Current Wireless
Networking Research
Directions from
MobiCom 2007 Conference
Bob Kinicki
PEDS September 24, 2007
Outline




Observations from Workshop on
Wireless Network Testbeds,
Experimental evaluation and
CHaracterization (WiNTECH 2007)
Keynotes and Panel Themes
Notes, highlights and trends from
MobiCom papers
Random thoughts based on poster
sessions and student demonstrations
PEDS September 24, 2007 – MobiCom 07 Research Directions
2
WinTECH Workshop

Keynote: GNU Radio as experimental
platform
– Publicly available tool for audio
experimentation on wireless testbeds.



Several wireless testbeds within
campus structure (e.g., Purdue)
Crossbow MicaZ seems to be the new
sensor node of choice.
There was new activity involving PHY –
MAC layer cross-layering.
PEDS September 24, 2007 – MobiCom 07 Research Directions
3
WinTECH Workshop


Wireless testbed architectures include
VINI (Princeton) and ORBIT (radio
grid ‘emulator’ system available at
Rutgers)
Physical Layer issues explored:
– Capture effect of stronger signal
– Inherent unfairness in overlapping AP
domains (e.g. use ‘traffic shaper’ to
throttle APs).
PEDS September 24, 2007 – MobiCom 07 Research Directions
4
Keynotes and Panels



SIGMOBILE's Outstanding Contributions Award
Lecture
David Culler
TinyOS and Low-Power Wireless Networking - a
Study in Realistic Abstraction
Keynote Address
Dr. David Tse
Breaking the Interference Barrier
Panel: Bonobos Vs Chimps: Cooperative and NonCooperative Behavior in Wireless Networks
Moderator: Jean-Pierre Hubaux, EPFL
Participants: Ramesh Johari, Stanford
P. R. Kumar, Illinois, Heather Zheng, UCSB
PEDS September 24, 2007 – MobiCom 07 Research Directions
5
MobiCom Papers
Session: Medium Access Control

Scheduling Algorithms for Multi-Carrier Wireless Data Systems
Matthew Andrews (Bell Labs, Lucent Technologies, US); Lisa Zhang (Bell Labs, Lucent
Technologies, US)
–
–

Superimposed Code based Channel Assignment in Multi-Radio Multi-Channel Wireless Mesh
Networks
Kai Xing (The George Washington University, US); Xiuzhen Cheng (The George Washington
Univ, US); Qilian Liang (The University of Texas at Arlington, US); Liran Ma (The George
Washington University, US)
–
–
–
–
–

Multi-carrier scheduling (CDMA, WIMAX, EVDO, LTE (OFDMA))
Idea: Assign different user types to different carrier technologies.
Important to support both unicast and broadcast
CSMA/CA {802.11} is inadequate for mesh networks
Used an Interference Model
MIMO multi-channel used for interference reduction
How do mesh networks know which channel to listen to and which channel to transmit on?
Optimal Channel Probing and Transmission Scheduling for Opportunistic Spectrum Access
Nicholas Chang (University of Michigan, US); Mingyan Liu (University of Michigan, US)
–
–
–
Channel quality is time-varying  need probes
Probe for quality using RTS/CTS; receiver sends SNR in CTS
This is a joint probing and scheduling problem
PEDS September 24, 2007 – MobiCom 07 Research Directions
6
MobiCom Papers
Session: Sensor Networks


Trade-offs Between Mobility and Density for Coverage in Wireless
Sensor Networks
Wei Wang (National University of Singapore, SG); Vikram Srinivasan
(National University of Singapore, SG); Kee Chaing Chua (National
University of Singapore, SG)
– Coverage is the issue here. Worry about cascaded moving.
– Considered homogeneous and heterogeneous WSNs where a
limited number of mobile sensors can be matched to holes.
Rendered Path: Range-Free Localization in Anisotropic Sensor
Networks with Holes
Mo Li (Hong Kong University of Science and Techonlogy, HK); Yunhao
Liu (Hong Kong University of Science and Technology, HK)
– Automatic localization popped up all over the conference. Here,
the believe is for some WSN applications, sensors need to know
where neighbors are located.
PEDS September 24, 2007 – MobiCom 07 Research Directions
7
MobiCom Papers
Session: Sensor Networks (cont.)
These two papers address a new ‘buzz’ topic – Barriers !!


Designing Localized Algorithms for Barrier Coverage
Ai Chen (Ohio State University, US); Santosh Kumar
(University of Memphis, US); Ten-Hwang Lai (Ohio State
university, US)
Reliable Density Estimates for Achieving Coverage and
Connectivity in Thin Strips of Finite Length
Paul Balister (University of Memphis, US); Amites Sarkar
(University of Memphis, US); Bela Bollobas (University of
Memphis, US); Santosh Kumar (University of Memphis, US)
PEDS September 24, 2007 – MobiCom 07 Research Directions
8
MobiCom Papers
Session: Security and Privacy

DARWIN: Distributed and Adaptive Reputation mechanism for Wireless ad-hoc
Networks
Juan Jose Jaramillo (University of Illinois at Urbana-Champaign, US); R. Srikant
(University of Illinois at Urbana-Champaign, US)
–

802.11 User Fingerprinting
Jeffrey Pang (Carnegie Mellon University, US); Benjamin Greenstein (Intel Research
Seattle, US); Ramakrishna Gummadi (University of Southern California, US); Srinivasan
Seshan (Carnegie Mellon University, US); David Wetherall (University of Washington,
US)
–
–

The issue is location privacy (i.e., worrying about tracking people locations through trends in
wireless node locations over time).
In this case, a unique MAC address is a problem!!
Robust Location Distinction using Temporal Link Signatures
Neal Patwari (University of Utah, US); Sneha Kasera (University of Utah, US)
–
–

Concerned with rewards/punishments for forwarding packets
The idea is to develop unique transmitter signature. {Difficult to do!}
When transmitter moves or attacker impersonates source, receiver can tell by signature change.
Mining call data to increase the robustness of cellular networks to signaling DoS attacks
Hui Zang (Sprint ATL, US); Jean Bolot (Sprint, US)
–
Used recorded cell phone behavior to speed up paging times on cell phones.
PEDS September 24, 2007 – MobiCom 07 Research Directions
9
MobiCom Papers
Session: Cross-layer Techniques

Adaptive Network Coding and Scheduling for Maximizing Throughput
in Wireless Networks
Prasanna Chaporkar (Norwegian University of Science and
Technology, NO); Alexandre Proutiere (Microsoft Research, UK)
–
–
–
–

Picks up on COPE algorithm (XOR packet sending scheme)
Network Coding (NC) was another buzz word at conference.
This paper shows NC can lower throughput.
Hence, transmission scheduling needs to be NC aware.
Beyond the Bits: Cooperative Packet Recovery Using PHY Information
Grace Woo (Massachusetts Institute of Technology, US); Pouya
Kheradpour (MIT, US); Dawei Shen (MIT, US); Dina Katabi (MIT,
US)
– SOFT is another cross-layering idea that recovers a correct frame from its
faulty reception by using confidence values for 0 or 1 which are available in
PHY.
– They used GNU radio application and interfaces for implementation and
testing.
PEDS September 24, 2007 – MobiCom 07 Research Directions
10
MobiCom Papers
Session: Mobility/Interference Models


Crossing Over the Bounded Domain: From Exponential To Power-law Intermeeting Time in MANET
Han Cai (North Carolina State University, US); Do Young Eun (North Carolina
State University, US)
– Claim: Inter-meeting time is a key wireless metric.
– They show this time has exponential tail up to a point and then becomes
power-law tail.
– There results indicate this behavior is due to a finite boundary around the
domain space.
A General Model of Wireless Interference
Lili Qiu (The University of Texas at Austin, US); Yin Zhang (University of
Texas at Austin, US); Feng Wang (University of Texas at Austin, US); Mi
Kyung Han (University of Texas at Austin, US); Ratul Mahajan (Microsoft
Research, US)
– This paper is part of buzz on Interference Modeling for wireless networks.
– They claim to develop a measurement-based interference model.
– ‘Heavy’ queuing theory but used traces and simulation to show accuracy of
theoretical model.
PEDS September 24, 2007 – MobiCom 07 Research Directions
11
MobiCom Papers
Session: Mobility/Interference Models (Cont.)


Power law and exponential decay of inter contact times between
mobile devices
Thomas Karagiannis (Microsoft Research, UK); Jean-Yves Le Boudec
(EPFL, CH); Milan Vojnovic (Microsoft Research, UK)
– Similar to first paper in session in results presented.
Study of a Bus-Based Disruption Tolerant Network: Mobility
Modeling and Impact on Routing
Xiaolan Zhang (University of Massachusetts, Amherst, US); James F.
Kurose (University of Massachusetts at Amherst, US); Brian Levine
(University of Massachusetts at Amherst, US); Don Towsley
(University of Massachusetts at Amherst, US); Honggang Zhang
(Suffolk University, US)
– Some what obvious results in bus networks over UMass campus
where laptops travel on buses and record information about
closeness to facilitate relaying information.
PEDS September 24, 2007 – MobiCom 07 Research Directions
12
MobiCom Papers
Session: Challenges

Challenges: Towards Truly Scalable Ad Hoc Networks
Zheng Wang (University of California Santa Cruz, US); Hamid Sadjadpour
(University of California, Santa Cruz, US); J.J. Garcia-Luna-Aceves
(University of California at Santa Cruz, US)
–

Challenges: Peers on Wheels - A Road to New Traffic Information Systems
Jedrzej Rybicki (Heinrich Heine University Duesseldorf, DE); Bjorn
Scheuermann (Heinrich Heine University Dusseldorf, DE); Wolfgang Kiess
(Heinrich Heine University Duesseldorf, DE); Christian Lochert (Heinrich
Heine University Dusseldorf, DE); Pezhman Fallahi Khorasani (Heinrich Heine
University Dusseldorf, DE); Martin Mauve (Heinrich Heine University
Dusseldorf, DE)
–
–

Very theoretical presentation – all big O notation.
VANETs was another buzz at the conference.
This talk focused on the fact that VANETs did not solve the problem wrt traffic and in
the future these traffic systems would be used.
Challenges: Device-free Passive Localization for Wireless Environments
Moustafa Youssef (University of Maryland, US); Matthew Mah (University of
Maryland, US); Ashok K. Agrawala (University of Maryland, US)
–
More about localization.
PEDS September 24, 2007 – MobiCom 07 Research Directions
13
MobiCom Papers
Session: Measurements

Adaptive Contact Probing Mechanisms for Delay Tolerant Applications
Wei Wang (National University of Singapore, SG); Vikram Srinivasan
(National University of Singapore, SG); Mehul Motani (National University of
Singapore, SG)
–

A Measurement-Based Approach to Modeling Link Capacity in 802.11-based
Wireless Networks
Anand Kashyap (SUNY at Stony Brook, US); Samir Das (SUNY at Stony
Brook, US); Samrat Ganguly (NEC Labs, US)
–
–

Interested in and measured contact patterns of volunteer cell phone users in
Singapore.
Developed an analytic model for 802.11 link capacity that put significant importance
on AP interference/interaction.
‘Validated’ model on a controlled WLAN and induced only UDP traffic through
neighboring APs.
MDG: Measurement-Driven Guidelines for 802.11 WLAN Design
Ioannis Broustis (University of California, Riverside, US); Konstantina
Papagiannaki (Intel Research, US); Srikanth Krishnamurthy (University of
California, Riverside, US); Michalis Faloutsos (University of California
Riverside, US); Vivek Mhatre (Bell Labs, IN)
–
–
Interested in AP interference.
Measure and develop a new algorithm that considers frequency selection, user
association to an AP and power control.
PEDS September 24, 2007 – MobiCom 07 Research Directions
14
MobiCom Papers
Session: Routing and Multicasting
{I had to leave and did not attend this session}
 Multicast Capacity for Wireless Networks
Xiang-Yang Li (Microsoft Research Asia, Beijing; Illinois
Institute of Technology, US); Shao-Jie Tang (Illinois
Institute of Technology, US); Ophir Frieder (Illinois Institute
of Technology, US)
 On Designing Collusion-Resistant Routing Schemes for NonCooperative Wireless Ad Hoc Networks
Sheng Zhong (SUNY Buffalo, US); Fan Wu (State University
of New York at Buffalo, US)
 Weak State Routing for Large Scale Dynamic Networks
Utku Acer (Rensselaer Polytechnic Institute, US); Shivkumar
Kalyanaraman (Rensselaer Polytechnic Institute, US);
Alhussein Abouzeid (Rensselaer Polytechnic Institute, US)
PEDS September 24, 2007 – MobiCom 07 Research Directions
15
Posters and Demos
General Observations:
 The posters and demos were far more
practical.
 Many posters on Mesh networks, location
detection, security and VANETs.
 Several practical demos involving sensors.
 Except for the more theoretical posters,
WPI graduate students could produce
comparable practical results if we had easily
accessible testbeds.
PEDS September 24, 2007 – MobiCom 07 Research Directions
16
Questions?
Thank You!
PEDS September 24, 2007 – MobiCom 07 Research Directions
17