无线供能图像胶囊内窥镜的设计与实验分析

针对目前胶囊内窥镜受到能量限制的问题,设计了一种基于无线供能的微型化、低功耗的图像胶囊内窥镜。对无线供能电路,图像传感器电路,无线发射电路进行设计研究,搭建了无线能量传输系统平台,制作了无线供能图像胶囊内窥镜样机,并通过实验验证了无线能量传输系统发射线圈设计的合理性。通过与医院合作的猪大肠内部图像采集实验,验证了研制的图像胶囊系统样机的可行性。完整的图像胶囊内窥镜的尺寸仅为Φ10mm ×20mm ,图像传感器电路和无线发射电路的整体功耗最低约为65mW 。     

RF Localization for Wireless Video Capsule Endoscopy

RF localization science and technology started with the global positioning systems for outdoor areas, and it then transformed into wireless indoor geolocation. The next step in the evolution of this science is the transformation into RF localization inside the human body. The first major application for this technology is the localization of the wireless video capsule endoscope (VCE) that has been in the clinical arena for 12?years. While physicians can receive clear images of abnormalities in the gastrointestinal tract with VCE devices, they have little idea of their exact location inside the GI tract. To localize intestinal abnormalities, physicians routinely use radiological, endoscopic or surgical operations. If we could use the RF signal radiated from the capsule to also locate these devices, not only can physicians discover medical problems, but they can also learn where the problems are located. However, finding a realistic RF localization solution for the endoscopy capsule is a very challenging task, because the inside of the human body is a difficult environment for experimentation and visualization. In addition, we have no-idea how the capsule moves and rotates in its 3D journey in this non-homogeneous medium for radio propagation. In this paper, we describe how we can design a cyber physical system (CPS) for experimental testing and visualization of interior of the human body that can be used for solving the RF localization problem for the endoscopy capsule. We also address the scientific challenges that face and the appropriate technical approaches for solving this problem.     

一个适用于无线内窥镜系统的ASK中频接收机电路

实现了一个适用于无线内窥镜系统的低功耗ASK中频接收机电路.该接收机包括一个用于补偿信道衰减的自动增益控制环、一个ASK解调器和基于能隙基准源的偏置电路,接收机电路已采用0.25μm CMOS工艺实现.测试结果表明,该电路可以从功率在-30～10dBm之间的中频信号中正确解调出数字基带信号,中频工作频率为20MHz.电路采用2.5V电源,消耗的电流仅为2.1mA.     

一个适用于无线内窥镜系统的ASK中频接收机电路

实现了一个适用于无线内窥镜系统的低功耗ASK中频接收机电路.该接收机包括一个用于补偿信道衰减的自动增益控制环、一个ASK解调器和基于能隙基准源的偏置电路,接收机电路已采用0.25μm CMOS工艺实现.测试结果表明,该电路可以从功率在-30～10dBm之间的中频信号中正确解调出数字基带信号,中频工作频率为20MHz.电路采用2.5V电源,消耗的电流仅为2.1mA.     

用于无线内窥镜系统的高效、低复杂度的准无损和无损压缩算法

为了降低无线内窥镜系统中无线通信的带宽以及无线发射的功耗,该文提出了一种高效、低复杂度的基于类似BAYER 彩色图像阵列的数字图像无损和准无损压缩/解压缩算法。通过对标准图像库中的7幅图像进行压缩的结果表明,该文提出的压缩算法比常规先插值后压缩的算法以及先压缩后插值的算法均具有更高的压缩性能和更低的复杂度;可实现对指定ROI区域实现无损压缩,其它区域实现准无损压缩。算法对无线内窥镜图像进行压缩时,可以获得平均图像压缩码率2.18bit/pixel,且PSNR大于47.57dB。     

Octafilar Helical Antenna for Circular Polarization Wireless Capsule Endoscopy Applications

Wireless Personal Communications - This paper introduces a proposed design of a circularly polarized quadfilar or octafilar helical antenna (QFHA or OFHA) dedicated for wireless...     

Design of Computationally Efficient Sharp FIR Filter Utilizing Modified Multistage FRM Technique for Wireless Communications Systems

Modern wireless communications gadgets demand multi-standard communications facilities with least overlap between different input radio channels. A sharp digital filter of extremely narrow transition-width with lower stop band ripples offers alias-free switching among the preferred frequency bands. A computationally competent low pass filter (LPF) structure based on the multistage frequency response masking (FRM) approach is proposed for the design of sharp finite impulse response (FIR) filters which are suitable for wireless communications applications. In comparison of basic FRM with other existing multistage FRM structures, the proposed structure has a narrow transition bandwidth and higher stop band attenuation with significant reduction in terms of the number of computational steps. A design example is incorporated to demonstrate the efficiency of the proposed approach. Simulation results establish the improvement of the proposed scheme over other recently published design strategies.     

Comparative Performance Evaluation of RF Localization for Wireless Capsule Endoscopy Applications

This paper presents an assessment of the accuracy of cooperative localization of a wireless capsule endoscope (WCE) using radio frequency (RF) signals with particular emphasis on localization inside the small intestine. We derive the Cramer–Rao lower bound (CRLB) for cooperative location estimators using the received signal strength (RSS) or the time of arrival (TOA) of the RF signal. Our derivations are based on a three-dimension human body model, an existing model for RSS propagation from implanted organs to the body surface and a new TOA ranging error model for the effects of non-homogeneity of the human body on TOA of the RF signals. Using models for RSS and TOA errors, we first calculate the 3D CRLB bounds for cooperative localization of the WCE in three major digestive organs in the path of GI tract: the stomach, the small intestine and the large intestine. Then we analyze the performance of localization techniques on a typical path inside the small intestine. Our analysis includes the effects of the number of external sensors, the external sensor array topology, number of WCEs used in cooperation and the random variations in the transmitted power from the capsule.     

一种无线OFDM系统中的高效功率和比特分配算法

在限定无线OFDM通信系统的传输速率和最大误码率的情况下,该文提出了一种最小化发射功率的高效功率和比特分配算法。该算法首先利用注水水平和系统传输速率之间的关系求出无需预设步长和初始值的注水水平迭代公式,然后在部分子载波上使用简化的Greedy算法进行强制收敛。由于充分地利用了注水算法和Greedy算法的优点,该文算法不仅有效地避免了传统自适应算法的收敛性、初始值和步长选择等问题,而且计算效率更高。仿真结果验证了该算法的有效性。     

Computationally Efficient Physics-Based Compact CNTFET Model for Circuit Design

We present a computationally efficient physics-based compact model designed for the conventional CNTFET featuring a MOSFET-like operation. A large part of its novelty lies on the implementation of a new analytical model of the channel charge. In addition, Boltzmann Monte Carlo (MC) simulation is performed with the challenge to cross-link this simulation technique to the compact modeling formulation. The comparison of the electrical characteristics obtained from the MC simulation and from the compact modeling demonstrates the compact model accuracy within its range of validity. Then, from a study of the CNT diameter dispersion for three technological processes, the compact model allows us to determine the CNTFET threshold voltage distribution and to evaluate the resulting dispersion of the propagation delay from the simulation of a ring oscillator.     

Broadband Conformal Monopole Antenna Loaded with Meandered Arms for Wireless Capsule Endoscopy

Wireless Personal Communications - In this paper, a new conformal monopole antenna is presented. The proposed antenna is suitable for using in wireless capsule endoscopy (WCE) as transmitter...     

微小型无人机无线数字视频传输系统的设计与实现

系统采用MCP4010微处理器作为主控芯片,通过其外围接口,扩展了视频采集模块和无线网络模块,实现了视频数据的采集及无线发送功能。其机载部分基本实现了微型化,总重量仅为90 g,典型功耗4 W,可实时传输视频图像,传输有效半径为3 km（视距范围内）。该系统已成功应用在冀展为1.12 m的某微型多功能战术无人机上,并完成了搭载试验。     

基于FPGA的无线图像传输系统硬件设计与实现

针对图像传输过程中的多路径、非通视和高速移动等特点,提出了一种FPGA+W5300架构的COFDM无线图像传输系统,实现图像的无线发射和接收。该架构中采用Xilinx公司Spartan-6系列的XC6SLX150 FPGA作为主控芯片,用于实现COFDM数字调制、射频芯片的配置,同时为A/D转换器和D/A转换器提供工作时钟。采用W5300硬件TCP/IP协议栈通过网络进行数字信号的传输,提高数据的传输速率,外加ADL5385、LT5506等上下变频芯片及其相关外设电路,最终实现一个收发一体、发射频率可设、高灵敏度的无线图像传输系统硬件平台。测试结果表明,该硬件平台能够实现图像的无线传输,具有良好的抗多径和高动态性能。     

A Computationally Efficient QR-Successive Interference Cancellation Scheme for Simplified Receiver Implementation in SFBC-OFDM Systems

In this paper, we propose a computationally efficient square-root and division free recursive QR (SDRQR) decomposition based successive interference cancellation (SIC) receiver for space-frequency block coded orthogonal frequency division multiplexing (SFBC-OFDM) transmit diversity schemes. The performance of the proposed SDRQR-SIC receiver is semi- analytically evaluated taking into account the effects of channel estimation errors and error propagation during SIC. In addition, performance and complexity comparisons are drawn with previously proposed approaches. These comparisons show an excellent performance-complexity tradeoff achieved by SDRQR-SIC over the previous solutions under various channel conditions.     

Computationally Efficient Motion Estimation Algorithm for HEVC

In this paper, we present a novel computationally efficient motion estimation (ME) algorithm for high-efficiency video coding (HEVC). The proposed algorithm searches in the hexagonal pattern with a fixed number of search points at each grid. It utilizes the correlation between contiguous pixels within the frame. In order to reduce the computational complexity, the proposed algorithm utilizes pixel truncation, adaptive search range, sub-sampling and avoids some of the asymmetrical prediction unit techniques. Simulation results are obtained by using the reference software HM (e n c o d e r_l o w d e l a y_P_m a i n and e n c o d e r_r a n d o m a c c e s s_m a i n profile) and shows 55.49% improvement on search points with approximately the same PSNR and around 1% increment in bit rate as compared to the Test Zonal Search (TZS) ME algorithm. By utilizing the proposed algorithm, the BD-PSNR loss for the video sequences like B a s k e t b a l l P a s s_416 × 240@50 and J o h n n y_1280 × 720@60 is 0.0804 dB and 0.0392 dB respectively as compared to the HM reference software with the e n c o d e r_l o w d e l a y_P_m a i n profile.     

Computationally Efficient ESPRIT Method for Direction Finding

In this paper,a low complexity ESPRIT algorithm based on power method and Orthogo- nal-triangular (QR) decomposition is presented for direction finding,which does not require a priori knowledge of source number and the predetermined threshold (separates the signal and noise ei- gen-values).Firstly,according to the estimation of noise subspace obtained by the power method,a novel source number detection method without eigen-decomposition is proposed based on QR de- composition.Furthermore,the eigenvectors of signal subspace can be determined according to Q matrix and then the directions of signals could be computed by the ESPRIT algorithm.To determine the source number and subspace,the computation complexity of the proposed algorithm is approximated as (2log_2 n 2.67)M~3,where n is the power of covariance matrix and M is the number of array ele- ments.Compared with the Single Vector Decomposition (SVD) based algorithm,it has a substantial computational saving with the approximation performance.The simulation results demonstrate its effectiveness and robustness.     

一种双向、数字式微型无线内窥镜系统设计

通过分析目前消化道无线内窥镜的发展状况,提出了一种全新的双向、数字化的微型无线内窥镜系统方案设计,该系统具有实时观察病人图像、全消化道检查以及提供三维深度图像数据等功能,并对方案中各硬件模块及其关键技术进行了详细的论述,设计了该系统的FPGA验证环境,验证了整个方案的正确性。系统胶囊内的数模混合芯片已采用0.18μm CMOS工艺流片。     

Computationally Efficient Nonlinearity Compensation for Coherent Fiber-Optic Systems

Split-step digital backward propagation (DBP) can be combined with coherent detection to compensate for fiber nonlinear impairments.A large number of DBP steps is usually needed for a long-haul fiber system,and this creates a heavy computational load.In a trade-off between complexity and performance,interchannel nonlinearity can be disregarded in order to simplify the DBP algorithm.The number of steps can also be reduced at the expense of performance.In periodic dispersion-managed long-haul transmission systems,optical waveform distortion is dominated by chromatic dispersion.As a result,the nonlinearity of the optical signal repeats in every dispersion period.Because of this periodic behavior,DBP of many fiber spans can be folded into one span.Using this distance-folded DBP method,the required computation for a transoceanic transmission system with full inline dispersion compensation can be reduced by up to two orders of magnitude with negligible penalty.The folded DBP method can be modified to compensate for nonlinearity in fiber links with non-zero residual dispersion per span.