Optical SDMA for applying compressive sensing in WSN

In order to apply compressive sensing in wireless sensor network, inside the nodes cluster classified by the spatial correlation, we propose that a cluster head adopts free space optical communication with space division multiple access, and a sensor node uses a modulating retro-reflector for communication. Thus while a random sampling matrix is used to guide the establishment of links between head cluster and sensor nodes, the random linear projection is accomplished. To establish multiple links at the same time, an optical space division multiple access antenna is designed. It works in fixed beams switching mode and consists of optic lens with a large field of view（FOV）, fiber array on the focal plane which is used to realize virtual channels segmentation, direction of arrival sensor, optical matrix switch and controller. Based on the angles of nodes＇ laser beams, by dynamically changing the route, optical matrix switch actualizes the multi-beam full duplex tracking receiving and transmission. Due to the structure of fiber array, there will be several fade zones both in the focal plane and in lens＇ FOV. In order to lower the impact of fade zones and harmonize multibeam, a fiber array adjustment is designed. By theoretical, simulated and experimental study, the antenna＇s qualitative feasibility is validated.

A Reducing Iteration Orthogonal Matching Pursuit Algorithm for Compressive Sensing

In recent years, Compressed Sensing（CS） has been a hot research topic. It has a wide range of applications, such as image processing and speech signal processing owing to its characteristic of removing redundant information by reducing the sampling rate. The disadvantage of CS is that the number of iterations in a greedy algorithm such as Orthogonal Matching Pursuit（OMP） is fixed, thus limiting reconstruction precision.Therefore, in this study, we present a novel Reducing Iteration Orthogonal Matching Pursuit（RIOMP） algorithm that calculates the correlation of the residual value and measurement matrix to reduce the number of iterations.The conditions for successful signal reconstruction are derived on the basis of detailed mathematical analyses.When compared with the OMP algorithm, the RIOMP algorithm has a smaller reconstruction error. Moreover, the proposed algorithm can accurately reconstruct signals in a shorter running time.

SOME PROGRESS IN SENSOR NETWORK DECISION FUSION

The multisensor network decision/detection problem continue to attract much research interest in recent years since such system offers many advantages over that with a single sensor in terms of e.g., survivability, reliability, and robustness. This article surveys some previous progress, briefly presents a few new results, and proposes some challenging issues in communication direction of sensor network decision fusion.

Experimental and Theoretical Study on Piezoresistive Behavior of Compressible Melamine Sponge Modified by Carbon-based Fillers

High-performance compression sensors have been playing an increasingly important role in human motion detection,health monitoring and human-machine interfaces over recent years.However,it remains a great challenge to develop theoretical models providing practical guidance to the sensor design.Herein,carbon black(CB),carbon nanotubes(CNTs)and graphene nanoplatelets(GNPs)were respectively incorporated into porous melamine sponges by a facile approach of dip-coating to fabricate compression sensors.Uniaxial compression-resistance tests show that the compressibility,stability and piezoresistive sensitivity of sensors could be tailored by the filler type and concentration.A model considering the number of conductive pathways(NCP)is given to describe the relationship between the resistance change and applied compression,showing extremely good agreement with the experimental data.Also,the correlation between the equivalent filler volume fraction and conductivity is described by the other two models proposed by McLachlan and Kirkpatrick,revealing the electrical percolation thresholds(Φc)for the conductive systems under compression.Among the three fillers,CB particles endowed the composite with the best piezoresistive sensitivity but the largestΦc due to its small size and aspect ratio.A combination of experimental study and theoretical model opens up a way of further understanding the piezoresistive sensing behavior as well as optimizing the electrical property and piezoresistivity of compressive conductive polymer composite.