Average Request Research Articles

Resource allocation for edge computing over fibre‐wireless access networks

Edge Computing (EC) has been proposed as a promising approach to fulfil the requirements of high bandwidth and ultra-latency of mobile applications. However, existing researches on resource allocation only consider the computing resource of mobile devices and EC servers, while ignored the constraint of the networking resources once spreading applications among multiple EC servers via wireless and wired networks. Fibre-Wireless access networks (FiWi) combine the huge bandwidth of optical fibre networks and flexible access of wireless networks to address the above issue and bridge the coexistence of multiple EC servers. They propose a Virtualisation-based Architecture converging EC over FiWi (VAECFW) to centralise control and allocate networking and computing resources for serving requested services. In addition, they study the problem of resource allocation of EC over FiWi and propose two algorithms Revenue-based Virtual Network Embedding (R-VNE) and Balanced Central Processing Unit Resource Allocation with Virtual Network Embedding (BCRA-VNE). Simulation experiments show that the services acceptance ratio is increased about 35% under their proposed architecture, and the average service requests bandwidth utilisation of R-VNE is increasing from 50 to 66%, and the BCRA-VNE is from 37 to 48%. The two algorithms not only achieve higher revenue but also get better profit rate.

Lazy scheduling based disk energy optimization method

Reducing the energy consumption of the storage systems disk read/write requests plays an important role in improving the overall energy efficiency of high-performance computing systems. We propose a method to reduce disk energy consumption by delaying the dispatch of disk requests to the end of a time window, which we call time window-based lazy scheduling. We prove that sorting requests within a single time window can reduce the disk energy consumption, and we discuss the relationship between the size of the time window and the disk energy consumption, proving that the energy consumption is highly likely to decrease with increasing window size. To exploit this opportunity, we propose the Lazy Scheduling based Disk Energy Optimization (LSDEO) algorithm, which adopts a feedback method to periodically adjust the size of the time window, and minimizes the local disk energy consumption by sorting disk requests within each time window. We implement the LSDEO algorithm in an OS kernel and conduct both simulations and actual measurements on the algorithm, confirming that increasing the time window increases disk energy savings. When the average request arrival rate is 300 and the threshold of average request response time is 50 ms, LSDEO can yield disk energy savings of 21.5%.

A Virtual Network Resource Allocation Framework Based on SR-IOV

The workload of a data center has the characteristics of complexity and requirement variability. However, in reality, the attributes of network workloads are rarely used by resource schedulers. Failure to dynamically schedule network resources according to workload changes inevitably leads to the inability to achieve optimal throughput and performance when allocating network resources. Therefore, there is an urgent need to design a scheduling framework that can be workload-aware and allocate network resources on demand based on network I/O virtualization. However, in the current mainstream I/O virtualization methods, there is no way to provide workload-aware functions while meeting the performance requirements of virtual machines (VMs). Therefore, we propose a method that can dynamically sense the VM workload to allocate network resources on demand, and can ensure the scalability of the VM while improving the performance of the system. We combine the advantages of I/O para-virtualization and SR-IOV technology, and use a limited number of virtual functions (VFs) to ensure the performance of network-intensive VMs, thereby improving the overall network performance of the system. For non-network-intensive VMs, the scalability of the system is guaranteed by using para-virtualized Network Interface Cards (NICs) which are not limited in number. Furthermore, to be able to allocate the corresponding bandwidth according to the VM’s network workload, we hierarchically divide the VF’s network bandwidth, and dynamically switch between VF and para-virtualized NICs through the active backup strategy of Bonding Drive and ACPI Hotplug technology to ensure the dynamic allocation of VF. Experiments show that the allocation framework can effectively improve system network performance, in which the average request delay can be reduced by more than 26%, and the system bandwidth throughput rate can be improved by about 5%.

Multi-Controller Deployment Algorithm in Hierarchical Architecture for SDWAN

A software-defined network (SDN) is a new paradigm that separates control and forwarding. With the growth of SDN deployment scale, the centralized control plane becomes a bottleneck restricting the expansion of SDN networks. To avoid the problem of limited processing power in the wide area network (WAN), we focus on the multi-controller deployment in hierarchical architecture for software-defined WAN (SDWAN). The hierarchical architecture divides the control plane into multiple levels. The root controller has a global view. The domain controller is only responsible for the control in local networks. In this paper, we use the improved Louvain algorithm to discover the hierarchical community structure. Considering the load balancing and request delay in each partition and reliability of the control plane, we formulate the modeling and propose a hierarchical multi-controller deployment algorithm for the scalability of the SDWAN. The simulation results show that compared with the traditional algorithms, the proposed algorithm not only reduces the average request delay to a certain extent and effectively improves the performance of load balancing in each partition, but also efficiently enhances the reliability of the control plane in the SDWAN and achieves the good effect on the execution efficiency.

Gobierno electrónico y accesibilidad: Disponibilidad de servicio en las plataformas online estatales de la Argentina

Este artículo presenta los resultados de un relevamiento anual de calidad de servicio de servidores estatales de la Argentina. Por medio de ello, se busca dar cuenta de la importancia de la evaluación sistemática de la infraestructura pública digital de servicios de gestión e información gubernamental. En el caso de la infraestructura estatal, la importancia de su estabilidad técnica tiene una relevancia especial, en tanto la oferta de servicios estatales representa en muchos casos el acceso o la denegación de derechos tan básicos como la educación, la salud o el trabajo. El monitoreo se realizó durante 12 meses sobre 59 sitios dependientes del estado nacional, pudiendo observarse en ellos un rendimiento deficiente en comparación a los grupos de servicios seleccionados como grupos de referencia. Este peor rendimiento se registró tanto en su nivel de disponibilidad como en el tiempo total de respuesta a las solicitudes. Los sitios dependientes del Estado nacional mostraron a su vez patrones de falla diferenciados según grupo de pertenencia (ministerios nacionales, organismos estatales y Universidades nacionales) sugiriendo la existencia de infraestructuras y formas de trabajo heterogéneas que confluyen en todos los casos en altos niveles de no disponibilidad de las plataformas ofrecidas.

A Dynamic Placement Mechanism of Service Function Chaining Based on Software-defined Networking

To cope with the explosive growth of Internet services, Service Function Chaining (SFC) based on Software-defined Networking (SDN) is an emerging and promising technology that has been suggested to meet this challenge. Determining the placement of Virtual Network Functions (VNFs) and routing paths that optimize the network utilization and resource consumption is a challenging problem, particularly without violating service level agreements (SLAs). This problem is called the optimal SFC placement problem and an Integer Linear Programming (ILP) formulation is provided. A greedy heuristic solution is also provided based on an improved two-step mapping algorithm. The obtained experimental results show that the proposed algorithm can automatically place VNFs at the optimal locations and find the optimal routing paths for each online request. This algorithm can increase the average request acceptance rate by about 17.6% and provide more than 20-fold reduction of the computational complexity compared to the Greedy algorithm. The feasibility of this approach is demonstrated via NetFPGA-10G prototype implementation.

Empirical Evaluation and Enhancement of Enterprise Storage System Request Scheduling

Since little has been reported in the literature concerning enterprise storage system file-level request scheduling, we do not have enough knowledge about how various scheduling factors affect performance. Moreover, we are in lack of a good understanding on how to enhance request scheduling to adapt to the changing characteristics of workloads and hardware resources. To answer these questions, we first build a request scheduler prototype based on WAFL®, a mainstream file system running on numerous enterprise storage systems worldwide. Next, we use the prototype to quantitatively measure the impact of various scheduling configurations on performance on a NetApp®'s enterprise-class storage system. Several observations have been made. For example, we discover that in order to improve performance, the priority of write requests and non-preempted restarted requests should be boosted in some workloads. Inspired by these observations, we further propose two scheduling enhancement heuristics called SORD (size-oriented request dispatching) and QATS (queue-depth aware time slicing). Finally, we evaluate them by conducting a wide range of experiments using workloads generated by SPC-1 and SFS2014 on both HDD-based and all-flash platforms. Experimental results show that the combination of the two can noticeably reduce average request latency under some workloads.

Hierarchical resource allocation and consolidation framework in a multi‐core server cluster using a Markov decision process model

This paper investigates a service level agreements (SLAs)-based resource allocation problem in a server cluster. The objective is to maximise the total profit, which is the total revenue minus the operational cost of the server cluster. The total revenue depends on the average request response time, whereas the operating cost depends on the total energy consumption of the server cluster. A joint optimisation framework is proposed, comprised of request dispatching, dynamic voltage and frequency scaling (DVFS) for individual cores of the servers, as well as server- and core-level consolidations. Each DVFS-enabled core in the server cluster is modelled by using a continuous-time Markov decision process (CTMDP). A near-optimal solution comprised of a central manager and distributed local agents is presented. Each local agent employs linear programming-based CTMDP solving method to solve the DVFS problem for the corresponding core. On the other hand, the central manager solves the request dispatch problem and finds the optimal number of ON cores and servers, thereby achieving a desirable tradeoff between service response time and power consumption. To reduce the computational overhead, a two-tier hierarchical solution is utilized. Experimental results demonstrate the outstanding performance of the proposed algorithm over the baseline algorithms.

MinT: Middleware for Cooperative Interaction of Things.

This paper proposes an Internet of Things (IoT) middleware called Middleware for Cooperative Interaction of Things (MinT). MinT supports a fully distributed IoT environment in which IoT devices directly connect to peripheral devices easily construct a local or global network, and share their data in an energy efficient manner. MinT provides a sensor abstract layer, a system layer and an interaction layer. These enable integrated sensing device operations, efficient resource management, and active interconnection between peripheral IoT devices. In addition, MinT provides a high-level API to develop IoT devices easily for IoT device developers. We aim to enhance the energy efficiency and performance of IoT devices through the performance improvements offered by MinT resource management and request processing. The experimental results show that the average request rate increased by 25% compared to Californium, which is a middleware for efficient interaction in IoT environments with powerful performance, an average response time decrease of 90% when resource management was used, and power consumption decreased by up to 68%. Finally, the proposed platform can reduce the latency and power consumption of IoT devices.

Interconnection Contracts between Service and Content Provider with Partial Cloud Migration

This paper addresses interconnection contracts in content provisioning scheme with partial cloud migration. Model for traffic workload of such scheme based on content popularity factor is introduced. Monte Carlo simulation for bandwidth demand estimation is used. Cost analysis of content provider’s resources utilization regarding average requests’ rejection rate is observed. The performance analysis of content provider’s incentive for partial cloud migration is applied. Three interconnection contracts are analysed: Revenue Sharing, Cost Sharing and Wholesale Price contract. Obtained results show that partial cloud migration can reduce both content provider’s costs and average requests’ rejection rate. Under observed constellation, Revenue Sharing contract may represent satisfying solution for both providers.DOI: http://dx.doi.org/10.5755/j01.eie.22.6.17230

A Mechanism for Configurable Network Service Chaining and Its Implementation

Recently Service Function Chaining (SFC) is promising to innovate the network service mode in modern networks. However, a feasible implementation of SFC is still difficult due to the need to achieve functional equivalence with traditional modes without sacrificing performance or increasing network complexity. In this paper, we present a configurable network service chaining (CNSC) mechanism to provide services for network traffics in a flexible and optimal way. Firstly, we formulate the problem of network service chaining and design an effective service chain construction framework based on integrating software-defined networking (SDN) with network functions virtualization (NFV). Then, we model the service path computation problem as an integer liner optimization problem and propose an algorithm named SPCM to cooperatively combine service function instances with a network utility maximum policy. In the procedure of SPCM, we achieve the service node mapping by defining a service capacity matrix for substrate nodes, and work out the optimal link mapping policies with segment routing. Finally, the simulation results indicate that the average request acceptance ratio and resources utilization ratio can reach above 85% and 75% by our SPCM algorithm, respectively. Upon the prototype system, it is demonstrated that CNSC outperforms other approaches and can provide flexible and scalable network services.

Evaluation of freight forwarder risk to transportation market entry

Consideration of risks in managing freight forwarding processes allows decreasing potential losses as the result of market situation change for logistics system elements, which are involved in delivery process. Existing approaches to freight forwarders risks estimation are usually not based on technological process model; they take into consideration external factors, such as legal framework, traffic conditions, logistics system structure and others. In the paper in order to evaluate freight forwarder risk to entry the transportation market, a simulation model of servicing by the forwarding company of requests flow has been developed. Regression model, obtained on the basis of simulation results, allows to estimate numerically a measure of freight forwarder risk without the simulations of the process of requests servicing. Provided results of research allow to state, that forwarding company risk to entry the market monotonically increases with increasing of average requests interval in the serviced flow and monotonically decreases with increasing of the tariff on services of a freight forwarder. Research results should be considered while managing the process of freight forwarders entry to new markets.

Functional reliability of a real-time redundant computational process in cluster architecture systems

Functional reliability models are proposed for a real-time redundant computational process when an incoming request flow is distributed for redundant execution of request copies in several nodes of a cluster architecture system operating under conditions of faults, failures, and errors in nodes; in this case, the reliability, integrity, and timeliness of executing functional requests must be ensured. The effect of the organization and redundancy rate of computations on their timeliness and reliability, as well as on the average request waiting time, is analyzed taking into account faults, failures, and errors in cluster nodes.

COMPARISON OF ROUTING ALGORITHMS FOR STORAGE AND RETRIEVAL MECHANISM IN CYLINDRICAL AS/RS

The objective of this research is to propose new routing algorithms for the Storage and Retrieval Mechanism (SRM) in the Cylindrical Automated Storage and Retrieval System (C-AS/RS) and contribute to the system conceptualization by investigating the maximum achievable retrieval request rates for different routing algorithms and system parameters. For this purpose, flexible and detailed simulation model was developed and investigated for 2 SRM types, 3 routing algorithms and a feasible set of system movement and load transfer time parameters. Based on the simulation output, the regression models for different SRM types and routing algorithms were developed for predicting the maximum retrieval request rate. The differences of the average maximum retrieval request rate were evaluated for various system configurations and routing algorithms. The alternative to optimal routing algorithm was proposed, reducing the system performance only by 1.4÷2.4% on average, but requiring significantly less calculations when planning the SRM tour. In addition, the system analysis indicated that SRM vertical velocity and load transfer time have the highest impact on the system performance and for different SRM types the average maximum retrieval request rates differ by 22.2÷31.8%.

29. Patterns of EGFR mutation testing pre-and post-establishment of an in-house molecular pathology service

<h3>Background</h3> Molecular testing of tumours is a rapidly growing area, with anatomical pathology laboratories being asked more frequently to use their material to perform molecular testing, either in-house or as a send-out test. In addition to the expense of the test itself, the retrieval and preparation of material for testing may be both time-consuming and labour-intensive, particularly if archives are not on-site or if a pathologist is required to re-examine the case to identify appropriate material. Limited information exists in the literature regarding adherence to guidelines, and without this information it is difficult to determine if the additional workload on laboratory personnel is justified. <h3>Aims</h3> To determine the timing, appropriateness and rates of EGFR mutation testing at the Austin and to identify any changes to these measures following establishment of an in-house service. <h3>Methods</h3> For EGFR mutation testing, specimen type, average request rates, turnaround times and test failure rates were determined for the 12 month period from January to December 2012. Following the establishment of in-house EGFR mutation testing, these rates were determined for the 3 month period of January to March 2013. <h3>Results</h3> EGFR tests were requested appropriately on all cases and were confined to cases of primary or metastatic lung adenocarcinoma only. Turnaround times improved significantly following introduction of in-house testing (average TAT time pre-introduc-tion, 39 days; average TAT post-introduction, 7 days). Request rates increased following introduction of in-house testing. Failure rates remained unchanged. <h3>Conclusions</h3> Although EGFR testing may have additional unaccounted-for costs for anatomical pathology laboratories, these costs are justified at the Austin by clinically-appropriate testing. Our data confirms increasing request rates although the additional convenience of in-house availability and more rapid TATs may also be contributing factors.

Hierarchical DHT-based name resolution for information-centric networks

Information-centric network (ICN) architectures are an increasingly important approach for the future Internet. Several ICN approaches are based on a flat object ID namespace and require some kind of global name resolution service to translate object IDs into network addresses. Building a world-wide NRS for a flat namespace with 1016 expected IDs is challenging because of requirements such as scalability, low latency, efficient network utilization, and anycast routing that selects the most suitable copies. In this paper, we present a general hierarchical NRS framework for flat ID namespaces. The framework meets those requirements by the following properties: The registration and request forwarding matches the underlying network topology, exploits request locality, supports domain-specific copies of binding entries, can offer constant hop resolution (depending on the chosen underlying forwarding scheme), and provides scoping of publications.Our general NRS framework is flexible and supports different instantiations. These instantiations offer an important trade-off between resolution-domain (i.e. subsystem) autonomy (simplifying deployment) and reduced latency, maintenance overhead, and memory requirements. To evaluate this trade-off and explore the design space, we have designed two specific instantiations of our general NRS framework: MDHT and HSkip. We have performed a theoretical analysis and a simulation-based evaluation of both systems. In addition, we have published an implementation of the MDHT system as open source. Results indicate that an average request latency of (well) below 100ms is achievable in both systems for a global system with 12 million NRS nodes while meeting our other specific requirements. These results imply that a flat namespace can be adopted on a global scale, opening up several design alternatives for information-centric network architectures.

An Efficient Integrated Bandwidth Allocation Scheme for DOCSIS Networks

An efficient Integrated Bandwidth Allocation Scheme (IBAS) is proposed to serve the lower priority requests can be early assigned the bandwidth without waiting too long. These will speed up the channel capture by priority data to support the multimedia traffic over DOCSIS-compliant cable networks. The efficiency of IBAS is investigated by simulations. The results show that by adopting IBAS can not only shorten the collision period but also minimize the average request delay of lower priority requests. Performance has been improved in throughput and delay compares to the current DOCSIS specifications.

Improved RFID anti-collision algorithm

In this paper, we propose an improved anti-collision technique based on the binary search algorithm. The improvement is achieved thanks to the manner of the requests’ building. This latter reduces considerably the responding tag's numbers and therefore, decreases the probability of bit's collision. Further, the algorithm provides a noticeable advantage for the length of transmitted binary data compared against basic binary search and dynamic binary search algorithms. Besides, it provides same performance in terms of average request's number making the identification process faster, and the expose time of information is then reduced.

Analysis of adaptive proportional fair scheduling method on BD-GMD scheme for MIMO systems

The Proportional Fair Scheduling (PFS) algorithm is always exploited in multiple input multiple output systems to make a balance between maximising the system throughput and guaranteeing the data rate fairness among different users. Besides the traditional PFS, many modified PFS algorithms have also been proposed to further improve user fairness. Among these, an adaptive PFS algorithm attracts our attention. It defines a new priority number which is multiplying traditional PFS priority number by a factor. And this very factor is the ratio of instantaneous request rate over average request rate. What is different is that while the average transmission rate in traditional PFS has a fixed definition and updating strategy, the average request rate in the adaptive method may not. In this paper, we analyse the adaptive PFS algorithm under different definition and updating strategies on block-diagonal geometric mean decomposition scheme and investigate their performance.

Adaptive QoS provision for IEEE 802.16e BWA networks based on cross-layer design

This article proposes an integrated framework for adaptive QoS provision in IEEE 802.16e broadband wireless access networks based on cross-layer design. On one hand, an efficient admission control (AC) algorithm is proposed along with a semi-reservation scheme to guarantee the connection-level QoS. First, to guarantee the service continuity for handoff connections and resource efficiency, our semi-reservation scheme considers both users' handoff probability and average resource consumption together, which effectively avoids resource over-reservation and insufficient reservation. For AC, a new/handoff connection is accepted only when the target cell has enough resource to afford both instantaneous and average resource consumption to meet the average source rate request. On the other hand, a joint resource allocation and packet scheduling scheme is designed to provide packet-level QoS guarantee in term of "QoS rate", which can ensure fairness for the services with identical priority level in case of bandwidth shortage. Particularly, an enhanced bandwidth request scheme is designed to reduce unnecessary BR delay and redundant signaling overhead caused by the existing one in IEEE 802.16e, which further improves the packet-level QoS performance and resource efficiency for uplink transmission. Simulation results show that the proposed approach not only balances the tradeoff among connection blocking rate, connection dropping rate, and connection failure rate, but also achieves low mean packet dropping rate (PDR), small deviation of PDR, and low QoS outage rate. Moreover, high resource efficiency is ensured.