Qos-driven SCTP-based multimedia delivery over heterogeneous wireless networks

Stream Control Transport Protocol （SCTP）-based handover is supposedly the best suit for current mobile Internet users. However, prevalent SCTP-based handover solutions mostly evaluate candidate networks by a function of multiple attributes such as available bandwidth, delay, etc., which tend to vary often in burst and might cause the instability of handover decisions. Moreover, the SCTP congestion control strategy leads to sudden degradation of users＇ quality of experience for multimedia streaming service because of abrupt and frequent strong fluctuations in the transmission rate. In this paper, we propose a novel QoS-driven SCTP- based handover solution （SCTP-QD） appropriate for heterogeneous wireless multimedia transmission. A new network service and transport layer QoS-aware model is designed to help SCTP-QD accurately analyze the service stability and data transmission capacity for each path. A proper QoS-driven handover decision model is introduced in SCTP-QD in order to improve the SCTP handover efficiency while reducing unnecessary handoffs and fail-over probability. A proposal is finally addressed to help SCTP-QD avoid the slow start phase whenever handover occurs. The simulation results show that SCTP-QD outperforms existing solutions in terms of data delivery performance.     

SmallWorld Model-Based Polylogarithmic Routing Using Mobile Nodes

The use of mobile nodes to improve network system performance has drawn considerable attention recently. The movement-assisted model considers mobility as a desirable feature,where routing is based on the store-carry-forward paradigm with random or controlled movement of resource rich mobile nodes.The application of such a model has been used in several emerging networks,including mobile ad hoc networks(MANETs),wireless sensor networks(WSNs),and delay tolerant networks(DTNs).It is well known that mobility increases the capacity of MANETs by reducing the number of relays for routing,prolonging the lifespan of WSNs by using mobile nodes in place of bottleneck static sensors,and ensuring network connectivity in DTNs using mobile nodes to connect different parts of a disconnected network.Trajectory planning and the coordination of mobile nodes are two important design issues aiming to optimize or balance several measures, including delay,average number of relays,and moving distance.In this paper,we propose a new controlled mobility model with an expected polylogarithmic number of relays to achieve a good balance among several contradictory goals,including delay,the number of relays,and moving distance.The model is based on the small-world model where each static node has"short"link connections to its nearest neighbors and"long"link connections to other nodes following a certain probability distribution.Short links are regular wireless connections whereas long links are implemented using mobile nodes.Various issues are considered,including trade-offs between delay and average number of relays,selection of the number of mobile nodes,and selection of the number of long links.The effectiveness of the proposed model is evaluated analytically as well as through simulation.     

TCP Issues in Mobile Ad Hoc Networks: Challenges and Solutions

Mobile ad hoc networks （MANETs） are a kind of very complex distributed communication systems with wireless mobile nodes that can be freely and dynamically self-organized into arbitrary and temporary network topologies. MANETs inherit several limitations of wireless networks, meanwhile make new challenges arising from the specificity of MANETs, such as route failures, hidden terminals and exposed terminals. When TCP is applied in a MANET environment, a number of tough problems have to be dealt with. In this paper, a comprehensive survey on this dynamic field is given. Specifically, for the first time all factors impairing TCP performance are identified based on network protocol hierarchy, i.e., lossy wireless channel at the physical layer; excessive contention and unfair access at the MAC layer; frail routing protocol at the network layer, the MAC layer and the network layer related mobile node; unfit congestion window size at the transport layer and the transport layer related asymmetric path. How these factors degrade TCP performance is clearly explained. Then, based on how to alleviate the impact of each of these factors listed above, the existing solutions are collected as comprehensively as possible and classified into a number of categories, and their advantages and limitations are discussed. Based on the limitations of these solutions, a set of open problems for designing more robust solutions is suggested.     

State-chain sequential feedback reinforcement learning for path planning of autonomous mobile robots

This paper deals with a new approach based on Q-learning for solving the problem of mobile robot path planning in complex unknown static environments.As a computational approach to learning through interaction with the environment,reinforcement learning algorithms have been widely used for intelligent robot control,especially in the field of autonomous mobile robots.However,the learning process is slow and cumbersome.For practical applications,rapid rates of convergence are required.Aiming at the problem of slow convergence and long learning time for Q-learning based mobile robot path planning,a state-chain sequential feedback Q-learning algorithm is proposed for quickly searching for the optimal path of mobile robots in complex unknown static environments.The state chain is built during the searching process.After one action is chosen and the reward is received,the Q-values of the state-action pairs on the previously built state chain are sequentially updated with one-step Q-learning.With the increasing number of Q-values updated after one action,the number of actual steps for convergence decreases and thus,the learning time decreases,where a step is a state transition.Extensive simulations validate the efficiency of the newly proposed approach for mobile robot path planning in complex environments.The results show that the new approach has a high convergence speed and that the robot can find the collision-free optimal path in complex unknown static environments with much shorter time,compared with the one-step Q-learning algorithm and the Q(λ)-learning algorithm.     

Mobile agent-enabled framework for structuring and building distributed systems on the internet

Mobile agent has shown its promise as a powerful means to complement and enhance existing technology in various application areas. In particular, existing work has demonstrated that MA can simplify the development and improve the performance of certain classes of distributed applications, especially for those running on a wide-area, heterogeneous, and dynamic networking environment like the Internet. In our previous work, we extended the application of MA to the design of distributed control functions, which require the maintenance of logical relationship among and/or coordination of proc- essing entities in a distributed system. A novel framework is presented for structuring and building distributed systems, which use cooperating mobile agents as an aid to carry out coordination and cooperation tasks in distributed systems. The framework has been used for designing various distributed control functions such as load balancing and mutual ex- clusion in our previous work. In this paper, we use the framework to propose a novel ap- proach to detecting deadlocks in distributed system by using mobile agents, which dem- onstrates the advantage of being adaptive and flexible of mobile agents. We first describe the MAEDD (Mobile Agent Enabled Deadlock Detection) scheme, in which mobile agents are dispatched to collect and analyze deadlock information distributed across the network sites and, based on the analysis, to detect and resolve deadlocks. Then the design of an adaptive hybrid algorithm derived from the framework is presented. The algorithm can dynamically adapt itself to the changes in system state by using different deadlock detec- tion strategies. The performance of the proposed algorithm has been evaluated using simulations. The results show that the algorithm can outperform existing algorithms that use a fixed deadlock detection strategy.     

Ethernet based time synchronization for Raspberry Pi network improving network model verification for distributed active turbulent flow control

Friction drag primarily determines the total drag of transport systems. A promising approach to reduce drag at high Reynolds numbers(> 104) are active transversal surface waves in combination with passive methods like a riblet surface. For the application in transportation systems with large surfaces such as airplanes, ships or trains, a large scale distributed real-time actuator and sensor network is required. This network is responsible for providing connections between a global flow control and distributed actuators and sensors. For the development of this network we established at first a small scale network model based on Simulink and True Time. To determine timescales for network events on different package sizes we set up a Raspberry Pi based testbed as a physical representation of our first model. These timescales are reduced to time differences between the deterministic network events to verify the behavior of our model. Experimental results were improved by synchronizing the testbed with sufficient precision. With this approach we assure a link between the large scale model and the later constructed microcontroller based real-time actuator and sensor network for distributed active turbulent flow control.     

Parameter Selection and Performance Analysis of Mobile Terminal Models Based on Unity3D

Mobile platform is now widely seen as a promising multimedia service with a favorable user group and market prospect. To study the influence of mobile terminal models on the quality of scene roaming, a parameter setting platform of mobile terminal models is established to select the parameter selection and performance index on different mobile platforms in this paper. This test platform is established based on model optimality principle, analyzing the performance curve of mobile terminals in different scene models and then deducing the external parameter of model establishment. Simulation results prove that the established test platform is able to analyze the parameter and performance matching list of a mobile terminal model.     

Collaborative Interaction for Videos on Mobile Devices Based on Sketch Gestures

With the rapid progress of the network and mobile techniques, mobile devices such as mobile phones and portable devices, have become one of the most important parts in common life.Efficient techniques for watching, navigating and sharing videos on mobile devices collaboratively are appealing in mobile environment.In this paper, we propose a novel approach supporting efficiently collaborative operations on videos with sketch gestures.Furthermore, effective collaborative annotation and navigation operations are given to interact with videos on mobile devices for facilitating users’ communication based on mobile devices’ characteristics.Gesture operation and collaborative interaction architecture are given and improved during the interactive process.Finally, a user study is conducted showing that the effectivity and collaborative accessibility of video exploration is improved.     

The Application Analysis of Concurrent Multipath Transfer over Broadband Network

In the network for data transmission using CMT,there are multiple paths to choose,and the time delay of each path is not the same,there is a certain issue packet out-of-order.This article studied and analyzed the packet transmission in the sender,for each path assigned specific packet sequence number,in order to reduce the random sequence problem,improve the efficiency of network transmission.In the network for data transmission using CMT,there are multiple paths to choose,and the time delay of each path is not the same,there is a certain issue packet out-of-order.This article studied and analyzed the packet transmission in the sender,for each path assigned specific packet sequence number,in order to reduce the random sequence problem,improve the efficiency of network transmission.     

An enhanced framework for providing multimedia broadcast/multicast service over heterogeneous networks

Multimedia broadcast multicast service （MBMS） with inherently low requirement for network resources has been proposed as a candidate solution for using such resources in a more efficient manner. On the other hand, the Next Generation Mobile Network （NGMN） combines multiple radio access technologies （RATs） to optimize overall network performance. Handover performance is becoming a vital indicator of the quality experience of mobile user equipment （UE）. In contrast to the conventional vertical handover issue, the problem we are facing is how to seamlessly transmit broadcast/multicast sessions among heterogeneous networks. In this paper, we propose a new network entity, media independent broadcast multicast service center （MIBM-SC）, to provide seamless handover for broadcast/multicast sessions over heterogeneous networks, by extensions and enhancements of MBMS and media independent information service （MIIS） architectures. Additionally, a network selection scheme and a cell transmission mode selection scheme are proposed for selecting the best target network and best transmission mode. Both schemes are based on a load-aware network capacity estimation algorithm. Simulation results show that the pro- posed approach has the capability to provide MBMS over heterogeneous networks, with improved handover performance in terms of packet loss rate, throughput, handover delay, cell load, bandwidth usage, and the peak signal-to-noise ratio （PSNR）.     

A novel algorithm for routing and wavelength assignment considering the load balancing

For the problem of routing and wavelength assignment in Wavelength Division Multiplexing （WDM） optical transport network, an algorithm based on the state of links is proposed, which is named Tradeoff_LSDRAW, and which can select a path with the higher state level between a pair of nodes in a network. Finally, by an example network, we show that the algorithm has the stronger capability of selecting a better path between a pair of nodes, and can achieve the load balancing and reduce the congestion probability in WDM optical transport networks.     

网络环境中流式数据传输应用的开发问题

The problems of transportation using streaming data structures in network application software are discussed. In particular ,the relationship between high-speed network performance and development techniques are studied. The efficiency of development,on one hand ,and the efficiency of runing ,on the other hand ,are considered. A compromise upon them is possible ,hereby based on object-criented methodology a middle-level approach is conducted.     

Demand Priority Protocol simulation and evaluation

A new network protocol (Demand Priority Protocol)environment can provide more satisfying service for different urgent transmission requests.In this paper,in order to provide guidance for the selection of environment of multimedia data transmission in Computer Supported Cooperative Work better,an objectoriented protocol specification language based on C is used to design a virtual environment of multiworkstation of computer cooperative work and to simulate execution of demand priority network protocol and then the performances of various transmission requests are analyzed.Finally,an evaluation of the demand priority LAN is given.     

A New Subdivision Algorithm for the Bernstein Polynomial Approach to Global Optimization

In this paper,an improved algorithm is proposed for unconstrained global optimization to tackle non-convex nonlinear multivariate polynomial programming problems.The proposed algorithm is based on the Bernstein polynomial approach.Novel features of the proposed algorithm are that it uses a new rule for the selection of the subdivision point,modified rules for the selection of the subdivision direction,and a new acceleration device to avoid some unnecessary subdivisions.The performance of the proposed algorithm is numerically tested on a collection of 16 test problems.The results of the tests show the proposed algorithm to be superior to the existing Bernstein algorithm in terms of the chosen performance metrics.     

A hybrid distributed-centralized conflict resolution approach for multi-aircraft based on cooperative co-evolutionary

Conflict resolution （CR） plays a crucial role in safe air traffic management （ATM）. In this paper, we propose a new hybrid distributed-centralized tactical CR approach based on cooperative co-evolutionary named the CCDG （cooperative co-evolutionary with dynamic grouping） strategy to overcome the drawbacks of the current two types of approaches, the totally centralized approach and distributed approach. Firstly, aircraft are divided into several sub-groups based on their interdependence. Besides, a dynamic grouping strategy is proposed to group the aircraft to better deal with the tight coupling among them. The sub-groups are adjusted dynamically as new conflicts appear after each iteration. Secondly, a fast genetic algorithm （GA） is used by each sub-group to optimize the paths of the aircraft simultaneously. Thirdly, the aircraft＇s optimal paths are obtained through cooperation among different sub-groups based on cooperative co-evolutionary （CC）. An experimental study on two illustrative scenarios is conducted to compare the CCDG method with some other existing approaches and it is shown that CCDG which can get the optimal solution effectively and efficiently in near real time, outperforms most of the existing approaches including Stratway, the fast GA, a general evolutionary path planner, as well as three well-known cooperative co-evolution algorithms.     

Iterative learning control for nonlinear systems with uncertain state delay and arbitrary initial error

Most of the existing iterative learning control algorithms proposed for time-delay systems are based on the condition that the time-delay is precisely available, and the initial state is reset to the desired one or a fixed value at the start of each operation, which makes great limitation on the practical application of corresponding results. In this paper, a new iterative learning control algorithm is studied for a class of nonlinear system with uncertain state delay and arbitrary initial error. This algorithm needs to know only the boundary estimation of the state delay, and the initial state is updated, while the convergence of the system is guaranteed. Without state disturbance and output measurement noise, the system output will strictly track the desired trajectory after successive iteration. Furthermore, in the presence of state disturbance and measurement noise, the tracking error will be bounded uniformly. The convergence is strictly proved mathematically, and sufficient conditions are obtained. A numerical example is shown to demonstrate the effectiveness of the proposed approach.     

Genetic algorithm approach for QoS-based tree topology construction in IEEE 802.16 mesh networks

The topological characteristics of an IEEE 802.16 mesh network including the tree’s depth and degree of its nodes affect the delay and throughput of the network.To reach the desired trade-off between delay and throughput,all potential trees should be explored to obtain a tree with the proper topology.Since the number of extractable tree topologies from a given network graph is enormous,we use a genetic algorithm(GA) to explore the search space and find a good enough trade-off between per-node,as well as network-wide delay and throughput.In the proposed GA approach,we use the Pruefer code tree representation followed by novel genetic operators.First,for each individual tree topology,we obtain expressions analytically for per-node delay and throughput.Based on the required quality of service,the obtained expressions are invoked in the computation of fitness functions for the genetic approach.Using a proper fitness function,the proposed algorithm is able to find the intended trees while different constraints on delay and throughput of each node are imposed.Employing a GA approach leads to the exploration of this extremely wide search space in a reasonably short time,which results in overall scalability and accuracy of the proposed tree exploration algorithm.     

基于主从样式的移动代理安全模型的研究与实现

In the ages of current network technology, as a new technology, the emergence of mobile agent shows us a wider and wider application prospect in the fields of network technology, such as Network Management,Intelligence Information Retrieval and Electronic Commence and so on. The security is the essence of mobile agent technology. In this paper we analyze the security issues and survey some representative approaches to solve the problem in mobile agent systems. We focus on the issues about the agent's security and propose a master-slave designpattern based security model for mobile agent called SMAP(Secure Mobile Agent Platform). In the end we give anapplication example to show how to use these.     

On localization with robust power control for safety critical wireless sensor networks

A hybrid methodology is proposed for use in low power, safety critical wireless sensor network applications, where quality-of-service orientated transceiver output power control is required to operate in parallel with radio frequency-based localization. The practical implementation is framed in an experimental procedure designed to track a moving agent in a realistic indoor environment. An adaptive time synchronized approach is employed to ensure the positioning technique can operate effectively in the presence of dataloss and where the transmitter output power of the mobile agent is varying due to power control. A deterministic multilateration-based positioning approach is adopted and accuracy is improved by filtering signal strength measurements overtime to account for multipath fading. The location estimate is arrived at by employing least-squares estimation. Power control is implemented at two separate levels in the network topology. First, power control is applied to the uplink between the tracking reference nodes and the centralized access point. A number of algorithms are implemented highlighting the advantage associated with using additional feedback bandwidth, where available, and also the need for effective time delay compensation. The second layer of power control is implemented on the uplink between the mobile agent and the access point and here quantifiable improvements in quality of service and energy efficiency are observed. The hybrid paradigm is extensively tested experimentally on a fully compliant 802.15.4 testbed, where mobility is considered in the problem formulation using a team of fully autonomous robots.