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An analytical framework for computation of throughput capacity in multi-hop mobile ad hoc networks
, Article 18th Annual IEEE International Symposium on Personal, Indoor and Mobile Radio Communications, PIMRC'07, Athens, 3 September 2007 through 7 September 2007 ; December , 2007 ; 1424411440 (ISBN); 9781424411443 (ISBN) ; Hamdi, M ; Shafiee, K ; Sharif University of Technology
2007
Abstract
In this paper, we propose an analytical framework in order to compute the throughput capacity of a multi-hop ad hoc network with a finite number of mobile wireless nodes. The proposed framework consists of two related queueing networks; a closed BCMP queueing network to represent the mobility model of the wireless nodes and an open BCMP queueing network comprising symmetric M/G/l nodes to represent the multi-hop packet routing process from sources to destinations. In this respect, we consider very simple MAC and routing schemes and then map the related parameters onto several components of the queueing network. By solving the linear traffic equations corresponding to concerned queueing...
Capturing an intruder in product networks
, Article Journal of Parallel and Distributed Computing ; Volume 67, Issue 9 , 2007 , Pages 1018-1028 ; 07437315 (ISSN) ; Sarbazi Azad, H ; Zomaya, A. Y ; Sharif University of Technology
2007
Abstract
In this paper, we propose a solution to the problem of capturing an intruder in a product network. This solution is derived based on the assumption of existing algorithms for basic member graphs of a graph product. In this problem, a team of cleaner agents are responsible for capturing a hostile intruder in the network. While the agents can move in the network one hop at a time, the intruder is assumed to be arbitrarily fast in a way that it can traverse any number of nodes contiguously as far as no agents reside in those nodes. Here, we consider a version of the problem where each agent can replicate new agents. Thus, the algorithm starts with a single agent and new agents are created on...
The impact of stationary nodes on the performance of wireless mobile networks
, Article Third International Conference on Wireless and Mobile Communications 2007, ICWMC '07, Guadeloupe, 4 March 2007 through 9 March 2007 ; 2007 ; 0769527965 (ISBN); 9780769527963 (ISBN) ; Khosravi, A ; Sarbazi Azad, H ; Sharif University of Technology
2007
Abstract
In this paper, impact of the stationary nodes on the link excess life as an important performance parameter of wireless mobile networks is investigated First, a model for the link excess life is introduced. Based on this model, the relation between the probability density function (PDF) of the link excess life and the PDF of relative velocity is explored. In fact, the PDF of relative velocity is divided into three PDFs according to the three categories of links. The effect of each group on the resultant PDF of global link excess life for different percentages of stationary nodes is explored. Moreover, an approximation method defined in our previous work is proposed as a tool to evaluate the...
IPROMISE: Reliable multi-sender algorithm for peer-to-peer networks
, Article 2007 2nd International Conference on Communication System Software and Middleware and Workshops, COMSWARE 2007, Bangalore, 7 January 2007 through 12 January 2007 ; 2007 ; 1424406145 (ISBN); 9781424406142 (ISBN) ; Ronasi, K ; Pakravan, M. R ; Nasiri Avanaki, A ; Sharif University of Technology
2007
Abstract
Due to the constraints of P2P networks (such as bandwidth limitation) multiple senders should be employed for reliable multimedia streaming. This paper introduces a mathematic approach to select a set of senders among all available senders to provide the most reliable stream for the receiver. This selection is based on upload bandwidths and availability of peers as well as bandwidth of links connecting the senders and the receiver. Our method is called IPROMISE as it is an improved version of the PROMISE algorithm. Simulation results demonstrate improved media quality delivered to the receiver, while the complexity of sender selection remains the same. © 2007 IEEE
RAQNet: A topology-aware overlay network
, Article 1st International Conference on Autonomous Infrastructure, Management and Security, AIMS 2007, Oslo, 21 June 2007 through 22 June 2007 ; Volume 4543 LNCS , 2007 , Pages 13-24 ; 03029743 (ISSN); 3540729852 (ISBN); 9783540729853 (ISBN) ; Shahparian, J ; Ghodsi, M ; Sharif University of Technology
Springer Verlag
2007
Abstract
Peer-to-peer overlay networks provide a useful infrastructure for building distributed applications. These networks provide efficient and fault-tolerant routing and object locating within a self-organizing overlay network. This paper presents a multi-dimensional overlay network called RAQNet which is based on RAQ1. RAQ supports exact match queries and range queries over multi-dimensional data efficiently. Moreover, its routing cost does not depend on the dimension of the search space. In RAQNet, we have improved its original routing algorithms and extended it to have topology awareness property. In RAQNet, nodes are connected to each other if their labels are "close" to each other with...
Semantic HyperCup
, Article 39th Annual Hawaii International Conference on System Sciences, HICSS'06, Kauai, HI, 4 January 2006 through 7 January 2006 ; Volume 9 , 2006 , Pages - ; 15301605 (ISSN) ; 0769525075 (ISBN); 9780769525075 (ISBN) ; Habibi, J ; Rahnama, A ; Sharif University of Technology
2006
Abstract
Peer-to-peer networks are beginning to form the infrastructure of future applications. One of the problems with non structured peer-to-peer networks is their scalability limitation. These networks can't contain a large number of nodes because of the large amount of traffic that they have to handle. HyperCup is a structured overlay network that solves the scalability problem for message broadcasts. This overlay broadcasts search queries throughout the entire network and all nodes receive broadcasted messages. In this paper we introduce Semantic HyperCup, an extension of HyperCup which uses semantic data to route messages and reduce overlay network traffic through search queries. © 2006 IEEE
The nonlinear diffusion bandwidth: A simple tool for optimizing dispersion maps
, Article Optical Transmission, Switching, and Subsystems IV, Gwangju, 5 September 2006 through 7 September 2006 ; Volume 6353 I , 2006 ; 0277786X (ISSN) ; 0819464481 (ISBN); 9780819464484 (ISBN) ; Fischer, J. K ; Louchet, H ; Jamshidi, K ; Petermann, K ; Sharif University of Technology
2006
Abstract
The concept of a nonlinear transfer function of a fibre-optic communication link is reviewed. Also an approximation of the nonlinear transfer function is introduced, which allows to define an equivalent single-span model of a dispersion-managed multi-span system. In this paper we will show its limits of validity and try to extent these limits by enhancing the theoretical model. In this respect we will discuss the impact of dispersion precompensation and show the influence of residual dispersion per span, number of spans and local dispersion on transmission systems with on-off keying and differential phase-shift keying modulation formats. This approach allows fast assessment of the...
Performance evaluation of mobile ad hoc networks in the presence of energy-based selfishness
, Article 2006 3rd International Conference on Broadband Communications, Networks and Systems, BROADNETS 2006, San Jose, CA, 1 October 2006 through 5 October 2006 ; 2006 ; 1424404258 (ISBN); 9781424404254 (ISBN) ; Movaghar, A ; Sharif University of Technology
2006
Abstract
Cooperation of nodes for routing and packet forwarding is inevitable in a mobile ad hoc network. Selfishness in such networks is a significant challenge and can cause network performance to noticeably degrade. In this paper, we propose some new selfishness models elicited from psychological behavior of human beings. We also evaluate performance of MANET in the presence of different percentages of selfish nodes that act based on our selfishness models. Results show that energy-based selfishness is a serious problem that could affect performance depends on mobility of nodes, density of network, and time of simulation. This kind of selfishness needs a comprehensive mechanism to cope with and we...
A cutting plane optimization algorithm for intra-cell link adaptation problem
, Article 2005 IEEE 16th International Symposium on Personal, Indoor and Mobile Radio Communications, PIMRC 2005, Berlin, 11 September 2005 through 14 September 2005 ; Volume 3 , 2005 , Pages 1895-1899 ; 3800729091 (ISBN); 9783800729098 (ISBN) ; Yousefi, M. I ; Abolhassani, B ; Sadati, N ; Sharif University of Technology
2005
Abstract
Link adaptation of a wireless cellular network is of much attention due to the desire of maximizing both the a erage lin throughput and co erage reliability, which have conflicting effect on each other. In this paper, the intra-cell lin adaptation problem is formulated as a non-differentiable constrained optimization problem to maximize average link throughput while guaranteeing the best possible coverage reliability. To achieve this, a cutting plane optimization algorithm is employed. The performance of our method: adaptive modulation/coding with power management (AMCWPM) using proposed algorithm is compared with that of an adaptive modulation/coding (AMC) with no power management....
SkipTree: A Scalable range-queryable distributed data structure for multidimensional data
, Article 16th International Symposium on Algorithms and Computation, ISAAC 2005, Hainan, 19 December 2005 through 21 December 2005 ; Volume 3827 LNCS , 2005 , Pages 298-307 ; 03029743 (ISSN); 3540309357 (ISBN); 9783540309352 (ISBN) ; Toossi, M ; Ghodsi, M ; Sharif University of Technology
2005
Abstract
This paper presents the SkipTree, a new balanced, distributed data structure for storing data with multidimensional keys in a peer-to-peer network. The SkipTree supports range queries as well as single point queries which are routed in O(log n) hops. SkipTree is fully decentralized with each node being connected to O(logn) other nodes. The memory usage for maintaining the links at each node is O(log n log log n) on average and O(log2 n) in the worst case. Load balance is also guaranteed to be within a constant factor. © Springer-Verlag Berlin Heidelberg 2005
A simple transport protocol for wireless sensor networks
, Article 2005 Intelligent Sensors, Sensor Networks and Information Processing Conference, Melbourne, 5 December 2005 through 8 December 2005 ; Volume 2005 , 2005 , Pages 127-131 ; 0780393996 (ISBN); 9780780393998 (ISBN) ; Afsari, B ; Shahmansouri, H ; ARC Research Networks on Intelligent Sensors,; Australian Government, Australian Research Council ; Sharif University of Technology
IEEE Computer Society
2005
Abstract
In this paper, a new transport layer method is proposed utilizing a diversity scheme to make an end to end communication reliable and consequently reduce power consumption in large scale sensor networks. Sensor networks are composed of large number of battery powered nodes. Energy consumption is the most important design objective in sensor networks while delay and throughput are taken less into account. Wireless transmission is the other important characteristic of these networks. Small-scale fading decreases wireless communication performance. In a fading channel higher SNRs is needed and consequently more energy is consumed. In addition to error occurred because of poor communication...
A high-throughput low-complexity VLSI architecture for ZF precoding in massive MIMO
, Article IEEE International Workshop on Computer Aided Modeling and Design of Communication Links and Networks, CAMAD, 19 June 2017 through 21 June 2017 ; Volume 2017-June , 2017 ; 23784873 (ISSN) ; 9781509063024 (ISBN) ; Shabany, M ; Nezamalhosseini, S. A ; Emadi, M. J ; Sharif University of Technology
Abstract
In this work we present a high-throughput, low-complexity design for linear precoding in massive Multiple-Input Multiple-Output (MIMO) systems. Large number of Base Station (BS) antennas in massive MIMO at one hand has caused the performance of linear precoders to be near-optimal and at the other hand has increased their complexity due to the need for the inversion of matrices with large dimensions. To avoid this complexity, approximate inversion methods based on Neumann Series have been proposed. However, in this work, we propose an architecture for Zero Forcing (ZF) precoder based on the Neumann Series approximate inversion that further reduces the complexity by replacing matrix-matrix...
Performance analysis of multi-hop underwater wireless optical communication systems
, Article IEEE Photonics Technology Letters ; Volume 29, Issue 5 , 2017 , Pages 462-465 ; 10411135 (ISSN) ; Chizari, A ; Salehi, J. A ; Sharif University of Technology
Abstract
In this letter, we analytically evaluate the end-to-end bit error rate (BER) of point-to-point multi-hop underwater wireless optical communication (UWOC) systems with respect to all degrading effects of the UWOC channel, namely absorption, scattering, and turbulence-induced fading. To do so, we first derive the BER expression of a single-hop UWOC link as the building block for end-to-end BER evaluation. We also apply Gauss-Hermite quadrature formula to obtain the closed-form solution for the system BER in the case of lognormal underwater fading channel. Numerical results demonstrate that multi-hop transmission, by alleviating channel impairments, can significantly improve the system...
Cross-layer optimization of adaptive modulation and coding preserving packet average delay time
, Article 2008 IEEE Global Telecommunications Conference, GLOBECOM 2008, New Orleans, LA, 30 November 2008 through 4 December 2008 ; December , 2008 , Pages 1278-1282 ; 9781424423248 (ISBN) ; Ashtiani, F ; Sharif University of Technology
2008
Abstract
In this paper we introduce a novel cross layer design between MAC and physical layers. Our novel design is based on controlling the adaptive modulation and coding (AMC) transmission mode at the physical layer according to the queue length of finite buffer at the data link layer and each transmission mode of AMC. The aim is optimizing system performance over a wireless link, preserving the important Quality of Service (QoS) parameter, packet average delay time. Analytical expressions such as packet drop probability, channel packet error rate, packet loss rate and packet average delay time are derived both analytically and through simulations according to the system and channel parameters....
Adapting power for BER improvement in wireless channels
, Article 8th ACM Symposium on Modeling, Analysis and Simulation of Wireless and Mobile Systems, Montreal, Que., 10 October 2005 through 13 October 2005 ; Volume 2006 , 2006 , Pages 278-281 ; 1595931880 (ISBN); 9781595931887 (ISBN) ; Pakravan, M. R ; Hossein Khalaj, B ; Sharif University of Technology
2006
Abstract
Adaptive transmission is an effective way to improve the performance of communication links in time-varying channel environments. Former works use this technique to maximize the throughput; but we exploit it to minimize BER in a system with diversity reception. We do so by adapting power in response to the channel variations. We use analytical methods to derive our results. These expressions can be used for any type of channel fading and any modulation scheme. We then apply this method to a special case of 4-QAM over Rayleigh channel with MRC reception. Copyright 2005 ACM
On the optimization of mobile power-controlled cellular networks regarding practical limitations
, Article 2006 American Control Conference, Minneapolis, MN, 14 June 2006 through 16 June 2006 ; Volume 2006 , 2006 , Pages 6103-6107 ; 07431619 (ISSN); 1424402107 (ISBN); 9781424402106 (ISBN) ; Yousefi, M. I ; Sharif University of Technology
2006
Abstract
In this paper, the intra-cell link adaptation problem is formulated as a constrained nonconvex nondifferentiable optimization problem to maximize the average link throughput while guaranteeing the best possible coverage reliability. We proceed to solve the resulted nonsmooth optimization problem using proximal point bundle method known in nondifferentiable optimization context. For this purpose, we first exploit the problem structure and reduce the original large scale optimization problem to a sequence of one-dimensional problems coordinated by a master program using direct primal decomposition technique. Proximal bundle method with aggregation policy is then adopted in master program to...
A loss aware scalable topology for photonic on chip interconnection networks
, Article Journal of Supercomputing ; Vol. 68, Issue. 1 , April , 2014 , pp. 106-135 ; ISSN: 1573-0484 (online) ; Sarbazi Azad, H ; Khademzadeh, A ; Shabani, H ; Niazmand, B ; Sharif University of Technology
Abstract
The demand for robust computation systems has led to the increment of the number of processing cores in current chips. As the number of processing cores increases, current electrical communication means can introduce serious challenges in system performance due to the restrictions in power consumption and communication bandwidth. Contemporary progresses in silicon nano-photonic technology have provided a suitable platform for constructing photonic communication links as an alternative for overcoming such problems. Topology is one of the most significant characteristics of photonic interconnection networks. In this paper, we have introduced a novel topology, aiming to reduce insertion loss in...
An efficient method for identifying IDS agent nodes by discovering compromised nodes in MANET
, Article 2009 International Conference on Computer and Electrical Engineering, ICCEE 2009, 28 December 2009 through 30 December 2009, Dubai ; Volume 1 , 2009 , Pages 625-629 ; 9780769539256 (ISBN) ; Khavasi, A. A ; Movaghar, A ; Sharif University of Technology
Abstract
Intrusion Detection Systems (IDS) for Mobile Ad hoc NETworks (MANETs) are necessary when they are deployed in reality. In This paper, we have presented a combined method of selecting IDS agent nodes in mobile ad hoc networks. Since, the IDS agents in MANET due to more activities need to more battery power. In our method, first, compromised nodes are detected and then the nodes with the highest energy power from among valid nodes as IDS agent nodes are considered. So, with this method, some valid nodes contribute in intrusion detection activities and costs of the network monitoring will be reduced and the network lifetime will be increased. © 2009 IEEE
Design and performance evaluation of a fuzzy-based traffic conditioner for mobile Ad hoc networks
, Article Journal of Circuits, Systems and Computers ; Volume 17, Issue 6 , 2008 , Pages 995-1014 ; 02181266 (ISSN) ; Movaghar, A ; Sharif University of Technology
2008
Abstract
A mobile ad hoc network is a collection of mobile hosts forming a temporary network on the fly, without using any fixed infrastructure. Characteristics of mobile ad hoc networks such as lack of central coordination, mobility of hosts, dynamically varying network topology, and limited availability of resources make QoS provisioning very challenging in such networks. In this paper, we introduce a fuzzy QoS traffic conditioner for mobile ad hoc networks. The proposed traffic conditioner consists of fuzzy admission control (FAC), fuzzy traffic rate controller (FTRC), and fuzzy scheduler (FS). The proposed FAC monitors the delay and available bandwidth and decides whether to accept or reject the...