile Devices
• Mobile devices
– Smartphone, tablet, vehicle,
medical device, pollution
sensor
• Sensing capabilities
– Camera, microphone,
accelerometer, GPS
• Communication capabilities
huge opportunity
for
–A3G/4G,
WiFi, Bluetooth
mobile sensing
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Obstacles in Collecting Sensing Data
• Privacy concern
– Location, activity, health
• <location, noise>
• <amount of exercise>
• Cost of participation
– Power, bandwidth,
human attention
• Lack of network connectivity
– Devices without comms infrastructure (e.g., 3G)
– Circumstances of unavailable or cost-inefficient
infrastructure
Research Summary
More data collected from more
users
Privacy
concern
Obstacles
Cost of
participation
Lack of
network
connectivity
Solutions
Privacy-
Privacy-aware
aware
incentives
incentive
[PerCom’13]
Privacyaware
aggregation
[ICNP’12,PETS’13]
Secure opportunistic
mobile networking
[Infocom’10]: selfishness
More data collected from more
devices
[TDSC’13]: flood attack
[TIFS’12]: drop attack
Summary
• Efficient energy-aware web access in wireless networks
– reducing the power consumption of smartphones by dealing with
the special characteristic of the 3G/4G radio interface
• Social-aware data dissemination in delay tolerant networks
– Exploiting the knowledge of social contact patterns, social
interests, and social relationships.
– Two testbeds for data collection.
• Resilient and efficient data access in cognitive radio
networks
– mitigating the effects of primary user appearance
• Privacy-aware mobile sensing