• ETRI Journal
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• 제40권5호
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• pp.582-591
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• 2018

In this paper, we present a performance analysis of large-scale multi-input multi-output (MIMO) systems for wireless backhaul networks. We focus on fully connected N nodes in a wireless meshed and multi-hop network topology. We also consider a large number of antennas at both the receiver and transmitter. We investigate the transmission schemes to support fully connected N nodes for half-duplex and full-duplex transmission, analyze the achievable ergodic sum rate among N nodes, and propose a closed-form expression of the achievable ergodic sum rate for each scheme. Furthermore, we present numerical evaluation results and compare the resuts with closed-form expressions.

• Smart Structures and Systems
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• 제30권6호
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• pp.583-599
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• 2022

In this paper, a multi-objective wireless sensor network configuration optimization method is proposed. The proposed method aims to determine the optimal information and lifespan wireless sensor network for structural health monitoring of large-scale infrastructures. In particular, cluster-based wireless sensor networks with multi-type of sensors are considered. To optimize the lifetime of the wireless sensor network, a cluster-based network optimization algorithm that optimizes the arrangement of cluster heads and base station is developed. On the other hand, based on the Bayesian inference, the uncertainty of the estimated parameters can be quantified. The coefficient of variance of the estimated parameters can be obtained, which is utilized as a holistic measure to evaluate the estimation accuracy of sensor configurations with multi-type of sensors. The proposed method provides the optimal wireless sensor network configuration that satisfies the required estimation accuracy with the longest lifetime. The proposed method is illustrated by designing the optimal wireless sensor network configuration of a cable-stayed bridge and a space truss.

• 인터넷정보학회논문지
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• 제17권5호
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• pp.1-8
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• 2016

본 논문에서는 복잡계 네트워크 이론에 기반한 무선 네트워크 토폴로지를 구성하고, 실제 환경의 토폴로지 구성을 반영한 척도없는 네트워크의 노드 링크 분포 확률을 분석하여 실제 무선 네트워크를 위한 브로드캐스트 전송 스케줄링 알고리즘 기법을 제안한다. 본 논문에서는 기존의 브로드캐스트 스케줄링 알고리즘 기법들이 반영하지 못한 복잡계 네트워크의 특성을 분석하고 그 특성에 맞는 알고리즘 기법과 분석 기법에 대하여 제안한다. 실험 결과를 통해 제안하는 방식의 알고리즘법이 네트워크의 지연시간 감소와 전송효율에 있어서의 우수함을 밝히고, 복잡계 네트워크 기반 무선 네트워크의 전송효율과 전체지연시간에 대한 최적화 방식의 기법을 제안한다.

• 대한임베디드공학회논문지
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• 제18권2호
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• pp.67-73
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• 2023

Tree routing is one of appropriate routing schemes in wireless sensor network because the complexity of this approach is relatively low. But, congestion at a specific node may happen because a parent node toward a sink node is usually selected in one hop way, specially where large number of node are deployed. As feasible solution for this problem, multiple paths and sinks schemes can be applied. However, the performance of these schemes are not proved and analyzed yet. In this paper, we conduct diverse simulaton scenarios performance evaluation for these cases to identify the improvement and analyze the impact of schemes. The performance is measured in the aspects of packet transmission rate, throughput, and end-to-end delay as a function of amount of network traffic.

• 한국컴퓨터정보학회논문지
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• 제10권4호
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• pp.239-248
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• 2005

대규모 무선 센서 네트워크는 네트워크의 신뢰성과 에너지 효율을 동시에 고려해야 한다. 네트워크의 신뢰성을 높이기 위해서는 유니 캐스트 기반 데이터 전송 방법보다 브로드캐스트 기반 데이터 전송 방법을 사용해야 한다. 최근 발표된 GRAdient Broadcast (GRAB)는 브로드캐스트 기반 데이터 전송으로 네트워크의 신뢰성을 높일 수 있다. 하지만 한 개의 sink를 사용하기 때문에 네트워크 전체 에너지를 고르게 사용하지 못한다. 결국 네트워크의 동작 시간이 단축되는 단점이 있다. 이에 본 논문에서는 대규모 무선센서 네트워크에 적합한 Selective Multi Sink Gradient Broadcast (SMSGB)를 제안한다. SMSGB 는 여러 개의 sink를 사용하여 네트워크를 구성하고 한 개의 sink만 데이터를 수집한다. 특정한 이벤트가 발생이 되면 다른 sink가 데이터를 수집하게 된다. 이러한 방법을 통해 전체 네트워크의 에너지를 고르게 소모 할 수 있다. 또한 GRAB와 동일한 브로드캐스트 기반 데이터 전송으로 대규모 무선 센서 네트워크에서 신뢰성을 보장할 수 있다. 기존의 GRAB와 SMSGB를 비교한 모의실험을 통해 GRAB와 비슷한 신뢰성을 유지하면서 GRAB보다 SMSGB의 네트워크 동작 시간이 약 18% 이상 연장됨을 보인다.

• Smart Structures and Systems
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• 제6권5_6호
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• pp.525-543
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• 2010

Testing and validation processes are critical tasks in developing a new hardware platform based on a new technology. This paper describes a series of experiments to evaluate the performance of a newly developed MEMS-based wireless sensor node as part of a wireless sensor network (WSN). The sensor node consists of a sensor board with four accelerometers, a thermometer and filtering and digitization units, and a MICAz mote for control, local computation and communication. The experiments include calibration and linearity tests for all sensor channels on the sensor boards, dynamic range tests to evaluate their performance when subjected to varying excitation, noise characteristic tests to quantify the noise floor of the sensor board, and temperature tests to study the behavior of the sensors under changing temperature profiles. The paper also describes a large-scale deployment of the WSN on a long-span suspension bridge, which lasted over three months and continuously collected ambient vibration and temperature data on the bridge. Statistical modal properties of a bridge tower are presented and compared with similar estimates from a previous deployment of sensors on the bridge and finite element models.

• 대한임베디드공학회논문지
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• 제14권4호
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• pp.177-186
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• 2019

In wireless sensor networks, the transmission success ratio would be decreased when the scale of the WSNs increased. To defeat this problem, we propose a multipath routing based on opportunistic routing for improving end-to-end reliability in large-scale wireless sensor networks. The proposed scheme exploits the advantages of existing opportunistic routing and achieves high end-to-end success ratio by branching like a multipath routing through local decision without information of the whole network. As a result of the simulation result, the proposed scheme shows a similar or higher end-to-end transmission success ratio and less energy consumption rather than the existing scheme.

• 대한전자공학회:학술대회논문집
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• 대한전자공학회 2008년도 하계종합학술대회
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• pp.255-256
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• 2008

Distributed localization algorithms are required for large-scale wireless sensor network applications. In this paper, we introduce an efficient algorithm, termed weighted neighbor-node distribution localization(WNDL), which emphasizes simple refinement and low system-load for low-cost and low-rate wireless sensors. We inspect WNDL algorithm through MATLAB simulation.

• KSII Transactions on Internet and Information Systems (TIIS)
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• 제10권7호
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• pp.3213-3230
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• 2016

Sensor node (SN) is a crucial part in any remote monitoring system. It is a device designed to monitor the particular changes taking place in its environs. Wireless sensor network (WSN) is a system formed by the set of wirelessly connected SNs placed at different geographical locations within a target region. Precise placement of SNs is appreciated, as it affects the efficiency and effectiveness of any WSN. The manual placement of SNs is only feasible for small scale regions. The task of SN placement becomes tedious, when the size of a target region is extremely large and manually unreachable. In this research article, an automated mechanism for fast and precise deployment of SNs in a large scale target region has been proposed. It uses an assembly of rotating cannons to launch the SNs from a moving carrier helicopter. The entire system is synchronized such that the launched SNs accurately land on the pre-computed desired locations (DLs). Simulation results show that the proposed model offers a simple, time efficient and effective technique to place SNs in a large scale target region.

• Journal of Computing Science and Engineering
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• 제4권1호
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• pp.23-51
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• 2010

Wireless Sensor Networks (WSN) have proved to be useful in applications that involve monitoring of real-time data. There is a wide variety of monitoring applications that can employ Wireless Sensor Network. Characteristics of a WSN, such as topology and scale, depend upon the application, for which it is employed. Security requirements in WSN vary according to the application dependent network characteristics and the characteristics of an application itself. Key management is the most important aspect of security as some other security modules depend on it. We discuss application dependent variations in WSN, corresponding changes in the security requirements of WSN and the applicability of existing key management solutions in each scenario.