Efficient Duty Cycle Research Articles

Impact of interference free frequency channels on optimum time slot allocation for priority-based TSCH MAC

Time slotted channel hopping (TSCH), the most promising MAC protocol under IEEE 802.15.4 is meeting the growing demands of low power and determinism in time critical industrial wireless applications. An efficient duty cycle is a necessary mandate for time critical applications which can be achieved by an appropriate reduction of active time slots in the slot frame and this saves node power. Even though many attempts were done in realising an optimum scheduling protocol, the impact of the number of channels on the optimum time slot allocation is not yet considered which signifies importance with the present scenario of many channels being induced by interference from neighbouring wireless networks. Optimum time slot is essential for making efficient duty cycle. Hence, a study on the impact of the number of channels on the optimum time slot allocation is necessitated and is accomplished in this paper. It is found that increasing the number of channels beyond a certain value does not have an impact on the optimum slot allocation and there is a direct relationship between the number of channels and the number of links per track and number of root node branches.

Resource-Efficient Image Buffer Architecture for Neighborhood Processors

Neighborhood image processing operations on Field Programmable Gate Array (FPGA) are considered as memory intensive operations. A large memory bandwidth is required to transfer the required pixel data from external memory to the processing unit. On-chip image buffers are employed to reduce this data transfer rate. Conventional image buffers, implemented either by using FPGA logic resources or embedded memories are resource inefficient. They exhaust the limited FPGA resources quickly. Consequently, hardware implementation of neighborhood operations becomes expensive, and integrating them in resource constrained devices becomes unfeasible. This paper presents a resource efficient FPGA based on-chip buffer architecture. The proposed architecture utilizes full capacity of a single Xilinx Block-RAM (BRAM36 primitive) for storing multiple rows of input image. To get multiple pixels/clock in a user defined scan order, an efficient duty-cycle based memory accessing technique is coupled with a customized addressing circuitry. This accessing technique exploits switching capabilities of BRAM to read 4 pixels in a single clock cycle without degrading system frequency. The addressing circuitry provides multiple pixels/clock in any user defined scan order to implement a wide range of neighborhood operations. With the saving of 83% BRAM resources, the buffer architecture operates at 278 MHz on Xilinx Artix-7 FPGA with an efficiency of 1.3 clock/pixel. It is thus capable to fulfill real time image processing requirements for HD image resolution ( $1080\times 1920$ ) @103 fps.

Intelligent maximum power tracking control of a PMSG wind energy conversion system

AbstractA comparative control study for a maximum power tracking strategy of variable speed wind turbine is provided. The system consists of a direct drive permanent magnet synchronous generator (PMSG) and an uncontrolled rectifier followed by a DC/DC switch‐mode step down converter connected to a DC load. The buck converter is used to catch the maximum power from the wind by generating an efficient duty cycle. Distinct Maximum Power Point Tracking (MPPT) algorithms are analyzed and compared: a classical Proportional‐Integral controller (PI) and two based Fuzzy Logic Controllers (FLC), including a conventional Fuzzy‐PI and an Adaptive FLC‐PI. The main aim of the presented study is to develop an advanced control scheme for wind generators to ensure a high level operating of the system and a maximum power extraction from the wind. This is achieved by analyzing the behavior of the system under fluctuating wind conditions employing Matlab Simpower Systems tool. Simulation results confirm that the Adaptive FLC‐PI controller algorithm has better performances in terms of dynamic response and efficiency especially in comparison with the ones of a PI controller under variable wind speed.

Towards energy efficient duty cycling in underwater wireless sensor networks

Underwater Wireless Sensor Networks devices are usually battery powered and thereby their lifetime is limited. This issue leads to lose data measurements and thus to a performance loss of the underlying UWSN application. It also increases the maintenance cost in Internet of Underwater Things scenarios with a huge number of UWSN devices. Additionally, the unique characteristics of UWSNs pose several constraints such as the high energy consumption, long propagation delay, and node mobility. Duty Cycle management is one of the key technologies to solve this issue. In this context, the use of duty cycle based algorithms for opportunistic, autonomous and energy efficient duty cycle management can mitigate the undesirable impact of underwater communications, consequently, improve the overall efficiency of the algorithms designed for the UWSNs. In this article, we study the energy efficient data collection for asynchronous duty cycle MAC protocols for underwater sensor networks. To this end, we improve two previously proposed receiver initiated MAC protocols that use a nodes, (1) residual energy, and (2) its sleep-awake pattern to improve the overall network lifetime. We show that the considerations made in the protocols have a great impact on the performance of the network. Our results show that the protocols minimize the collisions while alleviating the need for excessive handshake and also the average active time of a node is minimized.

Low‐power low data rate FM‐UWB receiver front end

This study introduces a frequency modulated ultra-wideband (FM-UWB) receiver optimised for low power and fast start-up. The receiver consists of a front end amplifier converting a frequency modulated signal to an amplitude modulated signal which is applied to an envelope detector. The receiver front end is for 500 MHz channels centred at 3450 and 3950 MHz. The amplifier uses passive gain and four cascaded gain stages to achieve high radio-frequency gain without the need for super-regeneration. By simplifying the architecture this way, the front end has a 5 μs wake-up time to enable efficient duty-cycling. The measured front end receives a signal at −68 dBm while consuming 600 μW of power (excluding a test buffer) from a 1 V supply. Fabrication was done using the IBM 130-nm CMOS technology on a 1 mm × 1 mm loose die.

An Improved Energy Efficient Duty Cycling Algorithm for IoT based Precision Agriculture

There is an increasing focus on IoT based precision agriculture to increase the productivity and yield in the farm fields through real-time monitoring of agriculture field parameters. The data in the farm field is collected using sensors such soil sensor, temperature and humidity sensor, air quality sensor, and video camera mounted on drones. The data from each sensor is then aggregated at the base station and forwarded to a gateway. Recent research work conducted by Microsoft on IoT based precision agriculture has reported that designing the energy efficient data aggregation method for such IoT based networks is one of the classical research challenges. In this paper, we proposed a duty cycling data aggregation algorithm to improve energy efficiency performance of the base station. The proposed improved duty cycling algorithm reduces the energy consumption in special events such as cloudy weather. To further optimize the reliability and network lifetime, we proposed the efficient path selection approach based on the residual energy parameters. To evaluate the performance merit, we conducted simulations in Network Simulator (ns2). Network Simulator is an event driven tool which is widely used for research studies. The performance of various algorithms is compared using No Duty Cycling (NDC), Duty Cycling (DC) and the proposed Improved Duty Cycling algorithms (IDC). The results show that the proposed IDC outperforms the other two algorithms.

Powering In-pipe Wireless Sensors Using Flexible Piezoelectric Micro-generators

Abstract This paper presents a new piezoelectric energy harvester that generates sufficient energy to power wireless sensor nodes autonomously. Multiple PVDF-foils are layered alternately with electrode foils and wound to a spool. Due to induced turbulence inside standard flow pipes the piezoelectric foils are forced to oscillate converting kinetic energy into mechanical stress thus generating electrical charge. The new multilayer spool design tackles the common disadvantages of similar harvesters related to low piezoelectric coefficients of Polyvinylidene-fluoride or brittleness of Lead-zirconate-titanate. Wind channel experiments to prove the feasibility of the concept result in a harvested output power of 0.54 μW at a wind velocity of 7 m/s. With efficient duty cycling of the sensor node 324 μWs of energy are available for data transmission. The presented harvester is proposed as a universal power supply for sensors inside pipe systems. All of the systems components are included inside the pipe allowing for a maintenance-free deployment of sensors in remote locations.

Energy and Delay Efficient Duty-Cycle MAC Protocol for Multi-hop Wireless Sensor Networks

Low energy consumption has always been the most important main issue in wireless sensor networks. But many applications requiring low latency and high throughput have been emerged recently. Many existing duty-cycle MAC protocols such as S-MAC [1] and T-MAC [2] provide good power efficiency but introduce significant end-to-end delay. In this paper, we proposed an energy and delay efficient duty-cycle MAC protocol which reduces data transmission delay from source node to destination node and node energy consumption in multi-hop Wireless Sensor Networks. The main goal is to design a MAC protocol for object tracking application, in which large amounts of data need to be transmitted when an event occurs. An operation cycle of the proposed MAC protocol is consists of four periods as in LO-MAC [10]. But in the proposed MAC protocol all the nodes in the data path repeat the Sleep periods only when an event occurs. And during Data period nodes immediately go into sleep mode with overhearing the PION packet. Performance evaluation shows that the proposed MAC protocol improves the transmission delay and the throughput compared to the RMAC.

Efficient duty cycling through prediction and sampling in wireless sensor networks

We present BoostMAC, a CSMA-based MAC layer protocol for wireless sensor networks that provides an adjustable interface to achieve ultra-low power operation. To reach low power operation, we adapti...

Efficient duty cycling through prediction and sampling in wireless sensor networks

AbstractWe present BoostMAC, a CSMA‐based MAC layer protocol for wireless sensor networks that provides an adjustable interface to achieve ultra‐low power operation. To reach low power operation, we adaptively set two radio parameters. First, BoostMAC implements a preamble sampling scheme that allows a mote to dynamically set the length of its duty cycles. Second, we apply machine learning such that a sender can predict its destination's channel polling time and set each outgoing packet's preamble length accordingly. Our two improvements require no extra communication overhead, and each mote in the network implements simple, local models. Energy conservation is one of the most fundamental problems in sensor networks, and by optimizing low‐level operation at the MAC layer, sensor network applications realize an increase in overall performance.We choose habitat monitoring as a motivating sensor network application because it has unique MAC layer demands, such as fluctuating levels of network traffic. Static configuration at the MAC layer inhibits optimal energy conservation within habitat monitoring applications. We implemented BoostMAC in TinyOS simulator (TOSSIM), and we compare its performance to B‐MAC, a well‐known low power MAC protocol with static behavior. We found that BoostMAC saves energy relative to B‐MAC in bursty networks without affecting latency. Copyright © 2007 John Wiley & Sons, Ltd.

An Energy-Efficient OOK Transceiver for Wireless Sensor Networks

A 1-Mb/s 916.5-MHz on-off keying (OOK) transceiver for short-range wireless sensor networks has been designed in a 0.18-mum CMOS process. The receiver has an envelope detection based architecture with a highly scalable RF front-end. Untuned RF circuits are leveraged and optimized in the receiver to achieve superior energy efficiency compared to tuned RF circuits. The receiver power consumption scales from 0.5 mW to 2.6 mW, with an associated sensitivity of -37 dBm to -65 dBm at a BER of 10 -3. The transmitter consumes 3.8 mW to 9.1 mW with output power from -11.4 dBm to -2.2 dBm. The receiver achieves a startup time of 2.5 mus, allowing for efficient duty cycling

The statistics of gamma-ray burst lensing

view Abstract Citations (20) References (49) Co-Reads Similar Papers Volume Content Graphics Metrics Export Citation NASA/ADS The Statistics of Gamma-Ray Burst Lensing Grossman, Scott A. ; Nowak, Michael A. Abstract Possibly the only unambiguous verification that gamma-ray bursts (GRBs) are at cosmological distances would be the observation of multiple images of a gravitationally lensed burst. Each image would arrive at a different time, but would exhibit a light curve identical to those of the others. We improve upon previous calculations of GRB lensing by using revised cosmological burst models based upon better knowledge of burst spectra, and we consider several sets of cosmological parameters. Only lensing by the known population of galaxies is considered, and we compute the lensing rate and amplification bias using three different lens models. Assuming that 800 bursts per year are above the detection threshold of the BATSE experiment on the Compton Gamma-Ray Observatory, we predict one lensing event every 1.5-25 years, with a median time delay between images of about 7 days. However, BATSE has an instrumental efficiency of about 12% for detecting double bursts, decreasing the detection rate to fewer than one per century for some cosmological parameters. This inefficiency can be overcome partially if cases of quadruple imaging by elliptical potentials are common, but simulations show that lensing by elliptical potentials enhances the detection rate by only about 20%. We conclude that it is unlikely that the BATSE experiment will detect a lensed burst, but that a future experiment, which is either much more sensitive or has a much more efficient duty cycle, could. Publication: The Astrophysical Journal Pub Date: November 1994 DOI: 10.1086/174836 arXiv: arXiv:astro-ph/9401047 Bibcode: 1994ApJ...435..548G Keywords: Astronomical Models; Energy Spectra; Galaxies; Gamma Ray Astronomy; Gamma Ray Bursts; Gamma Ray Observatory; Gravitational Lenses; Cosmology; Luminosity; Mathematical Models; Red Shift; Astronomy; COSMOLOGY: GRAVITATIONAL LENSING; GAMMA RAYS: BURSTS; GAMMA RAYS: OBSERVATIONS; Astrophysics E-Print: 23 pages, plain TeX (revised to TeX easily), figures available by anonymous ftp full text sources arXiv | ADS |