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.     

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...     

A Hybrid RF and Vision Aware Fusion Scheme for Multi-Sensor Wireless Capsule Endoscopic Localization

A huge torrent of data traffic is generated from various heterogeneous applications and services at the Internet backbone. In general, at the backbone, all such applications and services are allocated spectral resources under a shared spectrum environment within elastic optical networks (EONs). In such a fully shared environment, connection requests (CRs) belonging to different traffic profiles compete for spectral resources. Hence, it is very challenging for network operators to resolve resource conflict that occur at the time of provisioning resources to such CRs. The heterogeneous traffic profile (HTP) considered in this work includes permanent lightpath demands (PLDs) and scheduled lightpath demands (SLDs). We propose various distance adaptive routing and spectrum assignment (DA-RSA) heuristics to resolve resource conflict among these two traffic profiles in EONs under a full sharing environment. Conventionally, preemption was the only technique to resolve such resource conflict among HTPs. Since preemption involves the overhead of selecting CRs to be preempted and then deallocating the resources given to those CRs, excessive preemption adversely affects the performance of the network. Therefore, in this work, we utilized bandwidth splitting as a solution to resolve resource conflict among HTPs under such a shared environment in EONs. Moreover, an integrated solution consisting of splitting and preemption is also proposed. We refer to this new integration as flow-based preemption. Our simulation results demonstrate that bandwidth splitting-based heuristics yield significant improvement in terms of the amount of bandwidth accepted in the network, link and node utilization ratio, number of transponders utilized and the amount of bandwidth dropped due to preemption. Moreover, the flow-based preemption approach is proved to be superior in performance amongst all proposed strategies.

     

RF CMOS Cells for Wireless Applications

There is increasing interest in the use of CMOS circuits for high frequency highly integrated wireless telecommunications systems. This paper presents the results of on-going work into the development of a cell library that includes many of the circuit elements required for the high frequency sub-systems of communications integrated circuits. The cell library studied included an RF control element, single ended Class A amplifier, RF isolator, and Gilbert cell mixer circuit topologies. Circuit design criteria and measurement results are presented. All cells were fabricated using standard 2.0, 1.2, and 0.8 m CMOS integrated circuit fabrication processes with no post-processing performed. The results indicate that 2.0 m CMOS can be used successfully up to approximately 250 MHz with 0.8 m cells useful up to approximately 1000 MHz.     

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.     

Accuracy of RSS-Based RF Localization in Multi-capsule Endoscopy

In this paper, we derive and analyze cooperative localization bounds for endoscopic wireless capsule as it passes through the human gastrointestinal (GI) tract. We derive the Cramer-Rao bound (CRB) variance limits on location estimators which use measured received signal strength (RSS). Using a three-dimension human body model from a full wave simulation software and log-normal models for RSS propagation from implant organs to body surface, we calculate bounds on location estimators in three digestive organs: stomach, small intestine and large intestine. We provide analysis of the factors affecting localization accuracy, including various organ environments, external sensor array topology, number of pills in cooperation and the random variations in transmit power of sensor nodes. We also do localization accuracy analysis for the case when transmit power of the sensor is random with known priori distribution. The simulation results show that the number of receiver sensors on body surface has more influence on the accuracy of localization than the number of pills in cooperation inside the GI tract, The large intestine is affected the most with the transmit power randomness.     

High Performance RF Passive Integration on a Si Smart Substrate for Wireless Applications

To achieve cost and size reductions, we developed a low cost manufacturing technology for RF substrates and a high performance passive process technology for RF integrated passive devices (IPDs). The fabricated substrate is a conventional 6“ Si wafer with a 25 μm thick SiO₂ surface. This substrate showed a very good insertion loss of 0.03 dB/mm at 4 GHz, including the conductive metal loss, with a 50 Ω coplanar transmission line (W=50 μm, G=20 μm). Using benzo cyclo butene (BCB) interlayers and a 10 μm Cu plating process, we made high Q rectangular and circular spiral inductors on Si that had record maximum quality factors of more than 100. The fabricated inductor library showed a maximum quality factor range of 30‐120, depending on geometrical parameters and inductance values of 0.35‐35 nH. We also fabricated small RF IPDs on a thick oxide Si substrate for use in handheld phone applications, such as antenna switch modules or front end modules, and high‐speed wireless LAN applications. The chip sizes of the wafer‐level‐packaged RF IPDs and wire‐bondable RF IPDs were 1.0‐1.5 mm² and 0.8‐1.0 mm², respectively. They showed very good insertion loss and RF performances. These substrate and passive process technologies will be widely utilized in hand‐held RF modules and systems requiring low cost solutions and strict volumetric efficiencies.     

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 。     

Design and Implementation of Computationally Efficient Image Compressor for Wireless Capsule Endoscopy

An image compressor inside wireless capsule endoscope should have low power consumption, small silicon area, high compression rate and high reconstructed image quality. Simple and efficient image compression scheme, consisting of reversible color space transformation, quantization, subsampling, differential pulse code modulation (DPCM) and Golomb–Rice encoding, is presented in this paper. To optimize these methods and combine them optimally, the unique properties of human gastrointestinal tract image are exploited. Computationally simple and suitable color spaces for efficient compression of gastrointestinal tract images are proposed. Quantization and subsampling methods are optimally combined. A hardware-efficient, locally adaptive, Golomb–Rice entropy encoder is employed. The proposed image compression scheme gives an average compression rate of 90.35 % and peak signal-to-noise ratio of 40.66 dB. ASIC has been fabricated on UMC130nm CMOS process using Faraday high-speed standard cell library. The core of the chip occupies 0.018 mm\(^2\) and consumes 35 \(\upmu {\text {W}}\) power. The experiment was performed at 2 frames per second on a \(256\times 256\) color image. The power consumption is further reduced from 35 to 9.66 \(\upmu \)W by implementing the proposed image compression scheme using Faraday low-leakage standard cell library on UMC130nm process. As compared to the existing DPCM-based implementations, our realization achieves a significantly higher compression rate for similar area and power consumption. We achieve almost as high compression rate as can be achieved with existing DCT-based image compression methods, but with an order of reduced area and power consumption.     

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...     

无线应用CMOS低噪声放大器的设计

基于射频CMOS集成电路技术, 设计出用于无线通信系统的CMOS低噪声放大器.对影响其增益、噪声系数的阻抗匹配进行了分析.采用TSMC的0.35 μm射频工艺库,在ADS仿真平台上对低噪声放大器电路进行了仿真.其中,低噪声放大器设计成差分结构,提供了13 dB增益、-10 dBm IIP3、-13 dBm P1dB、1.9 dB的噪声系数和55 mW的功耗.     

射频无线应用的体连接和图形化SOI LDMOSFET的比较

设计并制作了一种可应用于无线通信放大器的新型的图形化SOI LDMOSFET.该器件沟道下方的埋氧层是断开的.测试表明,输出特性曲线没有发现明显的翘曲效应,关态的击穿电压达13V,在VG=4V和VD=3.6V时fT为8GHz,直流和射频性能均优于同一芯片上相同工艺条件制备的体接触LDMOSFET.     

射频无线应用的体连接和图形化SOI LDMOSFET的比较

设计并制作了一种可应用于无线通信放大器的新型的图形化SOI LDMOSFET. 该器件沟道下方的埋氧层是断开的.测试表明，输出特性曲线没有发现明显的翘曲效应，关态的击穿电压达13V，在VG=4V和VD=3.6V时fT为8GHz，直流和射频性能均优于同一芯片上相同工艺条件制备的体接触LDMOSFET.     

射频无线应用的体连接和图形化SOI LDMOSFET的比较

设计并制作了一种可应用于无线通信放大器的新型的图形化SOI LDMOSFET.该器件沟道下方的埋氧层是断开的.测试表明,输出特性曲线没有发现明显的翘曲效应,关态的击穿电压达13V,在VG=4V和VD=3.6V时fT为8GHz,直流和射频性能均优于同一芯片上相同工艺条件制备的体接触LDMOSFET.     

The Performance Evaluation of Hybrid Localization Algorithm in Wireless Sensor Networks

As one of the key techniques in wireless sensor networks (WSN), localization algorithm has been a research hot topic and indispensable function in most wireless applications. In order to promote localization accuracy and efficiency, a lot of localization algorithms with different performances and computation complexities have been proposed. The paper discusses the drawbacks of some typical works on localization, and proposes a hybrid localization algorithm integrated with approximate point in triangle (APIT) and distance vector-hop (DV-HOP). To address the positioning accuracy and coverage rate, the objectives of this paper are three folds: firstly, adopting angle detection to determine the exact direction of unknown nodes. Then, the APIT algorithm is adopted over all unknown nodes within the triangle and its localization error is reduced from 14.7215 m in conventional APIT to 3.2348 m in the considered scenario. Finally, the DV-HOP algorithm is adopted with different weights for the nodes within the minimum hops, and localizes the rest unknown nodes in WSN with localization accuracy increased by 49%.     

CC1000 射频收发器在无线游戏控制器中的应用

无线游戏控制器正迅速被市场接受.射频(RF)技术对这一应用非常理想.     

一种应用于无线内窥镜的2.4GHz低功耗ASK发射机

提出了一种应用于无线内窥镜系统的2.4GHz低功耗ASK发射机.为了获得高的数据传输速率,采用了基于混频器的直接上变换发射机结构.为了节省功耗,提出了一种基于电流复用技术的伪差分堆栈结构的A类功放.低功耗发射机由两部分组成:基于恒幅度锁相环(PLL)的20MHz的ASK基带调制器和直接上变换的射频电路.该设计已经采用TSMC 0.25μm CMOS工艺实现并进行了验证.测试结果表明,发射数据速率为1Mbps时,发射机的输出功率为-23.217dBm.采用单2.5V的电源供电下,低功耗发射机消耗的电流约为3.17mA.     

A 2.4GHz Low Power ASK Transmitter for Wireless Capsule Endoscope Applications

提出了一种应用于无线内窥镜系统的2.4GHz低功耗ASK发射机.为了获得高的数据传输速率,采用了基于混频器的直接上变换发射机结构.为了节省功耗,提出了一种基于电流复用技术的伪差分堆栈结构的A类功放.低功耗发射机由两部分组成:基于恒幅度锁相环(PLL)的20MHz的ASK基带调制器和直接上变换的射频电路.该设计已经采用TSMC 0.25μm CMOS工艺实现并进行了验证.测试结果表明,发射数据速率为1Mbps时,发射机的输出功率为-23.217dBm.采用单2.5V的电源供电下,低功耗发射机消耗的电流约为3.17mA.