Electrical Engineering
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Browsing Electrical Engineering by Author "Eric Jonsson School of Engineering and Computer Science. Open Networking Advanced Research (OpNeAR) Laboratory."
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Item Ad Hoc 802.11b cooperative protocols: performance in a slow fading channel(The University of Texas at Dallas, 2013-05-24) Agarwal, Niraj, 1977-; ChanneGowda, Divya, 1981-; Kannan, Lakshmi Narasimhan, 1984-; Tacca, Marco, 1973-; Fumagalli, Andrea; Eric Jonsson School of Engineering and Computer Science. Open Networking Advanced Research (OpNeAR) Laboratory.This paper investigates the use of cooperative communications in the context of ad hoc IEEE 802.11b to combat radio signal degradations due to slow fading. The performance gain of both an existing cooperative protocol and the one proposed in the paper is discussed. It is quantitatively shown how much the two cooperative protocols increase throughput, lower delivery latency, and extend transmission span, when compared to the conventional IEEE 802.11b protocol. These features may help improve connectivity and network performance in ad hoc applications, where nodes’ relative locations are difficult to control and predict.Item An analytical model with improved accuracy of IEEE 802.11 protocol under unsaturated conditions(The University of Texas at Dallas, 2013-05-23) Vijayasankar, Kumaran, 1984-; Taufique, Azar; Kannan, Lakshmi Narasimhan, 1984-; Tacca, Marco, 1973-; Fumagalli, Andrea; Eric Jonsson School of Engineering and Computer Science. Open Networking Advanced Research (OpNeAR) Laboratory.In this work the authors present an analytical model that - compared to previously published work- more accurately captures the delay of IEEE 802.11 protocol under low, medium, and near-saturation load conditions. A Markov chain is used to keep track of the instantaneous number of (active) nodes that have a frame to transmit. The number of active nodes varies over time and is a function of various parameters, including the frame individual maximum retransmission count. One advantage of the proposed analytical model is its ability to estimate the IEEE 802.11 protocol latency and delivery ratio in the presence of quality of service (QoS) classes, each class being defined by a specific maximum retransmission count. Such QoS classes can be adopted to support real time applications for which both latency and delivery ratio must be closely monitored for satisfactory operation. The analytical estimation of these performance parameters may offer useful feedback to admission control schemes.Item An automatic repeat request protocol for cooperative slotted radio networks(The University of Texas at Dallas, 2013-06-18) Cerutti, Isabella, 1973-; Fumagalli, Andrea; Gupta, Puja, 1980-; Eric Jonsson School of Engineering and Computer Science. Open Networking Advanced Research (OpNeAR) Laboratory.In conventional (non-cooperative) radio networks, the data frames, that are corrupted by errors during the transmission in a fading environment, are retransmitted by the source. In cooperative radio networks, frame retransmission may be performed by a neighboring node that has successfully overheard the source’s frame transmission. The advantage of the latter is the spatial diversity that is provided by the cooperative node. In addition, the retransmitted frame may have incremental redundancy for improved performance. In this paper a simple automatic repeat request (ARQ) protocol is specified that takes advantage of coded cooperative communication in slotted, single-hop radio networks. An exact analytical formulation is presented to compute the delay experienced by Poisson arriving frames whose retransmission (when needed) is performed by one cooperative node. The study reports significant quantitative advantages of the coded cooperation ARQ protocol in terms of both throughput and latency, when compared to non-cooperative ARQ protocols.Item Building alternate multitasking trees in MPLS networks(The University of Texas at Dallas, 2013-05-23) Tang, Limin, 1977-; Billenhalli, Shreejith; Vardhan, Hars; Tacca, Marco, 1973-; Fumagalli, Andrea; Monti, Paolo, 1973-; Eric Jonsson School of Engineering and Computer Science. Open Networking Advanced Research (OpNeAR) Laboratory.; Next Generation Optical Network (NeGONet) Group; Kungl. Tekniska högskolan (KTH). Photonics and Microwave Engineering (FMI). School of Information and Communication Technology; Royal Institute of Technology (Kista, Sweden)An algorithm for computing alternate multicast trees in packet transport networks is proposed in this paper. The algorithm efficiently computes multiple sub-optimal tree candidates for a given multicast service request. The algorithm builds on the widely used computation of K ordered loopless shortest paths and can be applied to any connected network topology. Simulation experiments obtained for a multiprotocol label switching (MPLS) network are presented to evaluate the effectiveness and performance of the algorithm.Item Chromatic dispersion and self-phase modulation in multi-hop multi-rate WDM rings(The University of Texas at Dallas, 2013-06-18) Cerutti, Isabella, 1973-; Fumagalli, Andrea; Potasek, Mary J.; Eric Jonsson School of Engineering and Computer Science. Open Networking Advanced Research (OpNeAR) Laboratory.; New York University. Courant Institute.When compared to first generation and single-hop optical networks, multi-hop and multirate (M & M) network architectures have the advantage of significantly reducing network design cost under a variety of wavelength-to-terminal cost ratios. This report investigates how fiber chromatic dispersion and self-phase modulation may affect such cost reduction in M & M WDM rings.Item Combining cooperative link layer protocols with distributed routing protocols in mobile ad hoc networks – perspectives and performance analysis(The University of Texas at Dallas, 2013-06-18) Vijayasankar, Kumaran, 1984-; Kannan, Lakshmi Narasimhan, 1984-; Ilango, Sathya; Tacca, Marco, 1973-; Fumagalli, Andrea; Eric Jonsson School of Engineering and Computer Science. Open Networking Advanced Research (OpNeAR) Laboratory.In cooperative link layer protocols the use of relay nodes may increase the capacity of the radio links. The study in this paper investigates what (if any) performance gain may be passed onto the routing protocol of a mobile ad hoc network. Two popular routing protocols are considered, AODV and OLSR, as each provides a unique route acquisition mechanism. A distributed procedure to choose the relay node at the link layer is combined with the two routing protocols. Analysis via simulation confirms some expected (and perhaps some other less expected) benefits when using a cooperative link layer protocol in place of a non-cooperative one, e.g., improved delivery ratio, end-to-end delay, and reduced signaling overhead.Item Cooperative and non-cooperative ARQ protocols for microwave recharged sensor nodes(The University of Texas at Dallas, 2013-06-18) Tacca, Marco, 1973-; Monti, Paolo, 1973-; Fumagalli, Andrea; Eric Jonsson School of Engineering and Computer Science. Open Networking Advanced Research (OpNeAR) Laboratory.The Generic Autonomous Platform for Sensor Systems, or GAP4S, is a maintenance-free wireless sensor network in which the sensor battery needs not be replaced. Power is delivered to the sensor via a microwave signal that is radiated by a base-station. The base-station also acts as the entry point to a wider communication network, e.g., the Internet. This paper describes three automatic retransmission request (ARQ) protocols that may be used in GAP4S to yield reliable and fair data transmission from the sensor nodes to the base-station. Two of the protocols take advantage of cooperative communication, whereby neighboring sensor nodes help during the retransmission process. The analysis presented on the saturation throughput of the ARQ protocols helps quantify the gain achievable when cooperative communication is used in GAP4S in a variety of working conditions.Item Cooperative ARQ protocols in slotted radio networks(The University of Texas at Dallas, 2013-06-18) Cerutti, Isabella, 1973-; Fumagalli, Andrea; Gupta, Puja, 1980-; Eric Jonsson School of Engineering and Computer Science. Open Networking Advanced Research (OpNeAR) Laboratory.In conventional (non-cooperative) automatic repeat request (ARQ) protocols for radio networks, the corrupted data frames that cannot be correctly decoded at the destination are retransmitted by the source. In cooperative ARQ protocols, data frame retransmissions may be performed by a neighboring node (the relay) that has successfully overheard the source’s frame transmission. One advantage of the latter group of ARQ protocols is the spatial diversity provided by the relay. The first delay model for cooperative ARQ protocols is presented in this paper. The model is analytically derived for a simple set of retransmission rules that make use of both uncoded and coded cooperative communications in slotted radio network. The model estimates the delay experienced by Poisson arriving frames, whose retransmissions (when required) are performed also by a single relay. Saturation throughput, frame latency and buffer occupancy at the source, and relay are quantified and compared against two non-cooperative ARQ protocols.Item Cooperative communications in multihop networking: a case study based on the IEEE 802.11 protocol(The University of Texas at Dallas, 2013-05-24) Kannan, Lakshmi Narasimhan, 1984-; Vijayasankar, Kumaran, 1984-; ChanneGowda, Divya, 1981-; Agarwal, Niraj, 1977-; Fumagalli, Andrea; Tacca, Marco, 1973-; Eric Jonsson School of Engineering and Computer Science. Open Networking Advanced Research (OpNeAR) Laboratory.This paper combines multi-hop networking with single-hop cooperative communications. The solution is built upon the standard IEEE 802.11 protocol operating in the ad hoc mode. A simulation based comparison is carried out in order to evaluate the performance gains and benefit of cooperative communications applied to multi-hop networking. Preliminary results indicate that network performance in terms of both throughput and end-to-end delay improves. Additionally, cooperative communications increases robustness against uncertainties in the wireless channel.Item A cross layer routing metric with wireless cooperative protocols(The University of Texas at Dallas, 2013-06-18) Vijayasankar, Kumaran, 1984-; Kannan, Lakshmi Narasimhan, 1984-; Tacca, Marco, 1973-; Fumagalli, Andrea; Eric Jonsson School of Engineering and Computer Science. Open Networking Advanced Research (OpNeAR) Laboratory.Cooperative link layer protocols are typically used in single hop networks. In such protocols, a special node called the relay node helps deliver frames from a source to a destination. The performance benefits of cooperation at link layer can be streamlined into multi-hop networks as well. In multi-hop networks, a frame is sent from an original source to the final destination through a series of intermediate nodes. The paper extends the expected transmission time metric — proposed for multi-hop wireless ad hoc networks — to the context of cooperative IEEE 802.11 link layer protocol. The designed metric is called cooperative expected transmission time (CETT). CETT carefully accounts for the higher probability of successful frame transmission and therefore the reduction in expected transmission time brought about by the relay node in the cooperative protocol. CETT jointly optimizes both the route computation and the selection of the cooperative relay at the link layer. Route optimization helps jointly choose the best set of intermediate nodes and cooperation optimization helps choose the best relay node for each link in the multi-hop. As a result, CETT helps distinguish the case wherein it is better to use a node as a relay as compared to using it as an intermediate node. For comparison, the case where cooperation is applied after route computation is also presented. Minimizing the expected transmission time may result in more efficient link utilization and increased overall end-to-end network throughput. It is also shown that joint optimization of route and relay selection is better than finding routes and then applying cooperation.Item Destination-initiated wavelength-weighted reservation protocol in WDM rings(The University of Texas at Dallas, 2013-06-03) Pitchumani, Sudhakar, 1978-; Cerutti, Isabella, 1973-; Fumagalli, Andrea; Eric Jonsson School of Engineering and Computer Science. Open Networking Advanced Research (OpNeAR) Laboratory.In networks that require dynamic assignment of wavelengths, it is known that destination initiated reservation protocols lower the blocking robability - caused by unavailable wavelengths or convergence problems of the network status information -, when compared to source initiated reservation protocols [1]. Choosing the wavelength using weights based on past performance may further lower such blocking probability, when compared to random selection strategies [2]. This paper presents a Destination initiated Weighted-Wavelength Reservation DW2R protocol that improves the performance of destination initiated reservation protocol and does not require any additional signaling messages. Wavelength weights are computed based on past blocking probabilities and stored at the source. A meticulous simulation study carried out on ring networks reveals for the first time a number of interesting properties of the proposed DW2 R protocol: a reduced (backward) blocking probability when compared to other reservation protocols, a good scalability in the number of ring nodes (links) and in the number of wavelengths, and a contained performance degradation due to an increase of either the ring signaling latency or the frequency of traffic changes.Item Digital subcarrier cross-connects (DSXCs)(The University of Texas at Dallas, 2013-06-18) Hui, Rongqing; Huang, Wanjun, 1978; Razo, Miguel; Tacca, Marco, 1973; Fumagalli, Andrea; Eric Jonsson School of Engineering and Computer Science. Open Networking Advanced Research (OpNeAR) Laboratory.Traditional (analog) Frequency Division Multiplexing (FDM) was widely used in the pre-SONET/SDH era, to multiplex transport channels together using spectral diversity. These transport solutions were then gradually abandoned due in part to their low spectral efficiency and with the advent of Time Division Multiplexing (TDM), which lead to synchronous transmission techniques, such as SONET and SDH. Another problem of traditional FDM or Subcarrier Multiplexing (SCM) ─ being analog ─ is its susceptibility to accumulated waveform distortion and crosstalk. For these reasons FDM is not competitive in today’s transport networks. Digital signal processing continues to reach new record high rates, thus enabling Digital Subcarrier Crossconnects (DSXCs) to operate even at the high transmission rates of optical signals. In DSXC, the incoming subcarriers are switched to the outgoing subcarriers by a controlled Radio Frequency (RF) crossbar switch. The power consumption required to switch subcarriers in and out is estimated to be only a fraction of the power dissipated by current TDM and packet switching based transport network solutions. Multiple DSXCs can be combined to design Digital Subcarrier Optical Networks (DSONs) [1], which are a promising energy efficient alternative to current electronic-based transport network techniques, e.g., OTN/SONET/SDH/MPLS-TP. The DSXC’s basic functionalities and modules are introduced and discussed in this paper.Item Digital subcarrier optical networks (DSONs)(The University of Texas at Dallas, 2013-06-18) Huang, Wanjun, 1978-; Razo, Miguel; Tacca, Marco, 1973-; Fumagalli, Andrea; Hui, Rongqing; Eric Jonsson School of Engineering and Computer Science. Open Networking Advanced Research (OpNeAR) Laboratory.Energy efficient networks are increasingly becoming a desirable feature in today’s market. Both the number of users and the average amount of data traffic generated by each user continue to grow, requiring more powerful network routers and switches, which in turn dissipate large amount of electric power to operate. This problem is in part circumvented by deploying all-optical wavelength division multiplexing (WDM) solutions in the network, which eliminate any electronic processing of the in-transit data at the intermediate network nodes by dedicating a path of light (a wavelength) across the network to directly interconnect two edge nodes. However, the all-optical approach is only suitable when the average quantity of traffic to be exchanged by two edge nodes is sufficient large to warrant one entire (or many) dedicated wavelength(s). Considering that optical transmission rates are moving up from today’s 10 Gbps to 40, 100 and even 160 Gbps per wavelength, the fraction of edge nodes that exchange such amount of traffic is not (surprisingly) limited, as many of the edge node pairs would require only sub-wavelength connectivity. Sub-wavelength connectivity is today offered by either Optical Transport Network (OTN) or Multi Protocol Label Switching with Transport Profile (MPLS-TP). These solutions run on top of the WDM layer. Unfortunately, the amount of required electronic processing in these solutions is such that an order of magnitude higher power consumption results compared to all-optical networks. Part of this extra power consumption is due to the electronic buffering of the in-transit data at the intermediate nodes. This paper points to an alternative solution to achieving sub-wavelength bandwidth assignment to edge node pairs, which eliminates the need for data buffering at the intermediate nodes. Sub-wavelength channels or circuits are creating by using spectrally efficient orthogonal frequencies in each wavelength, with each frequency arrying a fraction of the wavelength bandwidth. By assigning one or more such frequencies to one edge node pair, an end-to-end sub-wavelength circuit is created. At the intermediate nodes, incoming frequencies are switched to outgoing frequencies via specially designed frequency selective switches or cross-connects. The power consumption required to switch frequencies in and out is estimated to be only a fraction of the power dissipated by current transport solutions, thus mitigating the energy consumption struggle when assigning subwavelength capacities to edge nodes.Item Finding a simple path with multiple must-include nodes(The University of Texas at Dallas, 2013-05-23) Vardhan, Hars; Billenahalli, Shreejith, 1982-; Huang, Wanjun, 1978-; Razo, Miguel; Sivasankaran, Arularasi; Tang, Limin, 1977-; Monti, Paolo, 1973-; Tacca, Marco, 1973-; Fumagalli, Andrea; Eric Jonsson School of Engineering and Computer Science. Open Networking Advanced Research (OpNeAR) Laboratory.This document presents an algorithm to find a simple path in the given network with multiple must-include nodes. The problem of finding a simple path with only one must-include node can be solved in polynomial time using lower bound max-flow approach. However, including multiple nodes in the path has been shown to be a NP-Complete. This problem may arise in network areas such as forcing the route to go through particular nodes, which have wavelength converter (optical), have monitoring provision (telecom), have gateway functions (in OSPF) or are base stations (in MANET). Also, network standards allow loose definition of routing by requiring one or more nodes to be in the routing of Link State Packet. In this document, a heuristic algorithm is described to find a simple path between a pair of terminals, which has constraint to pass through a certain set of other nodes. The algorithm is comprised into two main steps: (1) considering a pair of nodes in sequence from source to destination as a segment and then computing candidate paths between each segment, and (2) combining paths, one from each segment, in order to make simple path from source to destination. The max-flow approach is used to find candidate paths, a which provides maximum number of edge disjoint paths for individual segments. The second step of the algorithm uses backtracking algorithm for combining paths. The time complexity of the first step of the algorithm is O(kiVIIEI 2 ), where k is the number of must-include nodes. The time complexity of step (2) depends upon total number of candidate paths which are not touching any one of the candidates of other segments. So, the worse case time complexity of step (2) is O(.Ak), where .A is the maximum nodal degree of the network. However, we show that step (2) has minimal effect on the algorithm and it does not grow exponentially with k in this application. Later, we also show that initial re-ordering of the given sequence of must-include nodes can improve the result. The experimental results show that the algorithm is successful in computing near optimal path in reasonable time. keywords: constrained path computation, graph theory, heuristic algorithm, max flow, network route.Item A link state advertisement (LSA) protocol for optical transparency islands(The University of Texas at Dallas, 2013-06-18) Das, Shovan, 1979-; Tabrizi, Reza Roshani, 1976-; Monti, Paolo, 1973-; Tacca, Marco, 1973-; Fumagalli, Andrea; Eric Jonsson School of Engineering and Computer Science. Open Networking Advanced Research (OpNeAR) Laboratory.Plug and play optical (PPO) nodes can be used to ease the deployment of optical networks. Once plugged, PPO nodes provide all-optical circuits between client nodes to alleviate the electronic processing bottleneck of high speed networks. PPO nodes must self-adjust to changes of the optical physical topology and fiber propagation characteristics, and provide wavelength routing functionalities to client nodes. This paper presents a protocol, the TI-LSA protocol, for physical topology discovery at the PPO node layer, e.g., it may be used to advertise available optical resources and changing conditions of the optical physical layer. The protocol is based on the link state advertisement (LSA) principle and modified to take advantage of the transparency island (TI) properties in the optical data plane. As discussed in the paper, the proposed TI-LSA protocol is a scalable solution to the problem of topology discovery and update in PPO networks when the optical transparency island size is relatively small.Item Optimized transmission power levels in a cooperative ARQ protocol for microwave recharged wireless sensors(The University of Texas at Dallas, 2013-06-18) Monti, Paolo, 1973; Tacca, Marco, 1973-; Fumagalli, Andrea; Eric Jonsson School of Engineering and Computer Science. Open Networking Advanced Research (OpNeAR) Laboratory.The Generic Autonomous Platform for Sensor Systems, or GAP4S, is a maintenance-free wireless sensor network in which the sensor node battery does not need to be replaced. Power is delivered to the sensor node via a microwave signal that is radiated by a base-station. The base-station also acts as the entry point to a wider communication network, e.g., the Internet. This paper describes an automatic repeat request (ARQ) protocol that may be used in GAP4S to yield reliable and fair data transmission from the sensor nodes to the base-station. The protocol takes advantage of cooperative communication, whereby neighboring sensor nodes help during the retransmission process. The transmission power level is optimized at each sensor node to increase the saturation throughput of the ARQ protocol.Item The PlaNet-PTN module: a single layer design tool for packet transport networks(The University of Texas at Dallas, 2013-05-23) Razo, Miguel; Litovsky, Arie; Huang, Wanjun, 1978-; Sivasankaran, Arularasi; Tang, Limin, 1977-; Vardhan, Hars; Tacca, Marco, 1973-; Fumagalli, Andrea; Monti, Paolo, 1973-; Eric Jonsson School of Engineering and Computer Science. Open Networking Advanced Research (OpNeAR) Laboratory.PlaNet is a multilayer network planning tool developed at the University of Texas at Dallas. This paper illustrates some of the features of PlaNet-PTN, one of the modules available in the PlaNet tool. PlaNet-PTN can be used to design and plan a single layer packet transport network (PTN). Quality of protection, routing constraints, minimization of the network equipment cost, and user's desired run time of the tool are just some examples of the features available in PlaNet. As shown in the paper, the PlaNet-PTN planning module is able to provide, among others, optimization of Label Switched Path (LSP) routes, link capacity placement, node and link equipment configuration.Item A queueing model for PCEP (Path Computation Element Protocol)(The University of Texas at Dallas, 2013-06-18) Yu, Juanjuan, 1978-; He, Yue; Wu, Kai; Tacca, Marco, 1973-; Fumagalli, Andrea; Vasseur, Jean-Phillippe; Eric Jonsson School of Engineering and Computer Science. Open Networking Advanced Research (OpNeAR) Laboratory.Path computation elements (PCE’s) are used to compute end-to-end paths across multiple areas. Multiple PCE’s may be dedicated to each area to provide sufficient path computation capacity and redundancy. An open problem is which PCE should be chosen to send the path computation request to, that may be a non trivial problem if PCE’s have uneven processing capacities. This paper presents a product form queueing model to estimate the latencies in path computation while accounting for the arrival rate of path computation requests. The model is used to find the PCE selection policy to minimize the average expected latencies in path computation. The model is validated against two simulation benchmarks obtained using OPNET, i.e., a network of queues and the multi protocol label switching with traffic engineering (MPLSTE) network running the PCE communication protocol (PCEP). The study shows that the use of product form yields approximations that are up to 15% at practical offered loads. Moreover, the PCE selection policy derived under the product form assumption is showed to be effective in minimizing the overall expected latencies in path computation.Item Reconfigurable optical networks: a cross layer approach(The University of Texas at Dallas, 2013-05-24) Roshani-Tabrizi, Reza, 1976-; Monti, Paolo, 1973-; Tacca, Marco, 1973-; Fumagalli, Andrea; Eric Jonsson School of Engineering and Computer Science. Open Networking Advanced Research (OpNeAR) Laboratory.This paper presents the Pruning with Memory (PWM) algorithm, which computes a cross layer optimal reconfiguration sequence in reconfigurable IP/MPLS over optical networks.Item A scalable wavelength assignment algorithm using minimal number of wavelength converters in resilient WDM networks(The University of Texas at Dallas, 2013-06-18) Razo, Miguel; Billenahalli, Shreejith; Huang, Wanjun, 1978-; Sivasankaran, Arularasi; Tang, Limin, 1977-; Vardhan, Hars; Tacca, Marco, 1973-; Fumagalli, Andrea; Monti, Paolo, 1973-; Eric Jonsson School of Engineering and Computer Science. Open Networking Advanced Research (OpNeAR) Laboratory.; Royal Institute of Technology. NeGONet Group.Careful wavelength assignment (WA) to support lambda services is necessary to reduce the total number of wavelength converters (WCs), which are required every time the wavelength continuity constraint cannot be met in wavelength division multiplexing (WDM) networks. With the successful introduction of reconfigurable optical add-drop multiplexers (ROADMs) and related technologies, WDM networks are now growing in size, both in the number of optical nodes and number of wavelengths supported, thus requiring WA algorithms that scale with the network size. This paper presents a scalable and efficient WA algorithm that aims to reduce the total number of WCs in WDM networks bearing static lambda services. The WA algorithm is applicable to both unprotected and (dedicated) protected lambda services. In the latter case, wavelength continuity constraint between the working and the protection path is taken into account. The WA algorithm is then used to quantify the tradeoff between using tunable optical transceivers versus number of WCs to cope with the wavelength continuity constraint.