Yuh-Chung Lin

Improved Node Localization for WSN Using Heuristic Optimization Approaches

In Wireless Sensor Network, the localization of sensor nodes is an important problem in many applications. Normally in localization problem, the unknown position nodes will be determined their location through information of three or more anchors. In first part, some popular heuristic optimization methods like Genetic Algorithm (GA), Particle Swarm Optimization (PSO) will be compared with some recent optimization methods like Grey Wolf Optimizer (GWO), Firefly Algorithm (FA), and Brain Storm Optimization (BSO) algorithms in estimating the location of sensor nodes about accuracy. In second part, the improvement in localization algorithm is also proposed to enhance the number of nodes that can be localized. The results of our proposed improvement will be compared with original algorithm in both number of nodes that can be localized and the execute time with different deployment of networks.

Load-Balance Directed Diffusion in Wireless Sensor Networks

How to reduce the sensor node power consumption in wireless sensor networks is one of the important research issues. Many routing protocols based on the directed diffusion have been proposed to improve the network performance. Most of them calculate the gradient relied on power-related information and hop count, but do not maintain the selected path. In this paper, we propose a new path switching mechanism which automatically switches on the routes based on the known gradient information to achieve load balance.

Parallel Firefly Algorithm for Localization Algorithm in Wireless Sensor Network

Node localization has been a very active research topic in recent years. Accurate self-localization capability is highly desirable in wireless sensor network (WSN). In this paper, a node localization algorithm based on the received signal strength (RSS) measurements and Parallel Firefly Algorithm (PFA) in Wireless Sensor Networks (WSN) is proposed. By fully considering the distance factor, an improved objective function is defined, so the node localization problem in WSN could be transformed into a nonlinear unconstrained optimization problem. Giving the distances between a sensor and a few of its 1-hop neighbors, the proposed algorithm can estimate the sensor positions using Parallel Firefly Algorithm. Simulation results show that the proposed method can achieve better results than those obtained from the Particle Swarm Optimization (PSO), the Genetic Algorithm (GA) and the original methods in accuracy.

Dual migration for improved efficiency in cloud service

Wireless technologies enable users to retain their Internet access at anywhere and at anytime, without the tangling of wired cables. Users might want to keep enjoying their favor services when they are moving. However, the user mobility would causes longer and longer path to the serving server so that the QoS cannot be guaranteed. In order to maintain better QoS as a user moves, we proposed a novel and efficient cloud service architecture, named dual migration. The dual migration architecture keeps monitor the location of a user and migrates the contents what the user might need onto the closest server for the current location of the user. Therefore, the hop count of the path between a user and the corresponding server is short.

Implementation of indoor positioning using signal strength from infrastructures

Real time location system is not a brand new technology. The most typical approach is using global position system (GPS). However, GPS can only be used outdoors. It is unable to work completely indoors or in an environment with obstacles. Therefore, the development related to indoor position technology is quite important. In the system developed in this study, it makes use of Received Signal Strength Index value of low-power active RFID (Radio Frequency Identification) for movement detection. Besides, it adopts ZigBee wireless transmission technology as reference nodes for positioning detection. Information gathered by reference points is delivered to the server through the Internet. All positioning information is computed by the server. Positioning algorithm uses the average values of signals in its operation. The advantage is to compare many average values with the closing nodes in order to locate the closest position node for the mobile device and reduce the multi-path interference which is caused by other environmental factors. Positioning results can be accessed through the networked computer or mobile device with WiFi functionality. The experimental results are more stable than other positioning algorithms, and the installation of the system is more convenient.

Video-on-Demand with Differentiated QoS based-on Available Bandwidth in IPTV

In this paper we proposed a dynamic bandwidth detection scheme to adaptively switch the transportation quality of video streaming. Also an IPTV service system with a Video on Demand and Live video broadcast system is implemented to examine the performance of the dynamic bandwidth scheme. The result shows that it can adapt to the network environment to provide an appropriate video quality without suffering high delay or interruption.

Event-Based Clustering Architecture for Power Efficiency in Wireless Sensor Networks

In order to set up WSN in various rigorous environments, the size and power constraints are stricter due to the high demands for convenience and reliability. Therefore, power efficiency is very important for a WSN. For this, a novel architecture is presented in this paper. The proposed architecture categorizes sensors into different clusters by events. In each cluster, a minimum spanning tree is constructed for intracluster routing. The hierarchical architecture is useful in reducing the power consumption. In each intracluster routing tree, only leaf nodes are responsible for periodical detection. Data transmissions only occur when abnormal events are detected. An abnormality will be reported to the data center only if the majority of cluster members sense the same event. By reducing unnecessary data transmissions and shortening transmission distances, the proposed mechanism significantly reduces the power consumption and prolongs the network lifetime without influencing the accuracy of event response. The simulations show that the proposed architecture has about an 18-fold improvement rate in the device lifetime and avoids the false positive caused by the erroneous alarm of a single sensor. The proposed architecture is feasible, practical, and highly applicable to many applications.

An Efficient Packet Forwarding Mechanism Based on Bandwidth Prediction with Consideration of V2I and V2V Communications

In order to support users who are transporting by vehicles, more efforts are on the technology of vehicular networks. The high mobility and topology diversity of networks are the major challenges to develop technology for vehicular networks. For the sake of obtaining the status of vehicular networks in real time and estimating the quality of network connections accurately, this paper proposes an available real-time bandwidth estimation mechanism based on the properties of vehicular networks. By detecting the number of users within the transmission range and the mobile information provided by the vehicles, our paper focuses on accurately estimating the efficiency index of network connections. In this paper, we also propose an efficient packet forwarding mechanism to improve the transmission quality of network services requested by users and to enhance the overall network performance. The simulations are done to show the improvement of our proposed method.

Implementation of voice broadcasting systems using microcontrollers and SIP protocol

This paper presents our experience in using an 80MHz microprocessor and the SIP protocol to implement a cost-effective network based broadcasting system. At present, broadcasting systems generally use personal computer to transmit voice signals to terminals device. Several processes are involved in a network based broadcasting system, including voice sampling, coding, compression, transmission, decompression, and so forth. The system performance is generally limited by the operation system. Delay time in previous approaches can be up to 2 seconds or 3 seconds. The system in our design aims at a delay less than 1 second. In our design, a PC is replaced by a low-cost microprocessor. Issues on delay and synchronization become more critical. These problems are resolved dedicate chip for audio processing and synchronization using sequence number field within RTP protocol.