[Huawei cloud IOT] reading notes, "Internet of things: core technology and security of the Internet of things", Chapter 3 (I)

The first 3 Chapter , The perception and recognition technology system of the Internet of things

        No matter how the level of the Internet of things is divided , The bottom layer of the architecture is the perception layer . The perception layer realizes the perception of the Internet of things to the whole IOT world , Various sensing technologies in the sensing layer pass the sensing information of various objects and environments through communication modules and access gateways , To the Internet of things network transport layer （ Access layer ） in . The essence of perception technology is information collection , There are many technologies involved in the perception layer of the Internet of things , Through the identification technology in the book 、 Sensing technology and Sensor Networks 、 Feature recognition technology 、 Position sensing technology and human-computer intelligent interaction technology analyze the perception and recognition technology system , Since the third chapter , It involves some specific technologies of the Internet of things , It's not just an overview, as in the previous chapters , Overview knowledge , Because there are many chapters , The study notes will be divided into three parts , This time, I will mainly learn the sharing identification technology 、 Sensing technology and Sensor Networks . that , Just study hard ！

3.1 Identification technology

        As the name suggests, identification is to identify , to ” matter “ The name , It's just that the presentation is different , Sometimes it's a string of characters , Sometimes it's just an electronic tag that readers and writers can perceive , Sometimes it is the only one in the world ” The pointer “. Identification technology passed ” Naming “ Give Way ” matter “ Add the Internet of things in the perception layer .

        The technical elements of automatic identification are identification and reading , Identify the uniqueness of codes and features 、 Unity is crucial to the application of the Internet of things . Automatic identification technology encodes data 、 Data identification 、 Data collection 、 Data management 、 Standardized means such as data transmission , According to the specific implementation technology , Embodied in bar code recognition technology 、 RFID Technology 、 Magnetic recognition technology and IC Integrated circuit technology . Bar code and magnetic stripe / The information capacity of the card is small 、 The information it carries is relatively limited , Unable to show more accurate information , The anti-counterfeiting ability is also very limited , When identifying , Need to contact the reader , Unable to read from a distance . But as a relatively cheap and practical technology , It will be applied to some extent in the future , However, for the future dynamics of the Internet of things 、 Fast reading 、 Massive data and data collection with certain distance requirements 、 Automatic identity recognition has great limitations , Therefore, it is necessary to adopt radio frequency identification technology based on Wireless Technology （RFID） label .

        RFID It is a typical identification and recognition technology , It is also one of the key technologies of the Internet of things . RFID originated in World War II , Using aircraft radar detection technology ” Identification of enemy and friend “. Get into 21 century , With RFID Technology continues to evolve and develop , Its product categories are also more abundant , Active power 、 passive 、 Semi passive electronic tags have been developed , The cost keeps falling , The application scale continues to expand .

        RFID Commonly known as electronic label technology ,RFID Radio frequency identification is a non-contact automatic identification technology , It is mainly used to establish a unique identity for various items . Radio frequency identification uses the transmission characteristics of radio frequency signals and spatial coupling , Realize the automatic recognition of stationary or moving objects . Typical RFID The system consists of a reader and a writer （Reader）、 Electronic label （Tag） Or transponder （Transponder）, And computer network system . Every RFID Each chip has a globally unique code , Affix RFID After label , Relevant description information of the item needs to be established in the system server , And RFID Codes correspond one by one .RFID Labels can be divided into active 、 Semi active and passive tags . At present, passive tags are mostly used in practical applications , Power is supplied by extracting energy from the electromagnetic field emitted by the reader , The distance between the tag and the reader is short . It is divided into low frequency according to carrier frequency 、 Intermediate frequency 、 High frequency and microwave radio frequency identification ; It is divided into close coupling according to the action distance 、 Remote coupling and remote coupling labels ; According to the read-write function, it can be divided into read-only tags 、 Write multiple read tags and read-write tags at one time ; It is divided into credit card labels according to the packaging form 、 Linear labels 、 Paper label 、 Glass tube label 、 Circular labels and special-purpose special-shaped labels . in application , The electronic tag must be powered to work ; The way of obtaining electric energy is different according to the label at work , It is divided into active 、 Semi active and passive .

        RFID The main feature is to transmit identification information through electromagnetic coupling , It also has the function of reading and writing data 、 Miniaturization and diversification of electronic labels 、 Environmental resistance 、 reusable 、 System security and other characteristics . Typical RFID Applications such as highways ETC No parking charge system .

        Electronic code EPC The concept of MIT Auto ID The center proposed , And with the EPC Incorporated into the global unified identification system , send EPC It has become a truly revolutionary new technology . At present, there are three main technical standard systems in the global unified identification system ：EPC global,ISO Standard system , The ubiquitous center of Japan （UIC）.

      because RFID Wireless channel communication is used between tag and reader , Therefore, the safety problem should not be underestimated . Common attacks such as ： Eavesdropping and side channel attack 、 Fake attack 、 Man-in-the-middle attack 、 Replay attack 、 Denial of service attacks 、 Desynchronization attack 、 Backward traceability 、 Forward traceability 、 System virus 、 Server attack, etc , The specific attack concept explanation will not be repeated here , Interested friends can search or study this book by themselves . The idea of security prevention may need to be three-dimensional, not limited to the technology itself or the level itself （ Perception layer ）, It should be considered and studied as a whole , Three dimensional protection Internet of things security .

3.2 Sensors and Sensor Networks

        As one of the core technologies of the sensing layer of the Internet of things , It is a multidisciplinary modern science and Engineering Technology , It mainly studies how to obtain information from natural sources , And deal with it （ Transformation ） And identify . Sensors are responsible for the realization of things and things in the Internet of things 、 Information interaction between things and people , Sensing technology includes not only sensors , It also involves the processing and recognition of information perceived by sensors , And planning and design in its application 、 Development 、 networking 、 Testing and other activities . Information processing includes signal preprocessing 、 Post processing 、 Feature extraction and selection . The main task of identification is to identify and classify the processed information . It uses the correlation model between the feature information of the identified object to identify the input feature information set 、 Compare 、 Classification and judgment . Sensing technology and computer technology 、 Communication technology is called the three pillars of information technology , At the same time, as a new generation of information technology —— One of the basic technologies for the development of the Internet of things , Highly valued . The sensing technology applied in the Internet of things mainly includes sensors 、 Sensor system and sensor network based on various distributed sensor nodes .

        As the realization system of sensing technology , Sensors are responsible for the realization of things in the Internet of things 、 A necessary part of the information interaction between things and people . Sensors will be physical quantities in the physical world 、 Chemical quantity 、 Biomass is converted into digital signals for processing , So as to perceive the properties of objects in the physical world , Provide the source of information collection . In the Internet of things , What can be extracted from the perceptual object ” matter “ Data or information form , It mainly includes single data acquisition 、 The extension and expansion of sensory information 、 There are three kinds of intelligent processing and mining of perceptual information .

        A common sensor is just a device used to detect physical changes in the surrounding environment , It will feel the information into the form of electronic signals output , Common sensors such as ： temperature / humidity sensor 、 Force sensor 、 Acceleration sensor 、 Light sensor 、 Range sensors 、 Magnetic sensors 、 Microcomputer Sensor 、 Biosensors 、 Smart sensors 、 Sensor systems and Sensor Networks . And novel sensors are also booming , Such as ： Armed to the cow's IOT Sensor , A mirror that tracks body shape . The button is the push to talk sensor that orders , Sensors are all over the body ” Chinese Dragon “. Sensors are becoming more and more miniaturized 、 Multifunction 、 Digitization 、 Intelligent 、 Systematization and networking , Its application in portable multifunctional electronic equipment 、 robot 、 Unmanned technology and other industries .

        Single point sensor information , It cannot reflect the dynamics in a certain region 、 Overall 、 The characteristic of Vectoriality , Just like one eye can't feel the three-dimensional world well . From the acquisition of single attributes of objects to the acquisition of composite attributes , From single point information collection to multi-point information collection , From the understanding of single information to the comprehensive understanding of multi-source information , Sensor technology has moved towards systematization 、 Intelligent 、 Networked perception , So there is the ability to perceive cooperatively 、 A sensor network that collects and processes information about perceived objects in a certain geographical area . Sensor network nodes pass through （ Wired or wireless ） Communication network , Monitor various physical quantities and events through joint cooperation . We usually talk about Sensor Networks , Refers to Wireless Sensor Networks （WSN）.

        Wireless sensor network is a new information acquisition platform , It can send the real-time collected and monitored object information to the gateway node , Realize target detection and tracking in the network distribution area . In wireless sensor networks , A large number of sensor nodes are randomly deployed in or near the monitoring area , Node monitoring data is transmitted hop by hop along other sensor nodes , After multiple hops, it is routed to the sink node , Finally, the management node is reached through the Internet or satellite . The sensor node is an embedded microcomputer system , There are four basic units ： Sensor module 、 Processor module 、 Wireless communication module and energy supply module .

        The sensor nodes of wireless sensor networks are not limited by geographical environment , It has the characteristics of ： There are many nodes 、 Flexible distribution 、 Resources are severely limited 、 Data centric 、 Dynamic topology 、 Limited energy . The key technologies of wireless sensor networks are ： Location Technology 、 Network topology control 、 Data fusion 、 Network security 、 Time synchronization technology 、 New energy technology . Mobile Sensor Networks （MSN） It is a wireless sensor network with controllable mobility . Applications of wireless sensor networks, such as Shanghai Pudong airport , A large number of infrared sensors are used as intelligent nodes in Sensor Networks , Get the surrounding information , Together with the information collected by other types of sensors, it can be accurately and timely provided to the central processing system for information fusion , As the basis of automatic control decision .

        Wireless sensor response network （WSAN） It is composed of a large number of sensor nodes with limited resources and a few reaction nodes with rich resources , A new network model for performing distributed sensing and response tasks . It has several key technologies , Such as ：RGB-D Sensors and information processing 、 Multi perspective perception fusion 、 Autonomous Learning and experience sharing .WSN The security of includes internal communication security and data security , The goal is to resist foreign invasion , Ensure node security and sense the confidentiality of data 、 integrity 、 Verifiability and freshness .WSN The structure of is divided into physical layers 、 Data link layer 、 The routing layer 、 Transport control layer . Each layer corresponds to its own function , Of course, external attacks will also be targeted at each layer , From recent research , The main WSN Research direction of safety , In addition to lightweight encryption , And key management 、 Certificate authority 、 Secure routing 、 Access control, etc .

        This week's notes are as above , Because of the working relationship , Notes stagnated for two months , hope 7 Month begins , Finish the study of this book as soon as possible , It has been the second half of the year , Come on! ！ Let's see you next ！