• KSII Transactions on Internet and Information Systems (TIIS)
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• v.6 no.1
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• pp.270-286
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• 2012

In this paper, we propose a novel routing protocol called the Cartography Enhanced OLSR (CE-OLSR) for multi hop mobile ad hoc networks (multi hop MANETs). CE-OLSR is based on an efficient cartography gathering scheme and a stability routing approach. The cartography gathering scheme is non intrusive and uses the exact OLSR reduced signaling traffic, but in a more elegant and efficient way to improve responsiveness to the network dynamics. This cartography is a much richer and accurate view than the mere network topology gathered and used by OLSR. The stability routing approach uses a reduced view of the collected cartography that only includes links not exceeding a certain distance threshold and do not cross obstacles. In urban environments, IEEE 802.11 radio signals undergo severe radio shadowing and fading effects and may be completely obstructed by obstacles such as buildings. Extensive simulations are conducted to study the performances of CE-OLSR and compare them with those of OLSR. We show that CE-OLSR greatly outperforms OLSR in delivering a high percentage of route validity, a much higher throughput and a much lower average delay. In particular the extremely low average delay exacerbated by CE-OLSR makes it a viable candidate for the transport of real time data traffic in multi hop MANETs.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2010.10a
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• pp.475-477
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• 2010

In the power saving mechanism specified in IEEE 802.11, all node use the sam ATIM window size. Since the ATIM window size critically affects throughput and energy consumption, a fixed ATIM window does not perform well in all situations. This paper proposes the efficient power management mechanism considering network characteristic in 802.11. To reflect the network characteristic, the paper uses th (m,k)-firm deadline technique. Simulation result shows that proposed mechanism outperforms the IEEE 802.11 power saving mechanism in terms of the amount of power consumed.

• Journal of the Korea Society of Computer and Information
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• v.13 no.5
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• pp.45-52
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• 2008

In this paper, we propose an efficient dynamic workload balancing strategy which improves the performance of high-Performance computing system. The key idea of this dynamic workload balancing strategy is to minimize execution time of each job and to maximize the system throughput by effectively using system resource such as CPU, memory. Also, this strategy dynamically allocates job by considering demanded memory size of executing job and workload status of each node. If an overload node occurs due to allocated job, the proposed scheme migrates job, executing in overload nodes, to another free nodes and reduces the waiting time and execution time of job by balancing workload of each node. Through simulation, we show that the proposed dynamic workload balancing strategy based on CPU, memory improves the performance of high-performance computing system compared to previous strategies.

• ETRI Journal
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• v.43 no.3
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• pp.414-426
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• 2021

In the task of data routing in Internet of Things enabled volatile underwater environments, providing better transmission and maximizing network communication performance are always challenging. Many network issues such as void holes and network isolation occur because of long routing distances between nodes. Void holes usually occur around the sink because nodes die early due to the high energy consumed to forward packets sent and received from other nodes. These void holes are a major challenge for I-UWSANs and cause high end-to-end delay, data packet loss, and energy consumption. They also affect the data delivery ratio. Hence, this paper presents an energy efficient watchman based flooding algorithm to address void holes. First, the proposed technique is formally verified by the Z-Eves toolbox to ensure its validity and correctness. Second, simulation is used to evaluate the energy consumption, packet loss, packet delivery ratio, and throughput of the network. The results are compared with well-known algorithms like energy-aware scalable reliable and void-hole mitigation routing and angle based flooding. The extensive results show that the proposed algorithm performs better than the benchmark techniques.

• International Journal of Computer Science & Network Security
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• v.23 no.10
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• pp.169-178
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• 2023

Wireless sensor network is wieldy use for IoT application. The sensor node consider as physical device in IoT architecture. This all sensor node are operated with battery so the power consumption is very high during the data communication and low during the sensing the environment. Without proper planning of data communication the network might be dead very early so primary objective of the cluster based routing protocol is to enhance the battery life and run the application for longer time. In this paper we have comprehensive of twenty research paper related with clustering based routing protocol. We have taken basic information, network simulation parameters and performance parameters for the comparison. In particular, we have taken clustering manner, node deployment, scalability, data aggregation, power consumption and implementation cost many more points for the comparison of all 20 protocol. Along with basic information we also consider the network simulation parameters like number of nodes, simulation time, simulator name, initial energy and communication range as well energy consumption, throughput, network lifetime, packet delivery ration, jitter and fault tolerance parameters about the performance parameters. Finally we have summarize the technical aspect and few common parameter must be fulfill or consider for the design energy efficient cluster based routing protocol.

• Biotechnology and Bioprocess Engineering:BBE
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• v.9 no.2
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• pp.86-92
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• 2004

In this paper miniaturized disposable micro/nanofluidic components applicable to bio chip, chemical analyzer and biomedical monitoring system, such as blood analysis, micro dosing system and cell experiment, etc are reported. This system includes various microfluidic components including a micropump, micromixer, DNA purification chip and single-cell assay chip. For low voltage and low power operation, a surface tension-driven micropump is presented, as well as a micromixer, which was implemented using MEMS technology, for efficient liquid mixing is also introduced. As bio-reactors, DNA purification and single-cell assay devices, for the extraction of pure DNA from liquid mixture or blood and for cellular engineering or high-throughput screening, respectively, are presented.

• Journal of Communications and Networks
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• v.6 no.4
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• pp.295-306
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• 2004

In this paper, a novel air-interface is presented for Fleet-Net1, a self-organizing network for inter-vehicle and vehicle-toroadsidecommunication. The air-interface is based upon the lowchip-rate version of UMTS/TDD. To adapt the cellular UMTS standard to an air-interface for ad hoc networks, changes of the physical layer, medium access control sub-layer and radio resource management are required. An overview of the required modifications is given here. Particularly, a decentralized synchronization mechanism is presented and analyzed by means of simulations. Furthermore, changes for the medium access control are explained in detail, which allow for an efficient operation in partly meshed networks and prioritization. Performance results of the overall system considering throughput and delay are derived by means of analytical evaluations and event-driven simulations. Based on realistic mobility models, it is shown that the presented solution provides a robust communication platform even in vehicular environments. The proposed air-interface is a cost-effective solution not only for inter-vehicle communication, but also for ad hoc networking in general, benefiting from the mass-market of UMTS.

• ETRI Journal
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• v.26 no.6
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• pp.615-621
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• 2004

Next generation mobile communication system, such as IMT-2000, adopts Turbo codes due to their powerful error correction capability. This paper presents a block-wise maximum a posteriori (MAP) Turbo decoding structure with a low memory requirement. During this research, it has been observed that the training size and block size determine the amount of required memory and bit-error rate (BER) performance of the block-wise MAP decoder, and that comparable BER performance can be obtained with much shorter blocks when the training size is sufficient. Based on this observation, a new decoding structure is proposed and presented in this paper. The proposed block-wise decoder employs a decoding scheme for reducing the memory requirement by setting the training size to be N times the block size. The memory requirement for storing the branch and state metrics can be reduced 30% to 45%, and synthesis results show that the overall memory area can be reduced by 5.27% to 7.29%, when compared to previous MAP decoders. The decoder throughput can be maintained in the proposed scheme without degrading the BER performance.

• Proceedings of the KIEE Conference
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• 2008.04a
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• pp.161-162
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• 2008

본 연구는 무선 통신 시스템에서 다수의 가입자 또는 connection이 존재할 때 트래픽 패킷의 전송 우선순위를 결정하는 방법에 관한 것으로, 특히 시스템 상에 QoS를 만족해야하는 실시간 트래픽 전송을 요구하는 connection과 비실시간 트래픽 전송을 요구하는 connection이 동시에 존재하는 경우에 대한 것이다. 패킷 기반의 시스템에서 각 frame에 할당하는 트래픽 패킷의 우선순위를 결정하는 방법이 반드시 존재해야 한다. 가입자 당 전송하는 트래픽 패킷은 실시간 트래픽과 비실시간 트래픽으로 구분할 수 있다. 실시간 트래픽 전송의 경우 허용전송지연시간 내에 전송하지 못하는 패킷이 발생할 확률을 일정 수준 이하로 유지하는 것이 중요하기 때문에, 일반적으로 비실시간 트래픽에 비해 우선순위를 가진다. 본 연구에서는 실시간 트래픽에 대해 허용전송지연시간 초과 패킷 확률을 일정 수준 이하로 유지하면서 미레적인 방법을 통해 비실시간 트래픽 패킷에 대한 실시간 트래픽 패킷의 우선순위를 제한하여 시스템의 평균 throughput을 향상시키는 것을 목적으로 한다. 시뮬레이션을 통해 분석한 결과 비례적인 방법을 통해 실시간 트래픽 패킷을 보다 효율적으로 전송할 수 있다는 것을 검증할 수 있었다.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.8 no.8
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• pp.2691-2707
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• 2014

Medium access control is critical in wireless networks for efficient spectrum utilization. In this paper, we introduce a novel collision resolution method based on the technique of known interference cancellation, and propose a new MAC protocol named as CR-MAC, in which AP tries to decode all the collided data packets by combining partial retransmissions and known interference cancellation. As the collided transmissions are fully utilized, less retransmission is required, especially in a crowded network. The NS-2simulation and MATLAB numerical results show that, under various network settings, CR-MAC performs much better than the IEEE 802.11 DCF in terms of the aggregation throughput and the expected packet delay.