Duc Minh Pham

Energy Efficient Image Transmission in Wireless Multimedia Sensor Networks

The key obstacle to communicating images over wireless sensor networks has been the lack of suitable processing architecture and communication strategies to deal with the large volume of data. High packet error rates and the need for retransmission make it inefficient in terms of energy and bandwidth. This paper presents novel architecture and protocol for energy efficient image processing and communication over wireless sensor networks. Practical results show the effectiveness of these approaches to make image communication over wireless sensor networks feasible, reliable and efficient.

Object extraction scheme and protocol for energy efficient image communication over wireless sensor networks

To date, wireless sensor networks lack the most powerful human sense - vision. This is largely due to two main problems: (1) available wireless sensor nodes lack the processing capability and energy resource required to efficiently process and communicate large volume of image data and (2) the available protocols do not provide the queue control and error detection capabilities required to reduce packet error rate and retransmissions to a level suitable for wireless sensor networks. This paper presents an innovative architecture for object extraction and a robust application-layer protocol for energy efficient image communication over wireless sensor networks. The protocol incorporates packet queue control mechanism with built-in CRC to reduce packet error rate and thereby increase data throughput. Unlike other image transmission protocols, the proposed protocol offers flexibility to adjust the image packet size based on link conditions. The proposed processing architecture achieves high speed object extraction with minimum hardware requirement and low power consumption. The system was successfully designed and implemented on FPGA. Experimental results obtained from a network of sensor nodes utilizing the proposed architecture and the application-layer protocol reveal that this novel approach is suitable for effectively communicating multimedia data over wireless sensor networks.

Efficient parallel architecture for multi-level forward discrete wavelet transform processors

A resource efficient and high-performance architecture for a two-dimensional multi-level discrete wavelet transform processor is presented in this paper. The JPEG2000 standard integer lossless 5-3 filter has been implemented. It achieves optimal hardware utilisation with minimal combinational logic block slices and high frequency of operation. To reduce the hardware complexity and to achieve high performance the proposed architecture implements lifting scheme with a single multiplier-free processing element to perform both predict and update operations. Symmetric extension is used at image boundaries without requiring any extra clock cycle. The generic architecture is very flexible and can perform up to five levels of forward transform on any arbitrary image size. Synthesis of the 5-level architecture on Xilinx Virtex 5 FPGA shows that the processor can achieve a maximum frequency of operation of 221.44MHz. The reduced hardware complexity and high frequency of operation render the design suitable for incorporation in image processing applications requiring fast operations. The 5-level design has been successfully implemented on a Xilinx Spartan 3E FPGA, utilising only 1104 slices for a 512-by-512 pixel test image, the lowest hardware requirements for a 5-level discrete wavelet transform processor reported to date.

A Real-Time Localization System for an Endoscopic Capsule Using Magnetic Sensors

This paper presents a real-time magnetic tracking system for an endoscopic capsule intended to deliver biomarkers around specific locations of the gastrointestinal (GI) tract. Unlike radio frequency (RF) and ultrasonic signals, static magnetic signals suffer negligible attenuation within the human body. The magnetic tracking systems proposed to date use a large number of sensors, making them too complex to apply in practice. In this paper, a new magnetic tracking system is proposed with much reduced complexity. In this system, the capsule only needs a magnet for localization, and does not require any electronics or battery. Mathematical model and a tracking algorithm were developed to find the location of a magnetic marker in the gut. Laboratory test results and in vivo animal trials show that the system is capable of tracking a magnetic marker with expected accuracy.

FPGA-Based Image Processor Architecture for Wireless Multimedia Sensor Network

This paper presents the architecture of a FPGA-based efficient processing system suited to Wireless Multimedia Sensor Networks. The core is a 16-bit RISC microprocessor, which is designed to operate at low frequency and is optimized for handling instructions and operations of the Wireless Sensor Networks. A part of the processor is empowered with image processing functions, optimized for handling image processing instructions and operates at high frequency. The image processing function of the processor is optimized to achieve high speed processing with minimal hardware and power consumption. Experiments have been conducted to verify the image compression and transmission ability of the proposed design and to investigate other WMSN issues such as image packetization, power management and system synchronization. These experiments reveal that the proposed approach is suitable for WMSN applications and removes a many issues associated with using off-the-shelf processors.

An energy efficient image compression scheme for Wireless Sensor Networks

While wireless sensor networks are finding an ever increasing number of applications in many areas, they still lack the most powerful human sense - vision. This is largely due to the problems associated with processing and communicating the large volume of image data over energy constrained sensor nodes. Available wireless sensor nodes are severely constrained in both processing capability and energy. This paper presents an innovative architecture and protocol for energy efficient processing and communication of images over wireless sensor networks. The proposed hardware architecture is optimized to achieve high speed image compression with minimum hardware requirement and low power consumption. An efficient and reliable transmission protocol for compressed image is also presented. It incorporates an effective image packet queue control strategy to reduce packet error rate and increase image transmission throughput. Experimental results demonstrate the effectiveness of these novel approaches to make image compression and communication over wireless sensor networks feasible, reliable and efficient.

FPGA architecture for object extraction in Wireless Multimedia Sensor Network

This paper presents the architecture of a FPGA-based efficient image processing system suited to Wireless Multimedia Sensor Networks. The system consists of two major processing elements: a customized processor for the networking functions and an image processing block. The latter enables the system to detect and extract any updated objects in captured images in real-time. The proposed architecture is optimized to achieve high speed processing with minimum hardware requirement and power consumption. Experimental results show that for a detected object of average size, the proposed architecture helps to reduce the total energy consumption by approximately twenty times compared to the energy consumed for raw image transmission. The system was successfully designed and implemented on FPGA. Implementation results of a network utilizing the proposed architecture reveal that this novel approach is suitable for Wireless Multimedia Sensor Network due to low hardware and low energy requirement for image communication.

A real-time localization system for an endoscopic capsule

This paper presents a real-time magnetic tracking system for an endoscopic capsule intended to deliver biomarkers around specific locations of the gastrointestinal (GI) tract. Unlike radio frequency (RF) and ultrasonic signals, static magnetic signals suffer negligible attenuation within the human body. The magnetic tracking systems proposed to date use a large number of sensors, making them too complex to apply in practice. In this paper, a new magnetic tracking system is proposed with much reduced complexity. In this system, the capsule only needs a magnet for localization, and does not require any electronics or battery. Mathematical model and a tracking algorithm were developed to find the location of a magnetic marker in the gut. Laboratory test results and in vivo animal trials show that the system is capable of tracking a magnetic marker with expected accuracy.

On Efficient Design of LDPC Decoders for Wireless Sensor Networks

Low density parity check (LDPC) codes are error-correcting codes that offer huge advantages in terms of coding gain, throughput and power dissipation in digital communication systems. Error correction algorithms are often implemented in hardware for fast processing to meet the real-time needs of communication systems. However,traditional hardware implementation of LDPC decoders require large amount of resources, rendering them unsuitable for use in energy constrained sensor nodes of wireless sensor networks (WSN). This paper investigates the use of short-length LDPC codes for error correction in WSN. It presents the LDPC decoder designs, implementation, resource requirement and power consumption to judge their suitability for use in the sensor nodes of WSN. Due to the complex interconnections among the variable and check nodes of LDPC decoders, it is very time consuming to use traditional hardware description language (HDL) based approach to design these decoders. This paper presents an efficient automated high-level approach to designing LDPC decoders using a collection of high-level modelingtools. The automated high-level design methodology provides a complete design flow to quickly and automatically generate, test and investigate the optimum (length) LDPC codes for wireless sensor networks to satisfy the energy constraints while providing acceptable bit-error-rate performance.

A simple and inexpensive enteric-coated capsule for delivery of acid-labile macromolecules to the small intestine *

Understanding the ecology of the gastrointestinal tract and the impact of the contents on the host mucosa is emerging as an important area for defining both wellness and susceptibility to disease. Targeted delivery of drugs to treat specific small intestinal disorders such as small bowel bacterial overgrowth and targeting molecules to interrogate or to deliver vaccines to the remote regions of the small intestine has proven difficult. There is an unmet need for methodologies to release probes/drugs to remote regions of the gastrointestinal tract in furthering our understanding of gut health and pathogenesis. In order to address this concern, we need to know how the regional delivery of a surrogate labeled test compound is handled and in turn, if delivered locally as a liquid or powder, the dynamics of its subsequent handling and metabolism. In the studies we report on in this paper, we chose 13C sodium acetate (13C-acetate), which is a stable isotope probe that once absorbed in the small intestine can be readily measured non-invasively by collection and analysis of 13CO2 in the breath. This would provide information of gastric emptying rates and an indication of the site of release and absorptive capacity. In a series of in vitro and in vivo pig experiments, we assessed the enteric-protective properties of a commercially available polymer EUDRAGIT® L100-55 on gelatin capsules and also on DRcaps®. Test results demonstrated that DRcaps® coated with EUDRAGIT® L100-55 possessed enhanced enteric-protective properties, particularly in vivo. These studies add to the body of knowledge regarding gastric emptying in pigs and also begin the process of gathering specifications for the design of a simple and cost-effective enteric-coated capsule for delivery of acid-labile macromolecules to the small intestine.總結目 的通过开展胃肠道远端释放药物的研究,以增加对肠道健康和发病机制的理解。创新点本研究选择了13C 醋酸钠作为同位素探针,通过收集和分析呼吸中的13CO2 来非侵入测量其在小肠吸收的情况。这将提供胃排空率的信息及释放和吸收位点的指标。方 法在一系列体外和体内的猪实验中,评估了 EUDRAGIT® L100-55 和DRcaps®两种胶囊的肠溶保护特性。结 论包覆有EUDRAGIT® L100-55 的DRcaps®具有增强的肠溶保护性能,特别是在体内。本研究增加了对猪胃排空的了解,同时也开始设计用于递送酸度敏感大分子到小肠的简易且廉价的肠溶胶囊。