Comparison of access methods: ADSL, LAN, HFCs, and PLC

Currently, home users' broadband access can be achieved through ADSL, LAN, HFCs, and PLC. Due to network restrictions, any broadband access service provider can only provide one or two access methods for users. In practice, these solutions vary in terms of network access methods, user costs, and service content that can be provided. When selecting a broadband access service provider, you must first consider which access method is more suitable for your needs, and then determine the service provider. Therefore, the competition for access to the market is the competition for access methods. The following describes the features, application scenarios, and advantages and disadvantages of these solutions.

1) ADSL Access Method

ADSLAsymmetricalDigitalSubscriberLine (Asymmetric Digital user loop) is a technology that provides broadband data services through common telephone lines, it has become another new, faster, and more efficient access method after Modem and ISDN. The biggest feature of the ADSL solution is that there is no need to transform the signal transmission line, and the common copper telephone line can be used as the transmission medium, as long as it is equipped with a dedicated Modem to achieve high-speed data transmission, the valid transmission distance is 3 ~ The longer the distance, the slower the speed.

ADSL supports the uplink speed of 640kbps to 1 Mbps, And the downlink speed of 1 Mbps to 8 Mbps. Can this bandwidth meet your needs? Currently, the most bandwidth-consuming demand for home broadband users is to watch videos online. Generally, streaming media on the internet is played at a rate of 128 kbps, kbps, or kbps, currently, the downstream transmission rate of Beijing Telecom is 512 kbps, which can theoretically meet various online playback needs and is basically suitable for family users.

Ii) LAN Access Mode

The LAN access method uses optical fiber access. The entire city network consists of the core layer, convergence layer, edge convergence layer, and access layer. The access from the Community end to the end user is usually the last kilometer. The LAN mode uses optical fiber cables and twisted pair wires for Integrated Wiring to the community. The total length of twisted pair wires generally does not exceed 100 meters, and the distance between the wires is short. Therefore, the line quality is better guaranteed. The bandwidth service in LAN mode is generally sent to the residential area through the gibit optical fiber. The 10/100 M optical fiber is delivered to the building, which is more than 180 times faster than the dial-up speed, the transmission rate can basically meet various user needs.

Because of the use of optical fiber access, in terms of anti-interference, the LAN method is superior to the ADSL method for data transmission over normal telephone lines. At the same time, the uplink and downlink speeds of LAN access are the same, so there is no interference caused by the uplink speed limit. The LAN adopts the Ethernet access method, so it is subject to certain restrictions in the region. This access method can only be used in a community with a LAN.

3) access to the HFCs

The access method of the HFCs is provided based on the cable TV network. Due to its natural monopoly in the industry, the current broadband access method can only be provided by radio/TV-related enterprises. Most of the network structures in the fiber-optic network are star networks, and tree-like networks are used in the cable network. This network structure is quite advantageous for cable TV networks, but it is not very reasonable for Broadband High-Speed Integrated Service Networks, mainly because cable TV networks and integrated information networks have different reliability requirements, comprehensive information networks require high network reliability. The cable TV network fails, and only some users cannot watch TV programs for a certain period of time. However, once a fault occurs in the integrated information network, it cannot be repaired in time, it may cause irreparable losses to users.

Two-way transformation is performed on a one-way basis for transmission. Because it shares a channel, its bandwidth will be continuously reduced when the number of users increases, and mutual interference is too high. No network has more than 5000 users on CABLE. Currently, cable TV networks still have defects in bandwidth sharing, network security, and network management. The common feature of the two modes is that the existing network infrastructure is used. Their common disadvantage is that the bandwidth expansion capability is limited.

4) PLC access method

Power Line Communication Technology (PLC) is a communication method that uses power lines to transmit data and voice signals. The technology is to load the high frequency of information contained in the current, and then transmit it using a wire. the modem that receives the information then separates the high frequency from the current and transmits it to a computer or phone, to transfer information. On the basis of no re-wiring, this technology can carry data, voice, video, and other services on existing wires, that is, to achieve the integration of four networks. End users can connect to the Internet by plugging in the power plug.

PLC uses the range of m to 30 m to transmit signals. During transmission, the user data is modulated using GMSK or OFDM modulation technology, and then transmitted on the power line. at the receiving end, the modulated signal is filtered out by the filter and then demodulated, the original communication signal can be obtained. The current communication rate varies between MB and MB depending on the specific device ~ Between 45 MB. The PLC device is divided into local terminal and modem. Local terminal is responsible for communication with internal PLC modem and external network connection. During communication, data from the user enters the modem modulation and is transmitted to the local device through the user's distribution line. The local device decrypts the signal and then forwards it to the external Internet.

Conclusion:

Although every broadband service provider emphasizes that its broadband access method is the most advanced and convenient, we should see that, due to factors such as the network size, technical level, and length of employment of broadband access service providers, there is a huge gap between the theoretical value of various access methods and the actual use effect of users. For example, in LAN mode, although theoretically the user's Internet access rate can reach 10 M, in fact, the current rate of each home user is also several hundred kbps. The four Broadband Access Modes of ADSL, LAN, HFCs, and PLC have their own characteristics, and their advantages and disadvantages are also very obvious.

Most of your home has been connected to power lines and cable TV lines. Therefore, you do not need to strip the cables in your home without changing the original facilities in your home by using two broadband access methods: HFCs and PLC. However, it takes a short period of time to provide broadband access through the HFCs and PLCs, and the technology is not complete yet. Due to many interference factors, users may encounter various defects during use, so it is not widely accepted by users.

Currently, the main ways for home users to achieve broadband Internet access are ADSL and LAN. With mature LAN technology, low cost, simple structure, stable connection, good scalability, and easy network upgrade, the Internet access speed is faster for users. However, the LAN is subject to great restrictions in the region. This access method can only be used in the community where the LAN is already deployed. In addition, a network cable must be set up when accessing the user's home, damage the decoration in users' homes. In addition, the LAN method also faces problems such as the relatively lack of high-end devices, the large number of IP Address resources required, and the high level of operation and management requirements.

The ADSL mode does not require large-scale network transformation. If a modem is added to both ends of the existing copper wire pair, the transmission rate can be increased by dozens of times. The advantages of using ADSL technology to carry out broadband access services are obvious. First, we can make full use of the existing copper resources of the Telecom Network, reduce capital investment, and give full play to the potential of copper wires. Second, users can access the Internet at any time, without having to establish a new connection each time, without affecting the use of the phone. Each user can enjoy an exclusive expressconnect without blocking problems. In addition, ADSL access features high confidentiality and security and reliability. Therefore, ADSL has become the first broadband access service for telecom operators. However, the maximum rate provided by the ADSL line is very sensitive to distance and copper quality. When distance increases, the increase in crosstalk, especially remote crosstalk, will degrade the line quality.

In short, none of the current broadband access methods are the best. What users really want to choose is the most suitable method.

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