• Journal of Information Processing Systems
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• v.13 no.5
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• pp.1229-1242
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• 2017

In this paper, an interference aware distributed multi-channel MAC (IDMMAC) protocol is proposed for wireless sensor and actor networks (WSANs). The WSAN consists of a huge number of sensors and ample amount of actors. Hence, in the IDMMAC protocol a lightweight channel selection mechanism is proposed to enhance the sensor's lifetime. The IDMMAC protocol divides the beacon interval into two phases (i.e., the ad-hoc traffic indication message (ATIM) window phase and data transmission phase). When a sensor wants to transmit event information to the actor, it negotiates the maximum packet reception ratio (PRR) and the capacity channel in the ATIM window with its 1-hop sensors. The channel negotiation takes place via a control channel. To improve the packet delivery ratio of the IDMMAC protocol, each actor selects a backup cluster head (BCH) from its cluster members. The BCH is elected based on its residual energy and node degree. The BCH selection phase takes place whenever an actor wants to perform actions in the event area or it leaves the cluster to help a neighbor actor. Furthermore, an interference and throughput aware multi-channel MAC protocol is also proposed for actor-actor coordination. An actor selects a minimum interference and maximum throughput channel among the available channels to communicate with the destination actor. The performance of the proposed IDMMAC protocol is analyzed using standard network parameters, such as packet delivery ratio, end-to-end delay, and energy dissipation, in the network. The obtained simulation results indicate that the IDMMAC protocol performs well compared to the existing MAC protocols.

• Journal of Advanced Marine Engineering and Technology
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• v.37 no.4
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• pp.418-424
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• 2013

Both simulation and physical implementation are valuable tasks in sensor network routing protocols. In this paper, we propose an efficient underground utilities monitoring method within several constraints using wireless sensor network. First, in order to physically implement protocol of network which is applied, the distributed event-based simulation, which applies an existing nesC codes of sensor network routing protocols, is implemented and analyzed. Also, we have performed the simulation and analyzed the execution results for application model of routing protocols for monitoring underground utilities in the VIPTOS(Visual Ptolemy and TinyOS) environments which combine TOSSIM and Ptolemy II based on distributed event.

• Proceedings of the Korea Information Processing Society Conference
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• 2006.05a
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• pp.1147-1150
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• 2006

Stream Control Transmission Protocol (SCTP) uses the 32-bit checksum in the common header, by which a corrupted SCTP packet will be regarded as a lost packet and then discarded. This may result in degradation of SCTP's throughput performance over wireless networks. This paper proposes a new chunk checksum scheme for SCTP, in which each data chunk contains its own checksum field and SACK chunk carry corresponding Transmission Sequence Number (TSN) with timestamp for every corruption event. The proposed chunk checksum scheme is introduced with the following three purposes: 1) to distinguish the chunk corruptions from the chunk losses; 2) to avoid the unnecessary halving of the congestion window (cwnd) in the case of chunk corruption; 3) to avoid the unwanted timeouts which can be induced in conventional SCTP in the case that the retransmitted data chunks are corrupted again in wireless networks. Simulation results show that the proposed chunk checksum scheme could improve the SCTP throughput in the wireless environments with a high bit error rate.

• Proceedings of the IEEK Conference
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• 2008.06a
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• pp.131-132
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• 2008

It is necessary to develop a high-speed wireless transmission system, which is able to send medical informations to the emergency medical center during emergency patient transportation. In this research, a system which transmits patient’s vital signs and a real-time audio/video contents of the event has been designed, developed, and the suitability of the system has been verified. Test results indicate that the system is capable of transmitting vital signal data, including 17 numeric data, 12 waveforms and 113 events, reading the affected part by forwarding a $320{\times}240$ pixel image at 2fps. Also, the full-duplex voice transmission of the system at 8bit/64kbps is enough to make stable communication between emergency medical technicians and hospital professionals possible. After numerous hours of driving, the packet loss of patient vital signs is 0.013%.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2000.11a
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• pp.717-720
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• 2000

Event-driven communication protocols such as CAN(Controller Area Network) have inherent packet delays due to the contention process for the use of network medium. These delays are stochastic in nature because most packets arrive at random time instants. The stochastic property of the delay adversely influences the control system's performance in terms of stability, responsiveness and steady-state error. Another problem for safety-critical application such as brake-by-wire systems is the reliability of the communication modules that can fail abruptly. This paper deals with two methods to overcome the above problems : (i) scheduling method that can maintain packet delays under some acceptable level, and (ii) redundancy management of communication modules that prescribes dual-redundancy modules' behavior when one of them fails.

• Journal of the Korea Institute of Military Science and Technology
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• v.11 no.3
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• pp.58-66
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• 2008

In this paper, we have proposed a method and procedure which can find out the unknown network protocol. Although it seems to be difficult to identify the protocol, we can find out the rule in the packet according to the method we have proposed. We have to recognize functions of the system and make the list of events first. Then we capture the network packet whenever the event are occurred. The captured packets are examined by means of the method that is finding repeated parts, changed parts according to the input value, fixed parts and changed parts according to regular rules. Finally we make the test program to verify the protocol. We applied this method and procedure to upgrade Electronic Warfare Test System which is operated by ADD. We have briefly described the redesign of control and analysis software for Electronic Warfare Test System

• The Journal of Korean Institute of Communications and Information Sciences
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• v.40 no.7
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• pp.1313-1329
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• 2015

In MANET, frequent route breaks lead to repeated route discovery process and this increases control packet overhead and packet drop. AODV-I improves performance of AODV by using the event driven approach which removes periodic Hello message. Unlike the Hello message, Interrupt message which is sent for each event can detect and predict the link failure because it allows node to know the status of the neighbor node. From this characteristics of Interrupt message, performance of AODV-I can be further improved by adding a processing procedures for each type of Interrupt message and it is also possible to improve AODV-I by adding the Backup path scheme because it originally has problems due to a single path of AODV. In this paper, we propose AODV-IB that combines improved Backup path scheme and Interrupt message approach of AODV-I in order to reduce transmission delay and the number of route discoveries. AODV-IB improves AODV-I by adding proper processing procedures for the link failure prediction and detection for each Interrupt message. We also implement improved Backup path strategy in AODV-IB by minimizing delay without additional Control packet. Simulation results, using the simulator QualNet 5.0, indicate that proposed AODV-IB performs better than AODV-I.

• Journal of the Korea Society of Computer and Information
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• v.13 no.6
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• pp.59-68
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• 2008

In this paper, we propose a method for selecting meaningful event packets from which can receive before anything else from seismograph according to allotted priority and estimate epicenter using selected packets. Event packets which received from each station will be evaluated with their onset time, signal period and SNR by statistical method and will be selected packets related with real earthquake's P-wave. And estimated epicenters using by 'Application of epicenter estimation using first P arrivals'. With local earthquakes occurred in 2007 were announced by KMA, collected event packets on earthquake happened date and selected p-wave related packets and estimated epicenter. After result of experiment, if an earthquake occurred within seismic networks, can estimate epicenter with small misfits just after event packets arrived from above 4 stations. Considering average distance of each station, in case of using all stations' data include other organization, can estimate and alert rapidly. It show this method is useful when construct a local earthquake early warning system later.

• The Journal of the Acoustical Society of Korea
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• v.38 no.4
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• pp.427-432
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• 2019

In this paper, we propose a home monitoring system using sound event detection based on a bidirectional gated recurrent neural network for the hard-of-hearing. First, in the proposed system, packet loss concealment is used to recover a lost signal captured through wireless sensor networks, and reliable channels are selected using multi-channel cross correlation coefficient for effective sound event detection. The detected sound event is converted into the text and haptic signal through a harmonic/percussive sound source separation method to be provided to hearing impaired people. Experimental results show that the performance of the proposed sound event detection method is superior to the conventional methods and the sound can be expressed into detailed haptic signal using the source separation.

• Journal of Information Processing Systems
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• v.11 no.4
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• pp.616-629
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• 2015

A mobile terminal will expect a number of handoffs within its call duration. In the event of a mobile call, when a mobile node moves from one cell to another, it should connect to another access point within its range. In case there is a lack of support of its own network, it must changeover to another base station. In the event of moving on to another network, quality of service parameters need to be considered. In our study we have used the Markov decision process approach for a seamless handoff as it gives the optimum results for selecting a network when compared to other multiple attribute decision making processes. We have used the network cost function for selecting the network for handoff and the connection reward function, which is based on the values of the quality of service parameters. We have also examined the constant bit rate and transmission control protocol packet delivery ratio. We used the policy iteration algorithm for determining the optimal policy. Our enhanced handoff algorithm outperforms other previous multiple attribute decision making methods.