RPATS – Reliable power aware time synchronization protocol

Many applications of Wireless Sensor Networks (WSNs) need the local clocks of the individual sensor nodes (SN) to be synchronized. Almost any form of sensor data fusion or coordinated actuation requires synchronized physical time for reasoning about events in the physical world. However, while the clock accuracy and precision requirements are often stricter in WSN than in traditional distributed systems, energy and channel constraints limit the resources available to meet these goals. In this paper, we present a power aware time synchronization protocol, of type sender–receiver, suitable for implementation in duty-cycled WSN. By using this proposal most of the non-deterministic time delays during packet transfer (media access, waiting packets in queues, propagation delay) as dominant ones (order of several hundred milliseconds), in respect to data processing (interrupt handling, testing status registers in program loop) as minor (up to hundred microseconds), are bypassed. In addition reliable and unreliable data transfer between SNs is considered. With aim to compensate SN’s oscillator instability, i.e. error in time synchronization, we propose duty cycle time extension. Apart from that, in order to evaluate the low-power capability of the proposed protocol we have involved quantitative performance metric called lifetime efficiency and compared it with equivalent (same) metric of the well known Reference-Broadcast Synchronization, RBS, and Timing-sync Protocol for Sensor Networks, TPSN, protocols, for different error prone environment and different period of time synchronization.     

A spread‐slotted random‐access protocol with multi‐priority for personal and mobile communication networks carrying integrated traffic

This paper describes and analyzes a medium access protocol for wireless personal communication networks serving integrated traffic. A multipriority mechanism, which is implemented and controlled explicitly by the users and without any involvement from the network is incorporated into the protocol. We examine the proposed protocol under reservation and nonreservation policies and evaluate its performance when handling integrated voice and data traffic. The proposed protocol is suitable to be used in Personal Communication Systems aiming to provide integrated (voice/data) services.     

EPCM – an efficient power controlled MAC protocol for mobile ad hoc network

To reduce interference and to save a significant amount of energy, a control of transmission power is employed in Mobile Ad hoc Network. Many researchers have reported numerous transmission power control schemes to achieve the objective. Some of those techniques use higher transmission power for control packets (Request To Send/Clear To Send) and lesser power for Data and ACK packets. These schemes, though save some amount of energy, achieve least aggregate throughput due to poor spatial reuse and hidden terminal interference. In this paper, an efficient Power Controlled Medium Access Control (EPCM) scheme is evinced, which uses uniform interference aware and minimum transmission power for both Control and Data packet. The performance of EPCM is evaluated and compared with three reported Medium Access Control protocols which are based on transmission power control schemes and is observed that the proposed protocol achieves better throughput and minimal energy consumption while avoiding the hidden terminal problem.     

Moisture diffusion modeling – A critical review

Techniques for enforcing the continuity of solute field in heterogeneous solvent under the conditions of steady temperature-humidity, steady temperature but dynamic humidity, and dynamic temperature are reviewed. The continuity of the wetness technique is justified on the principle of equality of chemical potential. The partial pressure technique is one of the many possible forms of pseudo techniques that can be derived from the wetness technique. The direct concentration technique is fundamentally flaw. The peridynamic technique in its original form is restricted to homogeneous solvent. The saturated concentration of solute in solvents decreases with increasing temperature; the rate of change with temperature differs between solvents and this leads to discontinuity of wetness along the interface of solvents. Continuity of wetness at the interface may be enforced using the intervention technique, the internal source technique, or the explicit finite difference scheme. These three techniques have been mutually validated in a reported study.     

A task‐oriented priority queue for telephone switch design: with modified FCFS and forking

When developing a telephone switch, it is useful to know how long it will take to process the various tasks associated with call processing. The model developed in this paper gives expected sojourn times for those tasks. It is a priority queueing model with a modified firstcome firstserved (FCFS) service discipline, which mimics the treatment of tasks in actual system software. The model is an M/G/1 queueing model with preemption (preemptive resume). It consists of multiple queues, one for each distinct priority, where each task has been preassigned a constant priority. Within each priority queue, the tasks are further grouped by type. An arriving task will join the back of the group of tasks of its type, regardless of where this group is positioned in the queue. Upon completion of a task, several tasks of different types can enter the priority queues. This is referred to as forking. Call processing involves many ordered sets of tasks (jobs or classes), some of which will contain forks. The model produces results that compare favorably with those obtained by simulation.     

A 1 Gsps and 840 µW fully dynamic asynchronous pipelined binary search ADC

In this paper a very low power asynchronous 5-bit ADC in CMOS 45 nm process technology is described which combines the pipeline and binary search architectures. Due to utilization of dynamic non-linear amplifier, power consumption of the converter is very low. The ADC circuit uses digital calibration technique to update the reference voltages of the comparators. The power consumption of ADC is 840 µW, and the ENOB is 4.05 at 1 Gsps with input signal at the Nyquist rate. At sampling rate of 10 0Msps, the power consumption is reduced to 89 µW and the ENOB is equal to 4.6 again at the Nyquist rate.     

Multiservices MAC‐protocol for wireless ATM

ATM is the future networking technology in the area of broadband networks. Using fiber optical cabling offers high bandwidth and low error rates. It is supposed to support different kinds of services, e.g., file transfer, videoconferencing, and speech transmissions. To support seamless end-to-end quality of service in a mobile environment a suitable extension to the fixed network part is necessary. In a wireless ATM environment the medium access protocol takes a prominent position. It is responsible for an efficient and fair media access on the shared radio resource. Due to the limited available bandwidth and the much higher error rates on the radio link special provisions must be provided. The compliance of traffic contracts for connections with different quality of services is the aim of our proposed protocol. This is the base of true end-to-end services with quality of service assurance in wireless ATM. This revised version was published online in June 2006 with corrections to the Cover Date.     

A versatile window function for linear ion drift memristor model – A new approach

The memristor is a nano-scaled resistive switching device which is widely investigated in analog and digital applications. We report here our success in formulating a new window function as applicable to linear ion drift model. Accordingly, this paper identifies the demerits of other existing window functions and the requirement of a versatile window function to mimic the current-voltage characteristics of a physical memristor device. The proposed new window function overcomes the demerits of existing window functions such as boundary effect, boundary lock (with respect to frequency of operation), and the scalability. The main significance of proposed model is to facilitate the nonlinearity in linear ion drift memristor model that produces the pinched hysteresis loop (a signature of a memristor) for any typical applied voltage within the frequency range (0.05 ≤ f < 2 Hz). The validation of which has been verified in a memristor based op-amp circuitry. It exhibits a high gain compared to other existing models and produces low power dissipation compared to CMOS based op-amp.     

Discrete micropayment protocol based on master-slave payword chain

Using the idea of Payword, the new concept of master-slave payword chain (MSPC) is proposed in this article. MSPC consists of one master payword chain and one slave payword chain. On the basis of MSPC, a new micropayment protocol called discrete micropayment protocol (DMP), is presented in this article. DMP consists of three sub-protocols: registration, payment, and settlement. Both part fairness and non-unit-wise payment can be provided by DMP.     

Model-driven engineering of Manufacturing Automation Software Projects – A SysML-based approach

This paper comprises a SysML-based approach to support the model-driven engineering (MDE) of Manufacturing Automation Software Projects (MASP). The Systems Modeling Language (SysML) is adapted to define the SysML-AT (SysML for automation), a specialized language profile that covers (non-)functional requirements, corresponding software applications and properties of proprietary hardware components. Furthermore, SysML-AT supports an automated software generation for run-time environments conforming to IEC 61131-3. A prototypical tool support was realized for adapted SysML Parametric Diagrams (PD) inside an industrial automation software development tool. Coupling the model editor and online data from the provided run-time environment enables direct debugging inside the model. The approach was evaluated by several case studies and additional usability experiments. With the latter, the suitability of the MDE approach for future users was proven.     

Robustness Validation – A physics of failure based approach to qualification

Product reliability is crucial to the success of a company. Product qualification today is based on standards that follow a stress-test driven approach, meaning pre-defined stress tests with pre-defined stress conditions. However, reliability requirements have increased, while at the same time both designs of semiconductor components and usage of these components in the applications have increasingly been pushed to the limits. This development raises the question, how far the standard procedures are still suitable for reliability assessment. Robustness Validation is an approach to a failure-mechanism-driven qualification that was primarily initiated by the automotive industry but has a much wider range of applicability. The paper will give an introduction to the basic ideas of Robustness Validation. Some limitations including statistical aspects will also be discussed.     

Feasibility and modelling for convergence of optical-wireless network – A review

Now a days, the convergence of wireless and optical network gaining popularity to enhance the data carrying capacity, QoS and to support future multimedia applications. The queue theory plays an important role for analytically evaluating such converged networks. In the everyday state of affairs, queue phenomena are observed in the several situations like the health clinic, railway reservation system, automobile laundry centre, bank cash counter, call centre, etc. Similarly, the phenomenon of congestion is ascertained in the telephone network, computer network, communication systems and the Internet wherever nonstop enhancements need to be created to stay up with the quickly growing demand. The subsistence of these adverse clogging effects has lead toward the improvement of queuing theory-based statistical models. Therefore, these queues based statistical models answering to optimising queries corresponding to the way for assigning resources in converged optical and wireless networks. During this paper, a review on the role of the queuing model in wireless & optical communication is presented that concentrate on the present and future aspects of research.     

The privacy paradox – Investigating discrepancies between expressed privacy concerns and actual online behavior – A systematic literature review

Also known as the privacy paradox, recent research on online behavior has revealed discrepancies between user attitude and their actual behavior. More specifically: While users claim to be very concerned about their privacy, they nevertheless undertake very little to protect their personal data. This systematic literature review explores the different theories on the phenomenon known as the privacy paradox.Drawing on a sample of 32 full papers that explore 35 theories in total, we determined that a user’s decision-making process as it pertains to the willingness to divulge privacy information is generally driven by two considerations: (1) risk-benefit evaluation and (2) risk assessment deemed be none or negligible. By classifying in accordance with these two considerations, we have compiled a comprehensive model using all the variables mentioned in the discussed papers. The overall findings of the systematic literature review will investigate the nature of decision-making (rational vs. irrational) and the context in which the privacy paradox takes place, with a special focus on mobile computing. Furthermore, possible solutions and research limitation issues will be discussed.     

On advance towards sub-sampling technique in phase locked loops – A review

This paper presents a symmetric review of academic and accomplished research endeavors in the field of Sub-Sampling Phase Locked Loop (SSPLL) design. Adequate emphasis has been given to understand the yearn for development of Sub-Sampling PLLs. Techniques that have emerged over the recent few years in context of better FOM, Jitter and Phase Noise reduction while maintaining extraordinary circuit performance in Sub-Sampling PLLs with CMOS/VLSI technology, have been captured in this paper. Consecutively, the main inspiration of this study is to present an overview of the PLL fundamentals, furtherance from analog to Digital PLL and various noises encountered in the different PLL components, important for the reader to have a better understanding about the design and analysis of Sub-Sampling PLLs.     

A sub-nanosecond Synchronized MAC – PHY cross-layer design for Wireless Sensor Networks

In this paper, we present a Wireless Sensor node implementation which aims at solving two major issues in Wireless Sensor Networks. This solution provides nanosecond-scale synchronization between nodes and high data-rate transmission thanks to cross-layer design and the time-domain properties of UltraWide Band (UWB) modulation schemes. The high data rate is achieved through a specific implementation of a IR-UWB physical layer. Specific algorithms are also implanted into the MAC and physical layers and form a cross-layered synchronization protocol for deterministic Wireless Sensor Networks named WiDeCS (Wireless Deterministic Clock Synchronization). This protocol propagates master time reference to nodes of a cluster tree network. WiDeCS Cross layered scheme is possible thanks to flag signals rising in the physical layer. These signals, owing to the UWB time domain properties, capture precise timestamps of transmission and reception. Hardware level simulations show a clock synchronization precision of 2 ns with a 2 GHz bandwidth signal, and an ASIC demonstrator shows 374 ps synchronization precision and 677 ps of standard deviation with the same bandwidth. In this paper, the physical layer implementation is detailed, and the cross-layered WiDeCS scheme is demonstrated.     

ARMOR – A system for adjusting repair and media scaling for video streaming

To optimize scarce network resources and present the highest quality video, streaming video systems need adapt to the video content as well as the network conditions. This paper presents ARMOR, a video streaming system that dynamically adjusts repair and media scaling to meet current video and network conditions. In order to adapt effectively, ARMOR, and any dynamic video adaptation system, needs to predict the video quality as perceived by end users over the range of scaling and repair choices. Thus, this paper first proposes a novel video quality metric called distorted playable frame rate that provides estimation of user perceptual quality considering temporal and quality degradations. Comprehensive user studies show distorted playable frame rate is more accurate than other video quality metrics. Analytic experiments with distorted playable frame rate and the ARMOR optimization algorithm illustrate the predictive power of the metric in a dynamic, streaming video system. Lastly, implementation and experiments of a complete, fully-functioning ARMOR system show the effective practicality of the proposed approach.     

Systematic Literature Review on Energy Efficient Routing Schemes in WSN – A Survey

Mobile Networks and Applications - In wireless sensor networks (WSN), routing is quite challenging area of research where packets are forwarded through multiple nodes to the base station. The...     

Uncertainty quantification in nanowire growth modeling – A precursor to quality semiconductor nanomanufacturing

Mitigating the uncertainties associated with nanowire growth models have significant ramifications for the quality and reliability of nanomanufacturing of semiconductor nanowires. This research is focused on the development of a sectional-based mechanistic model of nanowire growth and the determination of the level of impacts the model parameters have on the growth of nanowires, characterized in terms of their weight, diameter and length. After testing the model with experimental growth data of silica (Si) nanowire weight, ZnO average diameter and length, it was observed that the direct top impingement growth coefficient (α_im) had the largest influence on the nanowire growth, in comparison to other model parameters → sidewall diffusion growth coefficient (α_sw), maximum allowable growth weight or length (W^(max)) and initial weight or length (W₀). The knowledge of the impact of uncertainty in these parameters on the overall growth of the nanowire can be leveraged on for robust design of the nanofabrication process that will impact on the quality, reliability, yield and cost of nanomanufacturing.