畢業(yè)論文外文翻譯-通用分組無線服務(wù)GPRS

1、大連科技學(xué)院2013屆本科生畢業(yè)設(shè)計（論文）外文翻譯 大連交通大學(xué)信息工程學(xué)院畢業(yè)設(shè)計(論文)外文翻譯學(xué)生姓名 專業(yè)班級 信息工程09-2班 指導(dǎo)教師 職 稱 所在單位 電氣工程系信息工程教研室 教研室主任 完成日期 2013 年 4 月 15 日GPRS1 GPRS OverviewGPRS is the General Packet Radio Service English abbreviations, for General grouping wireless business in Chinese, is a kind of wireless Packet switching tec

2、hnology based on GSM system, provides end-to-end, wide-area wireless IP connection. Relatively original GSM dial-up way way of circuit-switched data transmission, GPRS is packet switching technology, has a real-time online, volume pricing and quick login, high speed transmission and freely switch. I

3、nformally, GPRS is a high-speed data processing technology, the method is in the form of group send data to the users hands. Although GPRS as the existing GSM network to make the transition to the third generation mobile communication technology, but it has a significant advantage in many ways.Due t

4、o the use of the group technology, Internet users relative stability, to avoid the unnecessary short-term bring trouble. In addition, the use of GPRS Internet method is different from a WAP, with WAP web site like online at home, dial-up first, and on the Internet and cant use the phone line at the

5、same time, the GPRS download materials and can simultaneously. Technically, the transmission of sound (voice) continue to use the GSM, and can use the GPRS data transmission, in this way, the mobile phone application to promote to a higher level. Development of GPRS technology is economy, because on

6、ly need to use the existing GSM network. GPRS usage is very extensive, including through the mobile phone to send and receive E-mail, browsing on the Internet, etc.GPRS and past continuous in the channel transmission in different ways, to transmit the Packet (Packet) tense, so the burden of cost cal

7、culation is based on the transmission data unit, not to use its entire channels, theoretically cheaper. GPRS transmission rate can be up to 56 or 114 KBPS.2 An essential part of the GPRSPacket control unit (PCU) : mainly used for the completion of RLC/MAC function with the Gb interface and transform

8、ation. PCU in physical implementation can have three ways: PCU Settings in the BTS; PCU is set in the BTS; PCU independent setting, A physical entity (contain multiple PCU unit) likely connected to multiple BSC, equipped with the base station subsystem of PCU send packet business through the Gb inte

9、rface to SGSN, send via A voice service interface to MSC.Service GPRS support node (SGSN) : perform the function of mobility management, security and access control and routing, and other functions. Between the SGSN and HLR Gr interface used in the SGSN and HLR passed between mobility management of

10、related signaling. SGSN and SMS - GMSC/SMS - IWMSC between Gd interface is used to send short message service via GPRS. Between MSC/VLR and SGSN Gs interface used in the SGSN cooperate with MSC/VLR implementation such as joint location updates, via GPRS for CS paging, etc.Gateway GPRS support node (

11、GGSN) : responsible for providing GPRS PLMN and outer packet data network interface, and provide the necessary network security mechanisms (such as a firewall). Between the GGSN and HLR Gc interface as optional interface, is used to contact the HLR GGSN MS routing information. The SGSN and GGSN can

12、be set independently, can also be fellow. The same PLMN by designed.the Gn interfaces for communication between the GSN, different PLMN by Gp interface for communication between the GSN.Border gateway (BG) : border gateway for PLMN interconnection between the GPRS backbone, it should have basic secu

13、rity function, moreover can also according to the roaming agreements between operators increase the related functions. Border gateway can be independent of the physical entity, can also with the GGSN fellow.Billing gateway (CG) : charging gateway through Ga interface and GPRS network entities such a

14、s GSN communication, used to collect the GSN send billing data records and billing.Domain name server (DNS) : responsible for providing internal SGSN and GGSN GPRS network nodes of DNS and parse the APN.Mobile station (MS) : A user using the equipment, according to the function can be divided into A

15、, B, C three types, by the mobile terminal (MT) and terminal equipment (TE).LIG: lawful intercept gateway, collect information of GPRS users, transmitted to the monitoring agency.Other equipment: BTS, BSC, HLR, MSC/VLR, SMS - GMSC/SMS - IWMSC must be extended to support GSM, such as original equipme

16、nt associated with the GPRS function. The definition and function reference 900/1800 MHZ TDMA digital public land honeycomb mobile communication network technology system. In a basic network, GPRS base station subsystem can be through the frame relay network are connected to the SGSN, E1 leased line

17、. SGSN and GGSN, BG, CG, DNS, etc. The core network entity is through the IP transmission network signaling and data transmission. In addition, in the core network, SGSN and HLR, MSC/VLR, short message center and GGSN to no. 7 signaling network and HLR to communicate.3 GPRS service typeAccording to

18、the types of services provided by, now some GPRS Class types have A, B, C three types:Class A can on the Internet of answering the phone at the same time, the technical means and support package exchange (data) and the circuit exchange (voice).Class B can go online and answer the phone, but not at t

19、he same time, the technical means, while also supporting circuit switching and packet switching, but at the same time.Class C can only access to the Internet, when it cant make a phone call, its technology means that it only supports packet switching. So far, the only Class B type I know mobile phon

20、e, that is to say, it can be either GPRS Internet, also can make a phone call, but not simultaneously.But my reasoning is that GPRS service type of the Class is not entirely determined by the phone, but need to GPRS network operators to provide corresponding service to proceed. They are cooperate wi

21、th each other and interdependent relationship.4 The working principle of GPRSGPRS English full name is: General Packet Radio Service (translation General Packet Radio Service), it is to use the Packet (Packet Switched) developed the concept of a set of wireless transmission mode. So-called packet is

22、 the Data encapsulated into many separate packets, out of these packets to each other again, in the form similar to the post office to send the parcel. Its role is to take only when there is data need to transmit bandwidth, but also in transport of data amount, this is a reasonable way of charging f

23、or the masses of users, because such as the Internet data transmission bandwidth is idle most of the time.GPRS network is based on the existing GSM network. In the existing GSM network need to add some nodes, such as the GGSN (Gateway GPRS Supporting Node, support GPRS Gateway Node) and SGSN (Servin

24、g GSN, GPRS support Node), GSN is the most important network Node in the GPRS network. GSN has mobile routing management function, it can connect to various kinds of data network, and can be connected to GPRS registers. GSN can complete data transfer between mobile terminal and a variety of data net

25、work and format conversion. GSN can is a kind of independent equipment similar to the router, can also with MSC integration of GSM. GSN has two types: one for the SGSN (GSN Serving GSN, services), another for the GGSN (GSN) Gateway GSN, Gateway, SGSNs main function is to record the current position

26、information of mobile terminal, and between the mobile terminals and the GGSN complete mobile packet data sending and receiving. GGSN mainly plays a role of the gateway, it can and a variety of data network connection, such as ISDN, PSPDN and LAN. Some material called GGSN GPRS router even abroad. G

27、GSN can put GSM GPRS packet in the packet, protocol conversion, in order to put these packets grouped data to a remote TCP/IP or x. 25 network.GPRS is working, by addressing and routing management data connections, and GPRS routing management performance in the following three aspects: the mobile te

28、rminal sends data routing establishment; Mobile terminal receives the data routing establishment; And the establishment of the mobile terminal in roaming data routing.For the first case, when the mobile terminal generates a PDU packet data unit), the PDU through SNDC layer processing, called SNDC da

29、ta unit. And then through the LLC layer processing for LLC frame through the air interface to the GSM network in the mobile terminal of the SGSN. SGSN sends data to the GGSN. GGSN put received message in solution processing, are converted to can be in the format of the transfer in a public data netw

30、ork (PSPDN as PDU), and eventually to a public data network users. In order to improve the transmission efficiency, and ensure the security of data transmission, can be on the air interface of data compression and encryption processing.In the second case, a public data network users to send data to

31、the mobile terminal, the first through the standard protocols to establish data network and data network routing between the GGSN. Data network user data unit (PDU) in such as PSPDN, through the establishment of good routing gave GGSN PDU data unit.The GGSN again give the PDU to mobile terminal is l

32、ocated on the SGSN, GSN PDU encapsulation into SNDC data unit, again through the LLC layer processing of the LLC frame unit, finally through the air interface for mobile terminals.The third condition is a data network users to send data to a mobile user is roaming. This case to pass belongs to the G

33、GSN of data transfer, and then sent to A user terminal.5 The application of GPRS technology fieldChatting on the net;Textual and visual information;Static and dynamic image;Web browsing;Document sharing and collaboration;Audio;Work assignment;Enterprise internal E-mail;The Internet E-mail;Vehicle po

34、sitioning;The remote LAN access;File transfer;Home automation, etc.6 The current research status of GPRS wireless transmissionBased on general packet radio service GPRS wireless data transmission is very suitable for remote data transmission means of communication. Compared with the traditional way

35、of transmission, GPRS has low running cost, is not subject to regional restriction, high real-time performance advantage. One of the most important is a GPRS network, the network operators from the daily maintenance of network and network construction investment, can be greatly reduced in order to a

36、chieve the purpose of protecting the environment, saving energy and reducing consumption, and resource sharing. Due to these advantages, construction and development of GPRS network at home and abroad soon. The technology originated in Europe, Chinas network development started relatively late compa

37、red to other countries. Can be seen through the domestic and foreign research literature, the research of GPRS network terminal application, in most cases, using the GPRS data transmission module. Module manufacturers have focused on Germanys Siemens, MOTOROLA Wavecome company in France and the Unit

38、ed States, such as domestic firms, such as ZTE, HUAWEI, also has the GPRS data transmission module products. Compared with overseas in this field of application is relatively mature, the hardware and software products are also relatively stable, and the application of GPRS services in domestic resea

39、rch is still in its infancy, the applied research in the field of space is relatively large. Believe that in the next few years, the application of GPRS technology will have great development.In recent years, research on GPRS wireless data transmission is various, some dedicated to mobile data commu

40、nication of a full range of solutions, in view of the consumer electronics, industrial control, environmental monitoring and remote telemetry, such as different industries, the development of targeted physical products, including data acquisition, data communication, data management and other functi

41、ons. Some in order to make the embedded engineer focus on application development of GPRS network communication protocol stack which research, provide transparent IP channel for upper development, thereby ignore is relatively large, complex network communication protocol. And, according to the theor

42、y of GPRS wireless data transmission performance problems, put forward a series of changes, such as reliability, security, etc for GPRS was improved, to further improve the performance of GPRS wireless transmission, so as to expand the application field of the GPRS.通用分組無線服務(wù)1 GPRS概述GPRS是General Packe

43、t Radio Service的英文簡稱，中文為通用無線分組業(yè)務(wù)，是一種基于GSM系統(tǒng)的無線分組交換技術(shù)，提供端到端的、廣域的無線IP連接。相對原來GSM的撥號方式的電路交換數(shù)據(jù)傳送方式，GPRS是分組交換技術(shù)，具有“實時在線”、“按量計費(fèi)”、“快捷登錄”、“高速傳輸”、“自如切換”的優(yōu)點(diǎn)。通俗地講，GPRS是一項高速數(shù)據(jù)處理的技術(shù)，方法是以“分組”的形式傳送資料到用戶手上。雖然GPRS是作為現(xiàn)有GSM網(wǎng)絡(luò)向第三代移動通信過渡的技術(shù)，但是它在許多方面都具有顯著的優(yōu)勢。由于使用了“分組”技術(shù)，用戶上網(wǎng)相對穩(wěn)定，避免了不必要的短線帶來的困擾。此外，使用GPRS上網(wǎng)的方法與WAP不同，用WAP上網(wǎng)就

44、如在家中上網(wǎng)，先“撥號連接”，而上網(wǎng)后便不能同時使用該電話線，但GPRS下載資料和通話可以同時進(jìn)行。從技術(shù)上說，聲音的傳送（即通話）繼續(xù)使用GSM，而數(shù)據(jù)的傳送便可使用GPRS，這樣，就把移動電話的應(yīng)用提升到一個更高的層次。發(fā)展GPRS技術(shù)也十分“經(jīng)濟(jì)”，因為只需沿用現(xiàn)有的GSM網(wǎng)絡(luò)即可。GPRS的用途十分廣泛，包括通過手機(jī)發(fā)送及接收電子郵件，在互聯(lián)網(wǎng)上瀏覽等。GPRS和以往連續(xù)在頻道傳輸?shù)姆绞讲煌且苑獍≒acket）式來傳輸，因此使用者所負(fù)擔(dān)的費(fèi)用是以其傳輸資料單位計算，并非使用其整個頻道，理論上較為便宜。GPRS的傳輸速率可提升至56甚至114Kbps。2 GPRS的基本組成部分分組

45、控制單元（PCU）：主要用于完成RLC/MAC功能和與Gb接口的轉(zhuǎn)換。PCU在物理實現(xiàn)上可以有三種方式：PCU設(shè)置在BTS中；PCU設(shè)置在BTS中；PCU獨(dú)立設(shè)置，一個物理實體(包含多個PCU單元)有可能和多個BSC相連， 配備了PCU的基站子系統(tǒng)把分組業(yè)務(wù)經(jīng)Gb接口送往SGSN，把話音業(yè)務(wù)經(jīng)A接口送往MSC。服務(wù)GPRS支持節(jié)點(diǎn)（SGSN）：執(zhí)行移動性管理、安全功能和接入控制和路由選擇等功能。SGSN與HLR之間的Gr接口用于SGSN與HLR之間傳送移動性管理的相關(guān)信令。SGSN與SMS-GMSC/SMS-IWMSC之間的Gd接口用于經(jīng)GPRS傳送短消息業(yè)務(wù)。SGSN與MSC/VLR之間的

46、Gs 接口用于SGSN與MSC/VLR配合實現(xiàn)諸如聯(lián)合位置更新、經(jīng)由GPRS進(jìn)行CS尋呼等功能。網(wǎng)關(guān)GPRS支持節(jié)點(diǎn)（GGSN）：負(fù)責(zé)提供GPRS PLMN與外部分組數(shù)據(jù)網(wǎng)的接口，并提供必要的網(wǎng)間安全機(jī)制（如防火墻）。GGSN與HLR之間的Gc接口為可選接口，用于GGSN向HLR查詢MS的路由信息。SGSN和GGSN可以獨(dú)立設(shè)置，也以合設(shè)。同一PLMN中的GSN之間通過Gn接口進(jìn)行通信，不同PLMN中的GSN之間通過 Gp 接口進(jìn)行通信。邊界網(wǎng)關(guān)（BG）：邊界網(wǎng)關(guān)用于PLMN間GPRS骨干網(wǎng)的互連，它應(yīng)具有基本的安全功能，此外還可以根據(jù)運(yùn)營商之間的漫游協(xié)定增加相關(guān)功能。邊界網(wǎng)關(guān)可以是獨(dú)立的物理

47、實體，也可以與GGSN合設(shè)。計費(fèi)網(wǎng)關(guān)（CG）：計費(fèi)網(wǎng)關(guān)通過Ga接口與GPRS網(wǎng)絡(luò)中的計費(fèi)實體如GSN等通信，用于收集各GSN發(fā)送的計費(fèi)數(shù)據(jù)記錄并進(jìn)行計費(fèi)。域名服務(wù)器（DNS）：負(fù)責(zé)提供GPRS網(wǎng)內(nèi)部SGSN、GGSN等網(wǎng)絡(luò)節(jié)點(diǎn)的域名解析以及APN的解析。移動臺（MS）：用戶使用的設(shè)備，按功能可分為A、B、C三類，由移動終端（MT）和終端設(shè)備（TE）構(gòu)成。LIG：合法監(jiān)聽網(wǎng)關(guān)，收集GPRS用戶的相關(guān)信息，傳送給監(jiān)聽機(jī)構(gòu)。其他設(shè)備：BTS、BSC、HLR、MSC/VLR、SMS-GMSC/SMS-IWMSC等GSM原有設(shè)備應(yīng)擴(kuò)展以支持相應(yīng)的與GPRS有關(guān)的功能。具體定義及功能參考“900/1800

48、MHz TDMA數(shù)字公用陸地蜂窩移動通信網(wǎng)技術(shù)體制”。在一個GPRS基本網(wǎng)絡(luò)中，基站子系統(tǒng)可以通過幀中繼網(wǎng)、E1專線等方式與SGSN相連。SGSN、GGSN、BG、CG、DNS等核心網(wǎng)實體是通過IP傳輸網(wǎng)進(jìn)行信令與數(shù)據(jù)傳輸?shù)?。此外，在核心網(wǎng)中，SGSN與HLR、MSC/VLR、短消息中心以及GGSN與HLR之間通過7號信令網(wǎng)進(jìn)行通信。3 GPRS的服務(wù)類型按所提供的服務(wù)種類來說，現(xiàn)在有的GPRS的Class類型有A、B、C三種：（1）Class A可以在上網(wǎng)的同時接聽電話，其技術(shù)含義是同時支持包交換（數(shù)據(jù)）和電路交換（語音）。（2）Class B可以上網(wǎng)和接電話，但不能同時進(jìn)行，其技術(shù)含義是雖

49、然也支持包交換和電路交換，但不可在同一時刻支持包交換和電路交換，狀態(tài)可以切換。（3）Class C則只能上網(wǎng)，什么時候都不能打電話，其技術(shù)含義是它只支持包交換。到目前為止，我所知道的手機(jī)只有Class B類型，也就是說，它既可以GPRS上網(wǎng)，也能打電話，但不能同時進(jìn)行。不過我的推論是，GPRS的服務(wù)類型Class并不完全由手機(jī)決定，而是需要GPRS網(wǎng)絡(luò)運(yùn)營商提供相應(yīng)服務(wù)才能進(jìn)行。兩者是互相配合和依存的關(guān)系。4 GPRS的工作原理GPRS的英文全稱是：“General Packet Radio Service”（譯作“通用分組無線服務(wù)”），它是利用“包交換”（PacketSwitched）的概念

50、發(fā)展起來的一套無線傳輸方式。所謂“包交換”就是將Data封裝成許多獨(dú)立的封包，再將這些封包一一傳送出去，形式上有點(diǎn)類似郵局中的寄包裹。其作用在于只有當(dāng)有資料需要傳送時才會占用頻寬，而且可以以傳輸?shù)馁Y料量計價，這對廣大用戶來說是較合理的計費(fèi)方式，因為像Internet這類的數(shù)據(jù)傳輸大多數(shù)的時間頻寬是閑置的。GPRS網(wǎng)絡(luò)是基于現(xiàn)有的GSM網(wǎng)絡(luò)來實現(xiàn)的。在現(xiàn)有的GSM網(wǎng)絡(luò)中需增加一些節(jié)點(diǎn)，如GGSN（Gateway GPRS Supporting Node，GPRS網(wǎng)關(guān)支持節(jié)點(diǎn)）和SGSN（Serving GSN，GPRS服務(wù)支持節(jié)點(diǎn)），GSN是GPRS網(wǎng)絡(luò)中最重要的網(wǎng)絡(luò)節(jié)點(diǎn)。GSN具有移動路由管理

51、功能，它可以連接各種類型的數(shù)據(jù)網(wǎng)絡(luò)，并可以連到GPRS寄存器。GSN可完成移動終端和各種數(shù)據(jù)網(wǎng)絡(luò)之間的數(shù)據(jù)傳送和格式轉(zhuǎn)換。GSN可以是一種類似于路由器的獨(dú)立設(shè)備，也可以與GSM中的MSC集成在一起。GSN有兩種類型：一種為SGSN（Serving GSN，服務(wù)GSN），另一種為GGSN（Gateway GSN，網(wǎng)關(guān)GSN），SGSN的主要作用是記錄移動終端的當(dāng)前位置信息，并且在移動終端和GGSN之間完成移動分組數(shù)據(jù)的發(fā)送和接收。GGSN主要是起網(wǎng)關(guān)作用，它可以和多種不同的數(shù)據(jù)網(wǎng)絡(luò)連接，如ISDN、PSPDN和LAN等。國外有些資料甚至將GGSN稱為GPRS路由器。GGSN可以把GSM網(wǎng)中的GP

52、RS 分組數(shù)據(jù)包進(jìn)行協(xié)議轉(zhuǎn)換，從而可以把這些分組數(shù)據(jù)包傳送到遠(yuǎn)端的TCPIP或X.25網(wǎng)絡(luò)。GPRS工作時，通過路由管理來進(jìn)行尋址和建立數(shù)據(jù)連接，而GPRS的路由管理表現(xiàn)在以下三方面：移動終端發(fā)送數(shù)據(jù)的路由建立；移動終端接收數(shù)據(jù)的路由建立；以及移動終端處于漫游時數(shù)據(jù)路由的建立。對于第一種情況，當(dāng)移動終端產(chǎn)生了一個PDU分組數(shù)據(jù)單元)，這個PDU經(jīng)過SNDC層處理，稱為SNDC數(shù)據(jù)單元。然后經(jīng)過LLC層處理為LLC幀通過空中接口送到GSM網(wǎng)絡(luò)中移動終端所處的SGSN。SGSN把數(shù)據(jù)送到GGSN。GGSN把收到的消息進(jìn)行解裝處理，轉(zhuǎn)換為可在公用數(shù)據(jù)網(wǎng)中傳送的格式（如PSPDN的PDU），最終送給公

53、用數(shù)據(jù)網(wǎng)的用戶。為了提高傳輸效率，并保證數(shù)據(jù)傳輸?shù)陌踩?，可以對空中接口上的?shù)據(jù)做壓縮和加密處理。在第二種情況中，一個公用數(shù)據(jù)網(wǎng)用戶傳送數(shù)據(jù)到移動終端時，首先通過數(shù)據(jù)網(wǎng)的標(biāo)準(zhǔn)協(xié)議建立數(shù)據(jù)網(wǎng)和GGSN之間的路由。數(shù)據(jù)網(wǎng)用戶發(fā)出的數(shù)據(jù)單元（如 PSPDN中的PDU），通過建立好的路由把數(shù)據(jù)單元PDU送給GGSN。 而GGSN再把PDU送給移動終端所在的SGSN上,GSN把PDU封裝成SNDC數(shù)據(jù)單元，再經(jīng)過LLC層處理為LLC幀單元，最終通過空中接口送給移動終端。 第三種情況是一個數(shù)據(jù)網(wǎng)用戶傳送數(shù)據(jù)給一個正在漫游的移動用戶。這種情況下的數(shù)據(jù)傳送必須要經(jīng)過歸屬地的GGSN，然后送到用戶A端。5 GPR

54、S技術(shù)的應(yīng)用領(lǐng)域網(wǎng)上聊天；文本和可視信息；靜態(tài)和動態(tài)圖像；網(wǎng)頁瀏覽；文檔共享和協(xié)同工作；音頻；工作分派；企業(yè)內(nèi)部電子郵件；因特網(wǎng)電子郵件；車輛定位；遠(yuǎn)程局域網(wǎng)接入；文件傳輸；家庭自動化等。6 GPRS無線傳輸?shù)难芯楷F(xiàn)狀基于通用分組無線業(yè)務(wù)的GPRS無線數(shù)據(jù)傳輸是非常合適的遠(yuǎn)程數(shù)據(jù)傳輸?shù)耐ㄐ攀侄?。與傳統(tǒng)的傳輸方式相比，GPRS具有運(yùn)行成本低，不受地域限制，實時性高等優(yōu)勢。最重要的是由網(wǎng)絡(luò)運(yùn)營商投資的GPRS網(wǎng)絡(luò)，免除了網(wǎng)絡(luò)的日常維護(hù)，可以大大降低網(wǎng)絡(luò)建設(shè)投資，以達(dá)到保護(hù)環(huán)境的目的，節(jié)能降耗，資源共享。由于這些優(yōu)勢，國內(nèi)外的GPRS網(wǎng)絡(luò)的建設(shè)和發(fā)展很快。這項技術(shù)起源于歐洲，中國的網(wǎng)絡(luò)建設(shè)相比其他國

55、家起步較晚。通過國內(nèi)外的研究文獻(xiàn)可以看出，目前的GPRS網(wǎng)絡(luò)終端應(yīng)用研究，在大多數(shù)情況下，采用了GPRS數(shù)據(jù)傳輸模塊。模塊制造商主要集中在德國的西門子，法國的Wavecome公司和美國的摩托羅拉公司等，國內(nèi)企業(yè)，如中興、華為，也有GPRS數(shù)據(jù)傳輸模塊產(chǎn)品。相比之下，國外在這一領(lǐng)域的應(yīng)用是比較成熟的，硬件和軟件產(chǎn)品也相對穩(wěn)定，而GPRS服務(wù)在國內(nèi)的應(yīng)用研究尚處于起步階段，這一領(lǐng)域應(yīng)用研究的空間還比較大。相信在未來幾年內(nèi)，GPRS技術(shù)的應(yīng)用會有長足的發(fā)展。近年來關(guān)于GPRS無線數(shù)據(jù)傳輸?shù)难芯恳彩嵌喾矫娴?，有的致力于移動?shù)據(jù)通信的全套解決方案，針對消費(fèi)電子、工業(yè)控制、環(huán)境監(jiān)控和遙控遙測等不同行業(yè)，開

56、發(fā)了具有針對性的實體產(chǎn)品，包括數(shù)據(jù)采集、數(shù)據(jù)通信、數(shù)據(jù)管理等各種功能。有的為了讓嵌入式工程師專注于應(yīng)用開發(fā)而進(jìn)行GPRS的網(wǎng)絡(luò)的通信協(xié)議棧的研究，為上層開發(fā)提供透明的IP通道，從而不用理會相對龐大、復(fù)雜的網(wǎng)絡(luò)通信協(xié)議。還有的針對GPRS無線數(shù)據(jù)傳輸中的性能問題，提出了一系列改進(jìn)的方案，如針對GPRS的可靠性、安全性等方面進(jìn)行改進(jìn)，進(jìn)一步提高了GPRS無線傳輸?shù)男阅埽瑥亩卣沽薌PRS的應(yīng)用領(lǐng)域。五分鐘搞定5000字畢業(yè)論文外文翻譯，你想要的工具都在這里!在科研過程中閱讀翻譯外文文獻(xiàn)是一個非常重要的環(huán)節(jié)，許多領(lǐng)域高水平的文獻(xiàn)都是外文文獻(xiàn)，借鑒一些外文文獻(xiàn)翻譯的經(jīng)驗是非常必要的。由于特殊原因我翻譯外文文獻(xiàn)的機(jī)會比較多，慢慢地就發(fā)現(xiàn)了外文文獻(xiàn)翻譯過程中的三大利器：Google“翻譯”頻道、金山詞霸（完整版本）和CNKI“翻譯助手。具體操作過程如下： 1.先打開金山詞霸自動取詞功能