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A single ended 8-transistor (8T) static random access memory (SRAM) cell is presented which is designed for sub-threshold operation with improved data stability. The proposed 8T cell involves the breaking-up of feedback between the true storing nodes that enhances the writability of the cell at ultra-low voltage (ULV) power supply (VDD). During read operation, as 8T is isolated from the bit-lines...
The live implantation of micro-electrode arrays allows the observation of populations of neural activity. There is a strong need for unsupervised adaptable neural spike extraction and spike-sorting methods, which would significantly reduce data throughput and allow for implantation and wireless transmission. We present a method for neural spike feature-extraction that involves the generation and use...
Wireless Sensor Networks (WSNs) are deployed in the field to collect some physical data and report the data to a management entity. The very context of WSN usage implies autonomous operation. Consequently fault tolerant attributes are of high interest in WSNs, and therefore an active area of research. Healthy sensor nodes can occasionally report readings that are outside of the expected range. These...
Sensor localization is a basic and important task of wireless sensor networks, and abundant localization algorithms have been proposed based on various ranging techniques, including time-of-arrival (TOA), time-difference-of-arrival (TDOA), received signal strength (RSS), angle-of-arrival (AOA) and etc. The accuracy of these ranging techniques rely on the line-of-sight (LOS) propagation of signals,...
This paper solves the problem of time synchronization in wireless sensor networks (WSNs) with noise. The consensus based approach is an improved average value based protocol. This algorithm, compared with the existing consensus-based synchronization approach, has the advantage of being totally distributed, asynchronous and robust to process and measurement noise. The main idea of this algorithm is...
In this paper, geometry-based algorithms for device-free localization (DFL) of a single target are proposed. The algorithms exploit the change in attenuation caused by the device-free target on radio links passing through the deployment area. By solving for the intersections of some of the attenuated links and taking the centroid of the intersection points, an estimate of the target's location is...
The world population is in the midst of a unique and irreversible process of aging. Fall, which is one of the major health threats and obstacles to independent living of elders, will aggravate the global pressure in elders' health care and injury rescue. Thus, automatic fall detection is highly in need. Current proposed fall detection systems either need hardware installation or disrupt people's daily...
In this work we propose a fail-safe control strategy to achieve a target network reliability by estimating the lifetime of nodes in a Wireless Sensor Network (WSN). In the proposed scheme, a network coordinator estimates the outage probability of small-scale uncorrelated fading channel uses and regulates the transmit power of each node in the network in order to simultaneously guarantee the outage...
Bayesian estimation methods are widely used for wireless localization systems. They employ priori information and current measurement error distribution models to derive the state of a mobile target. Cramér-Rao lower bound (CRLB) is a fundamental tool to analyze the performance of Bayesian estimators. Although CRLB is derived based on the measurement error distribution, only a few works have investigated...
There are applications that require long-range, low data rate and low power consumption communications that could be implemented with wireless sensor networks equipped with multiple antennas. We are implementing a transceiver for that purpose. The transceiver requires a specific reconstruction filter which isn't commercially available for our target technology, XFAB XH018. An integrated active DAC...
With today's increase in the usage of wireless devices and spectrum allocation, radio spectrum is becoming scarce and it is used partially. This has evolved a concept called the Cognitive radio to exploit the presence of these spectrum holes which utilizes cooperative spectrum sensing concept for primary user detection. This spectrum sensing concept has a drawback that an intruder can capture these...
Efficient dynamic spectrum access (DSA) policies rely on accurate spectrum sensing information to exploit spectrum white space optimally. Obtaining accurate channel state information (CSI) from local spectrum measurements is made difficult by wireless signal fading and the presence of thermal noise which distorts measured signals and leads to uncertainty regarding the occupancy of spectrum resources...
Expeditiously escalating need for the wireless communication puts forward the challenge of efficient spectrum utilization. The cognitive networks paradigm gives a tremendous provision to considerably influence and shift the implementation of underwater acoustic networks for an efficient utilization of acoustic spectrum. The capacity of underwater acoustic communication is intrinsically constrained...
Memristor is a good candidate for replacing CMOS-based flash and DRAM due to its superior scalability, low read energy and non-volatility characteristics. Relatively longer write time and high write energy are the main obstacles in the way of adapting memristor for on-chip memory to replace SRAM. The off-to-on resistance ratio for memristor are in excess of 1000x which provides adequate noise margin...
The accuracy of particle filtering estimation for the tracking system is prone to be influenced by the high measurement noise (or errors) in wireless sensor networks (WSNs). We first analyze the impact of instantaneous measurement noise which is introduced into the likelihood function and biases the particle filtering estimation. Based on our analysis, we propose a likelihood adaptation method considering...
We propose a novel distributed on-line expectation maximization method for passive target localization in wireless sensor networks where multiple sensors cooperate to process the location information obtained from the radio signal transmitted by the target. We consider the scenario where few or no sensors receive line of sight signals. Each sensor computes the time difference of arrival of the target's...
In this paper algorithms for wireless sensor networks (WSN) localization and tracking are presented. They are optimized for the exploration of inaccessible environments with unknown shape and dynamics. The algorithms are based on semidefinite programming (SDP) and unscented Kalman filtering (UKF). The SDP approach is derived from a recent solution for WSN localization with anchor node uncertainty,...
Wireless sensor networks have become an active topic of research over the last decades with a growing demand and interests. Wireless sensor nodes (or motes) are the fundamental unit in forming wireless sensor networks. There are many ready-made devices now available aiming for various wireless sensor network applications. In this paper, a novel mote, AWSAM-3, is presented targeting flexibility, low...
We introduce in this paper the fully distributed, Rao-Blackwellized Random Exchange Diffusion Particle Filter (RB ReDif-PF) to track a moving emitter using multiple received-signal-strength (RSS) sensors with unknown noise variances. In a simulated scenario with a partially connected network, the proposed RB ReDif-PF outperformed a suboptimal tracker that assimilates local neighboring measurements...
Interesting wireless networking scenarios exist wherein network services must be guaranteed in a dynamic fashion for some priority users. For example, in disaster recovery, members need to be able to quickly block other users in order to gain sole use of the radio channel. As it is not always feasible to physically switch off other users, we propose a new approach, termed selective packet destruction...
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