Prof. Bao's research interests extend over five areas
in wireless networks, based on both analytic frameworks and empirical
results.
- MAC protocol design and evaluation
- Routing protocols
- Mobility
management
- Localization algorithms
- Network security
provisioning
In additional to using the widely adopted network simulators,
such as NS2 and NCTUns, our research laboratory
establishes and utilizes
wide array of experimental testbeds, such as SDR nodes
based on
GNU
Radio and USRP, multiple wireless mesh routers based on COTS devices
and open-source projects, as well as the public PlanetLab site
at UCI.
1) MAC Protocol Design
Wireless networks, especially in multi-hop networking
scenarios, are
constrained by the limited communication channel capacity, governed by
Shannon’s law. On the other hand, ever-increasing demands on data
throughput squeeze out any budget dedicated to channel access
coordination functions in the distributed environments. Traditional
approaches to efficient channel access control have branched out in two
directions – randomized that allows collision-tolerant distributed
channel access control, or scheduled that generates conflict-free
transmission schedule at the cost of high system coordination overhead.
An ideal solution that achieves efficient conflict-free transmission
schedule with minimum amount of system coordination overhead is the
“Holy Grail” in MAC protocol design area. We have made significant
contributions towards the goal.
- L. Bao and J.J. Garcia-Luna-Aceves, "Distributed Channel Access Scheduling for
Ad Hoc Networks",
book chapter in "Algorithms and Protocols for Wireless and Mobile
Networks" , Edit. A. Boukerche, Publishers: CRC/Hall Publisher, 2004.
- L. Bao and J.J. Garcia-Luna-Aceves, "Computational
Time-Division and Code-Division Channel Access Scheduling in Ad Hoc
Networks", Journal of Networks (JNW), Academic
Publisher,
Issue 8, 2008.
- L. Bao and J.J. Garcia-Luna-Aceves, "Receiver-Oriented Multiple Access in Ad
Hoc Networks with Directional
Antennas", ACM/Kluwer Mobile Networks and Applications
(MONET), 2003.
- L. Bao and J.J. Garcia-Luna-Aceves, "Distributed
Dynamic Channel Access Scheduling for Ad Hoc Networks", In JPDC,
Special Issue on Wireless and Mobile Ad Hoc Networking and
Computing, Elsevier, 2002.
- L. Bao, "MALS:
Multiple Access Scheduling Based on Latin Squares", in Proc. IEEE
MILCOM 2004, Monterey, CA, October 31 - November 3, 2004.
- L. Bao and J.J. Garcia-Luna-Aceves, "Topology
Management in Ad Hoc Networks", The ACM International Symposium on
Mobile Ad Hoc Networking and Computing (MOBIHOC),
Annapolis, Maryland, June 1-3, 2003.
- L. Bao and J.J. Garcia-Luna-Aceves, "Hybrid
Channel Access Scheduling in Ad Hoc Networks", Proc. IEEE
ICNP 2002, Paris, France, November 12-15, 2002.
- L. Bao and J.J. Garcia-Luna-Aceves, "Transmission
Scheduling in Ad Hoc Networks with Directional Antennas", Proc.
ACM/IEEE MobiCom 2002, Atlanta, Georgia, USA, September 23-28,
2002.
- L. Bao and J.J. Garcia-Luna-Aceves, "Distributed
Transmission Scheduling Using Code-Division
Channelization", Proc. IFIP-TC6 Networking 2002,
Pisa, Italy, 19-24 May 2002.
- W. Kishaba, G. Vardakas, J.J. Garcia-Luna-Aceves, L.
Bao, and Y. Kang, "Ad Hoc Networking
with Beam Forming Antennas", Proc. IEEE MILCOM
2001,
Washington, D.C., October 28-31, 2001.
- L. Bao and J.J. Garcia-Luna-Aceves, "A
New Approach to Channel Access Scheduling for Ad Hoc Networks",
Proc. ACM/IEEE MobiCom 2001, Rome, Italy, July 16-21, 2001.
- L. Bao and J.J. Garcia-Luna-Aceves, "Channel
Access Scheduling in Ad Hoc Networks with Unidirectional
Links", Proc. ACM/IEEE DIAL-M 2001, Rome, Italy, July 21, 2001.
- L. Bao and J.J. Garcia-Luna-Aceves, "A
New Collision-Free Medium Access Control Protocol", Proc. IEEE
MILCOM 2000, Los Angeles, California, October 22-25, 2000.
- L. Bao, "Neighbor-aware
control in ad hoc networks", Dissertation, University of
California, Santa Cruz, 2002.
Besides the traditional channel access coordination
problems in homogeneous wireless networks, we brought up new MAC
problems for heterogeneous wireless systems, in which different
wireless systems, such as WiFi and GSM, share the same channel in a
TDMA fashion, uniquely different from cognitive radio to solve the
spectrum scarcity problem. Heterogeneous wireless system coexistence is
supported by NSF
(2007-2010).
- L. Bao and S. Liao, “Temporal Spectrum Access
Scheduling in Heterogeneous Wireless Systems”, accepted for
publication in The International Conference on Information Networking
(ICOIN), Busan, Korea, 2009.
- S. Liao and L. Bao, “Spatial Spectrum Reuse in
Heterogeneous Wireless Systems”, accepted for publication in The
International Conference on Information Networking (ICOIN), Busan,
Korea, 2009.
- L. Bao and S. Liao, “Spectrum
Access Scheduling among Heterogeneous Wireless Systems”,
accepted for publication as a book chapter in Emerging Wireless
Networks:
Concepts, Techniques and Applications, ed. C. Makaya and S. Pierre,
Auerbach Publications, Taylor & Francis Group, 2009.
- L. Bao and S. Liao, "Scheduling Heterogeneous Wireless Systems
for Efficient Spectrum Access",
accepted for publication in EURASIP Journal on Wireless
Communications and
Networking, special issue on Wireless Network Algorithms, Systems, and
Applications, 2010.
- L. Bao, S. Liao and E. Bozorgzadeh, "Spectrum Access Scheduling among
Heterogeneous Wireless Systems", accepted for publication by SDR
Forum Technical Conference and Product Exposition (SDR), Washington,
DC, 2009.
- S. Liao and L. Bao, "Implementing
a Base Station Using the SDR Platform for Coexistence of Heterogeneous
Wireless Systems", Demo accepted for presentation in SDR
Forum
Technical Conference and Product Exposition (SDR), Washington, DC, 2009.
- A. Gholamipour, E. Bozorgzadeh and L.
Bao, "Seamless Sequence of Software
Defined
Radio Designs through Hardware Reconfigurability of FPGAs",
The
International Conference on Computer Design (ICCD), Lake Tahoe, CA,
Oct. 12-15, 2008.
Additionally, we also designed channel sharing scheme in
the SDMA (spatial division multiple access) fashion for heterogeneous
wireless systems coexistence, and derived analytic and experimental
results in order to deploy DSSS-based WiFi systems in the communication
channels used by the GSM systems.
2) Routing Protocol Design
We have done extensive research in designing routing
protocols for wireless ad hoc and sensor networks under special
constraints, such as unidirectional link, underground tunnel
environments or dense ad hoc and sensor network deployments. A related
topic, topology management, was extensively studied in our research
group as well. One of the publications on topology management was
actually one of three key references in the DoD Navy SBIR proposal
solicitation Topic
N08-198 SPAWAR, directed by Mr. Steve Stewart.
- L. Bao and J.J. Garcia-Luna-Aceves, "Unidirectional
Link-State Routing with Propagation Control", Proc. IEEE Mobile
Multimedia Communications (MoMuC) 2000, Tokyo, Japan,
November 2000.
- L. Bao and J.J. Garcia-Luna-Aceves, "Link
State Routing in Networks with Unidirectional Links", Proc.
IEEE IC3N 99, Boston, Massachusetts, October 11-13, 1999.
- D. Wu, R. Li and L. Bao, "A
Holistic Routing Protocol Design in Underground Wireless Sensor Networks",
in Proc. of The 4th International Conference on Mobile Ad-hoc and
Sensor Networks (MSN), Wuhan, China, Dec. 10-12, 2008.
- L. Bao and J.J. Garcia-Luna-Aceves, "Stable
Energy-Aware Topology Management in
Ad Hoc Networks", accepted for publication in Ad Hoc
Networks Journal, Elsevier, 2009.
- J. Luo, H. Liu, R. Li and L. Bao, "QoS-Oriented
Asynchronous Clustering Protocol in Wireless Sensor Networks", in
Proc. of the IEEE Intl Conference on Wireless Communication, Networking
and Mobile Networking (WICOM), Dalian, China, Oct. 12-14, 2008.
- H. Tan, W. Zeng, L. Bao and T. Suda, "A
Unified Framework for Topology Management in Multi-Rate Ad Hoc Networks",
IEEE International Conference on Wireless and Mobile Computing,
Networking and Communications (WIMOB), Montreal, Canada, August 22
¨C
24, 2005.
- H. Tan, W. Zeng and L. Bao, "PATM:
Priority-based Adaptive Topology Management for Efficient Routing in Ad
Hoc Networks", The International Conference on Computational
Science 2005 (ICCS), Atlanta, GA, May 22-25, 2005.
- H. Tan, W. Zeng and L. Bao, "Performance
Evaluation of Topology Management in Multi-Rate Ad Hoc Networks",
IEEE Wireless and Communications and Networking Conference (WCNC), New
Orleans, Louisiana, March 13-17, 2005.
- L. Bao, "MALS:
Multiple Access Scheduling Based on Latin Squares", in Proc. IEEE
MILCOM 2004, Monterey, CA, October 31 - November 3, 2004.
- L. Bao and J.J. Garcia-Luna-Aceves, "Topology
Management in Ad Hoc Networks", The ACM International Symposium on
Mobile Ad Hoc Networking and Computing (MOBIHOC),
Annapolis, Maryland, June 1-3, 2003.
3) Mobility Management
Freedom to roam in wireless networks comes at the
complexity of mobility management on both end-user mobile devices and
the network infrastructure backbone. Among possible solutions at each
layer of the networking stack, we addressed the issues at layer-2, the
DLL (data link layer), and proposed a Personal AP protocol to hide the
mobility management details from the mobile devices by moving the
layer-two mobile-to-network communication contexts to the APs that
currently associate with the mobile station.
- J. Wang and L. Bao, "Layer-2 Mobility Management in Hybrid
Wired/Wireless Systems", The
Second International Conference on Quality of Service in Heterogeneous
Wired/Wireless Networks (QSHINE), Orlando, FL, August 22 - 24, 2005.
- L. Zan, J. Wang and L. Bao, "Personal AP Protocol for Mobility
Management in IEEE 802.11 Systems",
The Second Annual International Conference on Mobile and Ubiquitous
Systems: Networking and Services (MOBIQUITOUS), San Diego, CA, July
17-21, 2005.
- J. Wang and L. Bao, "Mobile Context Handoff in Distributed IEEE
802.11 Systems", International Conference on Wireless
Networks, Communications, and
Mobile Computing (WIRELESSCOM), Maui, HI, June 13-16, 2005.
In order to track the topology locations of mobile
hosts, we also proposed a distributed packet traceback mechanism using
Bloom filters, called CAPTRA (CoordinAted Packet Traceback), by taking
advantage of open-air transmission characteristics of wireless media so
that wireless nodes observing packets in the channel may help packet
tracking and tracing operations later.
- D. Sy and L. Bao, "
CAPTRA:
CoordinAted Packet TRAceback",
The Fifth International Conference on Information
Processing in Sensor Networks (IPSN), Nashville, TN, April 19-21, 2006.
4) Localization Algorithms
Location information is crucial in wireless network
management and applications. we have worked on two localization
algorithms for target tracking and networking mapping, respectively.
These applications present opposite goals for localization algorithms –
the first one usually uses multiple reference locations to collectively
identify the location of a single node, whereas the latter uses a
single mobile node to identify the locations of multiple other network
stations, sometimes even without the knowledge of the number of these
target nodes.
- D. Wu, L. Bao and R. Li, "UWB-Based
Localization in Wireless Sensor Networks", International
Journal of Communications, Network and System Sciences (IJCNS),
Scientific Research Publishing, Inc. 2009.
- D. Wu, R. Li and L. Bao, "UWB-Based Localization in Wireless Sensor
Networks", The 5th International Conference on Mobile Ad-hoc and
Sensor Networks (MSN), 2009.
- Y. Zhang, L. Bao, M. Welling and S.H. Yang, "Base Station Localization in Search of
Empty Spectrum Spaces for Cognitive Radio Networks", The 5th
International Conference on Mobile Ad-hoc and Sensor Networks (MSN),
2009.
- D. Wu and L. Bao, "Design
and Evaluation of Localization Protocols and Algorithms in Wireless
Sensor Networks Using UWB", in Proc. of the 27th
International
Performance Computing and Communications Conference (IPCCC), Austin,
TX, Dec. 7-9, 2008.
A derivative work on the localization algorithms was to
solve the location-dependent network coverage problems in WSNs. we have
designed probabilistic algorithms to maintain sufficient sensing
coverage in the network while reducing the energy consumption of WSNs.
One of the papers received the IFIP Best Paper Award in EUC’05.
- J. Lu and L. Bao and T. Suda, "Probabilistic Self-Scheduling for Coverage
Configuration in Wireless Ad-hoc Sensor Networks",
International Journal of Pervasive Computing and
Communications, Vol.
3, No. 1, Emerald Group Publishing Limited, 2008.
- J. Lu and L. Bao and T. Suda, "Coverage-Aware
Sensor
Engagement in Dense Sensor Networks", Journal of
Embedded
Computing (JEC), Special Issue on Embedded System Optimization, IOS
Press, 2007.
- J. Lu, L. Bao and T. Suda, "Coverage-Aware
Sensor Scheduling in Dense Sensor Networks",
in Proc. IFIP International Conference on Embedded And Ubiquitous
Computing (EUC), Nagasa, Japan, 6-9 December 2005. The best paper award.
- J. Lu, L. Bao and T. Suda, "Probabilistic
Self-Scheduling for Coverage Configuration in Sensor Networks",
in Proc. of the International Conference on Sensing Technology (ICST),
Palmerston North, New Zealand, Nov. 2005.
5) Network Security
Our work on provisioning network security focused on two
areas – anonymous routing and network access control in wireless ad hoc
networks. Our work on anonymous routing was the first to use Bloom
filters as a routing mechanism in wireless networks.
- L. Bao, "A New Approach to Anonymous Multicast
Routing in Ad Hoc Networks",
In Proc. of The Second International Conference on Communications and
Networking in China (CHINACOM), Shanghai, China, August 21-24, 2007.
- D. Sy, R. Chen and L. Bao, "ODAR:
On-Demand Anonymous Routing in Ad
Hoc Networks", in Proc. of The Third IEEE International
Conference on Mobile Ad-hoc and Sensor Systems (MASS), Vancouver,
Canada, October 9-12, 2006.
Our work on network access control was a novel application of our prior
research on mobility management (Personal AP) for location-based
network access control purposes.
- Y. Cho, L. Bao and M.T. Goodrich, "Secure Location-Based Access Control in WLAN Systems",
book chapter in "Wireless and Sensor Networks Security", Edit. Jiang
Zhen,
Publisher: Nova Science Publishers, Inc., 2007.
- Y. Cho and L. Bao, "Secure
Access Control for Location-Based Applications in WLAN Systems",
In Proc. of The Second International Workshop on Wireless and Sensor
Networks Security (WSNS), Vancouver, Canada, October 9-12, 2006.
- Y. Cho, L. Bao and M.T. Goodrich, "LAAC:
A Location-Aware Access
Control Protocol", In Proc. of International Workshop on Ubiquitous
Access Control (IWUAC), San Jose, CA, July 17, 2006.
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