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Channel aggregation (CA) techniques can offer flexible channel allocation and improve overall system performance in multi-channel cognitive radio networks (CRNs). Although many CA techniques have been proposed and studied, the impact of guard-band on CA for channel access has not been addressed in-depth. In this paper, we study the guard-band allocation mechanisms in discontinuous-orthogonal frequency...
Connected vehicles are promoted with the use of different communication technologies for diverse applications. A host with multiple network devices is referred to as a multi-homed node. Stream Control Transmission Protocol (SCTP) is an IETF standard which supports multi-homing. However, original SCTP multi-homing functionality is only used when the primary address becomes unavailable. This paper presents...
Several redundancy and recovery schemes have been developed to enhance the reliability of storage systems. The effectiveness of these schemes has predominately been evaluated based on the mean time to data loss (MTTDL) metric, which has been proven useful for assessing tradeoffs, for comparing schemes, and for estimating the effect of the various parameters on system reliability. In the context of...
More and more researches have demonstrated the benefits of cognitive radio technology in improving flexibility and efficiency of spectrum utilization. In order to encourage primary users (PUs) to share their idle spectrum resources with secondary users (SUs), spectrum trading frameworks are developed. In this paper, the investment problem of spectrum service provider (SSP) is considered which obtains...
Peer-to-Peer (P2P) networks are distributed systems where no central authority rules the behavior of the individual peers. These systems rely on the voluntary participation of the peers to help each other and reduce congestion at the data servers. BitTorrent is a popular file-sharing P2P application originally designed for non real-time data. With minor modifications concerning the peer selection...
In this paper, an innovative TCP flow control method is presented. An algorithm is proposed that combines RED (Random Early Detection) with TCP window adjustment to improve the network performance. Leveraging the advantages of RED and window adjustment, the algorithm demonstrates fast response and superior stability with controlled packet dropping rate, while still fully utilizing the network resource...
This paper presents an analytical model to evaluate the performance of an optical wavelength-routed network for inter- and intra-data center interconnection, designed to work according to the cloud computing paradigm. Such a scenario calls for anycast routing of service requests to find a network path that best suits both connectivity and IT resource requirements. The analytical model is based on...
Peer to peer file exchange systems such as BitTorrent are changing the way in which content is distributed in the Internet. Service capacity for a certain content adjusts dynamically as a function of peer population, thus achieving scalability. This dynamic behavior has been the subject of recent analytical studies. In this paper, we propose a partial differential equation model for BitTorrent-like...
Connection admission control (CAC) is an important element for quality of service (QoS) provisioning in wireless networks, such as IEEE 802.16 standard, which is also known as worldwide interoperability for microwave access (WiMAX). While the standard defines PHY and MAC requirements, CAC is left to the vendors to design and implement for service differentiation and QoS support. In this paper a Quadra-Threshold...
The heterogeneous nature of Peer-to-Peer (P2P) networks can be exploited to optimize a wide range of applications. But this requires an accurate characterization of peer heterogeneity, which is difficult due to huge population and disparate properties of individuals. To overcome this barrier, we conduct a thorough inspection of peer heterogeneity in terms of individual churn and resource capacity...
We present a new loss model for the call-level analysis of a single link, which accommodates calls of different service-classes with elastic bandwidth requirements. Calls arrive in the link according to a Batch Poisson process, a process that can be used to model traffic, which is more 'peaked' and 'bursty' than the Poisson process. The available link bandwidth is shared to calls according to the...
Certified Wireless Universal Serial Bus (WUSB) is one of different varieties of Wimedia standard for distributed medium access control (MAC) protocol for ultra wide band (UWB) communications in the wireless personal area network (WPAN). To the best of our knowledge, no technical contributions exist in the open literature at present simulating WUSB and its performance. In this paper, we investigated...
In this paper we present a new admission control (AC) for IEEE 802.16. The AC aims to accept new connections according to the negotiated service class (UGS, rtPS, nrTPS, and BE). To achieve this goal we propose to use the token bucket concept that provide QoS for real time traffics without degrading the QoS of non real time traffic. To show the benefit of the proposed AC, an analytical model based...
Most of current cellular networks are designed for transmitting packet data and voice services. Several types of traffic such as voice, WAP, Web, FTP and E-mail with different ON/OFF distributions have to be supported by these networks. It is therefore important to know their performance in such systems. In this paper we develop a performance analytical model which takes into account the different...
The base station in IEEE 802.16, or WiMAX, networks allocates contention-based time slots for the mobile stations to transmit their requests for additional bandwidth. Using a technique called subchannelization, multiple concurrent transmissions by mobile stations can be admitted by the base station during the same contention period. For transmission during this period, each station employs a contention-resolution...
The WiMAX channel access is controlled by one of the several available Medium Access Control (MAC) procedures. This paper studies the contention-based bandwidth request procedure based on our original analytical model, facilitated by numerical analysis and simulation. We optimize the key parameters of the contention procedure in order to minimize the average bandwidth access delay, thus ensuring the...
For peer-to-peer (P2P) networks continually to flourish, QoS provision is critical. However, the P2P networks are notoriously dynamic and heterogeneous. As a result, QoS provision in P2P networks is a challenging task with nodes of the varying and intermittent throughput. This raises a fundamental problem: is stable and delicate QoS provision achievable in the highly dynamic and heterogeneous P2P...
A challenging issue in performance evaluation of parallel storage systems through trace-driven simulation is to accurately characterize and emulate I/O behaviors in real applications. The correlation study of inter-arrival times between I/O requests, with an emphasis on I/O-intensive scientific applications, shows the necessity to further study the self-similarity of parallel I/O arrivals. This paper...
Peer-to-Peer (P2P) networks are distributed systems where no central authority rules the behavior of the individual peers. A typical application is the sharing of files of some class (movies, music, ...), our object of interest here. These systems relay on the voluntary participation of the peers to help each other. However, it is not uncommon to find users that have initiated a file transfer and...
Future access networks will have to meet the ever increasing demand for capacity. Optical access systems are now considered as a viable alternative solution to the xDSL technologies for delivering future integrated broadband services. Nowadays, passive optical networks are the most promising and cost-effective class of fiber access systems. In this paper we develop teletraffic loss models for calculating...
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