Introduction to network lines for video conferencing

As a video conferencing system that relies on the network to operate, the network environment plays a decisive role in the effect of the conference. As the application scope of video conferencing continues to expand, the requirements for network environment are becoming increasingly diversified, and different industries have different requirements. At present, the mainstream network lines on the market include IP metropolitan area network access, ADSL access and CableModem access. What are the differences between these three access methods, and how can users choose according to their own needs? The following editor will briefly introduce them for your reference.

1. IP metropolitan area network access

"IP MAN" is what we usually call broadband network. It is an Internet based on IP protocol (Internet Protocol) within the city, based on multiple transmission media, using TCP/IP protocol as the communication protocol, and realizing the routing and exchange transmission of IP data packets through router networking.

Currently, IP metropolitan area network access methods are generally divided into LAN access (network cable) and FTTX access (optical fiber). LAN access refers to pulling the network cable directly from the node of the metropolitan area network to the user's home through the switch and hub. Its advantages are that LAN technology is mature, the price of network cables and intermediate equipment is relatively cheap, and it can achieve a smooth transition from 1M, 10M, and 100M. LAN access is one of the main ways to access home broadband networks.

FTTX access refers to the fiber optic cable being directly pulled to the user's home (FTTH fiber to the home) or computer (FTTD fiber to the desktop). Due to the high price of fiber optic network products, it has not yet reached the popularization stage, but its unlimited bandwidth capacity is the direction of future broadband network development. At present, fiber optic cable is mainly used for the connection between the backbone network and each node, and some enterprises with higher bandwidth requirements will also adopt this access method.

2. ADSL access:

ADSL (Asymmetrical Digital Subscriber Loop) is a new Internet access method that is praised by developed countries such as Europe and the United States as the "express train on the modern information highway". It uses an existing pair of copper twisted pairs (i.e. ordinary telephone lines) to provide users with asymmetric transmission rates (bandwidth) for upstream and downstream. The upstream (from the user to the network) is low-speed transmission; the downstream (from the network to the user) is high-speed transmission. It is deeply loved by the majority of users for its high downstream rate, wide bandwidth, and excellent performance. It has become another new, faster and more efficient access method after MODEM and ISDN.

The main advantages of ADSL access include: one line for multiple uses, you can make phone calls while surfing the Internet without affecting each other; low cost, it is a "dedicated line" Internet access method, you do not need to pay phone bills when surfing the Internet, saving money; easy installation, you can directly use the existing user telephone line, there is no need to apply for additional lines, you only need to install an ADSL modem and a telephone splitter on the user side, and install an Internet card on the computer to use it; it has a wide range of applications, and can be conveniently used for home office, remote office, high-speed Internet access, distance education, telemedicine, VOD video on demand, video conferencing, and network interconnection.

3. Cable Modem access method

Cable Modem is a commonly used access method in the radio and television system. This access method uses the existing cable television (CATV) network, Cable (coaxial cable) or HFC (Hybrid Fiber/Coax) network as the transmission channel, and uses Cable Modem (cable modem) technology to access the network. The biggest advantage of Cable Modem access is its high speed and low resource occupation. Its downlink transmission rate can reach 27~56Mbit/s depending on the bandwidth and modulation method, and the uplink transmission rate can reach 10Mbit/s.

In actual use, Cable Modem only occupies a small part of the available spectrum of the cable TV system, so it does not affect watching TV and using the phone when surfing the Internet. As long as no data is sent or received, even if the computer stays online 24 hours a day, it does not occupy any network and system resources. Specifically, the transmission medium of an ordinary Modem is independent between the user and the switch, that is, the user has exclusive communication medium. However, Cable Modem is not a simple modem, it integrates the functions of Modem, tuner, encryption/decryption device, bridge, network interface card, SNMP agent and Ethernet hub. There is no need to dial up to the Internet, no telephone line is occupied, and only a certain transmission band needs to be modulated and demodulated, which is the biggest difference between it and ordinary dial-up Internet access.

Since the bandwidth of the cable TV network is shared by all users, the bandwidth occupied by each user is not certain, but depends on the number of users sharing the bandwidth at a certain moment. As the number of users increases, the actual bandwidth allocated to each user will be significantly reduced, and may even be lower than the ADSL bandwidth exclusively enjoyed by the user. Moreover, since it is a shared network, data transmission is based on a broadcast mechanism, and the security of communication is not high enough. At present, the cable TV network is mainly laid in residential areas, so its application scope is not very wide.

4. Wireless access technology

Wireless access refers to the use of wireless access technology from the switching node to the user terminal in part or in whole. Currently, wireless access technology can be divided into two categories: mobile access and fixed access.

Mobile wireless access network includes cellular mobile phone network, wireless paging network, cordless telephone network, trunking telephone network, satellite global mobile communication network and even personal communication network, etc. It is one of the most active fields in the current communication industry. Mobile access can be divided into high-speed and low-speed. High-speed mobile access can generally be used in cellular systems, satellite mobile communication systems, trunking systems, etc., while low-speed access systems can be used in PGN micro-cells, zones and milli-cells, such as CDMA's WILLJACS, PHS, etc., and GPRS, etc.

Fixed access is wireless access from the switching node to the fixed user terminal. It is actually a wireless extension of PSTN/ISDN. Its goal is to provide users with transparent PSTN/ISDN services. The terminals of the fixed wireless access system have no or only limited mobility. Access methods include microwave one-point multiple access, fixed application of cellular mobile access, wireless user loop and satellite VSAT network.

Fixed wireless access systems mainly provide narrowband services, which are basically telephone services. Currently, there are three main types of fixed wireless access technologies, namely, the multi-channel multi-point distribution service (MMDS) and direct broadcast satellite system (DBS) that have been put into use, and the local multi-point distribution service (LMDS). The first two are well known, while LMDS is an emerging broadband wireless access technology that has just emerged and has only recently become a hot topic. LMDS usually uses high-frequency wireless signals in the 20-40GHz frequency band to send and receive digital signals between user front-end equipment and base stations. The uplink/downlink transmission rate can reach several megabits per second. Its main advantage is that it almost does not require external cable lines, and the installation is quick and flexible. However, in real applications, this method is not only expensive in terms of equipment price, but also has problems such as channel interference, rain attenuation, and line-of-sight transmission.

Conclusion:

When choosing a network access method, users should comprehensively consider the video conferencing products they purchase and the application environment's requirements for network bandwidth and network quality in order to maximize the use of their investment.