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Mobile telecom munications protocols for data networks phần 5

Truy cập băng thông rộng không dây được dựa trên khái niệm hai Layer (TLN) mạng, trong đó thuê bao được chia thành các nhóm microcells, được nhúng vào một macrocell. Phạm vi bảo hiểm microcells sử dụng lặp địa phương hoạt động ở 5,8 GHz cho ăn một BS thông qua 40 liên kết GHz. OFDM điều chế được sử dụng để cho phép việc tiếp nhận với plug-nhận đặt bên trong các tòa nhà. Một băng tần 40 GHz cố định. | 94 NETWORK ARCHITECTURE SUPPORTING WIRELESS APPLICATIONS Figure 6.2 WAE logical model. All resources on the WWW are named using Internet standard Uniform Resource Locators URLs . All classes of data on the WWW are given as specific types allowing the user agent to correctly distinguish and present them appropriately. The WWW defines a variety of standard content formats supported by most browser user agents including the HTML the JavaScript scripting language and other formats like bitmap image formats. The WWW defines a set of standard networking protocols allowing any browser to communicate with any origin server for example Hypertext Transfer Protocol HTTP . The WAE logical model is shown in Figure 6.2. In the WAE model the content is transported using standard protocols in the WWW domain and an optimized HTTPlike protocol in the wireless domain. The content and services in WAE architecture are hosted on standard Web origin servers using proven technologies like Common Gateway Interface CGI . The content is located by using WWW standard URLs. WAE supports WAE ARCHITECTURE 95 Mobile Network Services such as Call Control and Messaging. WAE architecture supports low bandwidth and high latency networks and considers CPU processing constraints in MTs. WAE assumes the existence of gateway functionality responsible for encoding and decoding data transferred from and to the mobile client. The purpose of the encoding content delivered to the client is to minimize the size of data sent to the client Over The Air OTA and to minimize the computational energy required by the client to process the data. The gateway functionality can be added to origin servers or placed in dedicated gateways. The main elements of the WAE model are WAE user agents content generators standard content encoding and WTA. WAE user agents interpret network content referenced by a URL. Content generators are the applications or services on origin servers like CGI scripts that produce standard content