Survey of Resources Allocation Techniques with a Quality of Service (QoS) Aware in a Fog Computing Environment

The tremendous advancement in distributed computing and Internet of Things(IoT)applications has resulted in the adoption of fog computing as today’s widely used framework complementing cloud computing.Thus,suitable and effective applications could be performed to satisfy the applications’latency requirement.Resource allocation techniques are essential aspects of fog networks which prevent unbalanced load distribution.Effective resource management techniques can improve the quality of service metrics.Due to the limited and heterogeneous resources available within the fog infrastructure,the fog layer’s resources need to be optimised to efficiently manage and distribute them to different applications within the IoT net-work.There has been limited research on resource management strategies in fog networks in recent years,and a limited systematic review has been done to compile these studies.This article focuses on current developments in resource allocation strategies for fog-IoT networks.A systematic review of resource allocation techniques with the key objective of enhancing QoS is provided.Steps involved in conducting this systematic literature review include developing research goals,accessing studies,categorizing and critically analysing the studies.The resource management approaches engaged in this article are load balancing and task offloading techniques.For the load balancing approach,a brief survey of recent work done according to their sub-categories,including stochastic,probabilistic/statistic,graph theory and hybrid techniques is provided whereas for task offloading,the survey is performed according to the destination of task offloading.Efficient load balancing and task-offloading approaches contribute significantly to resource management,and tremendous effort has been put into this critical topic.Thus,this survey presents an overview of these extents and a comparative analysis.Finally,the study discusses ongoing research issues and potential future directions for developing effective management resource allocation techniques.

Sequential generation of self-starting diverse operations in all-fiber laser based on thulium-doped fiber saturable absorber

Self-starting Q-switching,Q-switched mode-locking and mode-locking operation modes are achieved sequentially in an all-fiber erbium-doped fiber laser with thulium-doped fiber saturable absorber for the first time.The central wavelengths of Q-switching,Q-switched mode-locking and mode-locking operation modes are 1569.7 nm,1570.9 nm,and 1572 nm,respectively.The mode-locking operation of the proposed fiber laser generates stable dark soliton with a repetition rate of 0.99 MHz and signal-to-noise ratio of 65 dB.The results validate the capability of generating soliton pulse by doped fiber saturable absorber.Furthermore,the proposed fiber laser is beneficial to the applications of optical communication and signal processing system.

Propagation Characterization and Analysis for 5G mmWave Through Field Experiments

The 5G network has been intensively investigated to realize the ongoing early deployment stage as an effort to match the exponential growth of the number of connected users and their increasing demands for high throughput,bandwidth with Quality of Service(QoS),and low latency.Given that most of the spectrums below 6 GHz are nearly used up,it is not feasible to employ the traditional spectrum,which is currently in use.Therefore,a promising and highly feasible effort to satisfy this insufficient frequency spectrum is to acquire new frequency bands for next-generation mobile communications.Toward this end,the primary effort has been focused on utilizing the millimeter-wave(mmWave)as the most promising candidate for the frequency spectrum.However,though the mmWave frequency band can fulfill the desired bandwidth requirements,it has been demonstrated to endure several issues like scattering,atmospheric absorption,fading,and especially penetration losses compared to the existing sub-6 GHz frequency band.Then,it is fundamental to optimize the mmWave band propagation channel to facilitate the practical 5G implementation for the network operators.Therefore,this study intends to investigate the outdoor channel characteristics of 26,28,36,and 38 GHz frequency bands for the communication infrastructure at the building to the ground floor in both Line of Sight(LOS)and Non-Line of Sight(NLOS)environments.The experimental campaign has studied the propagation path loss models such as Floating-Intercept(FI)and Close-In(CI)for the building to ground floor environment in LOS and NLOS scenarios.The findings obtained from the field experiments clearly show that the CI propagation model delivers much better performance in comparison with the FI model,thanks to its simple setup,accuracy,and precise function.

Science Letters:Finite time-horizon Markov model for IEEE 802.11e

We model wireless local area network channel utilization over a finite interval through a finite time-horizon Markov(FTHM) model.By accurately capturing time-varying utilization,the FTHM model allows for generally distributed transmis-sion-opportunity(TXOP) duration,which most existing models do not account for.An absorbing state is introduced to limit the lifetime of the counting process,resulting in a non-ergodic Markov chain that is solved via transient analysis.The model predic-tions for time-varying utilization are validated by simulation with errors of no more than 0.1% after eight beacon intervals.Moreover,we show that the FTHM model prediction error is below 4% for Poisson distributed and uniformly distributed TXOP durations.

Agarose coated micro-bottle sensor for relative humidity detection

The whispering gallery mode(WGM)based micro-bottle resonator(MBR)sensor has been proposed and demonstrated for relative humidity measurement by using an agarose gel as a transducer.MBR was fabricated by using a soften-and-compress method to form a 190μm bulge bottle.The micro-bottle was optically excited by a 3μm tapered fiber and it exhibits a resonance with a Q factor in an order of 10^(5).The agarose coated MBR produces a good sensing response towards humidity with the sensitivity of 0.107 d B/%RH and linearity of 99.614%.The agarose hydrophilic nature and its changing porosity and refractive index with increasing relative humidity made the coated MBR structure to be more sensitive than the uncoated structure.This humidity sensor has a simple fabrication and is showing good sensitivity,linearity,resolution,response time and operational in a wide humidity range.