• The Journal of Korean Institute of Communications and Information Sciences
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• v.31 no.1A
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• pp.23-29
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• 2006

In wireless sensor networks(WSNs), it is crucial to maintain network connectivity as long as possible since nodes are battery-powered and unchange-able. We propose a new routing protocol called Energy Aware Source Routing(EASR) which can be efficient in respect of network lifetime and long-term connectivity. Our protocol is multipath source routing, only one path will be selected at the same time and each path has probability to be selected like as Energy Aware Routing(EAR) protocol. The route discovery procedure of EASR protocol is reformed from the route discovery procedure of Split Multipath Routing(SMR) protocol. However, there is the difference between SMR and EASR. In EASR, we define an overhearing ratio in order to reduce energy waste due to overhearing effect among each selected path. Thus, we can establish energy efficient multiple paths by making use of overhearing ratio. The simulation results are also demonstrated that our scheme increases in network lifetimes, and achieves reasonable packet latency time.

• Journal of Communications and Networks
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• v.17 no.2
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• pp.184-197
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• 2015

This paper builds on a recent method, chain routing with even energy consumption (CREEC), for designing a wireless sensor network with chain topology and for scheduling the communication to ensure even average energy consumption in the network. In here a new suboptimal design is proposed and compared with the CREEC design. The chain topology in CREEC is reconfigured after each group of n converge-casts with the goal of making the energy consumption along the new paths between the nodes in the chain as even as possible. The new method described in this paper designs a single near-optimal Hamiltonian circuit, used to obtain multiple chains having only the terminal nodes different at different converge-casts. The advantage of the new scheme is that for the whole life of the network most of the communication takes place between same pairs of nodes, therefore keeping topology reconfigurations at a minimum. The optimal scheduling of the communication between the network and base station in order to maximize network lifetime, given the chosen minimum length circuit, becomes a simple linear programming problem which needs to be solved only once, at the initialization stage. The maximum lifetime obtained when using any combination of chains is shown to be upper bounded by the solution of a suitable linear programming problem. The upper bounds show that the proposed method provides near-optimal solutions for several wireless sensor network parameter sets.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.10 no.11
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• pp.2107-2112
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• 2006

As growing up of elderly population, the interesting on healthcare system in normal life using W is increasing. An integrated u-healthcare service architecture with IEEE 802.11 and IEEE 802.15.4 based sensor network and code divisi(m multiple access(CDMA) public mobile telecommunication networks was designed and developed. Sensor nodes with electrocardiogram(ECG), body core temperature sensors are attached on the patients' body. The healthcare parameters are transferred to web server via CDMA mobile network or through existed LAN network. The existed LAN network is suggested to be used for continuous monitoring of patient's health status in hospital while mobile networks can be used for general purpose at home or outdoor where infra networks unavailable. This system enable healthcare personal to be able to continuously access, review, monitor and transmit the patients information whereever they are, whenever they want. And immediately check their status by using cellular phone and obtain detail information by communication with medical information server through CDMA. By using this developed integrated u-healthcare service architecture, we can monitor patients' health status for 24 hours.

• Spatial Information Research
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• v.21 no.2
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• pp.23-33
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• 2013

W ith the recent advancement of IoT (Internet of Things) technology, there has been much interest in the spatial query processing which energy-efficiently acquires sensor readings from sensor nodes inside specified geographical area of interests. Therefore, various kinds of spatial query processing algorithms and distributed spatial indexing methods have been proposed. They can minimize energy consumption of sensor nodes by reducing wireless communication among them using in-network spatial filtering technology. However, they cannot optimize multiple spatial queries which w ill be w idely used in IoT, because most of them have focused on a single spatial query optimization. Therefore, we propose a new multiple spatial query optimization algorithm which can energy-efficiently process multiple spatial queries in a sensor network. The algorithm uses a concept of 'query merging' that performs the merged set after merging multiple spatial queries located at adjacent area. Here, our algorithm makes a decision on which is better between the merged and the separate execution of queries. For such the decision making, we additionally propose the cost estimation method on the spatial query execution. Finally, we analyze and clarify our algorithm's distinguished features using the spatial indexing methods of GR-tree, SPIX, CPS.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.3 no.5
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• pp.423-443
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• 2009

We present the design and implementation of a unique sensing and actuation application -- the Illuminator: a sensor network-based intelligent light control system for entertainment and media production. Unlike most sensor network applications, which focus on sensing alone, a distinctive aspect of the Illuminator is that it closes the loop from light sensing to lighting control. We describe the Illuminator's design requirements, system architecture, algorithms, implementation and experimental results. The system uses the Illumimote, a multi-modal and high fidelity light sensor module well-suited for wireless sensor networks, to satisfy the high-performance light sensing requirements of entertainment and media production applications. The Illuminator system is a toolset to characterize the illumination profile of a deployed set of fixed position lights, generate desired lighting effects for moving targets (actors, scenic elements, etc.) based on user constraints expressed in a formal language, and to assist in the set up of lights to achieve the same illumination profile in multiple venues. After characterizing deployed lights, the Illuminator computes optimal light settings at run-time to achieve a user-specified actuation profile, using an optimization framework based on a genetic algorithm. Uniquely, it can use deployed sensors to incorporate changing ambient lighting conditions and moving targets into actuation. Experimental results demonstrate that the Illuminator handles various high-level user requirements and generates an optimal light actuation profile. These results suggest that the Illuminator system supports entertainment and media production applications.

• 한국정보컨버전스학회:학술대회논문집
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• 2008.06a
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• pp.199-204
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• 2008

Sensor nodes have various energy and computational constraints because of their inexpensive nature and ad-hoc method of deployment. Considerable research has been focused at overcoming these deficiencies through faster media accessing, more energy efficient routing, localization algorithms and system design. Our research attempts to provide a method of improvement MAC performance in these issues. We show that traditional carrier-sense multiple access(CSMA) protocols like IEEE 802.11 do not handle the first constraint adequately, and do not take advantage of the second property, leading to degraded latency and throughput as the network scales in size, We present more efficient method of a medium access for real-time wireless sensor networks. Proposed MAC protocol is a randomized CSMA protocol, but unlike previous legacy protocols, does not use a time-varying contention window from which a node randomly picks a transmission slot. To reduce the latency for the delivery of event reports, it carefully decides a fixed-size contention window, non-uniform probability distribution of transmitting in each slot within the window. We show that it can offer up to several times latency reduction compared to legacy of IEEE 802.11 as the size of the sensor network scales up to 256 nodes using widely used simulator ns-2. We, finally show that proposed MAC scheme comes close to meeting bounds on the best latency achievable by a decentralized CSMA-based MAC protocol for real-time wireless sensor networks which is sensitive to latency.

• Proceedings of the Korean Information Science Society Conference
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• 2004.10b
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• pp.526-528
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• 2004

본 논문은 센서 네트워크 환경에서 사용자 센싱을 통한 입력장치인 MGlove (Multiple-sensing Clove)의 구현에 대해 기술한다. 본 입력장치는 버튼 없이 2축 가속 센서, 2축 자기 센서, 포토 다이오드의 세 가지 종류의 센서를 사용하여 사용자의 손동작을 통해 입력을 감지하고 RF 모듈을 이용하여 무선으로 통신 가능하다. 구현한 MGlove는 유비 쿼터스 센서 네트워크 환경을 위한 입력 장치로 context-aware input device로의 발전 가능성이 있으며, 센서 추적 기법을 통해 사용자의 자세, 위치, 방향에 관계없이 입력 가능하고 RF모듈을 통해 먼 거리에서도 조작이 가능한 특징을 가진다.

• Journal of the Institute of Electronics Engineers of Korea SC
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• v.45 no.6
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• pp.42-47
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• 2008

In this article a novel constant amplitude precoding for impulse UWB system is proposed. According to IEEE 802.15.4a, impulse UWB can be used in indoor localization and sensor data transmission. Most USN(ubiquitous sensor networks) needs multiple access. However impulse UWB system has a limited capability to detect superpositioned signal induced by multiple access. To overcome this problem we have adopted the concept of CAMC(Constant Amplitude Multi-Code) deviced by Wada and Kim. The proposed system consists of systematic constant amplitude precoding and LDPC decoding. And this system shows a good BER performance in computer simulation.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.10 no.6
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• pp.1060-1064
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• 2006

Data collected by sensors in field are transmitted to the base station gathering all of data. Because sensors have to gather data in surroundings and periodically transmit data to the base station, it makes energy consumed much. In this paper, we mose the scheme that is to avoid traffic congestion with achievement of energy efficiency, so collected data is transmitted efficiently. This is to adjust transmission rate differently in case of increasing or decreasing traffic and minimize the energy consumption with setting ideal options up basic CSMA(Carrier Sense Multiple Access) protocol in each sensor. Through the simulation, we find the ideal CSMA options and apply the proposed scheme of traffic control mechanism to them and analyze them, then show energy efficiency and effective traffic control mechanism.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.24 no.1
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• pp.145-148
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• 2020

Wearable computing is growing rapidly as research on body area communication network using wireless sensor network technology is actively conducted. In particular, there is an increasing interest in smart clothing measuring unrestrained and insensitive bio signals, and research is being actively conducted. However, research on smart clothing is mainly based on 1: 1 wireless communication. In this paper, we propose a multi-access monitoring system that can measure bio-signals by multiple users wearing smart clothing. The proposed system consists of wireless access device, multiple access control server and monitoring system. It also provides a service that allows multiple users to monitor and measure bio signals at the same time.