What kinds of access methods does the Internet have?

There are many ways to access the Internet, usually with the following access methods.

1. Access by public telephone network

Use a phone line that connects your ISP, an account number, and a modem dial-up access. Its advantages are simple, low cost, the disadvantage is slow transmission speed, poor reliability of the line, affect the telephone communication.

2. Integrated Services Digital Network (integrated service Digital NETWORK,ISDN)

Narrowband ISDN (N-ISDN) is based on a public telephone network and uses synchronous time division multiplexing technology. It evolved from a telephone integrated digital network (integrated Digital Network) to provide end-to-end connectivity to users, supporting all voice, digital, image, and fax services. At present, the application is more extensive. Although the telephone line is used as the communication medium, it does not affect the normal telephone communication. While broadband ISDN (B-ISDN) is a transmission medium of the optical fiber backbone, the asynchronous transmission Communication mode ATM technology is used.

3. Asymmetric digital subscriber lines (asymmetric Digital subscriber line, ADSL)

ADSL is the ordinary telephone line as the transmission medium, on the twisted pair of uplink up to 640 Kbps transmission speed, downlink up to 8 Mbps transmission speed. You can get ADSL broadband services by simply installing ADSL devices at both ends of the line. Using ADSL Internet, ADSL Modem produces three information channel, namely one is standard telephone channel; one for 640 kbps~1 Mbps uplink: A high-speed downlink channel for 1 mbps~8 Mbps. Telephone communication uses the low frequency segment of 4~4 khz (the actual phone can have 2 m of bandwidth). ADSL adopts discrete multi sound multiplexing technology in modulation mode, transmission of telephone audio with 0~4 kHz on a pair of copper wires, transmitting data with a khz~1.1 MHz and dividing it into 25 uplink and 249 downlink channels with a width of 4 kHz, encoded and modulated by the input data, Sent to the sub channel. Passed to the data room, after the separator, voice signal to the program-controlled room, the data signal left on the data equipment, ITI after the Internet access.

4. Cable TV Network (Cable Modem)

The cable television network is suitable for the whole country, many places provide the cable modem access Internet way, the rate can reach more than Mbps. However, the cable modem is a total-Heng bandwidth, and in a certain period of time (busy) there will be a decline in rate phenomenon.

5. Optical fiber access (FDDI)

The high-speed metropolitan area network built with fiber optic cable can reach up to 10 Gbps and offer broadband access. Optical fiber can be laid to the user's roadside or building, can be accessed at more than the rate of Mbps (optical fiber is not in the household). In theory, the direct access rate can reach Mbps (access to large enterprises or the entire region), but access users can reach about a Mbps, currently in our country the actual downward rate is usually 1~3 Mpbs.

In recent years, the rapid promotion of wireless access, especially to carry portable computer users to bring great convenience. The user through the High-frequency antenna and ISP connection, the general distance of about 10km, under the 3G standard rate of up to 2~11 Mbps, currently in fact the downlink rate of about Kbps, cost-effective, widely popular. But the terrain and distance are limited.

6. Satellite access

Some ISP service providers provide satellite access to the Internet, which is suitable for users in remote areas who need higher bandwidth. Small-caliber terminals (VSAT), including antennas and receiving devices, are required for the downlink data transmission rate of approximately 1 Mbps, uplink to the ISP via ISDN.

7. DDN Line

The use of the special line is exclusive by the user, the expense is very high, has the high rate, has the fixed IP address, the line operation is reliable, the connection is permanent. Bandwidth range in Kbps~8 Mbps.

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