Ai Chen Department of Computer Science and
Engineering Office:
BO 118 Phone: (614)292-8377
(O) Email: chenai (AT) cse (DOT) ohio-state
(DOT) edu I'm a PhD
candidate. My advisor is Prof. Ten
H. Lai. My research
interest is wireless networking. [Bio] [Research]
[Publications] [Teaching]
[Miscellaneous]
Ai Chen is a PhD
candidate in the Department of Computer Science and Engineering
at The Ohio State University,
and is advised by Prof. Ten H. Lai.
Ai Chen received the ME degree and the BE degree from Tsinghua University in 2004 and 2001
respectively.
- Wireless and Sensor Networks
- Mobile Computing
- Network Security
- Parallel and Distributed
Systems
Research
Projects
Local Barrier Coverage
(September 2006 – present)
- It has been proved that given a
sensor deployment, sensors cannot locally determine whether the deployment
provides (global) barrier coverage, making it impossible to develop
localized algorithms, thus limiting its use in practice. We proposed a new
model of coverage, called local barrier coverage, to address this
limitation. Local barrier coverage guarantees the detection of all
movements whose trajectory is confined to a slice to the belt region of
the deployment. We proved that individual sensors can locally determine
the existence of local barrier coverage. To demonstrate that local barrier
coverage can be used to design localized algorithms, we designed a
localized sleep-wakeup algorithm for barrier coverage, called Localized
Barrier Coverage Protocol (LBCP), for maximizing the network lifetime. We
proved that LBCP guarantees local barrier coverage and showed that it
provides close to optimal enhancement in the network lifetime, while
providing global barrier coverage most of the time. Part of this work has
been published in ACM MobiCom 2007.
- In the literature, researchers
only consider whether or not a sensor network provides barrier coverage.
This is equivalent to measuring its quality as either 0 or 1. We believed
quality of barrier coverage is not binary and applied local barrier
coverage as a metric to measure it. We designed an algorithm to identify
all local regions that need to be repaired when the measured quality is
short of a desired value. We proved that the identified regions are minimum in the sense that if one of them is not
repaired then the resulting network will still be short of quality. Part
of this work has been published in ACM MobiHoc
2008.
Multicasting Support in
Wireless Networks (January 2005 – June 2006)
- The IEEE 802.11 protocol has no
specific mechanism for MAC layer multicasting. It implements multicasting
using broadcasting at the base transmission rate. We identified two
fundamental reasons for performance limitations of this approach in
presence of interference and realistic time-varying channels: (a)
Channel-state Indifference: irrespective of the current quality of the
channel to the receivers, the transmission always uses the base
transmission rate; (b) Demand Ignorance: packets are transmitted by a node
even if children in the multicast tree have received those packets by
virtue of overhearing. We proposed a solution for MAC layer multicasting
called HIMAC that uses the following two mechanisms: Unary Channel
Feedback (UCF) and Unary Negative Feedback (UNF) to respectively address
the shortcomings of 802.11. This work has been published in IEEE MASS 2006
and Elsevier COMCOM.
- Support for efficient
multicasting in Wireless LANs (WLANs) can enable
new services. However, for a solution to be viable, the multicast services
must minimally impact the existing unicast
services. We focused on three objective functions motivated by different
revenue functions and network scenarios: maximizing the number of users,
balancing the load among access points (APs),
and minimizing the load of APs. We show that
these problems are NP-hard and present centralized approximation
algorithms and distributed approaches to solve them. This work has been
published in IEEE ICDCS 2007 and Elsevier COMNET.
Communication in
Interconnection Networks (September 2001 – July 2004)
- We designed new fault-tolerant unicasting, multicasting, and broadcasting protocols
for hypercubes, meshes, and tori
to improve the network throughput and communication latency. Parts of this
work have been published in IEEE Trans. on Reliability, Elsevier Parallel
Computing, and Elsevier Journal of Parallel and Distributed Computing.
- Measuring and Guaranteeing Quality of
Barrier-Coverage for General Belts with Wireless Sensors,
Ai Chen, Ten H. Lai, and Dong Xuan,
ACM Transactions on Sensor Networks (TOSN), To Appear. - Efficient
Multicasting over Large-Scale WLANs through Controlled Association,
Ai Chen, Dongwook Lee, and Prasun Sinha,
Elsevier Computer Networks (COMNET), Vol. 53, Issue 1, pp. 45-59, Jan. 2009. - High
Throughput MAC Layer Multicasting over Time-Varying Channels,
Ai Chen, Dongwook Lee, Gayathri Chandrasekaran, and Prasun Sinha,
Elsevier Computer Communications, Vol. 32, Issue 1, pp. 94-104, Jan. 2009. - Measuring
and Guaranteeing Quality of Barrier-Coverage in Wireless Sensor Networks,
Ai Chen, Ten H. Lai, and Dong Xuan,
Proc. of ACM MobiHoc, Hong Kong SAR, China, May 2008.
(Acceptance Rate: 14.7% = 44/300) - Designing
Localized Algorithms for Barrier Coverage,
Ai Chen, Santosh Kumar, and Ten H. Lai,
Proc. of ACM MobiCom, Canada, Sep. 2007.
(Acceptance Rate: 11.2% = 26/233) - Optimizing
Multicast Performance in Large-Scale WLANs,
Ai Chen, Dongwook Lee, and Prasun Sinha,
Proc. of IEEE ICDCS, Toronto, Canada, Jun 2007.
(Acceptance Rate: 13.4% = 71/528) - HIMAC:
High Throughput MAC Layer Multicasting in Wireless Networks,
Ai Chen, Gayathri Chandrasekaran, Dongwook Lee, and Prasun Sinha,
Proc. of IEEE MASS, Vancouver, Canada, Oct 2006.
(Acceptance rate: 24.8% = 49/197) - Fault-Tolerant Multicasting in
Hypercubes Using Local Safety Information,
Dong Xiang, Ai Chen, and Jiaguang Sun,
Elsevier Journal of Parallel and Distributed Computing, vol. 66, no. 2, pp. 248-256, 2006. - Fault-Tolerant Routing and
Multicasting in Hypercubes Using a Partial Path Set-up,
Dong Xiang, Ai Chen, and Jiaguang Sun,
Elsevier Parallel Computing, vol. 31, no. 1, pp. 389-411, 2005. - Fault-Tolerant Routing in 3D Meshes/Tori
Based on Locally Formed Fault Blocks,
Dong Xiang, Ai Chen, and Jiaguang Sun,
Chinese Journal of Computers, vol. 27, no. 5, pp. 611-618, 2004 (in Chinese). - Reliable Broadcasting in
Wormhole-Routed Hypercube-Connected Networks Using Local Safety Information,
Dong Xiang, Ai Chen and Jie Wu,
IEEE Trans. on Reliability, vol. 52, no. 2, pp. 245-256, June 2003. - Partial Path Set-up for
Fault-Tolerant Routing in Hypercubes,
Dong Xiang and Ai Chen,
Proc. of IEEE International Workshop on PMEO-PDS03 with IPDPS03, Apr. 2003. - Local-Safety-Information-Based
Fault-Tolerant Broadcasting in Hypercubes,
Dong Xiang, Ai Chen and Jie Wu,
Journal of Information Science and Engineering, no. 19, pp. 467-478, 2003. - Fault-Tolerant Broadcasting for
Hypercubes via Local Safety Information,
Dong Xiang, Ai Chen and Jie Wu,
Proc. of IEEE International Conference on Parallel and Distributed Systems, Taiwan, Dec. 2002. - Fault-Tolerant Routing in 2D
Tori or Meshes Using Limited-Global-Safety Information,
Dong Xiang and Ai Chen,
Proc. of IEEE ICPP, Vancouver, Aug. 2002. - Local-Safety-Information-Based
Broadcasting in Hypercube Multicomputers with Node and Link Faults,
Dong Xiang, Ai Chen and Jie Wu,
International Journal of Interconnection Networks, vol. 2, no. 3, pp. 365-378, 2001.
Reviewer for
Journals
- IEEE Transactions on Parallel
and Distributed Systems
- IEEE Transactions on Computers
- IEEE Transactions on Vehicular
Technology
- Journal of Parallel and
Distributed Computing (Elsevier)
- Wireless Networks (Springer)
- CSE 459.21 Programming in C
[WI06] [SP06] [AU06] [WI07] [SP07] [AU09]
- CSE 459.22
Programming in C++ [SU06] [SU07] [SU08] [AU08] [WI09] [SP09] [SU09]
- CSE 459.23
Programming in Java [AU07] [SU08] [SU09]
- Course Resource Configuration
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