Input Queues Research Articles

An Ant Colony Optimization-Simulated Annealing Algorithm for Solving a Multiload AGVs Workshop Scheduling Problem with Limited Buffer Capacity

In this paper, we address a multiload AGVs workshop scheduling problem with limited buffer capacity. This has important theoretical research value and significance in the manufacturing field in considering the efficient multiload AGVs widely used today, and in the limited buffer area in production practice. To minimize the maximum completion time, an improved ant colony optimization-simulated annealing algorithm based on a multiattribute dispatching rule is proposed. First, we introduce a multiattribute dispatching rule, which combines two attributes, delivery completion time and input queue through dynamic weights that are determined by the information about the system, using the multiattribute dispatching rule to construct the initial solution. Then, with the ant colony optimization-simulated annealing algorithm as the basic framework, we propose a method for calculating transfer probability based on the multiattribute dispatching rule, which obtains heuristic information through the proposed rule. Further, we propose a path branch mechanism and dynamic equilibrium mechanism, aiming to efficiently construct the ant path and dynamically adjust ant path distribution. We propose a key job strategy and design a 2-opt neighborhood search method based on key jobs. Data experiments demonstrate the multiattribute dispatching rule is superior over other heuristic dispatching rules; the algorithm improvement strategies proposed are effective when used simultaneously or separately. Further, the proposed algorithm in this paper is superior over other heuristic algorithms and adapts to all kinds of instances.

Quality of Service (QoS) Performance Analysis in a Traffic Engineering Model for Next-Generation Wireless Sensor Networks

Quality of Service (QoS) refers to techniques that function on a network to dependably execute high-priority applications and traffic reliably run high-priority applications and traffic even when the network’s capacity is limited. It is expected that data transmission over next-generation WSNs (Wireless Sensor Networks) 5G (5th generation) and beyond will increase significantly, especially for multimedia content such as video. Installing multiple IoT (Internet of Things refers to the network of devices that are all connected to each other) nodes on top of 5G networks makes the design more challenging. Maintaining a minimal level of service quality becomes more challenging as data volume and network density rise. QoS is critical in modern networks because it ensures critical performance metrics and improves end-user experience. Every client attempts to fulfill QoS access needs by selecting the optimal access device(s). Controllers will then identify optimum routes to meet clients’ core QoS needs in their core network. QoS-aware delivery is one of the most important aspects of wireless communications. Various models are proposed in the literature; however, an adaptive buffer size according to service type, priority, and incoming communication requests is required to ensure QoS-aware wireless communication. This article offers a hybrid end-to-end QoS delivery method involving customers and controllers and proposes a QoS-aware service delivery model for various types of communication with an adaptive buffer size according to the priority of the incoming service requests. For this purpose, this paper evaluates various QoS delivery models devised for service delivery in real time over IP networks. Multiple vulnerabilities are outlined that weaken QoS delivery in different models. Performance optimization is needed to ensure QoS delivery in next-generation WSN networks. This paper addresses the shortcomings of the existing service delivery models for real-time communication. An efficient queuing mechanism is adopted that assigns priorities based on input data type and queue length. This queuing mechanism ensures QoS efficiency in limited bandwidth networks and real-time traffic. The model reduces the over-provisioning of resources, delay, and packet loss ratio. The paper contributes a symmetrically-designed traffic engineering model for QoS-ensured service delivery for next-generation WSNs. A dynamic queuing mechanism that assigns priorities based on input data type and queue length is proposed to ensure QoS for wireless next-generation networks. The proposed queuing mechanism discusses topological symmetry to ensure QoS efficiency in limited bandwidth networks with real-time communication. The experimental results describe that the proposed model reduces the over-provisioning of resources, delay, and packet loss ratio.

Simulation and analysis models of hybrid software­configured devices

The analysis of the algorithm, based on which the simulation and analytical model of the hybrid software-configurable device is automatically synthesized, was carried out. The solution for modeling OpenFlow equipment was also considered, and an original OpenFlow switch model was developed, which is distinguished by the ability to manage delays based on the results of its mathematical model. The operation scheme of a hybrid switch that supports both traditional switching and OpenFlow switching has been developed. This scheme allows solving complex tasks in the physical infrastructure of virtualized networks. A module has been developed to create a realistic delay and limit the capacity and performance of the hybrid switch model, which can work according to the data obtained as a result of the experimental study. Additional traffic processing schemes have been developed for a more detailed implementation of the hybrid software-configurable equipment model. The basic model of the switch presented in the INET OMNeT++ framework is considered. The switch is represented by a set of modules interacting through the OMNeT transmission system. The most detailed modules of Ethernet interfaces are implemented, in particular, there are implementations of the input queue of the Tail-Drop type, output queues of the FIFO, RED, WRED, PQ, CBFQ types, as well as the implementation of the transmission delay on the line. The virtualization technology of network functions, which is built on the basis of software-configured networks, has been studied, and the most popular Linux-based solutions are used as a software-controlled Open vSwitch switch. The considered methods of forming a model of such a switch. Open vSwitch is architecturally different from both classical and OpenFlow real switches, as there are no dedicated packet refactoring units (except for network cards with hardware header processing and FPGAs), dedicated memory and processors for switching, Open vSwitch uses a kernel module (or module DPDK for direct transmission without the participation of the kernel) to transmit packets based on information from the OVSDB database or OpenFlow tables.

Customers' joining behavior in an unobservable <i>GI/Geo/m</i> queue

<p style='text-indent:20px;'>This paper studies the equilibrium balking strategies of impatient customers in a discrete-time multi-server renewal input queue with identical servers. Arriving customers are unaware of the number of customers in the queue before making a decision whether to join or balk the queue. We model the decision-making process as a non-cooperative symmetric game and derive the Nash equilibrium mixed strategy and optimal social strategies. The stationary system-length distributions at different observation epochs under the equilibrium structure are obtained using the roots method. Finally, some numerical examples are presented to show the effect of the information level together with system parameters on the equilibrium and social behavior of impatient customers.</p>

Simulation Study of Scheduling Heuristics for Parallel Machines with Sequence-Independent Setups

In this paper we examine a dynamic job scheduling problem on identical, parallel machines. Jobs that belong to different families arrive to the system at random time intervals. Stochastic processing times of jobs are considered and each family has different due date allowances. The manufacturing system consists of a single input queue and several machines. When switching from one job type to another on some machine, a sequence-independent setup is incurred. The scheduling of jobs is performed by some priority rule and nine alternative rules are considered in this study. The discrete-event simulation model of the system is developed and the performance of the scheduling heuristics is assessed in terms of the metrics of mean cycle time, mean earliness and mean tardiness. A total of thirteen simulation cases is considered, where the differentiating factors of the cases are the average job interarrival times, the due date and the setup parameters of jobs.

Synchronized abandonment in discrete-time renewal input queues with vacations

<p style='text-indent:20px;'>We consider a discrete-time infinite buffer renewal input queue with multiple vacations and synchronized abandonment. Waiting customers get impatient during the server's vacation and decide whether to take service or abandon simultaneously at the vacation completion instants. Using the supplementary variable technique and difference operator method, we obtain an explicit expression to find the steady-state system-length distributions at pre-arrival, random, and outside observer's observation epochs. We provide the stochastic decomposition structure for the number of customers and discuss the various performance measures. With the help of numerical experiments, we show that the method formulated in this work is analytically elegant and computationally tractable. The results are appropriate for light-tailed inter-arrival distributions and can also be leveraged to find heavy-tailed inter-arrival distributions.</p>

Performance analysis of renewal input queues with multiple vacations and synchronized abandonment

ABSTRACT This paper studies a single server renewal input queueing model with multiple vacations in the presence of impatient customers. The server follows an exhaustive vacation policy whenever the system is empty. During vacation, waiting customers become impatient and decide independently whether to abandon the system simultaneously or avail service at the vacation completion instant. Using the supplementary variable and difference equation techniques, we obtain the steady-state system-length distributions at pre-arrival and arbitrary epochs. We present the stochastic decomposition structure for the number of customers in the system and derive several performance measures including the sojourn time. Moreover, we examine the impact of various parameters on the system performance measures. A potential application of the model in the inventory management of an e-commerce company with fresh agricultural products is illustrated. Numerical results discuss the effects of the system parameters and provide insight into the performance of such systems.

PCOI: Packet Classification‐Based Optical Interconnect for Data Centre Networks

To support cloud services, Data Centre Networks (DCNs) are constructed to have many servers and network devices, thus increasing the routing complexity and energy consumption of the DCN. The introduction of optical technology in DCNs gives several benefits related to routing control and energy efficiency. This paper presents a novel Packet Classification based Optical interconnect (PCOI) architecture for DCN which simplifies the routing process by classifying the packet at the sender rack and reduces energy consumption by utilizing the passive optical components. This architecture brings some key benefits to optical interconnects in DCNs which include (i) routing simplicity, (ii) reduced energy consumption, (iii) scalability to large port count, (iv) packet loss avoidance, and (v) all-to-one communication support. The packets are classified based on destination rack and are arranged in the input queues. This paper presents the input and output queuing analysis of the PCOI architecture in terms of mathematical analysis, the TCP simulation in NS2, and the physical layer analysis by conducting simulation in OptiSystem. The packet loss in the PCOI has been avoided by adopting the input and output queuing model. The output queue of PCOI architecture represents an M/D/32 queue. The simulation results show that PCOI achieved a significant improvement in terms of throughput and low end-to-end delay. The eye-diagram results show that a good quality optical signal is received at the output, showing a very low Bit Error Rate (BER).

Analysis of bulk queue with additional optional service, vacation and unreliable server

The present investigation deals with the performance analysis of group input queueing system with unreliable server. The server is capable of rendering essential as well as optional services. After getting essential service, the customer may choose any one of the available optional services if required. The server has choice either to avail the vacation for the short period after completion of the service or may continue to provide the service to other customers. The server may fail at any instant of the essential/optional service and undergoes repair immediately. The queueing model is developed by introducing the supplementary variables corresponding to elapsed setup time, service time, and repair time and vacation duration for obtaining the queue size distribution. The maximum entropy principle is employed to determine the approximate results of the system state probabilities and the waiting time of the customers in the queue. The numerical simulation and sensitivity analysis are performed by taking the numerical illustration to study the effect of system parameters on the various performance measures and cost function.

ControCity: An Autonomous Approach for Controlling Elasticity Using Buffer Management in Cloud Computing Environment

Cloud computing has been one of the most popular distributed computing paradigms. Elasticity is a crucial feature that distinguishes cloud computing from other distributed computing models. It considers the resource provisioning and allocation processes can be implemented automatically and dynamically. Elasticity feature allows cloud platforms to handle different loads efficiently without disrupting the normal behavior of the application. Therefore, providing a resource elasticity analytical model can play a significant role in cloud resource management. This paper presents Controlling Elasticity (ControCity) framework for controlling resources elasticity through using “buffer management ” and “elasticity management ”. In the proposed framework, there are two essential components called buffer manager and elasticity manager in the application layer and middleware layer, respectively. The buffer management controls the input queue of the user's request and the elasticity management controls the elasticity of the cloud platform using learning automata technique. In the application layer, applications are received by cloud applications and, then, placed in the control of the buffer. Buffer manager controls the queue of requests, and elasticity manager of the middleware layer using the learning automata provides a solution for controlling the elasticity of the cloud platform. The experimental results indicate that the ControCity reduces the response time by up to 3.7%, and increases the resource utilization and elasticity by up to 8.4% and 5.4%, respectively, compared with the other approaches.

Qualidade de serviços em eventos: aplicação do TOURQUAL na 16ª Fenaostra – Florianópolis - Brasil

A percepção de qualidade por visitantes pode ser considerada o início de um ciclo de satisfação ou gestão da reputação e imagem e consequente desenvolvimento do serviço. No turismo, tal fato se intensifica por se tratar de um serviço altamente experiencial. A partir disso, esta pesquisa objetiva verificar a qualidade percebida por consumidores na 16º Fenaostra, com o intuito de auxiliar a gestão do evento na melhoria dos serviços oferecidos. Para tanto, foi realizada uma pesquisa descritiva, quantitativa, do tipo de campo. A amostra foi composta por 1.052 visitantes. O instrumento de coleta de dados foi o questionário baseado no protocolo TOURQUAL©. Os dados foram coletados nos cinco dias de festa (16 a 20 de setembro de 2015) na praça de alimentação do evento. Os principais resultados indicam que a qualidade percebida é boa, entretanto, a gestão deve se atentar aos indicadores de: localização, estacionamento e acesso; acessibilidade para pessoas com deficiências; filas de entrada, bares, restaurantes e banheiros; som e acústica; níveis de preço; e tecnologia disponibilizada no evento.

An Accurate and Efficient Modeling Framework for the Performance Evaluation of DPDK-Based Virtual Switches

Data plane development kit (DPDK) works as a specialized library that enables virtual switches to accelerate the processing of incoming packets by, among other things, balancing the incoming flow of packets over all the CPU cores and processing packets by batches to make a better use of the CPU cache. Although DPDK has become a de facto standard, the performance modeling of a DPDK-based vSwitch remains a challenging problem. In this paper, we present an analytical queueing model to evaluate the performance of a DPDK-based vSwitch. Such a virtual equipment is represented by a complex polling system in which packets are processed by batches, i.e., a given CPU core processes several packets of one of its attached input queues before switching to the next one. To reduce the complexity of the associated model, we develop a general framework that consists in decoupling the polling system into several queueing subsystems, each one corresponding to a given CPU core. We resort to servers with vacation to capture the interactions between subsystems. Our proposed solution is conceptually simple, easy to implement and computationally efficient. Tens of comparisons against a discrete-event simulator show that our models typically deliver accurate estimates of the performance parameters of interest (e.g., attained throughput, packet latency or loss rate). We illustrate how our models can help in determining an adequate setting of the vSwitch parameters using several real-life case studies.

Birkhoff-Von Neumann Switch Based on Greedy Scheduling

It is important to develop high performance packet switches that are highly scalable. Among the popular solutions are input queued (IQ) switches and load balanced Birkhoff-von Neumann (LB-BvN) switches. However, both solutions have their drawbacks. Switch configuration pattern in IQ switches is random which can limit the supported port speed. On the other hand, LB-BvN switches require two switching stages which increase the overall cost. Also, some LB-BvN solutions suffer from the packet out of sequence problem. In this paper, we propose a novel packet switch architecture that combines the best properties of the IQ and LB-BvN switches and eliminates their drawbacks.

Stationary Analysis and Optimal Control Under Multiple Working Vacation Policy in a GI/M(a,b)/1 Queue

This paper considers an infinite buffer renewal input queue with multiple working vacation policy wherein customers are served by a single server according to general bulk service (a, b)-rule (1 ≤ a ≤ b). If the number of waiting customers in the system at a service completion epoch (during a normal busy period) is lower than ‘a’, then the server starts a vacation. During a vacation if the number of waiting customers reaches the minimum threshold size ‘a’, then the server starts serving this batch with a lower rate than that of the normal busy period. After completion of a batch service during working vacation, if the server finds less than ‘a’ customers accumulated in the system, then the server takes another vacation, otherwise the server continues to serve the available batch with that lower rate. The maximum allowed size of a batch in service is ‘b’. The authors derive both queue-length and system-length distributions at pre-arrival epoch using both embedded Markov chain approach and the roots method. The arbitrary epoch probabilities are obtained using the classical argument based on renewal theory. Several performance measures like average queue and system-length, mean waiting-time, cost and profit optimization are studied and numerically computed.

The impact of processing order on performance: A taxonomy of semi-FIFO policies

Modern network processors increasingly deal with packets that require heterogeneous processing. We consider a bounded size input queue buffer where each packet requires several rounds of processing before transmission. Usually the transmission order of packets is induced by processing order, but processing order can have significant impact on the performance of buffer management policies even if the transmission order is fixed. We introduce the class of Semi-FIFO policies that decouple processing order from transmission order, restricting the latter to First-In-First-Out (FIFO). We build a taxonomy of Semi-FIFO policies and provide worst case guarantees for different processing orders. We consider various special cases and properties of Semi-FIFO policies: greedy, work-conserving, lazy, and push-out policies, and show how these properties affect performance. We generalize our results to additional constraints related to copying cost and conduct a comprehensive simulation study that validates our results.

Non‐blocking frame based multicast scheduler for IQ switches

It has been shown that input queued (IQ) switches have throughput limitations when loaded with multicast traffic. However, if circulation of packets is allowed, the IQ switches can be non-blocking for any admissible multicast traffic scenario using only a speedup of two. The non-blocking frame based algorithm for scheduling the multicast traffic is proposed.

Adaptive Q-aware Scheduling Algorithm for Multi-Service Flows in 802.16j Networks

The IEEE 802.16j standard defines Mobile Multi-hop Relay Wireless Cellular Networks. Introduction of Relays in WiMAX networks pose new challenges along with the advantages of High Throughput and Improved Coverage Area. Thus Scheduling plays a crucial role in Mobile Multihop Relay(MMR) Wireless Networks. The Queue aware scheduling algorithm [1] maximizes the throughput by considering Queues at Base Station(BS) and Relay Station(RS) as well along with Concurrent Transmission Technique. In Queue aware scheduling, as all the arrived packets are queued up in FCFS manner, the high priority packets are obviously delayed. In this paper, QOS guarantee is incorporated by considering multiple Queues for different service flows at Base Station for Queue aware scheduling algorithm. Real Time Adaptive Scheme (RTAS) [2] is modified to improve throughput and used for picking the packets from service class sub queues(SCSQ) to include them in BS input queue. The results show that high priority packets are given proper importance while considering low priority packets as well. Throughput is also increased because of Modified RTAS and Concurrent Transmission Technique of Queue aware scheduling. General Terms WiMAX, Scheduling, Algorithm, Throughput, Queue, Packet

Simple Countermeasures to Mitigate the Effect of Pollution Attack in Network Coding-Based Peer-to-Peer Live Streaming

Network coding based peer-to-peer streaming represents an effective solution to aggregate user capacities and to increase system throughput in live multimedia streaming. Nonetheless, such systems are vulnerable to pollution attacks where a handful of malicious peers can disrupt the communication by transmitting just a few bogus packets which are then recombined and relayed by unaware honest nodes, further spreading the pollution over the network. Whereas previous research focused on malicious nodes identification schemes and pollution-resilient coding, in this paper we show pollution countermeasures which make a standard network coding scheme resilient to pollution attacks. Thanks to a simple yet effective analytical model of a reference node collecting packets by malicious and honest neighbors, we demonstrate that i) packets received earlier are less likely to be polluted and ii) short generations increase the likelihood to recover a clean generation. Therefore, we propose a recombination scheme where nodes draw packets to be recombined according to their age in the input queue, paired with a decoding scheme able to detect the reception of polluted packets early in the decoding process and short generations. The effectiveness of our approach is experimentally evaluated in a real system we developed and deployed on hundreds to thousands peers. Experimental evidence shows that, thanks to our simple countermeasures, the effect of a pollution attack is almost canceled and the video quality experienced by the peers is comparable to pre-attack levels.

A hybrid congestion control algorithm for broadcast-based architectures with multiple input queues

The main purpose of this paper is to propose a hybrid congestion control algorithm to prevent congestion in 2-D broadcast-based multiprocessor architectures with multiple input queues. Our algorith...

On renewal input state dependent working vacations queue with impatient customers

This paper studies the effect of balking and reneging in a finite buffer renewal input queue with multiple working vacations. Arriving customers balk with a probability and renege according to exponential distribution. As soon as the system becomes empty, the server leaves for a working vacation. During working vacations the server works at a different rate rather than completely stopping service. Service times during a service period, during a working vacation period and vacation times are assumed to be exponentially distributed with state dependent rates. Employing the supplementary variable and recursive techniques, the steady-state system length distributions at pre-arrival and arbitrary epochs have been derived. Some performance measures of the model and cost analysis through simulated annealing have been discussed. Finally, sensitivity analysis is carried out through some numerical experiments.