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A novel micro-vibration sensor with MOS structure is proposed and two solutions to reduce high threshold voltage are developed. The proposed sensor exhibits prefect linearity up to 99.98% and high resolution of 0.19 muA/g. The vibration sensor can provide various potential applications, such as civil structural health monitoring, biomedical applications, low power consumption wireless sensor networks...
Directed diffusion is a classic data-centric routing protocol in Wireless Sensor Networks (WSNs). In directed diffusion based WSNs, data generated by sensor nodes is named by attribute-value pairs. A sink requests data by sending interests. The data that match the interests are then "drawn" down towards the sink. Intermediate nodes cache or transform data, and direct the interests based...
Localization is one of the crucial issues in wireless sensor networks. In range-based mechanisms, the nodes obtain pairwise distances or angles with extra hardware for high localization accuracy. On the other hand, the range-free schemes obtain the lower localization accuracy at low hardware cost. We present a range-free localization scheme by using a mobile anchor node equipped with a GPS. The mobile...
Readability is a very important factor for radio frequency identification (RFID) applications. One of the main reasons for readability degradation is field nulls (also called dead zones). In this paper, the causes of the dead zones are analyzed and simulated. Based on FSK-FM modulation, a novel RFID transceiver with enhanced readability under multipath environments is developed. The simulation results...
In wireless sensor networks (WSNs), sensor nodes are typically battery powered and energy consumption is critical. In this paper we present an efficient transmission power control algorithm based on the RTS/CTS mechanism in SMAC. The main contribution of our work is to introduce a low-cost power controlled transmission of RTS, CTS, DATA, and ACK frames while preserving the collision and overhearing...
Nowadays, radio frequency identification (RFID) has been widely used in our everyday life, and has aroused increasing concerns about privacy and security. Cryptographic techniques can be used to protect privacy but are too expensive for low-cost RFID tags. This paper addresses the problem and proposes a new RFID system structure. In our system, the RFID tag sends only the hashed tag ID number to the...
In this paper, we propose an energy-efficient data query method for wireless sensor networks (WSNs). Our method is flexible and adaptive. To solve the cluster head coverage problem in our method, we propose virtual grid clustering (VGC) protocol in which the clusters are constructed only in the query area when they are needed. The clusters are destroyed after the query ends. Theoretical analysis and...
In wireless sensor networks, sensor localization plays a critical role in many applications. Many algorithms, including range-based and range-free approaches, have been proposed to calculate the positions of randomly deployed sensor nodes. In some applications, sensor nodes are constantly moving. The current algorithms do not address such mobile wireless sensor networks (MWSN). In this paper we propose...
Hierarchy Mobile IPv6 (HMIPv6) is a scheme for micro mobility management to help basic Mobile IP reduce the signal cost and the packet loss during the periods of handover. In this paper, we describe and analyze the protocol based on, instead of the conventional ways of message sequence charts, but the Colored Petri Net (CPN). CPN is suitable to model a system from the dynamic perspective and has the...
Energy efficiency is one of the most important considerations in wireless sensor networks. In a clustered sensor network, some of the nodes become cluster heads. They aggregate the data from their cluster members and transmit it to the base station. In this paper, we propose a uniformly distributed adaptive clustering hierarchy routing protocol (UDACH). Unlike LEACH and LEACH-C, our protocol is based...
Radiofrequency identification (RFID) raises significant privacy concerns as it allows automated identification possibly without knowledge or permission of the tag bearer. Traditional cryptographic operations, such as authentication and encryption, to prevent unauthorized read are too costly for RFID tags to be deployed into cost-sensitive applications, e.g., into item-level applications in supply...
In wireless sensor networks (WSN), sensor nodes are powered by batteries. To make efficient use of battery energy is critical to sensor network lifetime. When targets are redundantly covered by multiple sensors, especially in randomly deployed sensor networks, it is possible to save battery energy by organizing sensors into mutually exclusive subsets and alternatively activating only one subset at...
Silicon-on-Nothing (SON) device is expected to be obtained by double He+ implantation. The leakage currents of the SON MOSFET using twice energy implants are lower for 1~2 order of magnitude than that of using single energy implant simulated by ATLAS Simulator on electrical characteristic of SON MOSFETs. The self-heating effect in SON device can be suppressed by etch-back sidewall of shallow trench...
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