Wireless Networks: WLAN & MANET
Nah-Oak Song
In this presentation, the research area of ANTD (Advanced Network Technologies Division) at NIST will be
briefly introduced, and my research activities in ANTD will be discussed in more detail. The presentation
will be concluded with future research plan.
Combined with wireless communication technologies such as Wireless LAN (WLAN), Bluetooth, and
HIPERLAN, powerful notebook computers and PDAs have created a new mobile computing environment.
In particular, the IEEE 802.11/WLANs have been a great technical and commercial success; the IEEE
802.11 (WLAN) has been widely deployed in a variety of network environments such as enterprise and
home networks. The performance of WLAN has been widely studied, but most of the analysis work is
based on simplified/modified models of WLAN. We have developed a more accurate analysis model and
have been investigating the performance in terms of throughput and delay. We have also proposed a backoff
algorithm to enhance the performance of WLAN. The proposed backoff algorithm significantly improves
the MAC performance of WLAN. We also studied the (binary) exponential backoff algorithm, which is
used in IEEE 802.11 and IEEE 802.3 (LAN). The research on WLAN technology will solve some of the
existing problems in WLAN as well as other wireless systems, and the result will positively contribute to
future wireless communication standards.
A MANET is an autonomous system of mobile nodes connected by wireless links, where communications
are often achieved by multi-hop links. In a MANET, it is assumed that the nodes are free to move randomly
while being able to communicate with each other without the help of existing network infrastructure, a
MANET is well suited for many situations where it is not feasible to build an infrastructure for deploying
a network. Some examples are battlefield communications, mobile conferencing, personal area networks,
emergency services, and sensor networks. Most of work on MANET has been on routing protocol. For
the comparison of routing protocols, many mobility models for MANET have been developed. However,
the availability of many different mobility models without unified quantitative measure of the mobility
have made it very difficult to compare the results of two independent performance stuidies of routing
protocols. To make the comparison possible, we have proposed a standard mobility measure for MANET.
Because of the promise of convenience intrastructure-free communication using MANETs, the development
of large-scale MANET has drawn a lot of attention. We have investigated the inherent scalability problem
of multi-hop networks by analyzing the relationship between the expected packet traffic and the network
size.
Biography: Nah-Oak Song received her B.S. and M.S. degrees from Yonsei University, Seoul, Korea, in
1989 and 1993, respectively. She received the Ph.D. degree from the University of Michigan, Ann Arbor,
MI, in 1999. From 1989 to 1991, she was with the Application Specific Integrated Circuit Research Institute,
Yonsei University, where she was involved in a project on echo cancellation. From 1999 to 2001, she was at
the Telecommunication R&D Center, Samsung Electronics, Korea, and participated in the development of
CDMA 2000 system. Since 2001, she has been working in the Advanced Network Technologies Division at
the National Institute of Standards and Technology, USA. Her main interest is in wireless networks with
emphasis on mobile ad hoc networks and wireless LAN. Her other interests include medium access control
protocol, Quality of Service, stochastic scheduling, and MPLS.