DESIGN AND DEVELOPMENT OF ENERGY EFFICIENT COMPRESSIVE SENSING BASED APPLICATIONS FOR WVSN A SYNOPSIS Submitted by SUBBULAKSHMI T.C. in partial fulfilment of the requirements for the degree of DOCTOR OF PHILOSOPHY FACULTY OF COMPUTER SCIENCE AND ENGINEERING ANNA UNIVERSITY CHENNAI 600 025 OCTOBER 2018 2 1. INTRODUCTION Due to the advancement of technology, several real-time applications are presented to the society for improvising the quality of life. The real-time applications are claimed to be successful only when better accuracy rates with reasonable speed is proven. In order to improve the quality of service and the standard of the application, several changes are incorporated to the existing technologies. On that front, the Wireless Sensor Networks (WSN) are tailored with respect to the requirements of the application. Wireless Visual Sensor Networks (WVSN) is one among many kinds of network and it has gained substantial research interest due to its wider applicability. Usually, the WVSN is employed for real-time intelligent systems. A WVSN is composed of numerous wireless nodes, which are packed with a processor, power back-up, image sensor and transceiver [1, 2]. The nodes of this network sense and share the data with the Base Station (BS) or the powerful sink node, which is meant for processing the data locally. As WVSN is based on WSN, the basic characteristics such as distributed environment, wireless communication and energy restriction are inherited to it. The major functionality deviation of WVSN from WSN is the capability of environment sensing. The sensor nodes of WVSN capture the environment in three different dimensions in the place of normal one. Hence, WVSN is usually employed in environment monitoring and surveillance based applications. The sensor nodes of WVSN take the video of the specific area and forward the captured video to the processing unit by means of relay nodes. The underlying point here is that it is unnecessary to transmit the video to the processing unit, unless some variation or change is involved in the video. This idea conserves energy, which in turn helps in maximizing the lifetime of the 3 network. At this juncture, the concept of Compressive Sensing (CS) comes into picture. The CS technique accumulates and forwards the mandatory components (X) instead of the entire Y samples [3]. Though the complete samples are not forwarded, the CS ensures the better data recovery. This is achieved by computing the sparsity degree of the signal. The sensor node of WVSN takes the video of a scene and performs CS for computing the sampling measurements. The so computed sampling measurements are forwarded to the destination and the video is rebuilt by the recovery algorithm. This research work is based on the utilization of immobile cameras, such that the background is the same at all times. Hence, in order to conserve energy the background part of the video can be subtracted. In other words, the foreground of the video can easily be processed, which is the target of any application. Understanding the benefits of compressive sensing, this research work intends to propose three different research solutions for WVSN that ensure energy efficiency. The initial research phase aims to present a forepart detection mechanism with dynamic compressive measurements. The second research phase proposes a compressive sensing technique by considering the texture content of the input. The final phase of this research introduces a technique to fuse images with the help of compressive sensing. The performances of all the proposed approaches are tested in terms of standard performance measures and the proposed approaches yield satisfactory results. 2. RELATED LITERATURE This section aims to provide the related works in the existing literature with respect to compressive sensing in WSN. 4 In [4], a parking lot occupancy detection system is proposed by utilizing WVSN. This system analyses the video and performs compression. This system is claimed to be flexible and can be utilized in the environment with multiple camera nodes. A relevance based approach for multi-sink mobility is presented for smart city application by WVSN in [5]. This work presents an algorithm for effective localization of several mobile sinks over the roads and streets. This approach increases the data transmission rate by placing the mobile sink node closer to the source nodes with better sensing relevance. In [6], an energy efficient low bit rate image compression is presented in wavelet domain for image sensor networks. This work proposes a new approximation band transform algorithm and it works by extracting and encoding the image approximations by means of fixed-point arithmetic. This idea conserves the energy of resource constrained sensor networks. The sensing, coding and transmission functionalities of visual sensor networks for smart city applications are modelled by means of fuzzy based approach in [7]. This work configures the activities of the sensors such as sensing, coding and transmission in a dynamic way by utilizing different parameters. An energy efficient image compressive transmission scheme is proposed for wireless camera networks in [8]. This work states that this work can extract the regions of interest, controls the quality of image and carries out better image communication. The performance of this approach is tested in terms of image quality, execution time and energy consumption. In [9], an energy efficient image transmission scheme for wireless multimedia sensor networks is presented on the basis of block based compressive sensing. The encoding algorithm of CS measurements is proposed by considering Bernoulli measurement matrix. The performance of the proposed approach is tested in terms of energy consumption and image quality. 5 In [10], an image coding scheme based on compressive sampling is presented for visual communication. This work encodes the image by performing polyphase down-sampling. Additionally, the local random convolutional kernel is utilized before the process of down-sampling. These measurements are utilized for preserving the features with greater frequency and to remove redundancy. An efficient image coding and transmission system based on scrambled block compressive sensing is presented in [11]. This work employs scrambled block compressive sampling for performing image measurement by means of a sensing operator. This is followed by the execution of progressive nonuniform quantization and the progressive non-local low-rank reconstruction is utilized at the decoder side. In [12], a Discrete Cosine Transform (DCT) based multi-focus image fusion scheme is presented for VSN. The fusion system mainly focuses on the Alternating Current (AC) coefficients computed in the DCT domain. This method is claimed to prove better image quality and minimal energy consumption. A clustering based data compression scheme based on k-means algorithm is proposed for wireless imaging sensor networks in [13]. This work compresses the images by means of k-means algorithm by considering the colour of image pixels and the image is compressed. A survey on sensor coverage, visual data acquisition, processing and transmission is presented in [14]. An adaptive compressed sensing rate assigning algorithm based on standard deviation of the image blocks for wireless image sensor network is presented in [15]. In this work, all the image blocks are fixed with a static sampling rate. Additionally, an adaptive sampling rate is passed into all the blocks, such that greater sampling rates are allotted to blocks that are minimal 6 compressible. Finally, the fixed and the adaptive measurements are considered together to form the final measurements. In [16], an adaptive compressive sensing for tracking the targets in WVSN based surveillance is presented. The adaptive compressive sensing can achieve greater compression rates with respect to the sparsity nature of different datasets. In addition to this, it is unnecessary to compress the whole image; instead the relative blocks that contain the target can alone be compressed. The image compression algorithms for wireless multimedia sensor networks are reviewed in [17]. In [18], a video compressed sensing framework is presented for wireless multimedia sensor networks by utilizing a combination of several matrices. This work utilizes the combination of Discrete Wavelet Transform (DWT) and Discrete Cosine Transform (DCT) for performing compression. This work is proven to be better than Gaussian matrix. 3. RESEARCH MOTIVATION Due to the advent of modern automation technology, the WSN flourishes with several interesting branches. WVSN is one of the important branches, which attempts to capture videos from different places and it plays an important role in the area of security. As the WVSN deals with real-time videos, the energy of the sensors must be utilized wisely. Considering this fact, this research work pays utmost attention to bring in energy efficiency by incorporating the concept of compressive sensing in all the three research phases. Each phase is unique and the overall theme of this work is to ensure energy efficiency. The energy efficiency of the sensors results in improvised lifespan of the network. 7 4. RESEARCH GOALS The central goal of this research is to attain energy efficiency in WVSN, such that the lifespan of the network is reasonable and purposeful. As WVSN deals with multimedia data, the energy of the sensors drains faster. The energy consumption of the sensors is balanced and controlled with the help of compressive sensing. The aim of compressive sensing is to control the amount of data transfer, which contributes a lot in conserving energy efficiency. All the three phases of the research work employs compressive sensing to manage the energy consumption and proves better energy conservation. 5. ALGORITHM AND METHODOLOGY The initial research phase presents an energy conserving scheme that extracts the forepart from the background scene. The compressive measurements are dynamically computed by this work, which reduces the overhead and energy consumption. This work selects minimal yet, optimal compressive measurements and forwards it to the destination side. The destination side rebuilds it with the help of Compressive Sampling Matching Pursuit (CoSaMP) algorithm. The second phase of this research intends to present an adaptable compressive sensing scheme by considering the textural pattern of the input frame. This idea overthrows the concept of standardized compressive sensing, which treats all the parts of the frame similarly. However, the adaptable compression sensing scheme considers the texture pattern of the frame and adjusts itself. This idea guarantees better image quality after the process of rebuilding. The overall algorithm of this research work is summarized and presented as follows. 8 Overall Algorithm //Research Phase I Input : Videos Output : Forepart detection Begin 𝑓𝑔 Assess 𝑘𝑡𝑝 from the compressive measurements; Assess cross validation measurements; Detect forepart; If (𝑝𝑡 ≥ 𝑠𝑡𝑡𝑝 ) Transmit to the destination; Else Discard the measurements; End if; // Destination Rebuild by CoSaMP; End; //Research Phase II Input :Videos Output : Adaptable compressive sensing Begin Sample the input video frame; Calculate the texture by GLVP; Fix the sampling rate; Construct the transformation matrix mat; Process mat and rebuild the image by CoSaMP; End; //Research Phase III Input : Videos from different sensors Output : Detailed images Begin Extract video frames; 9 For all video frames do Apply Shearlet and Curvelet over the image frames; Compute local spatial frequency row-wise and column-wise; Fuse the video frames; End do; End; The third phase of the research attempts to fuse the images being captured by different sensors based on compressive sensing, so as to gain more information about the image. This concept of image fusion results in better visibility of the image by providing intricate details. Hence, all the three phases employ compressive sensing for achieving better energy efficiency, while preserving the quality of the frame. The performance of the proposed approaches is validated by means of standard performance measures such as energy efficiency and quality based measures such as Peak-Signal-to-Noise-Ratio (PSNR) and Mean Square Error (MSE). 6. RESULTS The proposed approach is simulated in Matlab environment on a stand alone computer with 8 GB RAM. The proposed approach is analysed by utilizing different video streams downloaded randomly. The size of the video frame is 288 × 352, the sparsity and the compressive measurements are dynamic. The sample results of the proposed approaches are tabulated as follows. 10 Table 1: Experimental Results of Proposed Approaches Research Phase 1 – Energy Conserving Forepart Detection Scheme with Dynamic Compressive Measurements based on Compressive Sensing for WVSN Comparative Techniques Performance measures Precision Recall (%) F-Measure Average Energy (%) (%) Consumption Rate (mJ) CS-BS [19] 37.8 38.2 37.99 68.56 CS-BS [20] 77.2 75.8 76.49 65.26 Hybrid Matrix Based [21] 87.9 84.4 86.11 8.3 Proposed 89.6 86.7 88.12 7.33 Research Phase 2 – Texture based Adaptable Compressive Sensing Scheme for WVSN Comparative Techniques PSNR Energy Execution Time (ms) Consumption Rate (mJ) Hybrid matrix based [21] 30.83 11.8 1943 Phase I 32.98 9.9 1876 Proposed 37.8 9.2 1765 Research Phase 3 – Compressive sensing based Image Fusion for WVSN Comparative Techniques PSNR Energy Execution Time (ms) Consumption Rate (mJ) Shearlet only 23.83 1897 8.9 Curvelet only 32.98 9.2 1869 Shearlet + Curvelet 10.1 1949 38.4 The above presented table presents the sample results of the proposed approaches. From the experimental results, it is evident that the proposed approaches perform well with better quality, while consuming reasonable energy. 7. ORGANIZATION OF THE THESIS The whole thesis is categorized into six chapters and the outline of each and every chapter is presented below. Chapter 1 presents the basic idea of WSN that includes the architecture and branches of WSN. The fundamental concept of WVSN and the challenges associated with it are explained. In addition to this, the motivation and objectives of the thesis are explored in this chapter. 11 Chapter 2 intends to study the related literature with respect to the energy efficiency of WVSN. Additionally, the state-of-the-art approaches are studied in this chapter. Chapter 3 presents an energy conserving forepart detection scheme with dynamic compressive measurements by employing compressive sensing for WVSN. The proposed approach is presented in detail and the performance of the work is analysed and compared with the existing approaches. Chapter 4 proposes a texture based Adaptable Compressive Sensing Scheme for WVSN. This work considers the texture of the video frames into account and the sampling rate is altered accordingly. This idea enhances the quality and is proven by the PSNR value. Chapter 5 introduces a compressive sensing based Image Fusion for WVSN, which attempts to fuse video frames captured by infrared and visible sensors. This work ensures better quality and preserves the energy as well. Chapter 6 presents the concluding remarks, which includes both positive and negative sides of the research. Additionally, the possible future research directions are also presented. References [1] Tavli, B., Bicakci, K., Zilan, R. and Barcelo-Ordinas, J.M., 2012. A survey of visual sensor network platforms. Multimedia Tools and Applications, 60(3), pp.689-726. 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K-Means clustering-based data compression scheme for wireless imaging sensor networks. IEEE Systems Journal. 2015 Oct 30. [14] Yap FG, Yen HH. A survey on sensor coverage and visual data capturing/processing/transmission in wireless visual sensor networks. Sensors. 2014 Feb 20;14(2):3506-27. [15] Zhang J, Xiang Q, Yin Y, Chen C, Luo X. Adaptive compressed sensing for wireless image sensor networks. Multimedia Tools and Applications. 2017 Feb 1;76(3):4227-42. [16] Fayed S, Youssef SM, El-Helw A, Patwary M, Moniri M. Adaptive compressive sensing for target tracking within wireless visual sensor networks-based surveillance applications. Multimedia Tools and Applications. 2016 Jun 1;75(11):6347-71. [17] ZainEldin H, Elhosseini MA, Ali HA. Image compression algorithms in wireless multimedia sensor networks: A survey. Ain Shams Engineering Journal. 2015 Jun 1;6(2):481-90. [18] Nandhini SA, Sankararajan R, Rajendiran K. Video compressed sensing framework for wireless multimedia sensor networks using a combination of multiple matrices. Computers & Electrical Engineering. 2015 May 1;44:51-66. [19] Cevher Volkan, Sankaranarayanan Aswin, Duarte Marco F, Reddy Dikpal, Baraniuk Richard G, Chellappa Rama. Compressive sensing for background subtraction. In: Computer vision-ECCV 2008. Berlin Heidelberg: Springer; 2008. p. 155–68. [20] Manimozhi S, Aasha Nandhini S, Radha S. Compressed sensing based background subtraction for object detection in WSN. In: IEEE international conference on communication and signal processing (ICCSP). [21] Sukumaran AN, Sankararajan R, Swaminathan M. Compressed sensing based foreground detection vector for object detection in wireless visual sensor networks. AEU-International Communications. 2017 Feb 1;72:216-24. Journal of Electronics and 14 Research Publications 1. Subbulakshmi T.C., Dr. Gnanadurai, D., Dr. Muthulakshmi I., 2018, “Energy Conserving Forepart Detection Scheme with Dynamic Compressive Measurements based on Compressive Sensing for WVSN”, Journal of Internet Technology, Accepted. 2. Subbulakshmi T.C., Dr. Gnanadurai, D., Dr. Muthulakshmi I., 2018, “Texture based Adaptable Compressive Sensing Scheme for WVSN”, International Journal Intelligent Engineering and Systems, Article in Review. 3. Subbulakshmi T.C., Dr. Gnanadurai, D., Dr. Muthulakshmi I., 2018, “Compressive sensing based Image Fusion for WVSN”, International Journal Engineering and Technology (UAE), Article in Review.