Zhi Zhong

Bio: Zhi Zhong is an academic researcher from Central South University. The author has contributed to research in topics: Wireless sensor network & Mobility model. The author has an hindex of 5, co-authored 6 publications receiving 66 citations.

Distributed image coding in wireless multimedia sensor networks: A survey

Abstract: There are a large number of video data have to be processed and transmitted in resource-constrained wireless multimedia sensor networks (WMSN). One possible way of achieving maximum utilization of those resources is to apply an adaptive image coding scheme, which must consider the trade-off between energy consumption and image quality. The the major research challenges and objectives of image coding for WMSN are discussed. Distributed image coding schemes especially designed for WMSN and some theoretical explorations are investigated and classified, including Wyner-Ziv coding and collaborative coding.

Design and realization of improved LZW algorithm for wireless sensor networks

Abstract: This paper proposes two improved lossless data compression schemes based on Lempel-Ziv-Welch coding (LZW) for wireless sensor networks. The schemes preprocess numeric data in different ways to adapt the data characteristics. In order to increase the compression rate, the value span of data is decreased by calculating increment between the sample sequence and the base value. Since the LZW is commonly effective for text data but do not apply to numeric data, the increments are replaced into the English characters respectively. Using the IAR 430 Development Environment for ultra-low power MSP430 series microcontrollers, the paper verifies the improved schemes, and the simulation tests show the improved lossless data compression schemes have remarkable superiority in reducing storage space and increasing the compression ratio.

Low complexity image compression for wireless multimedia sensor networks

Abstract: The problem of compression of video-surveillance sequences collected by a wireless multimedia sensor networks is studied. To reduce computation complexity, a low-complexity image compression scheme based on change detection and adapted JPEG is proposed. Change detection is used to locate the region of interest and cut down the data for transmission, fast DCT is used to reduce the computation complexity. Such an image compression scheme provides a graceful trade-off between the reconstructed images quality and the lifetime of sensor nodes. Simulations on the parking lot images are conducted to show the performance of our work.

A survey on mobile anchor assisted localization techniques in wireless sensor networks

Abstract: Identifying locations of sensor nodes in wireless sensor networks (WSNs) is significant for both network operations and most application level tasks. Although, geographical positioning system (GPS) based localization schemes are used for determining node locations but the cost of GPS devices and non-availability of GPS signals in indoor environments prevent their use in large scale WSNs. A substantial amount of research work exist that intend at obtaining precise and relative spatial locations of sensor nodes without requiring large amount of specialized hardware. Mobile anchor assisted localization is one typical approach that significantly reduces the implementation cost by using limited number of mobile anchors. In this survey, we present key issues and inherent challenges faced by the mobile anchor assisted localization techniques in WSNs. We take a closer look at the algorithmic approaches of various important fine-grained mobile anchor assisted localization techniques applicable in WSNs. In addition, we highlight the error refinement mechanisms adopted by the state-of-the-art works associated with their approaches. Well known mobile anchor trajectories presented in existing works are also reviewed. Finally, open research issues are discussed for future research scope in this field.

A Novel Architecture Based on Cloud Computing for Wireless Sensor Network

Abstract: Wireless sensor network (WSN) is widely applied in many fields since its emergence. However, the limited resources of a sensor, especially limited battery life, limited bandwidth and limited processing power, are the main challenges for deploying and operating WSNs. This paper proposes a novel architecture based on cloud computing for wireless sensor network, which can improve the performance of WSN. Based on this architecture, a cloud acts as a virtual sink with many sink points that collect sensing data from sensors. Each sink point is responsible for collecting data from the sensors within a zone. Sensing data are stored and processed in distributed manner in cloud. Our simulation results show that the proposed architecture improves the performance of WSN, e.g., reduced packet transmission error rate, decreased number of end-to-end hops, and improved efficiency of energy consumption.

Securing data exchange in wireless multimedia sensor networks: perspectives and challenges

Abstract: The emerging use of Wireless Multimedia Sensor Networks (WMSNs) and communication facilities have increased the need for network security measures to protect different types of multimedia data either real time or non-real time during the transmission period. A lot of researchers are becoming more interested on secure WMSNs due to the broad application necessities which can be range over smart environment, security surveillance and smart health-care; so requirements on secure aggregation of multimedia data, Quality of Service (QoS) and privacy should be satisfied. Current technologies vs. proposed security techniques in WMSNs and its pros and cons from a security point of view are explored in details. In addition to promising future trends of this research area by giving more attention for new challenging problems including secure routing protocol, fault tolerant, robustness and recovery process. We believe that this paper will add significantly a valuable discussion among the researchers and promote them to fetch new research ideas to design approximately best model by combining the most important security issues in order to reach secure WMSNs.

Energy Aware and Adaptive Cross-Layer Scheme for Video Transmission Over Wireless Sensor Networks

Abstract: Wireless multimedia sensor networks (WMSNs), is an ad hoc network of wirelessly connected sensor nodes that allow retrieving video and audio streams, still images, and scalar sensor data but such sensors are limited in energy, memory, communication, and computational power. Multimedia transmission over wireless sensor network (WSN) is a challenging task due to quality-of-service(QoS) guarantees such as huge amount of bandwidth, strict delay, and lower loss ratio. Recently, cross-layer approach adopted by WMSNs shows a promising approach that improves quality of multimedia transmitted over WSNs under different wireless conditions. In this paper, an energy aware and adaptive cross layer scheme to transmit multimedia content over WSNs is presented. It provides packet, queue, and path scheduling, so that it selects optimal video encoding parameters at application layer according to current wireless channel state, and schedules packets according to its type through an adaptive priority video queue so that less important packets are dropped in case of network congestion. Finally, path scheduling is introduced so that different packets types/priority are routed through different paths with different QoSs considering network lifetime. Simulation results show that new scheme transmits video over WSNs efficiently and meets QoS requirements and uses energy wisely to prolongs network lifetime.

On precise path planning algorithm in wireless sensor network

Abstract: Wireless sensor network is a collection of small devices called sensors nodes, which are deployed in the sensing field to monitor physical and environmental information. Location information of sen...