In addition to a wide variety of services, the biggest feature of satellite Internet access is its high speed. Compared with traditional modems, satellite Internet access speed is several tens to hundreds times faster, which is 28 times that of 14.4k modems. It supports all standard TCP/IP network protocols and applications, such as HTTP, FTP and SMTP. So you can download the big files you want quickly and effectively. The system equipment required for the satellite live broadcast network service is the network operation center (NOC), the 7- 1 1m diameter satellite transmitting antenna, and the uplink master station with 24M satellite bandwidth. At the same time, the network resources designated by users can be obtained by connecting to the Internet through broadband private lines. Satellite signals are converted into satellite signals by QPSK satellite modulation and coding in Ku band, and then broadcast and transmitted to users. The client only needs a Pentium /90, 16M, 20M HD or above, Windows 95 or NT Workstation4.0 operating system, 14.4kbps or above modem, 0.75-0.9m satellite antenna, Ku-band satellite signal receiver, satellite modem card, driver and application software suite. When in use, dial ISP with a common modem, and use satellite 400K rate for uplink and downlink. At the same time, it provides 3M broadcasting bandwidth for website broadcasting, securities information, data transmission, distance education and other functions. For general enterprises, digital packet express and multimedia transmission services with satellite Internet access can transmit digital information from a single point to multiple points very quickly, such as transmitting transmission software, electronic files or training courses in enterprises to branches, distributors, chain stores and members. In addition, the broadcasting function of satellite internet access can be arranged in advance like TV programs, or according to the requirements of users. Satellite Internet service is relatively reasonable in cost because of its high-speed and ideal transmission mode, so it is gradually developing into a brand-new broadband access mode. In June 5438+10, the national satellite broadband internet access fee was equivalent to ADSL.
China Satcom Satellite Broadband Beijing Gateway Station was handed over on 24th, and the Northeast, North China and Central China have since realized satellite broadband access to telephone, TV and Internet. It is estimated that by June 65438+ 10 this year, the gateway stations in Shanghai and Guangzhou will also be opened, and satellite broadband access will cover the whole country by then.
According to the person in charge of China Satcom, the use of large-capacity satellite broadband system is not only for high-end users such as individuals and groups who need stable broadband access, but also for urban blind areas and remote mountainous areas where ground networks are difficult to cover. The reporter learned that the capacity of broadband satellites is several times higher than that of traditional satellites, which makes satellite communication realize large-scale economic effects for the first time, thus reducing the use cost. The calculation shows that there is almost no difference between broadband satellite access and broadband access such as ADSL.
The new access technology can improve this situation to some extent, that is, the high-speed broadband multimedia access system using the Diiec PC technology of Hughes Company in the United States. This is a one-way satellite broadcasting system with asymmetric Internet access. A major feature of Internet application is the asymmetry of information transmission. When users browse the Internet, a short request may lead to the return of downloaded files, which contain thousands of times the requested information. If you download through a modem, it often takes a long time. So, can you reduce the bandwidth of uploading and increase the bandwidth of downloading?
DirecPC technology can solve this problem. Direc PC satellite transmission service is a high-speed broadband multimedia access technology introduced by Hughes Network Systems in the United States in 1996. 1996 won the gold medal for the latest product of Data Communication magazine in the United States. In recent years, Direc PC technology is popular all over the world, not only with a large number of users in the United States, but also widely used in Canada, Mexico, Germany, North Africa, the Middle East, India, Japan, South Korea, China, Taiwan Province Province of China and other countries and regions. The basic equipment of the satellite system is the Network Operation Center (NOC), which includes a satellite antenna with a diameter of 7 meters and a 54-meter uplink master station. Others include private broadband networks, which are used to connect to the Internet or broadcast to users through Ku-band QPSK satellite modulation encoders.
The working process of the system is: users access the Internet through dialing, ISDN or special lines, and transmit service requests such as browsing web pages and downloading files to the NOC of the network operation center for processing. Before requesting to leave the user's PC, the client software will attach a header code to the request information. After receiving the request information, NCO will delete the header code and obtain the required content from the corresponding website according to the information address. NOC then sends these contents to the satellite at an uplink speed of 24Mbps, and then the satellite transmits them to the user's receiving antenna and enters the computer. The minimum configuration of the client is a Pentium90 computer, 16M memory, 20M hard disk space, and a modem above14.4kbps. In addition, a satellite receiving antenna with a diameter of 0.75-0.9 m and a computer need to be installed. Operating system is Win95 or Win NT.
Technical features:
1, using asymmetric high-speed satellite transmission technology to optimize network bandwidth;
2. Support standard TCP/IP protocol, WWW, email, newsgroup and Telnet；;
3. Support one-way streaming video and audio real-time multicast;
4. Support one-to-many 3Mbps extremely fast data file transmission, and the receiver is not limited;
5. All transmitted data are encrypted by DES, which is safe and reliable.
At present, there are 1 1 ISPs providing similar services in the world, with about 65,438+million users, distributed in the United States, Japan, South Korea, Taiwan Province Province and other places.
In China, the satellite access systems of "Star Netcom" and Turbo 163, represented by the Engineering Department of Satellite TV Weekly, have been opened. As far as the cost is concerned, satellite access is reasonable, and its ideal transmission mode is high speed, which can be affordable for both enterprises and individual users. Now, Internet users all over the country can enjoy high-speed Internet access via satellite.
In order to access the Internet at high speed, broadband access technology came into being. This paper briefly compares several popular Internet broadband access methods, and emphatically introduces the satellite broadband access technology of the Internet, its application fields and development prospects.