Min-Chieh Yu

Energy Efficient Clustering Scheme for Prolonging the Lifetime of Wireless Sensor Network With Isolated Nodes

A suitable clustering algorithm for grouping sensor nodes can increase the energy efficiency of WSNs. However, clustering requires additional overhead, such as cluster head selection and assignment, and cluster construction. This paper proposes a new regional energy aware clustering method using isolated nodes for WSNs, called Regional Energy Aware Clustering with Isolated Nodes (REAC-IN). In REAC-IN, CHs are selected based on weight. Weight is determined according to the residual energy of each sensor and the regional average energy of all sensors in each cluster. Improperly designed distributed clustering algorithms can cause nodes to become isolated from CHs. Such isolated nodes communicate with the sink by consuming excess amount of energy. To prolong network lifetime, the regional average energy and the distance between sensors and the sink are used to determine whether the isolated node sends its data to a CH node in the previous round or to the sink. The simulation results of the current study revealed that REAC-IN outperforms other clustering algorithms.

Improving indoor positioning precision by using received signal strength fingerprint and footprint based on weighted ambient Wi-Fi signals

Positioning is the foremost process in the location based service (LBS). With the GPS signal strength obstructed by the wall, indoor users cannot obtain their positions with the assistance from the global positioning satellites. Most of the indoor positioning systems have relied on received signal strengths (RSSs) from indoor wireless emitting devices, such as Wi-Fi access points (APs). Integrating indoor position information into the application on the modern handheld devices can increase the application diversity and quality in an indoor environment. In this paper, we propose a novel indoor positioning scheme assisted by the RSS fingerprint and footprint. Smartphone users can get their indoor position based on RSSs from the surrounding Wi-Fi APs. With the assistance of collecting ambient Wi-Fi RSSs from not only the intrinsic APs but also the extrinsic APs, filtering RSSs by directions/orientations, and mitigating signal fluctuation, our proposed scheme can overcome the severe signal instability problem in the indoor environment and raise the positioning accuracy. In order to reduce the time complexity of the indoor positioning procedure, we design a close designated location set (CDLS) algorithm that only uses the designated locations with the similar footprints of current users position to determine the users location. The proposed RSS fingerprint and footprint matching mechanism can speed up the positioning process. Meanwhile, to lessen the possible negative effect of extrinsic APs, the weighted voting positioning (WVP) algorithm would assign higher reference weights to the signals from the intrinsic APs, and adjust the weights to the signals from the extrinsic APs by their failure probability. The evaluation results show that our proposed scheme can achieve a certain level of accuracy in the indoor environments and outperform other solutions.

BOB-RED queue management for IEEE 802.15.4 wireless sensor networks

Multimedia services over resource constrained wireless sensor networks (WSNs) face a performance bottleneck issue from the gateway node to the sink node. Therefore, the queue management at the gateway node is crucial for diversified messages conveyed from the front nodes to the sink node. In this article, beacon order-based random early detection (BOB-RED) queue management is proposed. BOB-RED is a dynamic adaptation scheme based on adjusting beacon interval and superframe duration in the IEEE 802.15.4 MAC superframe accompanied with RED queue management scheme to increase the transmission efficiency of multimedia over WSNs. We focus on the performance improvement upon different traffic loads over WSNs. Evaluation metrics include end-to-end delay, packet delivery ratio, and energy consumption in IEEE 802.15.4 beacon enabled mode. Simulation results show that BOB-RED can effectively decrease end-to-end delay and energy consumption compared to the DropTail scheme.

Design and implementation of various file deduplication schemes on storage devices

As smart devices are revolutionized in recent years, people may generate enormous amount of various sized data and store them in the local or remote file system in their daily lives. With cheaper and easy to use private cloud storage appliances helping to handle the increasing demand of storing and sharing big volume of data, effective file deduplication schemes can greatly increase the space efficiency in private cloud storage systems as well as preserve network bandwidth. In the paper, we aim at designing and implementing several file deduplication schemes built in the private cloud storage appliance, based on different duplication checking rules, including file name, file size, and file partial/full content hash value. Experiment results show using partial content hashing based file deduplication scheme achieves a reasonably balanced performance without overutilized limited local computational resources.

Improving Network Coding Based File Sharing for Unstructured Peer-to-Peer Networks

Abstract A network coding based peer-to-peer (P2P) file sharing system has been proposed in recent years. It uses the random combination of encoded pieces to make the file sharing more effective. Most of the conventional P2P file sharing systems adopt a random (or rarest piece first) transmission policy to avoid too many duplicated pieces and rare pieces occurring in the network. Network coding can simply solve this problem. However, some of the studies show that network coding brings the overhead of coding/decoding delay and message overhead; after all, the performance of network coding is not better than other schemes that are without network coding. Therefore, we propose a network coding based file sharing system over unstructured P2P networks considering the overhead from the network coding. We make comparisons with other schemes without network coding. Our simulation results show that the proposed network coding based file sharing system is better than others, when the network coding scheme and non-network coding scheme adopt the same network environment even though the network coding is executed under a limited computation resource.

Adaptive weighted scheme for improving mobile sensor node connectivity in IEEE 802.15.4 networks

Conventional IEEE802.15.4 wireless sensor network is suitable for fixed sensor nodes. However, there are some issues with mobile sensor nodes joining or leaving the sensor network since the mobile sensor node is easier to lose its connectivity compared to the fixed sensor nodes. In order to regain its connectivity, the mobile sensor nodes must spend more time and energy to perform the re-association procedure, resulting in an efficiency decay of the sensor network. To solve this problem, we refer to the previous research to design an adaptive weighted link quality indicator prediction based scheme in the media access layer. The proposed scheme can reduce the non-connectivity time of mobile sensor node by early performing the re-association procedure. Additionally, we design a simple procedure to lessen the Ping-Pong effect problem without additional computation overhead, thereby improving stability of the connection between the mobile sensor node and its corresponding coordinator.

Improving Security and Privacy of Images on Cloud Storage by Histogram Shifting and Secret Sharing

Nowadays people can easily use any smart device at hand to capture scenery and then upload it to the cloud storage. Cloud storages are widely used for storing the generated multimedia content. However, the risk of potential private data leakage may exist since cloud storages are normally in a public domain. To enhance the security and privacy of images on the cloud storage, we proposed an integrated scheme evolving invisible digital watermarking and masking which are based on the histogram shifting method. The histogram modification based scheme can achieve reversible data hiding, to ensure the integrity and the confidentiality of the image data. Additionally, we use the secret sharing scheme to keep the secret keys to further improve the security of data access. The evaluation results show that the proposed system can effectively prevent the malicious user from accessing the private images.

Kernel Weighted Scheme for Improving Mobile Sensor-Node Connectivity

In the past decade, interest in fixed wireless sensor networks shifted to reflect current developments in mobile sensor networks with prominent mobility. However, due to the issues caused by joining or leaving the sensor network, a mobile sensor node is vulnerable to lose its connectivity. To regain its connectivity, a mobile sensor node must spend more time and energy to perform the reassociation procedure, resulting in an efficiency decay of the sensor network. To overcome this problem, we design a kernel moving average scheme based on the quality indicator prediction in the media access layer. The proposed scheme can reduce the nonconnectivity time of mobile sensor node through early performance of the reassociation procedure.

A neuroevolution strategy using multi-agent incorporated hierarchical ensemble model

In this study, a neuroevolution strategy using Multi-Agent Incorporated Hierarchical Ensemble Model (MAIHEM) inspired by human incorporated company structure is proposed. It utilizes the hierarchical structure to ensemble modules of entities into firms to preserve complex structure at lower level, and at higher level incorporates firms into departments to facilitate multiple objectives. The corporate level structure from the top guides and reviews their overall performance. The ensemble structure not only compete within their own ranks, but also cooperate and swap/merger underlying units for fast adaptation without compromising their existing structures. The preliminary result with multi-constrained music melody generation shows this strategy can not only solve complex multi-objective tasks steadily but also preserve diversity in the population.

Enhancing security and privacy of images on cloud by histogram shifting and secret sharing

In contemporary society, people can easily use any smart device at hand to capture images of scenery and upload them to cloud storage. Cloud storage is widely used for storing user generated multimedia content. However, the risk of potential private data leakage exists because cloud storage is normally in a public domain. To protect the privacy information of images on cloud storage, we propose an integrated scheme involving invisible watermarking, masking and secret sharing methods. The histogram modification-based scheme can achieve reversible data hiding to ensure the integrity and confidentiality of image data. Additionally, a secret sharing scheme was used to further improve the security of data access. The evaluation results show that the proposed system may prevent malicious users from accessing private images.