Kyung Joon (KJ) Kwak

Email : [email protected]

General Information Publications Projects CV Related Links

Projects 2007 ~ present Self-Organizing Asynchronous Sleep-wake Sensor System: Synchronization at the initial phase in sensor network can be a huge burden since energy of each sensor is limited. It also prevents sensor networks being redeployed when sensors died. To overcome such deficit, we developed an asynchronous sleep scheduling based on the concept of cyclic cellular automata and its various characteristics are analyzed. (i.e., band of wake sensors, faster wave propagation speed, etc). This scheme virtually makes network lifetime endless. Whenever sensors fail, what we need to do is to grab a bag of sensors and dump over field. Newly deployed sensors will be a part of sensor system without complicated procedures and this comes from self-organizing property of cellular automata. 2007 ~ present Localization in Wireless Sensor Network: Most localization schemes assume isomorphic medium such that measurement is uniform over the sensor field. Currently, I’m developing a localization scheme that even can be applied to non-isomorphic geographic medium. This scheme uses geographical map to find the proper transfer function to map signal space to geographical space. 2007 Synchronous Sleep-wake Protocol in Wireless Sensor Networks: The goal of SToMP (Sensor Topology & Minimal Planning) is to create and utilize mathematical innovations to deduce global structure from local information in distributed and coordinated sensing platforms. We developed a scalable, easily implemented, self-organizing, energy conserving intrusion-detection sensor system applying concepts from cellular automata theory. To maintain synchronous periodic sleep schedule, each sensor follows simple local rule. By adopting simple local rule, self-organizing and fault tolerant property come to for free. Our scheme is pretty dynamic such that (smart) intruders will be detected soon enough. This sensor system is implemented with Java applet. Some experiments are provided at http://www.ee.columbia.edu/~kjkwak/ca. 2007 Stochastic Counting Protocol in Sensor Networks: One of the major applications of sensor networks is monitoring given area and count the object inside that area. Since one sensor are not be able to cover entire region, cooperation among multiple sensors is a critical factor. Furthermore, sensing is not error free and overlapping sensing area will produce over-counting problem. To eliminate such deficits, we developed a statistical method to recover target counting error and eliminate redundancy in data by using joint cumulants of data sample. This scheme performs in distributed fashion and only requires neighbour information 2005 ~ 2006 Retransmission Scheduling in OBS Networks: Optical Burst Switchingis lies between optical circuit switching (OCS) and optical packet switching (OPS). Each ingress node assembles multiple IP packets into a data burst. Once a data burst is assembled, the ingress node sends a header prior to data burst transmission in order to reserve available wavelengths at intermediate nodes. Once these reservations are set, the data burst will be transported along the designated path without any Optical-Electronic-Optical (OEO) conversion. We designed a retransmission scheme with fiber delay lines, in which triggers a retransmission in optical domain to dramatically reduce end-to-end delay and burst drop ratio. We also propose a facility location model suitable for optimizing the locations of sites with fiber delay lines when the number of such sites is limited 2005 Summer UPNP QoS Version 2 and 3 : Universal Plug and Play (UPnP) is a set of computer network protocols promulgated by the UPnP Forum and is the major protocol in home network. The goals of UPnP are to allow devices to connect seamlessly and to simplify the implementation of networks in the home. I participated in developing QoS version 2 and 3 and implemented home network printer user interface compatible with LG home appliance devices. 2004-2005 Routing Protocols in Sensor Networks: Armstrong project aims at experimental systems research and developing new technologies for wireless sensor and ad hoc networks. We developed solicitation-based forwarding (SOFA), a highly-responsive hop-by-hop routing protocol that results in increased application fidelity. SOFA represents a cost-effective, on-demand scheme that makes use of simple solicitation-based handshakes between a sender and multiple potential receivers at each wireless hop to negotiate the best forwarding path to a target destination (i.e., sink) when events occur in the sensor field. We showed that he forwarding decision of a sensor device should be based not on historical information but on the instantaneous link conditions at the exact time of packet communications. We also present the detailed design, implementation, and experimental evaluation of SOFA in a 36-node Mica2 test bed using TinyOS, The detail information can be provided at http://comet.columbia.edu/armstrong.