Access Network Technology-Wireless Access and large network access

Access Network Technology-Wireless Access

Wireless access can be divided into mobile access and fixed access. Mobile access can be divided into two types: high speed and low speed. High-speed mobile access is generally available in cellular systems, satellite mobile communication systems, and cluster systems. Low-speed access systems can use PGN micro-cells and micro-cells, such as cdma will, PACS, and PHS.

Fixed access refers to wireless access from switching nodes to fixed user terminals. It is actually a wireless extension of the PSTN/ISDN network. The goal is to provide users with transparent PSTN/ISDN services. the terminals of the Fixed Wireless Access system do not include or only contain limited mobility. The access methods include microwave one-point multi-access, fixed applications for mobile access in cellular areas, wireless user loops, and satellite VSAT networks. The Fixed Wireless Access system mainly provides narrowband services, which are basically telephone services.

There are three main types of broadband and fixed wireless access technologies, namely the multi-channel multi-point allocation (MMDS) service that has been put into use) and the live video satellite system DBS) as well as the local multi-point distribution service LMDS that are conducting field tests ). The first two are already well-known, while LMDS is just emerging and has recently become a hot emerging broadband wireless access technology.

A typical LMDS consists of multiple hub senders like a cellular configuration. Each sender can communicate with a fixed user in the service area through a multi-point wireless link. The coverage area of a single cell is 2 ~ 5kin. The coverage area is reselected from each other. The coverage area of each cell can be divided into multiple sectors to provide specific services in this sector as needed. This modular structure makes network resizing flexible and convenient.

In order to reduce equipment costs and improve quality, initial applications may be to simulate fm TV distribution services, each 20 MHz, about 50 channels. The next step is to gradually implement digital modulation channels and provide data and other services. In principle, LMDS can provide all services from TV distribution and telephone to full-exchange broadband multimedia services. However, the most favorable opportunity is the provision of interactive TVs and high-speed data. LMDS not only provides Internet access, but also can be used to interconnect local networks, which is expected to divert some profits from the public and enterprise user markets. When it is used only for One-Way Analog distribution of TV services, the cost is expected to be less than half of MMDS. If it is used only for voice, it can support 60 thousand telephone users.

The LMDS system is still in the field test phase. Whether the LMDS system can be developed depends largely on whether a low-cost 28GHS Transceiver can be developed. The amplifier in this band needs a single-chip millimeter wave integrated circuit based on the arsenic technology, which is not easy to achieve low cost and high performance. In addition, LMDS only supports line-of-sight transmission. To avoid blocking, the hub station may have to be set to 15 ~ 20 m, which is unfavorable for applications in some environments.

In general, broadband fixed wireless access technology represents a new trend that cannot be ignored in broadband access technology. It is not only fast, easy to maintain, but also cost-effective when users are relatively confidential, in addition, it has changed the traditional concept of local telecom business and is most suitable for effective competition between new domestic network competitors and traditional telecom companies and cable TV companies, it can also be used as an important supplement to the wired access of telecom companies.

Access Network Technology-Ethernet Access

With the decline in technical costs, the increasingly open telecommunications market, and the explosive growth of data services represented by IP addresses, network bandwidth and capacity have once again become a hot topic and a shortage of commodities. The backbone networks of the developed countries represented by the United States are moving towards ultra-high speed and ultra-large capacity development. up to 160 Gbit/S/Gbit/S) of WDM multiplexing systems have been put into use. At the same time, in order to adapt to this new situation, the broadband access technology of the access network also shows a new development trend.

Ethernet technology has always been the most popular method for enterprises and institutions, with 0.1 billion million users worldwide. Currently, 30 million new users are added each year. The main reason for adopting Ethernet as a means of access for enterprises and institutions is that there is already a huge network base and long-term experience. Currently, all popular operating systems and applications are also compatible with Ethernet, with advantages such as better performance and price, scalability, easy installation and activation, and high reliability.

The same Ethernet access mode is very suitable for the IP network, and the technology has already broken through LAN switching and large-capacity MAC address storage. The capacity is divided into 10 Mb/S, 100 Mb/S, and 1000 Mb/S, the 10000 Mbit/S Ethernet technology is coming soon. Using a dedicated full-duplex fiber connection without collision, the transmission distance of Ethernet can be greatly extended, fully meeting the application needs of access networks and man networks.

For more analysis on the technical development of access networks, please read:

Technology Development of access networks-optical fiber access technology

Development of access network technology-XDSL and hybrid Access Technology