• Journal of IKEEE
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• v.24 no.1
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• pp.326-332
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• 2020

This paper presents the design of a routing metric for energy-efficient and low-delay path selection and a new routing protocol utilizing the metric in duty-cycyled wireless sensor networks. The new routing metric based on duty cycle, EDW, can reduce the energy and delay of transmission paths, which represents total waiting time from source to destination due to duty cycle. Therefore, in this paper, we propose a new multipath routing protocol based on cross-layer information utilizing the new routing metric, and simulation results show that the proposed protocol shows better performance of end-to-end delay and energy consumption.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.36 no.10B
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• pp.1200-1209
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• 2011

In this paper, we propose a novel energy efficient MAC protocol which is based on orthogonal frequency division multiple access (OFDMA) and exploits the physical characteristic that propagation loss of acoustic wave depends on the distance. In the proposed scheme, sensor nodes are grouped according to the distance to sink node. Then, each group uses a different frequency band. The proposed scheme not only enables all sensor nodes to maintain the signal-to-noise ratio above a certain required level (Accepted Minimum SNR, AMS), but also reduces overall transmission power consumption. In addition, the dynamic sub-channel allocation is employed in order to improve data transmission rate. Simulations show that proposed MAC protocol has better performance in a delay-tolerant underwater acoustic sensor networks.

• Journal of the Korea Society of Computer and Information
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• v.13 no.7
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• pp.157-164
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• 2008

In this paper we suggest a scheduling algorithm that transmits periodic traffics efficiently in tree-structured wireless sensor networks (WSNs). The related research[l] showed the problems such as increasing the energy consumption and decreasing the data throughput as the depth of tree increases. To solve these problems. we use idle time slots and avoid the redundancy at data transmission. Also we suggest the algorithm that transmits the control packet when it is similar to a previously measured data. And if emergency data is occurred, our proposed algorithm transits that data in EDP(Emergency Data Period) for reducing the wait time. The proposed algorithm shows more data throughput and less energy consumption than that of the related research.

• Journal of KIISE:Information Networking
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• v.34 no.6
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• pp.435-445
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• 2007

Snoop protocol is one of the efficient schemes to compensate TCP packet loss and enhance TCP throughput in wired-cum-wireless networks. However, Snoop protocol has a problem: it cannot perform local retransmission efficiently under the bursty-error prone wireless link. To solve this problem, SACK-Aware-Snoop and SNACK mechanism have been proposed. These approaches improve the performance by using SACK option field between base station and mobile host. However in the wireless channel with high packet loss rate, SACK-Aware-Snoop and SNACK mechanism do not work well because of two reason: (a) end-to-end performance is degraded because duplicate ACKs themself can be lost in the presence of bursty error, (b) energy of mobile device and bandwidth utilization in the wireless link are wasted unnecessarily because of SACK option field in the wireless link. In this paper, we propose a new local retransmission scheme based on Cross-layer approach, called Cross-layer Snoop(C-Snoop) protocol, to solve the limitation of previous localized link layer schemes. C-Snoop protocol includes caching lost TCP data and performing local retransmission based on a few policies dealing with MAC-layer's timeout and local retransmission timeout. From the simulation result, we could see more improved TCP throughput and energy efficiency than previous mechanisms.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.11 no.8
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• pp.3809-3822
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• 2017

Wireless Sensor Networks hold the limelight because of significant potential for distributed sensing of large geographical areas. The radio duty cycling mechanism that turns off the radio periodically is necessary for the energy conservation, but it deteriorates the network congestion when the traffic load is high, which increases the packet loss and the delay too. Although many papers for WSNs have tried to mitigate network congestion, none of them has mentioned the congestion problem caused by the radio duty cycling of MAC protocols. In this paper, we present a simple and efficient congestion control technique that operates on the radio duty cycling MAC protocol. It detects the congestion by checking the current queue size. If it detects the congestion, it extends the network capacity by adding supplementary wakeup times. Simulation results show that our proposed scheme highly reduces the packet loss and the delay.

• Proceedings of the Korean Information Science Society Conference
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• 2008.06d
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• pp.276-280
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• 2008

무선 센서 네트워크의 연구는 이벤트 기반과 주기적 모니터링 기반미라는 두 가지 응용의 형태에 맞추어 진행되었다. 두 가지 응용의 핵심적인 요구 사항은 다르지만 안정적인 운용을 위해 공동적으로 낮은 전송 자연의 요구가 존재한다. 하지만 기존의 무선 센서 네트워크의 프로토콜은 에너지 효율성을 중심으로 연구가 진행되었기 때문에 전송 자연에 대한 고려가 부족하였다. 본 논문에서는 무선 센서 네트워크의 MAC 프로토콜인 RA-MAC(RTS Aggregation-Media Access Control) 프로토콜을 제안하였다. RA-MAC 프로토콜은 새로운 채널 접근 기법 및 RTS Aggregation 기법에 의해 에너지 효율성과 낯은 전송 자연을 이룰 수 있고 수신 노드의 전송 스케줄링에 의해 이벤트 기반과 주기적 모니터링 기반 응용의 요구 사항을 동시에 만족시킬 수 있다. 실험을 통해 RA-MAC 프로토콜은 기존에 제안된 에너지 효율적인 MAC 프로토콜과 비슷한 에너지 효율을 보이면서 좀 더 낮은 전송 지연을 이루고 전송률을 향상시킬 수 있음을 확인하였다.

• The Journal of Korean Association of Computer Education
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• v.23 no.3
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• pp.65-70
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• 2020

In wireless sensor networks, data packets are send to the sink node. So traffic increases near the sink node. This causes delay and collision. To solve this problem, the proposed mechanism used half rotation antenna. By using a half rotation antenna, the delay of data packets can be reduced. Also we propose a method to efficiently use the energy of the node using BRN(backup receiver node) and increase the lifetime of the entire networks. Our numerical analysis and simulation results show that our mechanism outperforms RI-MAC protocol in terms of energy consumption and transmission delay.

• Journal of Information Technology Applications and Management
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• v.12 no.4
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• pp.13-24
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• 2005

The sensor network is a key component of the ubiquitous computing system which is expected to be widely utilized in logistics control, environment/disaster control, medical/health-care services, digital home and other applications. Nodes in the sensor network are small-sized and exposed to adverse environments. They are demanded to perform their missions with very limited power supply only. Also the sensor network is composed of much more nodes than the wireless ad hoc networks are. In case that some nodes consume up their power capacity, the network topology should change, and rerouting/retransmission is necessitated. Communication protocols studied for conventional wireless networks or ad hoc networks are not suited for the sensor network resultantly. Schemes should be devised to control the efficient usage of node power in the sensor network. This paper proposes a medium access protocol to enhance the efficiency of energy consumption in the sensor network node. Its performance is analyzed by simulation.

• Journal of the Korea Society of Computer and Information
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• v.13 no.4
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• pp.177-184
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• 2008

The design goal of protocols in wireless sensor networks (WSN) is mainly energy efficiency because of their stringent resource and energy constraints. In this paper, we propose a simple cross-layered protocol for WSNs, so called EATD(Energy-Aware Tree based Delivery scheme). EATD is a tree-based energy aware data delivery algorithm by using a SYNC packet with link and node cost to maximize the network lifetime. Our simulation results show significant improvements compared with existing schemes in terms of energy efficiency and delay.

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.8 no.2
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• pp.29-34
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• 2008

In this paper, we proposed a system protocol for detecting injurious insect to support energy saving transmission in wireless bio sensor networks. The main ideas and features of the system are as follows. First, the route establishment method which is based on the energy efficiency and stability by using time-division tree structure. Second, multi-hop direction-based data gatering structure. In this structure, the selected fading method is used to transmit packet via the established tree structure for supporting power saving and route lifetime efficiently. Finally, we can get the node power saving and reduce transmission delay, thus network lifetime and efficiency are improved. The performance evaluation of the proposed protocol is via OPNET(Optimized Network Engineering Tool).