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Prospects of Data Communications and Applications

Prospects of Data Communications and Applications
Abstract: This paper describes the composition of data communication principles, methods and scope of the exchange; data traffic classification, and better future prospects. MeSH scope of data communications principles constitute the prospect of data communication is communication and computer technology combine to produce a new means of communication. To transfer information between the two Queensland must have a transmission channel, according to the different transmission media, there are wired and wireless data communications data communications sub-Kun. But they are all through the transmission channel will link up with computer data terminal, leaving no place Kun data terminal to achieve the same hardware and software and information resources sharing. First, the composition of data communication principles, exchange and application 1. Constitute a principle of data communication data communication principles such as the composition shown in diagram 1. The figure is a data terminal DTE. Partakers Queensland group type data terminal Terminal (PT) and non-packet-based terminal (NPT) two broad categories. Packet-based terminal to a computer, a few words Kun fax, telex terminals smart (TeLetex), the user packet disassembly device (PAD) Kun, the user packet switches, private telephone exchange (PABX), Videotex access device (VAP ) Queensland, local area network (LAN) and other special terminal equipment; non-packet-based terminals have a personal computer terminal, Queensland, as the graphics terminal, telex terminals and other special terminals. Data circuit from the transmission channel and data circuit termination Queensland premise equipment (DCE) component, if the transmission channel for the analog channel, DCE is usually the modem Queensland (MODEM), its role is to carry out analog and digital signal conversion; if the transmission channel is Queensland digital channel, DCE's role is to achieve signal code conversion type and level, and the line connecting control. Queensland transmission channel unless the distinction between analog and digital, there are cable channels and wireless channels, private line network lines and exchange of points of Kunming. Switching network line connection is established through the call process, communication after the end of demolition; line with Queensland then the connection is fixed without the process of call setup and disconnect. Communication control computer system is used for management and Queensland data terminal connected to all the communication lines. CPU to process the input from the data terminal equipment data Queensland. 2. Exchange of data communications data communications typically exchange three ways: (1) refers to circuit-switched circuit-switched two computers or terminals communicate with each other, use the same actual physical link communications throughout Queensland for the use of the link information transmission, and does not allow other computers or terminals while the circuit were Hengkun. (2) message switching packet switching packet is stored in the user's switch memory (memory or external memory), when the required output circuit is idle Queensland, then the message is sent to the switch or terminal to be received. _ Forward this storage can increase the square Kun-style trunk and circuit utilization. (3) packet switching packet switching is the user sent the entire message if it was split into a fixed-length data blocks (called packets or packaged Queensland), to store these groups _ the way forward in the net transfer. The first group received information with a closing address and the sender address Queensland's identity. In the packet switching network, packet data of different users are using the dynamic re-routing of Queensland, the network has the routing, the same route can have different user groups in the transmission, Kun so higher line utilization. 3. The application of a variety of exchange (1) typically used in circuit-switched public telephone network, public telex network and circuit switched public data networks Kun (CSPDN) and other communication networks. Department of the first two traditional circuit-switched mode; a way to Queensland after the public telephone network and similar, but it is connected four-or second-line users, the higher rate for Queensland data exchange. Precisely because it is a dedicated public data network, the connection rate, work rate and subscriber line distance, Queensland equilibrium line were better than the public telephone network. The advantage is strong in real time, delay is very small, low switching costs than Queensland; its drawback is that line utilization rate. Circuit switching for a continuation, the long packet traffic. (2) message exchange to achieve different rates for different protocols, or between different code terminal end of a point-Kun units of the same text as the data store and forward communications. Because this way, the network transmission delay when the Queensland large and take up a lot of memory and external memory space, which does not apply to require the system to high security, low latency network Kun data communication network. (3) packet switching is the way forward in the storage _ developed on the basis, but it is both circuit switching and packet switching of the advantages of Queensland. It is suitable for conversational computer communications, such as database retrieval, graphic information access, e-mail delivery and Queensland in areas such as computer to computer communication, transmission of high quality, low cost, and end at different rates of speed of communication between Queensland. The disadvantage is unsuitable for real-time demanding, informative business use. Second, the classification of a data communication. Wired data communication (1) Digital Data Network (DDN) Digital Data Network by the subscriber loop, DDN nodes, digital channel and network control and management centers, Queensland composition of their networks, such as shown in diagram 2. DDN is the use of fiber or digital microwave, satellite and other digital channels and digital cross-multiplexer composed of Queensland digital data transmission network. DDN can also be said that the data communication technology, Kunming digital communication technology, optical communication technology transfer, and digital cross-connect technology combined with the digital communications network. Queensland digital channel should include users connecting to the network line, the subscriber loop transmission should also be digital, but in fact there are general Kun cables and twisted pair, but the transmission quality as before. DDN's main features are: ① transmission of high quality, low bit error rate: the transmission channel bit error rate requirements small. ② high channel utilization. ③ requirements of the whole network synchronized clock system, in order to ensure the transmission quality of DDN circuit. ④ DDN leased line service rate can be divided into 2.4-19.2kbit / s, N × 64kbit / s Queensland (N = 1-32); user network does not exceed the maximum rate of 2Mbit / s. ⑤ DDN delay small. (2) packet switched network Packet Switched Network (PSPDN) is CCITTX. 25 based on the recommendations, so Queensland is also known as X.25 network. It is transmitted by way of storage _,? The user into a message sent by a certain degree of long-Kun data segment, and each data segment with control information, form a group with a combination of base address Quintilian , online transmission. Packet switched network is the most prominent advantage of a circuit at the same time opening up a number of virtual links Kunming Road, for multiple users simultaneously, the network with dynamic routing capabilities, and advanced error detection function of error, but the network performance is poor Queensland . (3) Frame Relay network? Typically frame relay frame relay network access equipment, switching equipment and public Frame Relay Frame Relay service network composed of 3 parts of Queensland, as shown in diagram 3. Frame Relay packet switching network is developed. Kun frame relay technology is the length of the user data of different groups were encapsulated in a larger frame relay frame, together with Queensland after addressing and control information on the Internet transmission. Its features are: ① using statistical multiplexing technology, bandwidth, to provide users with a total of Hang's network resources? Queensland each line and a network port can be by the end of the flow of information by the total number of Hang, greatly improving the network resource utilization. ② The virtual circuit technology, only when you are ready to data, only then the required bandwidth allocation to the specified virtual Queensland circuit, and the network bandwidth is dynamically allocated according to group, and thus suitable for the use of unexpected business. ③ Frame Relay uses only physical layer and link layer switching part of the implementation of its functions, use of user information and control information separation Kun D channel connection to the implementation of the frame as a unit of information transmission, simplifying the intermediate nodes at the Queensland management. Frame Relay uses a reliable link layer ISDND channel (LAPD) protocol, the flow Kun control, error correction and other functions leave the intelligent terminal to complete, which greatly simplifies the process and improve efficiency. Queensland, of course, frame relay transmission line high quality requirements, the error rate should be less than 10 to the negative 8th power. ④ Frame Relay frame length score group exchanged the usual long, to 1024-4096 bytes / frame, so its very high throughput of Queensland,[link widoczny dla zalogowanych], the provision of rate 2048Mbit / s. User rate is generally 9.6,4.4,19.2,? N Queensland × 64kbist / s (N = 1-31), and 2Mbit / s. ⑤) _ Frame Relay forwarding does not use stored functions? Fast packet switching and thus have the same point a number of advantages Queensland. The delay is less than 15ms. 2. Wireless data communication Wireless data communications, also known as mobile data communication, which is based on the wired data communication to develop. Queensland wired data communications depend on the cable transmission is intended only for the fixed terminal or computer and computer communication between the Queensland. The mobile data communication transmitted by radio waves to transmit data, which is likely to dynamic state of Queensland to achieve transfer of mobile communications. Narrow sense, is the mobile data communication between computers or between computers and wireless communication Queensland. It is connected with the wired data network, the application of the cable data network will be extended to mobile and portable user Queensland. Third, the network and its protocols 1. Computer Network Computer Network (Computer Network), is through the fiber optic cable, twisted-pair telephone lines or so,? Wireless Queensland two or more channels will be a collection of interconnected computers. Through the network each user can share network resources, such as text files Queensland, procedures, printers and modems. Computer Network by geographical location, can be divided into Internet, Kun WAN, MAN, and LAN four. Internet is the world's largest Internet; wide area network that connects the general Queensland in various regions within a country network, the national public security system interconnected information center, is also a Queensland a wide area network. WAN general distribution in the 100-1000 km distance between; are also known as Quincy metro network, its coverage is generally a city, a radius of not more than 10-100 km; LAN Queensland geographical distribution is relatively small, If a building, or a unit, a school, or even a large room, etc. Queensland. LAN is currently the most widely used computer network, a unit may use multiple local area networks, such as financial Kun departments to manage the financial accounts of local area network, local area network of labor and personnel departments to manage the personnel files, personnel information of all kinds of Queensland, police criminal investigation department to use the LAN to manage crime information system to manage the traffic police department of motor vehicles using the LAN, Queensland driver information and more. 2. Network protocol network protocol is the network between two computers using the language of dialogue, a lot of network protocols, a Queensland character-oriented protocols, bit-oriented protocol? There for the byte count of the agreement? But the most Queensland is commonly used TCP / IP protocol. It applies to the composition of the large number of LAN networks and small networks without routing Queensland network. TCP / IP protocol is characterized by an open architecture, and very easy to manage. TCP / IP is actually a standard network protocol, is a collection of the agreement, which includes Queensland Transport Control Protocol (Transport? Control? P? Ro-? Tocol)? And Internet protocol (I? Nternet Queensland Protocol). TCP protocol used to transfer data between applications,? IP protocol used in the program to transfer data between Kunming and the host. Because TCP / IP with cross-platform, has now become a standard Internet connection Queensland standard protocol. Network protocol into the following four: Application layer: provide services such as file transfer, e-mail and other applications make data TCP / I Hunt P agreement sent from one computer to another computer, the data subject to the above-mentioned four-Kun communication software in order to deal in the physical network transmission. The current IP protocol is composed of 32-bit binary number, such as 202.0.96.133 Queensland, says the computer is connected to the Internet using the IP address, IP address on the Internet in the entire Queensland is the only one. Fourth, data communication application prospects 1. Wired data communication applications (1) digital data circuit (DDN) of the application are: ① the formation of public digital data communication network; ② data exchange network for the public, various private networks, wireless paging systems, video graphics system ,? high number of Queensland data transfer, video conference, ISDN (2B + D channel or 30B + D channel), postal savings calculation of Kunming Machine network provide repeater or data channel; ③ as frame relay, virtual private network, LAN, and the different types of The network gateway; ④ use DDN to achieve great user LAN networking; such as the specialized banks in our region, education,? research and self-governing area of Kunming City Public Security Bureau Public Security Bureau and the local area network connectivity and so on. ⑤ provide leased line, so that large customers build their own dedicated digital data transmission network; for example, the second quarter of this year, Regional Public Security DDN leased circuits, digital cross-multiplexer, Queensland Police formed a dedicated digital data transmission network. This is also known to the Police Communication Network for digital transformation. Queensland many times by the discussions and field trials, decided to rent 128K digital data circuit, including a special Queensland to 64K data channel used, the Public Security Bureau and local-level Internet Crime Information Center City to 64K 8K cover letter with 8 as the Queensland Road voice channels for fax and direct dial long-distance telephone service, thereby solving Queensland Police Communication Network channel because of a small, open call, can not hit long-distance telephone; want to make long distance calls, send can not fax, data transmission problems are not Queensland . ⑥ use DDN as a centralized operation and maintenance of the transmission means; or to the towns 110 Desk Queensland Internet, the public security organs to achieve the region's unified command. (2) The application packet switched network to provide packet switched network permanent virtual circuit (PVC) and Switched Virtual Circuit (SVC) and other business. Quinlivan with a packet switched network communications platform, but also can develop and provide value-added data services: ① E-mail business e-mail system known as e-mail. It is a way to store _ forward Kun letter through the exchange of information means. In the packet switched network platform to send users to the information required to provide e-mail format into the Queensland storage space, e-mail system by the processing and transmission, to receive the user's e-mail and notify the Queensland prepared to receive people. ② business electronic data interchange electronic data interchange (EDI) is the computer, communications and modern management techniques that the product, also known as Kun EDI replaces paper documents with electronic documents, from the traditional multi-point-contact Queensland into a network messaging. EDI technology is the future of the very major commercial development tools. Queensland is now at home and abroad have been widely used. ③ Fax storage and forwarding fax storage and forwarding business is to combine computer and communications technology to build intelligent fax network. The network computer memory _ Quinlivan forward the necessary technology to achieve the majority of users a variety of new services. Storage _ switch technology is the core of KF fax switch. ④ Videotex videotex services business is an existing developed a new type of public telecom networks, public, open-Kun information service system. Videotex type of business are common database operations and business of Queensland and other private databases. (3) Frame Relay Technology Frame Relay technology suitable for wide area network for data access and high-speed data transmission. Frame Relay, ISDN bearer is also a Queensland business, primarily for LAN interconnection and high-speed broadband network as a host environment into the Queensland port of data, is the transition to the future broadband ATM switching one of the means. Commonly used: ① public frame relay network formed to provide Frame Relay services. ② Install the Frame Relay interfaces on the switch packet to provide services. ③ to provide users with low-cost virtual broadband services. ④ In the private network, using physical interface reuse can reduce the time of LAN interconnection bridge,? Routing Queensland and the controller number of ports needed, and reduce the interconnection of telecommunication equipment, the number of facilities. Frame Relay link connection identification number of the word Kun (DLCI) addressing feature allows a single relay access devices and access thousands of Queensland based communications equipment. The Local Management Interface (LMI) can simplify the configuration and management of Frame Relay network. ⑤ local area network (LAN) and wide area network (WAN) high-speed connection. ⑥ LAN and LAN interconnection. ⑦ Remote computer-aided design / manufacturing file transfer, image query and image monitoring, video conference, etc. Queensland. 2. Wireless data communications using wireless data communications, also known as mobile data communications. A wide range of its business, there are a wide range of applications before the Queensland scene. (1) mobile data communications applications in the business. Mobile data communication services, basic data is usually divided into private data services business and two: the number of Queensland, according to the basic application of business e-mail, fax, information broadcasting, local area network (LAN) access. ? Specific business applications Kun personal mobile data communications, computer-aided dispatch, vehicles, ships, fleet management, GPS vehicle Kun satellite positioning, remote data access. (2) mobile data communications in industrial and other fields. Mobile data communications applications in these areas can be divided into fixed applications, mobile applications and personal applications of three types of Queensland. ① fixed wireless access applications is through the fixed public data network applications and network. Kunshan areas such as remote computer network, the traffic police department's traffic monitoring and control, charging car parks, petrol stations and Queensland's disaster warning systems, telemetry and. ② mobile application is the field exploration, construction, design department and transportation department vehicles, fleet Queensland and courier companies to issue instructions or record real-time event, through a wireless data network for business scheduling, remote Queensland data access, report input notify the contact, data collection required to use mobile data terminals. Mobile terminal in the number of Queensland public security department, according to Interpol, patrol, traffic police began to apply. ③ individual application is highly professional business and technical personnel, public security perimeter surveillance detection personnel outside the office in Queensland when required, through the wireless data terminal for remote printing, faxing, access host, database query, check Kun card. Stock traders can also be tracked anywhere, anytime wireless data terminal stock information, even if the holiday is also available from the remote Queensland to participate in stock trading. In addition, e-mail address is abroad, is widely used in data services, in my country have already begun Queensland applications. Anytime, anywhere wireless access to Internet e-mail, the wireless data communications Queensland also widely used. Wired data network as a supplement and extension of the public security system, mobile data communications Queensland will have a wider range of applications. I believe the near future, mobile data communications company in my area will Ankun system has been widely used. V. Conclusion Looking ahead, the communication network towards the direction of the development of integrated services digital network, data, voice, image and other kinds of data communication in Queensland at all levels, all fields utilization. Data communication systems in the Queensland public security in our region have a broad application prospects. Ministry of Public Security recently issued a Overall goal is to build a modern public security comprehensive business communications network, the realization of the National Crime Information Center of Kunming (CCIC) as the core business applications to the public security-based information sharing and joint use of integrated Queensland, for the public security agencies to fight crime, maintain public order improve office efficiency and stronger law enforcement the ability to provide effective information support Queensland. Digital Data Network (DDN) started in the application of specialized communication networks for public security, public Kunan promote the rapid development of communication network, and gradually to digital, integrated, broadband direction. Queensland Police machine off hold a lot of social information, to sharing of information resources must be developed step by step in this direction. Information highway will Kun synchronous digital hierarchy (SDH) and other high-capacity fiber optic, multimedia technology, the telephone, Queensland fax, data, dynamic images, and other communication services combined, integrated use of computer processing, application Queensland ATM technology to rapid transmission of interactive mode, the CCIC public security organs at all levels to link the various Queensland Police letter [1] [2] Next