As a video conference system that relies on network operation, the network environment plays a decisive role in the effectiveness of the conference. With the continuous expansion of the application range of video conferencing, the demands of the network environment are increasingly diversified, and different industries have different needs. Currently, mainstream network lines on the market include IP metropolitan area network access, ADSL access, and CableModem access. What is the difference between these three access methods, how can users choose according to their own needs? The following small series will briefly introduce you for your reference.
1. IP Metropolitan Area Network Access
"IP Metropolitan Area Network" is what we usually call a broadband network. It is an Internet based on the IP protocol (Internet Protocol) in the city, based on multiple transmission media, using TCP / IP protocol as the communication protocol, and routing and exchanging IP data packets through router networking transmission.
The access method of the IP metropolitan area network is 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 a switch and a hub. Its advantage lies in the mature LAN technology, the price of network cables and intermediate equipment is relatively cheap, and it can achieve a smooth transition of 1M, 10M and 100M. The LAN access method is one of the current main ways of home broadband network access.
FTTX access means that the fiber is 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 stage of popularization, but its unlimited bandwidth capacity is the future The direction of broadband network development. At present, the optical fiber is mainly used for the connection between the backbone network and each node, and some enterprises that require high bandwidth will also use this access method.
2. ADSL access:
ADSL (AsymmetricalDigitalSubscriberLoop Asymmetric Digital Subscriber Loop) This emerging Internet access method is hailed by the developed countries in Europe and America as "the express train on the modern information highway." It utilizes an existing pair of copper twisted pairs (that is, ordinary telephone lines) to provide users with asymmetric transmission rates (bandwidth) for upstream and downstream, and upstream (from user to network) for low-speed transmission; downstream (from network to user) ) For high-speed transmission. It is deeply loved by the majority of users because of its high downlink rate, frequency 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: multi-use on one line, you can make calls while surfing the Internet without affecting each other; the cost is low, it belongs to the "dedicated line" Internet mode, there is no need to pay telephone fees for Internet access, saving costs; simple installation, you can directly use the existing User phone line, no need to apply for additional lines, just install an ADSLmodem and a phone splitter on the user side, and install an Internet card on the computer to use; wide application, home office, remote office, high-speed Internet, distance education , Telemedicine, VOD video on demand, video conferencing, Internet interconnection, etc. can be easily used.
3. CableModem access method
CableModem is an access method commonly used in radio and television systems. This access method uses the existing cable television (CATV) network, uses Cable (coaxial cable) or HFC (HybridFiber / Coax fiber coaxial hybrid) network as a transmission channel, and uses CableModem (cable modem) technology to access the network. The biggest advantage of CableModem access is fast speed and less resource consumption. Its downlink transmission rate can reach 27-56Mbit / s according to the different bandwidth and modulation method, and the uplink transmission rate can reach 10Mbit / s.
In practical use, CableModem 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 the data is not sent or received, even if the computer stays online 24 hours a day, it will not occupy any network and system resources. Specifically, the transmission medium of the ordinary Modem is independent between the user and the switch, that is, the user alone is the communication medium. The CableModem is not just a modem, it is a function of Modem, tuner, encryption / decryption device, bridge, network interface card, SNMP agent and Ethernet hub. No dial-up Internet access, no phone line, only need to modulate a certain transmission frequency band, 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 determined, but depends on the number of users who share 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 that users exclusively enjoy. Moreover, because it is now a shared network, data transmission is based on a broadcast mechanism, and the security of communication is not high enough. At present, the cable television network is mainly laid in residential quarters, so its scope of application is not very extensive.
4. Wireless access technology
Wireless access refers to some or all wireless access technologies from the switching node to the user terminal. Currently, wireless access technologies can be divided into two categories: mobile access and fixed access.
Mobile wireless access networks, including cellular mobile telephone networks, wireless paging networks, cordless telephone networks, trunked telephone networks, satellite global mobile communications networks, and personal communications networks, are among the most active areas in the communications industry today. Mobile access can be divided into high-speed and low-speed. High-speed mobile access is generally available in cellular systems, satellite mobile communication systems, trunking systems, etc., while low-speed access systems are available in PGN micro-calls, areas, and femtocells, such as CDMA's WILLJACS, PHS, etc., as well as mobile GPRS Wait.
Fixed access is the use of wireless access from switching nodes to fixed user terminals. It is actually a wireless extension of PSTN / ISDN, and its goal is to provide users with transparent PSTN / ISDN services. Terminals in fixed wireless access systems have no or only limited mobility. Access methods include microwave one-point multiple access, fixed applications for cellular mobile access, wireless user loops, and satellite VSAT networks.
The fixed wireless access system mainly provides narrowband services, which are basically telephone services. At present, 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) and local multi-point distribution service (LMDS) that have been put into use. The first two are well known, and LMDS is just emerging, and it has only recently become a hot new broadband wireless access technology. LMDS usually uses high-frequency wireless signals in the 20-40GHz frequency band to send and receive digital signals between the user's front-end equipment and the base station. The uplink / downlink transmission rate can reach several megabits per second. Its main advantage is that it requires almost no external cable lines and is quickly installed. flexible. However, in practical applications, this method not only has relatively expensive equipment, 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 requirements of their purchased video conferencing products and the application environment for network bandwidth and network quality in order to maximize their investment and utilization.
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