Research Areas

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Routing in Ad Hoc Networks

A network topology with directional links envisions a more general modeling of communication networks than traditional bidirectional link assumptions in heterogeneous networks, such as in satellite and terrestrial communications. Our research shows that a unidirectional link of the network can be used in routing only if it has an inclusive cycle. It incurs expensive overhead to maintain the inclusive cycle property of unidirectional links in heterogeneous networks.

  1. 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.
  2. 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.

We propose a set of anonymous multicast and unicast routing protocols in wireless ad hoc networks that enable anonymity of nodes, links, routing tables, and source routing paths/trees using Bloom filters, and sometimes with cryptographic means.

  1. 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.
  2. 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.

Channel Access Scheduling

Channel access schemes for ad hoc networks can be contention-based or scheduled. The advantage of contention-based schemes is that they are relatively easy to deploy. However, collision-avoidance schemes cannot prevent collisions of control packets and and capture effects on the channel due to inherent randomness and near-far phenomena. Scheduled access schemes prearrange or negotiate a set of timetables for individual nodes or links, such that the transmissions from these nodes or on these links are collision-free. Our research shows that the local topology can be sufficient for efficient channel-access scheduling in ad hoc networks.

  1. L. Bao and J.J. Garcia-Luna-Aceves, "Distributed Channel Access Scheduling for Ad Hoc Networks", Chapter 4, Handbook of Algorithms for
    Wireless Networking and Mobile Computing (A. Boukerche, Ed.), Chapman and Hall/CRC, 2006.
  2. L. Bao, "MALS: Multiple Access Scheduling Based on Latin Squares", in Proc. IEEE MILCOM 2004, Monterey, CA, October 31 - November 3, 2004.
  3. L. Bao, "Neighbor-aware control in ad hoc networks", Dissertation, University of California, Santa Cruz, 2002.
  4. 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.
  5. 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.
  6. 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, 2002.
  7. 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.
  8. 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.
  9. 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.
  10. 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.
  11. 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.
  12. 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 and J.J. Garcia-Luna-Aceves, "Flow Oriented Channel Access Mechanism Using Directional Antennas", Work in progress.

Topology Management

Mobile ad hoc networks feature constant topology changes, and communications in the network require ever-lasting control information exchanges to maintain network connectivity and to acknowledge destination reachability. The amount of control information flowing in any network depends not only on its communication protocols, but also on the network topology presented to these protocols. We present a topology management algorithm that constructs and maintains a virtual overlay topology based on the minimal dominating set (MDS) of the network.

  1. 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.
  2. 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.
  3. 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.
  4. 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.

Wireless Network Coverage

We study the network coverage problem in sensor networks and WiFi networks for monitoring and access control purposes.

  1. J. Huseynov, D. Sy, L. Bao, L. Bic and M. Dillencourt, "Probabilistic Agent Flooding for Target Detection in Sensor Networks", submitted to 26th Annual IEEE Conference on Computer Communications (INFOCOM), Anchorage, Alaska, USA, May 6-12, 2007.
  2. J. Lu and L. Bao and T. Suda, "Coverage-Aware Sensor Engagement in Dense Sensor Networks", to appear in Journal of Embedded Computing (JEC), Special Issue on Embedded System Optimization, IOS Press, 2007.
  3. Y. Cho, L. Bao and Michael Goodrich, "Secure Location-Based Access Control in WLAN Systems", to appear in "Wireless and Sensor Networks Security", Edit. Jiang Zhen, Publisher: Nova Science Publishers, Inc., 2007.
  4. 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.
  5. 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.
  6. 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.
  7. 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.
  8. L. Bao and J.J. Garcia-Luna-Aceves, "Reliable Broadcast Using Slotted-ALOHA in Wireless Sensor Networks", Work in progress.

Mobility Support

Wireless networks can support host mobility in different ways. In general, two types of mobility are considered -- micro-mobility and macro-mobility. Solutions can be host-transparent or network transparent implemented at different layers of the networking architecture, especially at data link layer, network layer and application layer in the TCP/IP protocol stack. We explore new approaches to the mobility-supporting architecture, considering existing services in the IP networks, and new paradigms and infrastructure for reliable, scalable mobile communications.

  1. 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.
  2. 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.
  3. 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.

Packet Traceback

Network-based attacks can be either persistent or sporadic. Persistent attack flows can be relatively easy to trace by mechanisms such as probablistic packet marking, traffic logging, data mining etc. Sporadic attacks are sometimes easily detected by the intrusion detection system (IDS) at the victim, but hard to trace back to the attack origins. Issues include traffic logging mechanism, traceback protocol design etc. We study the packet tracking problem in the sporadic attack scenarios.
  1. D. Sy and L. Bao, " CAPTRA: CoordinAted Packet TRAceback ", in The Fifth International Conference on Information Processing in Sensor Networks (IPSN), Nashville, TN, April 19-21, 2006.
  2. L. Bao and D. Sy, "Coordinated Packet Traceback in Wireless Mesh Networks", to appear in "Wireless Mesh Networking with 802.16, 802.11, and ZigBEE", Edit. George Aggelou, Publisher: McGraw-Hill, 2008.

Lichun Bao