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The power-saving class of type II (PSC II), a type of sleep mode operations in the IEEE 802.16e standard, is designed to reduce power consumption for a mobile station with unsolicited grant service and real-time variable-rate connections. However, the configuration of fixed-length listening windows in the PSC II incurs unnecessary energy consumption or packet loss for these types of connections. In...
The use of vehicular infrastructure to establish connectivity between isolated stationary Information Relay Sta- tions is an appealing application of Terrestrial Delay-Tolerant Networking. A source opportunistically releases data bundles to vehicles that randomly enter its range. In turn, those vehicles store the received bundles, carry and deliver them to their intended destination. It follows that...
Due to the uncertainty of transmission opportunities between mobile nodes, Delay Tolerant Networks (DTNs) exploits the opportunistic forwarding mechanism. This mechanism requires nodes to forward messages in a cooperative and selfish way. However, in the real word, most of the nodes exhibit selfish behaviors such as individual and social selfishness. At the same time, the energy is usually limited...
FPGA architects typically use experimental techniques to design new architectures. These techniques are time consuming, thus limiting the number of the architectures that can be investigated. Some previous works use analytical models to significantly accelerate the design of a new architecture. To properly capitalize on the benefits of the analytical models, the designers need to have an understanding...
This paper proposes a Markov model for analyzing the performance of periodic broadcast in vehicular ad hoc networks (VANETs). Since there is no packet retransmission in broadcast, we only consider a one-dimensional Markov model. In the proposed model, we assume that the traffic condition is unsaturated and introduce a state to represent the situation when there is no packet waiting for transmission...
Police departments in the United States strive to schedule officers so that a number of benchmarks are met. The police administration is often asked to justify to local governing bodies the size of the police force. To assess the effects of force size and scheduling strategies on the ability to meet the benchmark goals, we develop a discrete-event simulation for the calls for service (CFS). Using...
This paper presents a problem of queueing theoretic performance modeling and analysis of Orthogonal Frequency Division Multiple Access (OFDMA) under broad-band wireless networks. We consider a single-cell WiMAX environment in which the base station allocates subchannels to the subscriber stations in its coverage area. The subchannels allocated to a subscriber station are shared by multiple connections...
The management of supply risks has become a highly critical component of supply chain management. Supply failures effect on the supply chain can be costly and lead to significant customer delivery delays. Inventory management is an important tool to mitigate the risks arising due to these failures. But there has always been a confusion on which inventory method will be best for such situations and...
This paper provides simulation practitioners and consumers with a grounding in how discrete-event simulation software works. Topics include discrete-event systems; entities, resources, control elements and operations; simulation runs; entity states; entity lists; and entity-list management. The implementation of these generic ideas in AutoMod, SLX, and ExtendSim is described. The paper concludes with...
Simulating passenger flows within airports is very important as it can provide an indication of queue lengths, bottlenecks, system capacity and overall level of service. To date, visual simulation tools such as agent-based models have focused on processing formalities such as check-in, and not incorporate discretionary activities such as duty-free shopping. As airport retail contributes greatly to...
An important, but often neglected, part of any sound simulation study is that of modeling each source of system randomness by an appropriate probability distribution. We first give some examples of data sets from real-world simulation studies, which is followed by a discussion of two critical pitfalls in simulation input modeling. The two major methods for modeling a source of randomness when corresponding...
In this paper, we consider a wireless cellular network capable of supporting Machine-to-Machine (M2M) applications. According to the recent IEEE 802.16p proposals, a wireless M2M device may act as an aggregation point and communicate data packets on behalf of the other M2M devices, which may lack a cellular interface or have a poor communication link to the network. We propose a client relay scheme...
Call admission control (CAC) functionality is a critical requirement for guarantee the desired quality of service (QoS) for voice calls in IP-based wireless networks. In this paper, three different CAC strategies for voice over IP (VoIP) traffic over wireless access networks with packet buffering are mathematically analyzed through a joint call and packet level discrete time teletraffic model. The...
We develop a Markov model for a TCP CUBIC connection. Next we use it to obtain approximate expressions for throughput when there may be queuing in the network. Finally we provide the throughputs different TCP CUBIC and TCP NewReno connections obtain while sharing a channel when they may have different round trip delays and packet loss probabilities.
In paper, the time domain waveform is approximated for calculation of delay time, peak time, settling time, damping ratio and natural frequency for a second order RLCG interconnect model. It can also be used for multiple interconnect systems but higher order systems are ignored to avoid complexity. The model is applied to a single resistance-inductance-capacitance-conductance model which can also...
Most cluster tool scheduling studies assume identical access times between chambers, or do not discuss impact of the access times although the optimal scheduling rule and the cycle time can depend on the access times or physical configuration of parallel chambers. We examine cyclic scheduling problems for cluster tools that have non-identical access times. We first develop Petri net models of tool...
North American freight railroads are expected to experience increasing capacity constraints across their networks. To help plan for this increased traffic, railroads use simulation software to analyze the benefits of capacity expansion projects. Delay increases exponentially with volume as individual lines and the network become more saturated with traffic. Simultaneous operation of heterogeneous...
In the recent years, the use of hybrid automata has achieved a great success in the early design and verification of embedded systems. Once the hybrid model defined by means of hybrid automata has been verified, it would be valuable to reuse it to refine a corresponding hardware/software implementation. Some works have proposed the automatic refinement of hybrid automata specifications into HW/SW...
VoIP service demands strong QoS support for enhanced call quality and increased user satisfaction. Deploying VoIP in opportunistic communication models like cognitive radio requires thorough analysis of the factors involved in design and implementation. The objective of this paper is to implement VoIP successfully over a cognitive radio network and maintain the call quality at an acceptable limit...
In broadband wireless access network, continuous high speed data communication can be provided to mobile subscribers by well designed mobility management, where handover is a key element in maintaining air link to base station even in high velocity. When a mobile station changes its geographical position, it may also need to change its attachment point in the network in order to retain the quality...
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