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My name is Bach Duy Bui (Vietnamese order: Bui Duy Bach).

From Fall 2005,  I am a PhD student @ Real-time Systems Lab, Computer Science Department, University of Illinois at Urbana Champaign

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Research | Publications | Patents | CV | Contact Information

Research

 

Time Predictability in Highly Critical Embedded Systems

Real-time Wireless Communication for Embedded Systems

In these researches, we are interested in designing and implementing communication real-time services for multi-hop sensor networks which include MAC and Routing protocols. Because of the lossy nature of wireless communication, providing timing guarantee services is hard problem. It is even harder in a distributed settings of a multi-hop network. Since our goal is to provide a practical and implementable protocol, our design choices must be grounded on physical realities and standardized platform. 

1.  Mac protocol

We introduce real-time chain, a new prioritized MAC protocol to support real-time flow communication in wireless sensor networks. By avoiding packet collisions and limiting the effect of priority inversions, real-time chain is able to provide significant delay and bandwidth guarantees. Furthermore, the use of multiple channels enable high spatial reuse and transmission rates. Finally, we can achieve compatibility with IEEE 802.15.4 after minor modifications. The protocol has been fully  implemented on Crossbow MICAz hardware and its performance has been validated with a large set of both indoor and outdoor experiments.

2.  Routing protocol

We propose a hard real-time routing protocol which guarantees the end-to-end deadlines of multiple data flows running on a network. To do so, we first analyzed explicitly the souces of packet delay in wireless network. Second, by using the understanding of the packet delay sources and the Stage Delay Theorem (a new real-time theory), we cast the real-time routing problem into an optimization problem where one of the constraints is the end-to-end deadline of each flow and the objective is to maximize network lifetime. The optimization problem is calculated offline with the output is a set of routes such that all packets meet their deadline. The correctness of the algorithm is verified by simulations on Ns2. We have found that our proposed solution can guarantee hard real-time constraints whereas shortest path routing and RAP protocol would have failed. Apart form the offline technique, an online rediscovery real-time path algorithm in case of node failure is also proposed. We provide analytical proofs for the correctness of the offline algorithm as well as simulation results to show its effectiveness and communication overhead.

Other Projects

A Smart Home Infrastructure: this is my CS424 class project in which we created a software architecture for a smart home. The architecture was implemented and had a very cool demo at Room SC 2111.

Previous Researches

My master thesis investigates on localization protocol for wireless sensor networks which can works even in adversary environment. The designed protocol can be used on many location-aware applications. The protocol was also implemented as a service of the 802.15.4 MAC (IEEE standard) running on H2 sensor node platform.

 

Publications

  1. Bach D. Bui, Marco Caccamo, Lui Sha, Joseph Martinez, Design and Evaluation of a Cache Partitioned Environment for Real-Time Embedded Systems, in the Proceedings of the 14th IEEE International Conference on Embedded and Real-Time Computing Systems and Applications (RTCSA), KaoHsiung, Taiwan, 2008.

  2. Vartika Bhandari, Vivek Raghunathan, Bach D. Bui, Marco Caccamo, Impact of multiple transmission rates on real-time scheduling in wireless systems (extended abstract), ACM Mobicom 2007.

  3. Bach D. Bui, Rodolfo Pellizzoni, Marco Caccamo, Chin F. Cheah, Andrew Tzakis, Soft Real-Time Chains for Multi-hop Wireless Ad-Hoc Networks, in the Proceedings of the IEEE Real-Time and Embedded Technology and Applications Symposium (RTAS), Bellevue, WA, United States, 2007. (pdf)

  4. Bach D. Bui, Maifi Khan, A Deterministic Hard Real-time Routing Protocol for Sensor Networks, Technical Report.

  5. B. D. Bach, D. Kim, A Localization Algorithm with Parametric Learning-based Distance, in the Proceedings of the 14th International Conference on Computer Communication and Networks (ICCCN '05)(pdf).
  6. B. D. Bach, D. Kim, J. Yang , Y. Doh , A Hybrid Approach for Wireless Sensor Network Localization, in the Proceedings of The 15th Joint Conference on Communications and Information (JCCI '05). (Best paper award)
  7. B. D. Bach, D. Kim, A Localization Algorithm Extension for The Evolvable Sensor Network, in the Proceedings of the International Conference on Parallel and Distributed Computing and Systems (PDCS '04) (pdf).
  8. S. Lee, B. D. Bach, D. Kim, Remote Reconnaissance Sensor Network Platform using UAV, KISS Spring Conference, 2003.
Patents
  1. B. D. Bach, D. Kim, U.S. Patent: System, medium, and method for estimating distance in communication system having nodes.
  2. B. D. Bach, D. Kim, Korean Patent: An Adaptive Method for Localization in Wireless Ad-hoc Sensor Network. 
Contact Information

Bach Bui
305 N Lincoln Ave, Apt 301
Urbana, Illinois 61801
U.S.A.