Mobility and DTN Group

Group Overview

Our Mobility & DTN (Delay/Disruption Tolerant Network) research team consists of graduate students and faculties at North Carolina State University and KAIST (Korea Advanced Institute of Science and Technology) conducting research on Human mobility modeling, routing/content search and distribution in DTN/Ad Hoc environment. We are developing mobility models that describe super-diffusive characteristics and clustering nature of human mobility. We are also working on routing algorithms that utilize those characteristics of human mobility. We are also gathering real human traces in various sites such as university, parks and metropolitan area.

Latest News

• Our paper has been accepted to INFOCOM 2009.
• Our paper has been accepted to ACM MobiCom Workshop on Challenged Networks (CHANTS) 2008.
• Our paper has been accepted to ACM MobiHoc Workshop on Mobility Models 2008.
• Our papers have been accepted to ACM HotNets IV (2007) and INFOCOM 2008.

Current Projects

TLW (Truncated Levy Walk) Mobility Model

In this project, we show that human walks performed in outdoor settings of tens of kilometers resemble a truncated form of Levy walks commonly observed in animals such as monkeys, birds and jackals. The following figures show sample traces, flight length and pause time distributions in one of our data set, respectively. For more details, please visit here.

SLAW (Self-similar Least Action Walk)

In this project, we report that self-simillar/bursty hot spots are a key factor in causing the heavy-tail distribution of flights in human walks. The following figures show clusters of visit points (hotspots) viewed in different scales (4800x4800, 1200x1200, 300x300 meters, respectively). For more details, please visit here.

Trace data

To get mobility data, mail to rhee@ncsu.edu / shong@ncsu.edu.

• NCSU
• KAIST
• NYC
• Disney World
• NC State Fair

To analyze our trace/Inter Contact Time (ICT) data, we use MLE (Maximum Likelihood Estimation) and Akaike test.

• Data Analysis (MLE and Akaike test)

Download

Latest TLW MATLAB Simulation Code

We release the MATLAB implementation of TLW mobility model. Put the two files below in the same directory and run levy_walk_mobility_c_i_b.m.

File Name	HowTo	Comment	Last updated
levy_walk_mobility_c_i_b.m	Included in the source	-	5/26/2008
stabrnd.m	Included in the source	By Dr. McCulloch in OSU	12/18/1996

Typical values from measurements (Levy exponent of 30-degree angle model)

Site	alpha	beta
NCSU	0.86	0.99
KAIST	0.97	0.45
NYC	0.66	0.49
DW	1.02	0.80
SF	0.75	1.68

Typical values for simulation

parameter	value	unit	description
mu	0	N/A	constant velocity
f_min/f_max	5 / one side of a simulation area	meter	if it is a square area
s_min/s_max	0 / 28*60*60	second	from UCSD data set
fl_scale/pt_scale	10 / 1	N/A
time_size	60	second	sampling period
b_c	2	N/A	reflection boundary

Latest TLW NS2 Simulation Code

We release the MATLAB implementation of TLW mobility model that can be used as input to ns2 simulator.

File Name	How to use	Comment	NS Version	Results	Last updated
Levy_NS2.m	Included in the source				12/1/2008

Latest TLW GLOMOSIM Simulation Code

We release the GLOMOSIM implementation of TLW mobility model.

File Name	HowTo	Comment	GLOMOSIM Version	Last updated
Levy_GlomoSim.m	Included in the source			6/24/2008

Publications

Conferences & Workshops

• Kyunghan Lee, Seongik Hong, Seong Joon Kim, Injong Rhee and Song Chong, SLAW: A Mobility Model for Human Walks, INFOCOM, Rio de Janeiro, Brazil, 2009, PDF
• Minsu Shin, Seongik Hong and Injong Rhee, DTN Routing Strategies using Optimal Search Patterns, ACM MobiCom Workshop on Challenged Networks (CHANTS), 2008, PDF
• Seongik Hong, Injong Rhee, Seong Joon Kim, Kyunghan Lee and Song Chong, Routing Performance Analysis of Human-Driven Delay Tolerant Networks using the Truncated Levy Walk Model, ACM SIGMOBILE International Workshop on Mobility Models for Networking Research (Colocated with MobiHoc 08), Hong Kong, 2008 PDF
• Injong Rhee, Minsu Shin, Seongik Hong, Kyunghan Lee and Song Chong, On the Levy-walk Nature of Human Mobility, INFOCOM, Arizona, USA, 2008 PDF PPT
• Injong Rhee, Minsu Shin, Seongik Hong, Kyunghan Lee and Song Chong, Human Mobility Patterns and Their Impact on Delay Tolerant Networks, ACM HotNets IV, 2007 PDF

Technical Reports

• Kyunghan Lee, Seongik Hong, Seong Joon Kim, Injong Rhee and Song Chong, Demystifying Levy Walk Patterns in Human Walks, Technical Report, 2008, PDF
• K. Lee, B. C. Jung, I. Rhee, S. Chong, and D. K. Sung. Revisiting the transmission range model in mobile networks based on ieee 802.11a/g, Technical Report, 2008 PDF
• Injong Rhee, Minsu Shin, Seongik Hong, Kyunghan Lee and Song Chong, On the Levy-walk Nature of Human Mobility: Do Humans Walk like Monkeys?, Technical Report, Computer Science Department, North Carolina State University, 2007 . PDF
• Diffusion Regimes of Levy Walk, Technical Memo, Computer Science Department, North Carolina State University, 2007 . PDF

Members

Faculty

• Injong Rhee (NCSU)

Postdoctoral Fellows

• Seong Joon Kim (NCSU)
• Minsu Shin (Currently at Hanaro Telecom, Korea)

Ph.D Students

• Seongik Hong (NCSU)

Cooperating Members

Faculty

• Song Chong (KAIST)

Ph.D Students

• Kyunghan Lee (KAIST)

Members only

• Meeting
• Reference