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    FWM-based SAC label recognition for optical packet switched networks

    , Article 2013 IEEE Photonics Conference, IPC 2013 ; 2013 , Pages 519-520 ; 9781457715075 (ISBN) Nezamalhosseini, S. A ; Dizaji, M. R ; Fouli, K ; Chen, L. R ; Marvasti, F ; Sharif University of Technology
    2013
    Abstract
    We propose a flexible four-wave mixing-based label recognition technique for low-weight spectral amplitude codes in optical packet-switched networks. We experimentally demonstrate label recognition, packet switching, and error-free transmission  

    A method for performance analysis of earliest-deadline-first scheduling policy

    , Article 2004 International Conference on Dependable Systems and Networks, Florence, 28 June 2004 through 1 July 2004 ; 2004 , Pages 826-834 Kargahi, M ; Movaghar, A ; Sharif University of Technology
    IEEE Computer Society  2004
    Abstract
    This paper introduces an analytical method for approximating the fraction of jobs that miss their deadlines in a real-time system when earliest-deadline-first scheduling policy (EDF) is used. In the system, jobs either all have deadlines until the beginning of service or deadlines until the end of service. In the former case, EDF is known to be optimal and, in the latter case, it will be optimal if preemption is allowed. In both cases, the system is modeled by an M/M/1/EDF+M queue, i.e., a single server queue with Poisson arrival, and service times and customer impatience, which are exponentially distributed. The optimality property of EDF is used for the estimation of a key parameter, γn... 

    LPRE: Lost speech packet recovery withenhancement

    , Article 2007 IEEE International Conference on Communications, ICC'07, Glasgow, Scotland, 24 June 2007 through 28 June 2007 ; August , 2007 , Pages 1778-1783 ; 05361486 (ISSN); 1424403537 (ISBN); 9781424403530 (ISBN) Ajorloo, H ; Manzuri Shalmani, M. T ; Sharif University of Technology
    2007
    Abstract
    In the internet telephony, loss of IP packets causes instantaneous discontinuities in the received speech. In this paper, we have focused on finding an error resilient method for this problem. Our proposed method creates artificial correlation between speech samples that pre-distorts the speech signal. The receiver uses this correlation to reconstruct the lost speech packets. An appropriate speech enhancement technique is designed for the reduction of the processing error in the recovered speech caused by the speech codecs. The SegSNR results show the superiority of our proposed speech enhancement method over a recently proposed one. © 2007 IEEE  

    Overhead-free polymorphism in network-on-chip implementation of object-oriented models

    , Article Proceedings - Design, Automation and Test in Europe Conference and Exhibition, DATE 04, Paris, 16 February 2004 through 20 February 2004 ; Volume 2 , 2004 , Pages 1380-1381 ; 0769520855 (ISBN); 9780769520858 (ISBN) Goudarzi, M ; Hessabi, S ; Mycroft, A ; Sharif University of Technology
    2004
    Abstract
    We unify virtual-method despatch (polymorphism implementation) and network packet-routing operations; virtual-method calls correspond to network packets, and network addresses are allocated such that routing the packet corresponds to dispatching the call. As the run-time routing structure is inherent in Network-on-Chip platforms, this unification implements polymorphism/or free.1  

    Improving the Performance and Power Consumption of on-Chip Network Using Hybrid Switching

    , M.Sc. Thesis Sharif University of Technology Teimouri, Nasibeh (Author) ; Sarbazi Azad, Hamid (Supervisor)
    Abstract
    Switching as one of important characteristics of on-chip network affects on power consumption and performance. In general there are two switching methods as circuit-switching and packet-switching. Hybrid switching includes both switching to have both resource utilization and scalability of packet switching and low power consumption and improved latency of circuit switching. Also topology is another network attribute that greatly affects the power, performance, cost, and design time/effort of NoCs. In this thesis, we propose a novel NoC architecture which holds both fixed connections between adjacent nodes and long connections virtually connecting non-adjacent nodes. Our proposed NoC... 

    Power and performance efficient partial circuits in packet-switched networks-on-chip

    , Article Proceedings of the 2013 21st Euromicro International Conference on Parallel, Distributed, and Network-Based Processing, PDP 2013 ; 27 February - 1 March , 2013 , pp. 509-513 ; Print ISBN: 9781467353212 Teimouri, N ; Modarressi, M ; Sarbazi-Azad, H ; Sharif University of Technology
    Abstract
    In this paper, we propose a hybrid packet-circuit switching for networks-on-chip to benefit from the advantages of both switching mechanisms. Integrating circuit and packet switching into a single NoC is achieved by partitioning the link bandwidth and router data-path and control-path elements into two parts and allocating each part to one of the switching methods. In this NoC, during injection in the source node, packets are initially forwarded on the packet-switched sub-network, but keep requesting a circuit towards the destination node. The circuit-switched part, at each cycle, collects the circuit construction requests, performs arbitration among the conflicting requests, and constructs... 

    Time-scalable mapping for circuit-switched GALS chip multiprocessor platforms

    , Article IEEE Transactions on Computer-Aided Design of Integrated Circuits and Systems ; Vol. 33, issue. 5 , May , 2014 , p. 752-762 Foroozannejad, M. H ; Hashemi, M ; Mahini, A ; Baas, B. M ; Ghiasi, S ; Sharif University of Technology
    Abstract
    We study the problem of mapping concurrent tasks of an application to cores of a chip multiprocessor that utilize circuit-switched interconnect and global asynchronous local synchronous (GALS) clocking domains. We develop a configurable algorithm that naturally handles a number of practical requirements, such as architectural features of the target platform, core failures, and hardware accelerators, and in addition, is scalable to a large number of tasks and cores. Experiments with several real life applications show that our algorithm outperforms manual mapping, integer linear programming-based mapping after ten days of solver run time, and a recent packet-switched network on chip-based... 

    Power and performance efficient partial circuits in packet-switched networks-on-chip

    , Article Proceedings of the 2013 21st Euromicro International Conference on Parallel, Distributed, and Network-Based Processing, PDP 2013 ; February , 2013 , Pages 509-513 ; 9780769549392 (ISBN) Teimouri, N ; Modarressi, M ; Sarbazi Azad, H ; Sharif University of Technology
    2013
    Abstract
    In this paper, we propose a hybrid packet-circuit switching for networks-on-chip to benefit from the advantages of both switching mechanisms. Integrating circuit and packet switching into a single NoC is achieved by partitioning the link bandwidth and router data-path and control-path elements into two parts and allocating each part to one of the switching methods. In this NoC, during injection in the source node, packets are initially forwarded on the packet-switched sub-network, but keep requesting a circuit towards the destination node. The circuit-switched part, at each cycle, collects the circuit construction requests, performs arbitration among the conflicting requests, and constructs... 

    Performance analysis of slotted ALOHA random access Packet-Switching optical CDMA networks using generalized optical orthogonal codes and M-ary overlapping PPM signaling

    , Article Journal of Optical Communications and Networking ; Volume 3, Issue 7, Article number 5910463 , July , 2011 , Pages 568-576 Shoaie, M. A. (Mohammad A.) ; Khazrae, S. (Simin) ; Pakravan, M. R. (Mohammad Reza) ; Sharif University of Technology
    Abstract
    In this paper we study slotted ALOHA random access optical code division multiple access packet-switching networks with a chip-level receiver structure. We use generalized optical orthogonal codes (GOOCs) and the overlapping pulse position modulation (OPPM) signaling technique to improve system performance. The impact of physical layer parameters such as the GOOC cross-correlation value and the OPPM overlapping index on key performance benchmarks such as network throughput and delay are analyzed. We also study the stability of the network based on the number of backlogged users, using the expected state drift. It has been shown that using GOOC instead of strict optical orthogonal codes... 

    Virtual optical buffers: a novel interpretation of OCDMA in packet switch networks [electronic resource]

    , Article Journal of Lightwave Technology ; 2012, Volume 30, Issue 18, P. 2964-2975 Kazemi, R. (Reza) ; Rashidinejad, A. (Amir) ; Nashtaali, D. (Damoun) ; Salehi, J. A ; Sharif University of Technology
    Abstract
    Among all proposed structures for optical networks, the optical packet switching (OPS) scheme, due to its practical implementation of IPs in an optical configuration and the consequent advantages, is a prizeworthy candidate for being employed in metropolitan area network and local area network communication levels. One of the few problems frequently met using the OPS structure in the fiber-optics realm is the lack of optical buffers, thus deteriorating the system's flexibility and quality of service. For example, optical label switching networks that have been developed recently based on the generalized multiprotocol label switching protocol, profoundly suffer from this setback which is... 

    Virtual optical buffers: A novel interpretation of OCDMA in packet switch networks

    , Article Journal of Lightwave Technology ; Volume 30, Issue 18 , July , 2012 , Pages 2964-2975 ; 07338724 (ISSN) Kazemi, R ; Rashidinejad, A ; Nashtaali, D ; Salehi, J. A ; Sharif University of Technology
    IEEE  2012
    Abstract
    Among all proposed structures for optical networks, the optical packet switching (OPS) scheme, due to its practical implementation of IPs in an optical configuration and the consequent advantages, is a prizeworthy candidate for being employed in metropolitan area network and local area network communication levels. One of the few problems frequently met using the OPS structure in the fiber-optics realm is the lack of optical buffers, thus deteriorating the system's flexibility and quality of service. For example, optical label switching networks that have been developed recently based on the generalized multiprotocol label switching protocol, profoundly suffer from this setback which is... 

    Performance and power efficient on-chip communication using adaptive virtual point-to-point connections

    , Article 2009 3rd ACM/IEEE International Symposium on Networks-on-Chip, NoCS 2009, San Diego, CA, 10 May 2009 through 13 May 2009 ; 2009 , Pages 203-212 ; 9781424441433 (ISBN) Modarressi, M ; Sarbazi Azad, H ; Tavakkol, A ; IEEE Circuits and Systems Society; Council for EDA; ACM Special Interest Group on Computer Architecture (SIGARCH); ACM Special Interest Group on Embedded Systems (SIGBED); ACM Special Interest Group on Design Automation (SIGDA); Silistix, Inc ; Sharif University of Technology
    2009
    Abstract
    In this paper, we propose a packet-switched network-on-chip (NoC) architecture which can provide a number of low-power, low-latency virtual point-to-point connections for communication flows. The work aims to improve the power and performance metrics of packet-switched NoC architectures and benefits from the power and resource utilization advantages of NoCs and superior communication performance of point-to-point dedicated links. The virtual point-to-point connections are set up by bypassing the entire router pipeline stages of the intermediate nodes. This work addresses constructing the virtual point-to-point connections at run-time using a light-weight setup network. It involves monitoring... 

    Performance comparison of simple regular meshes and their k-ary n-cube variants in optical networks

    , Article 13th International Computer Society of Iran Computer Conference on Advances in Computer Science and Engineering, CSICC 2008, Kish Island, 9 March 2008 through 11 March 2008 ; Volume 6 CCIS , 2008 , Pages 543-550 ; 18650929 (ISSN); 3540899847 (ISBN); 9783540899846 (ISBN) Kianrad, A ; Dadlani, A ; Rajabi, A ; Aghajani, M. R ; Khonsari, A ; Seyed Razi, H ; Sharif University of Technology
    2008
    Abstract
    The need for supporting the ever-growing number of multi-computers in the contemporary Internet has persuaded researches worldwide to search for suitable underlying network topologies with desirable properties. Even in the presence of speedy optical technologies, the arrangement of nodes in a network can be highly influential. Among all the topologies investigated so far, k -ary n-cubes have been reported to be widely adopted in the literature. But in hybrid networks, where the network is composed of a mixture of different types of topologies, the type and size of k-ary n-cubes can greatly affect the performance factor of the network. In this paper, we study and compare the performance... 

    Novel FWM-based spectral amplitude code label recognition for optical packet-switched networks

    , Article IEEE Photonics Journal ; Volume 5, Issue 4 , 2013 ; 19430655 (ISSN) Nezamalhosseini, S. A ; Rezagholipour Dizaji, M ; Fouli, K ; Chen, L.R ; Marvasti, F ; Sharif University of Technology
    2013
    Abstract
    We propose and demonstrate a novel architecture for four-wave mixing (FWM)-based recognition of spectral amplitude code (SAC) labels in optical packet-switched networks. With a proper code design, a unique FWM idler for each SAC label, referred to as a label identifier (LI), is generated in a nonlinear medium. A serial array of fiber Bragg gratings is then used to reflect the LI wavelengths. Each LI is associated with a unique amount of delay between two optical signals received at two photodiodes (PDs). Label recognition is then achieved by measuring this unique time delay (referred to as the characteristic delay). The main advantages of the proposed method include the following: no... 

    Improving the performance of packet-switched networks-on-chip by SDM-based adaptive shortcut paths

    , Article Integration, the VLSI Journal ; Volume 50 , 2015 , Pages 193-204 ; 01679260 (ISSN) Modarressi, M ; Teimouri, N ; Sarbazi Azad, H ; Sharif University of Technology
    Elsevier  2015
    Abstract
    Abstract Reducing the NoC power is critical for scaling up the number of nodes in future many-core systems. Most NoC designs adopt packet-switching to benefit from its high throughput and excellent scalability. These benefits, however, come at the price of the power consumption and latency overheads of routers. Circuit-switching, on the other hand, enjoys a significant reduction in power and latency of communication by directing data over pre-established circuits, but the relatively large circuit setup time and low resource utilization of this switching mechanism is often prohibitive. In this paper, we address one of the major problems of circuit-switching, i.e. the circuit setup time... 

    An upper bound on the throughput for myopic policy in multi-channel opportunistic access

    , Article 2010 5th International Symposium on Telecommunications, IST 2010, 4 December 2010 through 6 December 2010 ; 2010 , Pages 29-32 ; 9781424481835 (ISBN) Salehkaleybar, S ; Majd, S. A ; Pakravan, M. R ; Sharif University of Technology
    Abstract
    We study myopic sensing policy for an opportunistic communication system in which the states of channels evolve as independent Markov chains. A Secondary User (SU) takes one channel to sense and access in each time slot by myopic sensing policy. In the myopic policy, SU ignores the impact of the current action on the future decisions and tries to maximize the expected immediate reward. We propose an upper bound on the throughput achieved by the myopic sensing policy for general case in which channels have different Markov models. In particular, the proposed bound is compared with the Zhao et. al's upper bound (UZhao) for the channels with identical models. We prove that there are conditions... 

    All-optical multiservice path switching in optical code switched GMPLS core networks

    , Article Journal of Lightwave Technology ; Volume 27, Issue 12 , 2009 , Pages 2001-2012 ; 07338724 (ISSN) Beyranvand, H ; Salehi, J.A ; Sharif University of Technology
    2009
    Abstract
    In this paper, we present a novel labeling scheme to provide multiservice path switching in a generalized multiprotocol label switching (GMPLS) network. The idea is based on optical code division multiplexing (OCDM) scheme in GMPLS network using multilength variable-weight optical orthogonal codes (MLVW-OOC) as signature sequences. The router architecture of the proposed multiservice GMPLS network is also presented. To provide a requested service, the length and the weight of codes are designed based on the service characteristics. Furthermore, to guarantee the desired service, we propose to limit the number of connections based on the activity coefficient of the connected paths. In order to... 

    Virtual point-to-point links in packet-switched NoCs

    , Article IEEE Computer Society Annual Symposium on VLSI: Trends in VLSI Technology and Design, ISVLSI 2008, Montpellier, 7 April 2008 through 9 April 2008 ; 2008 , Pages 433-436 ; 9780769531700 (ISBN) Modarressi, M ; Sarbazi Azad, H ; Tavakkol, A ; Sharif University of Technology
    2008
    Abstract
    A method to setup virtual point-to-point links between the cores of a packet-switched network-on-chip is presented in this paper which aims at reducing the NoC power consumption and delay. The router architecture proposed in this paper provides packet-switching, as well as a number of virtual point-to-point, or VIP (VIrtual Point-to-point) for short, connections. This is achieved by designating one virtual channel at each physical channel of a router to bypass the router pipeline. The mapping and routing algorithm exploits these virtual channels and tries to virtually connect the source and destination nodes of high-volume communication flows during task-graph mapping and route selection... 

    Efficient optical resource allocation and QoS differentiation in optical burst switching networks utilizing hybrid WDM/OCDM

    , Article Journal of Lightwave Technology ; Volume 30, Issue 15 , 2012 , Pages 2427-2441 ; 07338724 (ISSN) Beyranvand, H ; Salehi, J. A ; Sharif University of Technology
    2012
    Abstract
    In this paper, a QoS differentiation framework is proposed for an optical burst switching (OBS) multiservice network. Furthermore, hybrid wavelength division multiplexing and optical code division multiplexing (WDM/OCDM) scheme is used to mitigate the blocking probability of OBS networks. In our study, the measurement criteria of QoS are the blocking probability, OBS network delay, transmission rate, and OCDM probability of error. In order to increase the bandwidth efficiency and control the multiplexing interference effect of OCDM, an advanced optical resource allocation strategy is introduced. The proposed strategy is also compared with a conventional strategy based on random allocation.... 

    Analysis of power control for indoor optical wireless code-division multiple access networks using on-off keying and binary pulse position modulation

    , Article IET Communications ; Volume 4, Issue 16 , November , 2010 , Pages 1919-1933 ; 17518628 (ISSN) Khazraei, S ; Pakravan, M. R ; Aminzadeh Gohari, A ; Sharif University of Technology
    2010
    Abstract
    Wireless infrared optical code-division multiple access (W-OCDMA) is a new developing technique with many useful applications. Noting the limitation on power consumption and eye-safety requirements, wireless optical systems are power limited. Therefore control and efficient use of optical power is a key issue in analysis and design of these systems. Also, multi-user interference is the major source of impairment in these systems and power control is required to control and reduce this interference. Power control and the inevitable errors in its algorithms play an important role in design and implementation of these systems. In this article the authors study the uplink performance of W-OCDMA...