物联网翻译.docx

1、物联网翻译第一题：The proposed IoT architecture from a technical perspective is shown in Fig. 1. It is divided into three layers. The basic layer and their functionalities are summarized as follows:Perception layer: its main function is to identify objects and gather information. It is formed mainly by senso

2、rs and actuators, monitoring stations (such as cellphone, tablet PC, smart phone, PDA, etc.), nano-nodes, RFID tags and readers/ writers. Network layer: it consists of a converged network made up of wired/wireless privately owned networks, Internet, network administration systems, etc. Its main func

3、tion is to transmit information obtained from the perception layer.Application layer: it is a set of intelligent solutions that apply the IoT technology to satisfy the needs of the users.2.1. Perception layerThis layer provides context-aware information concerning the environment of disabled people.

4、 The components of this layer according to the disability of the person (visually impaired, hearing impaired or physically impaired) are described next.2.1.1. Visually impairedThe components designed for the visually impaired are:(1) body micro-and nano-sensors and (2) RFID-based assistive devices.

5、Next, those components are introduced.2.1.1.1. Body micro-and nano-sensors. In Schwiebert et al. (2001), a retinal prosthesis is developed to restore some vision to patients affected by retinitis pigmentosa and age-related macular degeneration, two diseases that cause degenerative blindness. Althoug

6、h these disorders are characterized by the progressive loss of photoreceptor (rod and cone)cells of the outer retina, they do not affect the inner retinal ganglion nerve cells which form the optic nerve(Ye etal.,2010). Consequently, a camera mounted on a pair of glasses can be used to transmit image

7、 data to an implant attached to the retina, which is formed by an array of body micro-sensors. This artificial retina (Schwiebert et al., 2001) uses electrical impulses to stimulate the appropriate ganglion cells, which convert these electrical impulses into neurological signals. The generated respo

8、nse is carried via the optical nerve to the brain. Currently, researchers are working to develop an artificial retina at the nanoscale. The venture Nano Retina is developing Bio-Retina, a bionic retina that incorporates several nano-sized components in a tiny retinal implant (see Fig. 2). Bio-Retina

9、 is designed to replace the damaged photoreceptor in the eye with the equivalent of a 5000 pixel (second generation)retinal implant. It transforms naturally received light into an electrical signal that stimulates the neurons, which send the images received by Bio-Retina to the brain. The implants n

10、ano-sized components are powered by a special pair of activation eyeglasses. In the next years, as technology evolves, it will be possible to send information concerning the images captured by the artificial retina towards the monitoring station (smart phone) (see Fig. 1), so that new IoT applicatio

11、ns to help people with visual impairments in their orientation, identification of faces, etc. will be developed.2.1.1.2. RFID-based assistive devices. An essential RFID-based application is the navigation system. It helps blind people find their way in an unfamiliar area. RFID tags are distributed t

12、hrough the area. They can for example be placed in the center of the sidewalks to orient the blind person and prevent possible falls near the border of the sidewalk (Saaid et al., 2009).The RFID cane (see Fig. 1) has a tag reader with an antenna that emits radio waves; the tags respond by sending ba

13、ck their stored data, hence identifying the location of the blind person. The tag reader (RFID cane) transmits via Bluetooth or ZigBee the data read from the RFID tag, which includes the tag ID string (DAtri et al., 2007). This data is sent from the monitoring station through the network layer to th

14、e RFID server of the application layer. The blind person can record the destinations name as a voice message using the monitoring station. Directions are received by the monitoring station and played as voice messages (Shiizu et al., 2007).An obstacle detection system based on an ultrasonic sensor c

15、an also be added (Martin et al., 2009). The sensor is mounted on the RFID cane to extend its effective range and perceive obstacles the cane alone would not be able to detect (such as a garbage can in Fig. 1). A voice message played at the monitoring station alerts the visually impaired when an obst

16、acle is detected. A multiple sensor-based shoe-mounted sensor interface is also developed in Zhang et al.(2010) as a supplementary device to the cane to detect obstacles within 61 cm ahead of the visually impaired.A widespread approach for outdoor navigation relies on Global Positioning System (GPS)

17、. It does not require tags to work. However, its resolution is limited (few meters) and it cannot work properly indoors. Therefore, some navigation systems for the visually impaired integrate both technologies (RFID and GPS) ( Yelamarthi et al., 2010).This layer (see Fig. 1) enables the access of th

18、e monitoring stations to the radio channel to transmit the information obtained from the perception layer. Although the Internet protocols were originally designed for fixed networks, there is a growing need for these protocols to accommodate mobile networks, as demonstrated by the use of many diffe

19、rent wireless access technologies in IoT (EU FP7 Project CASAGRAS, 2009). The different transmission media include Wireless Local Area Networks (WLANs) (IEEE 802.11 variants), Worldwide Interoperability for Microwave Access(WiMAX)(IEEE 802.16), Bluetooth(IEEE802.15.1), Ultra-wideband(UWB)(IEEE 802.1

20、5.4aandECMA-368),ZigBee(IEEE802.15.4),General Packet Radio Service(GPRS) and Wideband Code Division Multiple Access (WCDMA). Wireless ad hoc networks are a good option to establish wireless and mobile communications within the IoT, since they do not rely on a preexisting infrastructure, they require

21、 minimal config- uration and are deployed quickly with low cost. Networks composed of different access technologies are known as heterogeneous networks and they should maintain connectivity and service for different applications even with user mobility. The convergence of heterogeneous networks and

22、applications is possible due to the existence of a single Internet Protocol (IP)- based network. The IP for Smart Object (IPSO) Alliance is a non- profit association of more than 50 members from leading technology, communications and energy companies. They advocate the use of IP networked devices to

23、 build the IoT (Dunkels and Vasseur, 2010). They stress that IP is a long-lived and stable communication technology that supports a wide range of applications, devices and underlying communication technologies. In addition, the end-to-end IP architecture is lightweight, highly scalable and efficient

24、. Furthermore, the authors of Internet also recommend the use of the IP protocol to offer the Internets interoperability and scalability directly to embedded devices rather than needing gateways for protocol conversion (Gershenfeld and Cohen, 2006). It is necessary to ensure the connectivity, intero

25、perability and compatibility of heterogeneous networks. The low-power net- working industry, from ZigBee ad hoc control to industrial automation standards (e.g. ISA100), is quickly converging to the use of IP technology (Shelby and Bormann, 2009). In this sense, 6LoWPAN is the name of a working grou

26、p of the Internet Engineering Task Force (IETF) that has developed a set of Internet standards, which enable the efficient use of IPv6 over Low-power Wireless Personal Area Networks (6LoWPANs). 6LoWPAN enables resource-limited embedded devices (often battery-powered) in low-power wireless networks t

27、o be Internet-connected by simplifying IPv6 (header compression of IPv6 header fields) and taking the nature of wireless networks into account. The IPv6 protocol stack with 6LoWPAN is shown in Fig. 4. A small adaptation layer (named the LoWPAN adaptation layer) has been defined in the 6LoWPAN protoc

28、ol stack (see Fig. 4) to optimize the transmission of IPv6 packets over IEEE 802.15.4 and similar link layers (Shelby and Bormann, 2009). IEEE 802.15.4 is a standard that defines the physical and MAC layers for low-power, low-rate wireless embedded radio communications at 2.4 GHz, 915 MHz and 868 MH

29、z .The adoption of Internet protocols by wireless embedded devices is challenging due to several reasons (Shelby and Bormann, 2009):Battery-powered wireless devices require low duty cycles, whereas IP is based on always connected devices.Multicast is not supported natively in IEEE 802.15.4 but it is

30、 essential in many IPv6 operations.Sometimes it is difficult to route traffic in multi-hop wireless mesh networks to achieve the required coverage and cost efficiency.Low power wireless networks have low bandwidth (20250 kbit/s) and frame size (IEEE 802.15.4 packets are rather small, 127 bytes maxim

31、um at the physical layer, minus MAC/security and adaptation layer overhead). On the other hand, the minimum datagram size that all hosts must be prepared to accept, for IPv6 is 1280 bytes. IPv6 requires that every link in the Internet has a Maximum Transmission Unit (MTU) of 1280 bytes or greater. O

32、n any link that cannot convey a 1280-byte packet in one piece, link-specific fragmentation and reassembly must be provided at a layer below IPv6.Standard protocols do not perform well in low-power wireless networks. For example, TCP performs very poorly in wireless networks due to its inability to d

33、istinguish between packet losses due to congestion and those due to channel error.2.3. Application layerThis layer (see Fig. 1) provides an operation support plat form, which can be accessed by monitoring stations and applications. It provides important functionalities such as authentication, billing, service management, service acceptanc