4,360 research outputs found

    MH-REACH-Mote: supporting multi-hop passive radio wake-up for wireless sensor network

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    A passive wake-up radio in a wireless sensor network (WSN) has the advantage of increasing network lifetime by using a wake-up radio receiver (WuRx) to eliminate unnecessary idle listening. A sensor node equipped with a WuRx can operate in an ultra-low-power sleep mode, waiting for a trigger signal sent by the wake-up radio transmitter (WuTx). The passive WuRx is entirely powered by the energy harvested from radio transmissions sent by the WuTx. Therefore, it has the advantage of not consuming any energy locally, which would drain the sensor node's battery. Even so, the high amount of energy required to wake up a passive WuRx by a WuTx makes it difficult to build a multi-hop passive wake-up sensor network. In this paper, we describe and discuss our implementation of a battery-powered sensor node with multi-hop wake-up capability using passive WuRxs, called MH-REACH-Mote (Multi-hop-Range EnhAnCing energy Harvester-Mote). The MH-REACH-Mote is kept in an ultra-low-power sleep mode until it receives a wake-up trigger signal. Upon receipt, it wakes up and transmits a new trigger signal to power other passive WuRxs. We evaluate the wake-up range and power consumption of an MH-REACH-Mote through a series of field tests. Results show that the MH-REACH-Mote enables multi-hop wake-up capabilities for passive WuRxs with a wake-up range of 9.4m while requiring a reasonable power consumption for WuTx functionality. We also simulate WSN data collection scenarios with MH-REACH-Motes and compare the results with those of active wake-up sensor nodes as well as a low power listening approach. The results show that the MH-REACH-Mote enables a longer overall lifetime than the other two approaches when data is collected infrequently.Peer ReviewedPostprint (author's final draft

    Efficient time synchronized one-time password scheme to provide secure wake-up authentication on wireless sensor networks

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    In this paper we propose Time Synchronized One-Time-Password scheme to provide secure wake up authentication. The main constraint of wireless sensor networks is their limited power resource that prevents us from using radio transmission over the network to transfer the passwords. On the other hand computation power consumption is insignificant when compared to the costs associated with the power needed for transmitting the right set of keys. In addition to prevent adversaries from reading and following the timeline of the network, we propose to encrypt the tokens using symmetric encryption to prevent replay attacks.Comment: International Journal Of Advanced Smart Sensor Network Systems (IJASSN), Vol 3, No.1, January 2013 http://airccse.org/journal/ijassn/papers/3113ijassn01.pd

    Novel wireless modulation technique based on noise

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    In this paper, a new RF modulation technique is presented. Instead of using sinusoidal carriers as information bearer, pure noise is applied. This allows very simple radio architectures to be used. Spread-spectrum based technology is applied to modulate the noise bearer. Since the transmission bandwidth of the noise bearer can be made very wide, up to ultra-wideband regions, extremely large processing gains can be obtained. This will provide robustness in interference-prone environments. To avoid the local regeneration of the noise reference at the receiver, the Transmit-Reference (TR) concept is applied. In this concept, both the reference noise signal and the modulated noise signal are transmitted, together forming\ud the bearer. The reference and modulated signals are separated by applying a time offset. By applying different delay times for different channels (users) a new multiple access scheme results based on delay: Delay Division Multiple Access (DDMA). A theoretical analysis is given for the link performance of a single-user and a multi-user system. A testbed has been built to demonstrate the concept. The demonstrator operates in a 50 MHz bandwidth centered at 2.4 GHz. Processing gains ranging from 10¿30 dB have been tested. The testbed confirms the basic behavior as predicted by the theory

    Fly-By-Wireless for Next Generation Aircraft: Challenges and Potential solutions

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    ”Fly-By-Wireless” paradigm based on wireless connectivity in aircraft has the potential to improve efficiency and flexibility, while reducing weight, fuel consumption and maintenance costs. In this paper, first, the opportunities and challenges for wireless technologies in safety-critical avionics context are discussed. Then, the assessment of such technologies versus avionics requirements is provided in order to select the most appropriate one for a wireless aircraft application. As a result, the design of a Wireless Avionics Network based on Ultra WideBand technology is investigated, considering the issues of determinism, reliability and security

    Improving practical sensitivity of energy optimized wake-up receivers: proof of concept in 65nm CMOS

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    We present a high performance low-power digital base-band architecture, specially designed for an energy optimized duty-cycled wake-up receiver scheme. Based on a careful wake-up beacon design, a structured wake-up beacon detection technique leads to an architecture that compensates for the implementation loss of a low-power wake-up receiver front-end at low energy and area costs. Design parameters are selected by energy optimization and the architecture is easily scalable to support various network sizes. Fabricated in 65nm CMOS, the digital base-band consumes 0.9uW (V_DD=0.37V) in sub-threshold operation at 250kbps, with appropriate 97% wake-up beacon detection and 0.04% false alarm probabilities. The circuit is fully functional at a minimum V_DD of 0.23V at f_max=5kHz and 0.018uW power consumption. Based on these results we show that our digital base-band can be used as a companion to compensate for front-end implementation losses resulting from the limited wake-up receiver power budget at a negligible cost. This implies an improvement of the practical sensitivity of the wake-up receiver, compared to what is traditionally reported.Comment: Submitted to IEEE Sensors Journa

    Tahap penguasaan, sikap dan minat pelajar Kolej Kemahiran Tinggi MARA terhadap mata pelajaran Bahasa Inggeris

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    Kajian ini dilakukan untuk mengenal pasti tahap penguasaan, sikap dan minat pelajar Kolej Kemahiran Tinggi Mara Sri Gading terhadap Bahasa Inggeris. Kajian yang dijalankan ini berbentuk deskriptif atau lebih dikenali sebagai kaedah tinjauan. Seramai 325 orang pelajar Diploma in Construction Technology dari Kolej Kemahiran Tinggi Mara di daerah Batu Pahat telah dipilih sebagai sampel dalam kajian ini. Data yang diperoleh melalui instrument soal selidik telah dianalisis untuk mendapatkan pengukuran min, sisihan piawai, dan Pekali Korelasi Pearson untuk melihat hubungan hasil dapatan data. Manakala, frekuensi dan peratusan digunakan bagi mengukur penguasaan pelajar. Hasil dapatan kajian menunjukkan bahawa tahap penguasaan Bahasa Inggeris pelajar adalah berada pada tahap sederhana manakala faktor utama yang mempengaruhi penguasaan Bahasa Inggeris tersebut adalah minat diikuti oleh sikap. Hasil dapatan menggunakan pekali Korelasi Pearson juga menunjukkan bahawa terdapat hubungan yang signifikan antara sikap dengan penguasaan Bahasa Inggeris dan antara minat dengan penguasaan Bahasa Inggeris. Kajian menunjukkan bahawa semakin positif sikap dan minat pelajar terhadap pengajaran dan pembelajaran Bahasa Inggeris semakin tinggi pencapaian mereka. Hasil daripada kajian ini diharapkan dapat membantu pelajar dalam meningkatkan penguasaan Bahasa Inggeris dengan memupuk sikap positif dalam diri serta meningkatkan minat mereka terhadap Bahasa Inggeris dengan lebih baik. Oleh itu, diharap kajian ini dapat memberi panduan kepada pihak-pihak yang terlibat dalam membuat kajian yang akan datang

    Wake-up receiver based ultra-low-power WBAN

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