Showing papers in "IEEE Systems Journal in 2010"

A STATCOM-Control Scheme for Grid Connected Wind Energy System for Power Quality Improvement

Abstract: Injection of the wind power into an electric grid affects the power quality. The performance of the wind turbine and thereby power quality are determined on the basis of measurements and the norms followed according to the guideline specified in International Electro-technical Commission standard, IEC-61400. The influence of the wind turbine in the grid system concerning the power quality measurements are-the active power, reactive power, variation of voltage, flicker, harmonics, and electrical behavior of switching operation and these are measured according to national/international guidelines. The paper study demonstrates the power quality problem due to installation of wind turbine with the grid. In this proposed scheme STATic COMpensator (STATCOM) is connected at a point of common coupling with a battery energy storage system (BESS) to mitigate the power quality issues. The battery energy storage is integrated to sustain the real power source under fluctuating wind power. The STATCOM control scheme for the grid connected wind energy generation system for power quality improvement is simulated using MATLAB/SIMULINK in power system block set. The effectiveness of the proposed scheme relives the main supply source from the reactive power demand of the load and the induction generator. The development of the grid co-ordination rule and the scheme for improvement in power quality norms as per IEC-standard on the grid has been presented.

Short-Term Scheduling and Control of Active Distribution Systems With High Penetration of Renewable Resources

Abstract: Among the innovative contributions to electric distribution systems, one of the most promising and qualified is the possibility to manage and control distributed generation. Therefore, the latest distribution management systems tend to incorporate optimization functions for the short-term scheduling of the various energy and control resources available in the network (e.g., embedded generators, reactive power compensators and transformers equipped with on-load tap changers). The short-term scheduling procedure adopted in the paper is composed by two stages: a day-ahead scheduler for the optimization of distributed resources production during the following day, an intra-day scheduler that every 15 min adjusts the scheduling in order to take into account the operation requirements and constraints of the distribution network. The intra-day scheduler solves a non-linear multi-objective optimization problem by iteratively applying a mixed-integer linear programming (MILP) algorithm. The linearization of the optimization function and the constraints is achieved by the use of sensitivity coefficients obtained from the results of a three-phase power flow calculation. The paper shows the application of the proposed approach to a medium-voltage 120 buses network with five wind plants, one photovoltaic field, ten dispatchable generators, and two transformers equipped with on-load tap changers.

A Model for Reducing Power Consumption in Peer-to-Peer Systems

Abstract: Information systems based on the cloud computing model and peer-to-peer (P2P) model are now getting popular. In the cloud computing model, a cloud of servers support thin clients with various types of service like Web pages and databases. On the other hand, every computer is peer and there is no centralized coordinator in the P2P model. It is getting more significant to discuss how to reduce the total electric power consumption of computers in information systems to realize eco-society. In this paper, we consider a Web type of application on P2P overlay networks. First, we discuss a model for showing how much each server peer consumes electric power to perform Web requests from client peers. Then, we discuss algorithms for a client peer to select a server peer in a collection of server peers so that the total power consumption can be reduced while some constraint like deadline one is satisfied. Lastly, we evaluate the algorithms in terms of the total power consumption and throughput compared with traditional round robin algorithms.

Efficient Utilization of Renewable Energy Sources by Gridable Vehicles in Cyber-Physical Energy Systems

Abstract: The main sources of emission today are from the electric power and transportation sectors. One of the main goals of a cyber-physical energy system (CPES) is the integration of renewable energy sources and gridable vehicles (GVs) to maximize emission reduction. GVs can be used as loads, sources and energy storages in CPES. A large CPES is very complex considering all conventional and green distributed energy resources, dynamic data from sensors, and smart operations (e.g., charging/discharging, control, etc.) from/to the grid to reduce both cost and emission. If large number of GVs are connected to the electric grid randomly, peak load will be very high. The use of conventional thermal power plants will be economically expensive and environmentally unfriendly to sustain the electrified transportation. Intelligent scheduling and control of elements of energy systems have great potential for evolving a sustainable integrated electricity and transportation infrastructure. The maximum utilization of renewable energy sources using GVs for sustainable CPES (minimum cost and emission) is presented in this paper. Three models are described and results of the smart grid model show the highest potential for sustainability.

Downlink Spectrum Sharing for Cognitive Radio Femtocell Networks

Abstract: Femtocell is envisioned as a highly promising solution for indoor wireless communications. The spectrum allocated to femtocells is traditionally from the same licensed spectrum bands of macrocells. In this case, the capacity of femtocell networks is highly limited due to the finite number of licensed spectrum bands and also the interference with macrocells and other femtocells. In this paper, we propose a radically new communication paradigm by incorporating cognitive radio in femtocell networks. The cognitive radio enabled femtocells are able to access spectrum bands not only from macrocells but also from other licensed systems (e.g. TV systems) provided the interference from femtocells to the existing systems is not harmful. It results in more channel opportunities for femtocells. Thus, the co-channel interference in femtocells can be greatly reduced and the network capacity can be significantly improved. Because of the difference from other traditional wireless networks, we argue the traditional spectrum sharing schemes such as coloring methods are not efficient to femtocell networks especially for dense deployment scenarios. We formulate the downlink spectrum sharing problem in cognitive radio femtocell networks, and employ decomposition theories to solve the problem. Simulation results indicate that cognitive radio enabled femtocells could achieve much higher capacity than the femtocell networks which do not employ agile spectrum access. Simulation results also show that our proposed scheme without any iteration can achieve almost twice of the average capacity by coloring method when the number of available channels is less than five. Moreover, our proposed scheme can converge very fast with a typical value of only five iterations, and it can achieve around two percent extra average capacity than the fixed power control scheme.

Simulation and Pricing Mechanism Analysis of a Solar-Powered Electrical Microgrid

Abstract: A framework is proposed for an electrical power microgrid, such as for a colony or small township of homes that generate electrical power from solar energy and use it directly when possible, and via stored battery power at other times. The situation is described as a demand and supply problem in a multi-agent system with many consumers and suppliers and no explicit communication or coordination among the agents. Such a demand and supply problem is modeled as a Potluck Problem, a generalization of the Santa Fe Bar Problem. Power produced by PV panels and batteries may be used in the local market, in addition to being consumed locally. The proposed microgrid system model is able to determine the optimum operation of a solar-powered microgrid with respect to load demand, environmental requirements, PV panel and battery capacities. The results indicate the effect of various such parameters on the performance of these micro-grids. This paper also analyzes and proposes, based on auction theory, the most efficient and competing pricing mechanism in the proposed microgrid system model. Two important market bidding techniques, single bidding and discriminatory bidding, are considered. The microgrid is made to participate in the bidding process to serve the consumers at a reduced price and to provide better revenues. The viability of the model proposed is illustrated with analyses using realistic assumptions and published historical data.

A Novel Fuzzy Model and Control of Single Intersection at Urban Traffic Network

Abstract: This paper presents a novel fuzzy model and a fuzzy logic controller for an isolated signalized intersection. The controller controls the traffic light timings and phase sequence to ensure smooth flow of traffic with minimal waiting time and length of queue. Usually fuzzy traffic controllers are optimized to maximize traffic flows/minimize traffic waiting time under typical traffic conditions. Consequentially, these are not the optimal traffic controllers under exceptional traffic cases such as roadblocks and road accidents. We apply state-space equations to formulate the average waiting time vehicles in traffic network at fixed time control. also, We propose a novel fuzzy model and new fuzzy traffic controller that can optimally control traffic flows under both normal and exceptional traffic conditions. Results show that the performance of the proposed traffic controller at novel fuzzy model is better that of conventional fuzzy traffic controllers under normal and abnormal traffic conditions.

A Dynamic Decision Model for the Real-Time Control of Hybrid Renewable Energy Production Systems

Abstract: The use of renewable energy sources can reduce the greenhouse gas emissions and the dependence on fossil fuels. The main problem of the installations based on renewable energy is that electricity generation cannot be fully forecasted and may not follow the trend of the actual energy demand. Hybrid systems (including different subsystems such as renewable energy plants, energy storage systems based on hydrogen or dam water reservoirs) can help in improving the economic and environmental sustainability of renewable energy plants. In addition, hybrid systems may be used to satisfy other user demands (such as water supply or hydrogen for automotive use). However, their use should be optimized in order to fulfill the user demand in terms of energy or other needs. In this paper, a model representing an integrated hybrid system based on a mix of renewable energy generation/conversion technologies (e.g., electrolyzer, hydroelectric plant, pumping stations, wind turbines, fuel cell) is presented. The model includes an optimization problem for the control of the different ways to store energy. The goal is to satisfy the hourly variable electric, hydrogen, and water demands. A specific application area in Morocco is considered and the results obtained are discussed in detail.

Consensus Control for a System of Underwater Swarm Robots

Abstract: The control of a swarm of underwater robots requires both a control algorithm and a communication system. Unfortunately, underwater communications is difficult at the best of times and so large time delays and minimal information is a concern. The control system must be able to handle a large number of robots without a master control, i.e., a decentralized control approach. This paper describes Consensus control as a way to decentralize. Consensus control allows each robot to know the final goal and then to decide, based on the position of the other robots, its best move to help achieve the goal.

Systems-of-Systems Analysis of Ballistic Missile Defense Architecture Effectiveness Through Surrogate Modeling and Simulation

Abstract: Traditionally, the analysis of Ballistic Missile Defense System (BMDS) effectiveness has been limited in fidelity due to the inherent complexity of the subject. Indeed, the BMDS battle management process involves monitoring and controlling the actions of many interacting participants (e.g. radar sensors, communications networks and interceptor missiles) in a process whereby a target moves from launch through sensor detection through intercept kill assessment. Because the actions of each participant may evolve independently, the battle management process functions as a true system-of-systems (SoS). Proper SoS analysis requires architecture level engineering, dealing with component functional allocation and inter-component interaction rather than the internal workings of individual participants. Although prior work has been identified that addresses BMD effectiveness at the SoS level, each method sacrifices analysis fidelity of both process elements and individual participants to enable timely decision making. This paper proposes a modeling and simulation (M&S) framework that supports architecture level analysis of the BMDS. The key innovation is the application of neural network surrogate models, which are representations of other high- or medium-fidelity M&S tools, and can be executed rapidly with negligible loss in fidelity. Surrogate models were created of a BMDS analysis tool that included multisensor target tracking and fusion codes. Results will show the benefit of integrating M&S to architecture level analysis. Specific examples include sensitivity of operational level metrics to formation of an integration tracking picture, and the enabling architecture level decision making.

Microturbine Control Modeling to Investigate the Effects of Distributed Generation in Electric Energy Networks

Abstract: The great attention of research initiatives to sustainable energy systems calls for contributions in modeling new small size generation plants exploiting innovative technologies. In such a context, the paper presents detailed models of the components and controls forming the thermo-mechanical and electric subsystems of a microturbine power plantP. The modeled thermo-mechanical subsystem includes different control loops: a speed controller for primary frequency control (droop control), an acceleration control loop, which limits the rotor acceleration in case of sudden loss of load or in case of start-up, and a controller to limit the temperature of the exhaust gases below the maximum admissible temperature. The modeling of control schemes in the electric subsystem is another key issue of the paper in view of providing efficient energy production from distributed generation: an active power-voltage (PV) control is adopted for the inverter in case of the operation of a microturbine connected to the grid. This control scheme provides an innovative contribution with respect to the usually adopted active power-reactive power (PQ) control scheme. The adoption of the PV control scheme allows to evaluate the contribution of micro-turbines to voltage support in electric distribution grids. In case of isolated operation of the generation source a voltage-frequency (VF) control scheme is proposed. A test grid is set up for model validation and the simulation results are described and discussed.

A Review of Sustainability Assessment Models as System of Systems

Abstract: Many people believe that our society is at the crossroads today because of societal and environmental problems of scales ranging from the local to the global. Such problems as global warming, species extinction, overpopulation, poverty, drought, to name but a few, raise questions about the degree of sustainability of our society. To answer sustainability questions, one has to know the meaning of the concept and possess mechanisms to measure it. In this paper, we examine a number of approaches in the literature that do just that. Our focus is on analytical quantitative approaches. Since no universally accepted definition and measuring techniques exist, different approaches lead to different assessments. Despite such shortcomings, rough ideas and estimates about the sustainability of countries or regions can be obtained. One common characteristic of the models herein is their hierarchical nature that provides sustainability assessments for countries in a holistic way. Such models fall in the category of system of systems. Some of these models can be used to assess corporate sustainability.

Technology Planning for Electric Power Supply in Critical Events Considering a Bulk Grid, Backup Power Plants, and Micro-Grids

Abstract: This paper discusses a risk assessment approach to infrastructure technology planning aimed at improving power supply resiliency to natural disasters or other critical events. Cost as well as power supply availability are both fundamental decision factors considered in the study. The proposed planning process spans three phases during which the critical loads under study are subject to the effects of the extreme event: during the event, the immediate aftermath until potential infrastructure damage is repaired, and the long term aftermath until the load has recovered the same level existing before the critical event. The combined risk of these three phases is calculated considering likelihood of the critical event to occur, expected impact, and system vulnerability. This risk is then added to the system capital and normal operational costs to yield a lifetime cost that is used to compare technological options. Micro-grids are identified as a relevant technology with potential to achieve enhanced power supply during critical events. The analysis provides indications on how to better configure micro-grids in order to achieve high availability through diverse local distributed generation sources.

DLNA-Based Multimedia Sharing System for OSGI Framework With Extension to P2P Network

Abstract: Multimedia video sharing has been developed rapidly over the past years. P2P multimedia sharing mechanisms for P2P network such as PPLive, PPStream, Joost, have been used popularly. However, if Content Server and Client in home network have to transmit via P2P sharing, P2P network must be adopted, thus it is unable to increase the network transmission speed through this intranet connection. Although there are DLNA, HAVi, and Jini protocols in home network to share multimedia files, it cannot access P2P network due to the limitation of home network framework. Therefore, this paper proposes a DLNA-based Multimedia Sharing System for OSGI framework with Extension to P2P Network, which extends DLNA multimedia sharing mechanism to P2P network through OSGI platform, so that users can access multimedia resource on P2P Network via DLNA, and P2P network users can apply P2P network mechanism in OSGI bundle to access shared DLNA multimedia resource in home network.

Robust Fault Diagnosis of a Satellite System Using a Learning Strategy and Second Order Sliding Mode Observer

Abstract: This paper proposes a second-order sliding mode observer for fault diagnosis (FD) of a class of uncertain dynamical systems. In the proposed FD scheme, a modified super-twisting second-order sliding mode algorithm is firstly established to observe the system state in the presence of uncertainties and disturbances, and then the observer input is designed by using a PID-type iterative learning algorithm to detect, isolate, and estimate faults. The convergence of the sliding mode algorithm and the parameter update law for the iterative learning estimator are both theoretically and rigorously studied. Finally, the proposed fault diagnosis scheme is applied to the dynamics of a satellite with flexible appendages, and the simulation results demonstrate its effectiveness.

Energy-Efficient Long-Reach Passive Optical Network: A Network Planning Approach Based on User Behaviors

Abstract: Long-reach passive optical network (LR-PON) is a cost-effective solution for providing broadband access spanning large areas. LR-PON extends the coverage span of PONs from the traditional 20 km range to 100 km and consolidates the multiple optical line terminals (OLTs) and central offices, thus reducing the operational cost and serving many more users. There are two type of LR-PONs: “tree-and-branch” and “ring-and-spur” LR-PON. To “green” the LR-PON and make it energy-efficient, we study a network planning approach based on user behaviors. By considering the different network usage behaviors of different kind of users (i.e., daily bandwidth demand profiles), we can assign users (e.g., business and residential users) efficiently to different wavelengths in “tree-and-branch” or “ring-and-spur” LR-PONs at networking planning stage and achieve high network utilization at all times. Heuristic searches can provide such assignments and their approximate solutions are very close to the lower bound. The behavior-aware user assignment achieves significant improvement over the traditional method in terms of used wavelengths and could thus saves the energy consumed by the LR-PON.

Performance Analysis of Contention Based Bandwidth Request Mechanisms in WiMAX Networks

Abstract: WiMAX networks have received wide attention as they support high data rate access and amazing ubiquitous connectivity with great quality-of-service (QoS) capabilities. In order to support QoS, bandwidth request (BW-REQ) mechanisms are suggested in the WiMAX standard for resource reservation, in which subscriber stations send BW-REQs to a base station which can grant or reject the requests according to the available radio resources. In this paper we propose a new analytical model for the performance analysis of various contention based bandwidth request mechanisms, including grouping and no-grouping schemes, as suggested in the WiMAX standard. Our analytical model covers both unsaturated and saturated traffic load conditions in both error-free and error-prone wireless channels. The accuracy of this model is verified by various simulation results. Our results show that the grouping mechanism outperforms the no-grouping mechanism when the system load is high, but it is not preferable when the system load is light. The channel noise degrades the performance of both throughput and delay.

Agent-Based Factory Level Wireless Local Positioning System With ZigBee Technology

Abstract: Local positioning systems are able to track physical assets or people. Such systems can help, but are not limited to, factory automation, asset management. However, it is not easy to apply such systems at the factory level because they are limited by the challenging environment (e.g., obstacles and hostile environment). Advanced wireless technologies provide a chance to make such applications possible. One of the possible technologies is the ZigBee technology, whereas a brief review of the technology and specification of which is presented in this paper. Since the wireless local positioning systems could be represented as a sensor network, multi-agent system would be a good candidate to model such systems. In this connection, an agent-based wireless local positioning system with ZigBee technology is proposed in this paper. Based on this system, some applications are suggested.

Multiresponse Optimization of Stochastic WSN Deployment Using Response Surface Methodology and Desirability Functions

Abstract: Due to reliance on stochastic deployment, delivery of large-scale WSN presents a major problem in the application of wireless sensor networks (WSN) technology. When deployed in a stochastic manner, the WSN has the utmost challenge of guaranteeing acceptable operational efficiency upon deployment. The research presented in this paper evaluates application of the response surface methodology (RSM) and desirability functions for analysis and optimization of stochastic WSN deployments based on multiple efficiency metrics. Through case studies, the approach is proven successful in modeling individual efficiency metrics, and in providing a way for analyzing deployments, based on numerous efficiency metrics. Additionally, the approach may be used to quantify the effects of optimizing partial efficiency metrics on the overall deployment efficiency.

Flight-Like Ground Demonstrations of Precision Maneuvers for Spacecraft Formations—Part II

Abstract: As part of a multifaceted technology development program for the Terrestrial Planet Finder Interferometer (TPF-I) mission, system-level ground demonstrations of precision formation flying have been performed. These demonstrations were done in the Formation Control Testbed (FCT), a six degree-of-freedom, system-level testbed with flight-like hardware and software. The FCT is described in detail in a companion paper. The formation guidance, navigation/estimation, and control architecture and software used in these demonstrations are also discussed in the companion paper. The demonstrations consisted of synchronized rotations, which couple relative positions and attitudes. For TPF-I, this maneuver will require highest precision formation flying. This paper presents the experimental results for these demonstrations, which are the first major system-level demonstration of precision formation flying control for TPF-I. Multiple synchronized formation rotations were executed with real-time software and centimeterand arc minute-level relative position and attitude performance. The maneuvers occurred over two weeks to show a robust, repeatable capability. The FCT is subject to ongoing development. In particular, these demonstrations had five degrees of freedom: three rotational and two translational. The final translational degree of freedom has since been added. In addition, because terrestrial disturbances in the FCT are more severe than encountered on-orbit, the centimeterand arc minute-level performance of the FCT demonstrations is traced to the TPF-I flight requirements via a simulation-based error budget. We conclude with some directions for further development of formation flying technologies.

Reuse in Systems Engineering

Abstract: Reuse in systems engineering is a frequent but poorly understood phenomenon. Nevertheless, it has a significant impact on system development and on estimating the appropriate amount of systems engineering effort with models like the Constructive Systems Engineering Cost Model (COSYSMO). Practical experience showed that the initial version of COSYSMO, based on a “build from the scratch” philosophy, needed to be refined in order to incorporate reuse considerations that fit today's industry environment. The notion of reuse recognizes the effect of legacy system definition in engineering a system and introduces multiple reuse categories for classifying the four COSYSMO size drivers-requirements, interfaces, algorithms, and operational scenarios. It fundamentally modifies the driver counting rules and updates its definition of system size. It provides an enabling framework for estimating a system under incremental and spiral development. In this paper, we present: 1) the definition of the COSYSMO reuse extension and the approach employed to define this extension; 2) the updated COSYSMO size driver definitions to be consistent with the reuse model; 3) the method applied to defining the reuse weights used in the modified parametric relationship; 4) a practical implementation example that instantiates the reuse model by an industry organization and the empirical data that provided practical validation of the extended COSYSMO model; and 5) recommendations for organizational implementation and deployment of this extension.

Optimal Scheduling of Cooperative Spectrum Sensing in Cognitive Radio Networks

Abstract: In cognitive radio (CR) networks, secondary users can be coordinated to perform spectrum sensing so as to detect primary user activities more accurately. However, more sensing cooperations for a channel may decrease the transmission time of the secondary users, or lose opportunities for exploiting other channels. In this paper, we study this tradeoff by using the theory of oartially observable Markov decision process (POMDP). This formulation leads to an optimal sensing scheduling policy that determines which secondary users sense which channels with what miss detection probability and false alarm probability. A myopic policy with lower complexity yet comparable performance is also proposed. We further analytically study the properties and the solution structure for the myopic and the optimal policies under a simplified system model. Theoretical results reveal that under certain conditions, some simple but robust structures of the value function exist, which lead to an easy way to obtain the solution of POMDP. Moreover, the cooperative sensing scheduling problem embedded in our POMDP, which is generally a hard combinatorial problem, can be analyzed in an efficient way. Numerical and simulation results are provided to illustrate that our design can utilize the spectrum more efficiently for CR users.

Integrated Dynamic Bandwidth Allocation in Converged Passive Optical Networks and IEEE 802.16 Networks

Abstract: IEEE 802.16 and Passive Optical Network (PON) are two promising broadband access technologies for high-capacity wireless access networks and wired access networks, respectively. The convergence of 802.16 and PON networks can take the mobility feature of wireless communications and the bandwidth advantage of optical networks jointly. Dynamic bandwidth allocation (DBA) plays an important role in each of these two networks for QoS assurance. In converged 802.16 and PON networks, the integration of the DBA schemes in both networks plays an even more critical role, since bandwidth request/grant mechanisms used in 802.16 and PON are different and the performance of the integrated DBA directly determines the overall system performance. In this paper, we investigate integrated dynamic bandwidth allocation schemes and their signaling overhead. First, this paper starts with discussing the converged network architecture and especially the issues on integrating optical network unit (ONU) and 802.16 base station (BS). Second, it proposes a slotted DBA (S-DBA) scheme and its performance analytic model. The S-DBA scheme takes into account the specific features of the converged network, aiming to reduce signaling overhead caused by cascaded bandwidth requests and grants. The simulation results show that the proposed S-DBA scheme can effectively reduce signaling overhead and increase channel utilization.

Bichromatic Reverse Nearest-Neighbor Search in Mobile Systems

Abstract: In traditional reverse nearest-neighbor (RNN) search, the goal is to find the set of interest objects taking the query object as the nearest neighbor given that the interest objects and the query object have the same type. However, when the interest objects and the query object are of different types, this problem is called bichromatic reverse nearest neighbor (BRNN) search. The BRNN query has an increasing number of mobile applications and requires efficient algorithms for processing. In this paper, we present a novel approach for the BRNN search in the context of spatial network databases (SNDB). The main idea behind our approaches is to use Euclidean-based range search to prune the search space and use Euclidean distance in addition to network distance to minimize processing time. Finally, the experimental results confirm that our proposed algorithm have good performance on different network densities.

Precoding Design for Multi-Antenna Multicast Broadcast Services With Limited Feedback

Abstract: The provision for spectrally efficient multicast broadcast services (MBS) is one of the key functional requirements for next generation wireless communication systems. The challenge inherent to MBS is to ensure that all MBS users can be served, and one effective solution to this problem is to employ MIMO multicast transmit precoding. In previous works on MIMO multicast transmit precoding design, the authors either assumed (1) perfect transmitter-side channel state information (CSIT) or (2) special channel conditions that facilitate precoder design with imperfect CSIT. In this paper, we focus on transmit precoding design for MBS where the CSIT is obtained via limited feedback. In addition, we analyze the average minimum receive signal-noise-ratio (RxSNR) among the MBS users and study the order of growth with respect to the number of MBS users, the number of feedback bits, and the number of transmit antennas. Finally, we propose a threshold based feedback reduction scheme and study the tradeoff between feedback cost and performance loss.

Evaluation of PMI Feedback Schemes for MU-MIMO Pairing

Abstract: The status of codebook based MU MIMO feedback schemes in different wireless standards are briefly overviewed. Based on the Normal Feedback Scheme to feedback the preferred Precoding Matrix Index (PMI), a Best Companion Pairing (BCP) scheme and a Best Companion Cluster (BCC) scheme are introduced to make more efficient pairing. Besides the preferred PMI, UE need to feedback more PMIs for the BCP scheme or a cluster index for the BCC scheme to minimize the intracell or intercell interference. System level simulation results show that the BCC scheme can make a reasonable tradeoff between feedback overhead and throughput.

A Framework for Efficient Fingerprint Identification Using a Minutiae Tree

Abstract: Given the existence of large fingerprint databases, including distributed systems, the development of algorithms for performing fast searches in them has become the important topic for biometric researchers. In this paper, we propose a new indexing method for fingerprint templates consisting of a set of minutia points. In contrast to previously presented methods, our algorithm is tree-based and well addresses the efficiency needs of complex (possibly distributed) systems. One large index tree is constructed and the enrolled templates are represented by the leaves of the tree. The branches in the index tree correspond to different local configurations of minutia points. Searching the index tree entails extracting local minutia neighborhoods of the test fingerprint and matching them against tree nodes. Therefore, the search time does not depend on the number of enrolled fingerprint templates, but only on the index tree configuration. This framework can be adapted for different tree-building parameters (feature sets, indexing levels, bin boundaries) according to user requirements and different enrollment and searching techniques can be applied to improve accuracy. We conduct a number of the experiments on Fingerprint Verification Competition databases, as well as the databases of synthetically generated fingerprint templates. The experiments confirm the ability of the proposed algorithm to find correct matches in the database and the minimum search time requirements.

Rapid Prototyping for Wildlife and Ecological Monitoring

Abstract: Wildlife tracking and ecological monitoring are important for scientific monitoring, wildlife rehabilitation, disease control, and sustainable ecological development. Yet technologies for both of them are expensive and not scalable. Also it is important to tune the monitoring system parameters for different species to adapt their behavior and gain the best result of monitoring. In this paper, we propose using wireless sensor networks to build both short term and long term wildlife and ecological monitoring systems. For the short term system, everything used is off-the-shelf and can be easily purchased from the market. We suggest that before establishing a large scale wildlife/ecological monitoring network, it is worthwhile to first spend a short period of time constructing a rapid prototype of the targeted network. Through verifying the correctness of the prototype network, ecologists can find potential problems, avoid total system failure, and use the best-tuned parameters for the long-term monitoring network.

IGFS: A New MAC Protocol Exploiting Heterogeneous Propagation Delays in the Dynamic Bandwidth Allocation on WDM-EPON

Abstract: One of the most challenging issues of the Ethernet passive optical networks' (EPONs) architecture is the bandwidth allocation problem. Various dynamic allocation schemes have been proposed to schedule the subscribers' demands. However, the performance of all these schemes is significantly degraded when the round-trip times (RTTs) of the optical network units (ONUs) are dissimilar, due to the large number of gaps in the transmission schedule. Unfortunately, in real networks, RTTs are usually dissimilar. In this paper a new medium access control (MAC) protocol for multichannel EPONs, namely the Intelligent Gap Filling Strategy (IGFS) is proposed. The IGFS employs two algorithms: the DissimilarityExploitation algorithm, which exploits the RTTs' dissimilarities, and the MinimumLatencyScheduling algorithm, which rearranges the ONUs' service order in order to favor the requests that cause the minimum scheduling latency.

TCP Convergence Layer-Based Operation of DTN for Long-Delay Cislunar Communications

Abstract: Delay/disruption tolerant networking (DTN) is a class of network techniques developed to accommodate long link delay and frequent link disruptions. Little work has been done in evaluating the effectiveness and performance of the DTN protocols when they are applied for an interplanetary Internet (IPN). In this paper, we present an experimental evaluation of Transmission Control Protocol Convergence Layer (TCPCL)-based operation of DTN-2 (i.e., TCPCL/TCP) for long-delay cislunar communications, partially in comparison with Licklider Transmission Protocol (LTP)-based LTP/User Datagram Protocol (UDP). The experiment is conducted by transmitting a text file using the DTN protocol stack over a PC-based simulation test-bed. According to the experimental results, the TCPCL-based DTN protocol works effectively over less error-prone cislunar links with short delay and has performance advantage over LTP-based DTN. Along with the increase in link delay and channel noise, the performance of TCPCL-based DTN is getting far behind the LTP-based DTN. The TCPCL-based DTN protocol can successfully handle an experimented short link disruption around 30 s-120 s, even with an existence of a very long link delay and a high channel Bit-Error-Rate (BER), but its performance is poor compared to that of the LTP-based DTN.