In recent years, various types of access networks an increasing number of small devices, such as video phones, enterprise access points, residential gateways / routers, surveillance cameras, card readers at retail outlets, identity card scanner so, however, an obvious difficulty is the problem of such small-scale power supply terminal. Under normal conditions, these devices are as 15W power over the exchange are basically independent power supply. However, due to the current complexity of networks and applications, it is difficult to meet this need. Therefore, a direct network connection cable to the power of such devices has become a priority.
From the current view of network formation and network applications, Ethernet is the top priority.
Ethernet is a LAN technology, in large enterprises, SMEs and home network devices via twisted pair to provide DC power by power. Approved IEEE802.3af standard was originally developed to power IP phones, and in the absence of the AC outlet or AC power outlet is not convenient to use the place, this standard allows for scalable and manageable manner to VoIP and wireless 15W power access point equipment. To improve the supply power (in the 802.3af standards-based), IEEE802.3at Task Force is currently developing some norms, while pre-IEEE802.3at solutions are currently used to power a new generation of networking equipment, networking equipment, including those video phones, surveillance cameras, residential gateways / routers, retail card reader and a card scanners, these devices require higher power to work. According to market research firm Dell'Oro
research, relying on telephone and wireless Ethernet technology widely used to promote the growth of Power over Ethernet ports, beginning in 2005, Ethernet port per year will grow by approximately 50%. Dell'Oro in its report entitled "Summary of Ethernet 5-year forecast" (January 2007 release) in a research note: "In 2006, Ethernet delivery to 32 million ports in 2011, deliveries will increase to 145 million ports, an annual growth rate of more than 30%. "Dell'Oro expects:" IP phones will continue to be strong popular Power over Ethernet switch driver, of course, enterprise-class wireless LAN access points, security cameras, identity card scanners and other equipment will also be the driving factor. "
Ethernet Problems In fact, Ethernet is not new. For some low-power devices, Ethernet is easily solved, but with new types of network applications and equipment in use. Ethernet is also facing many problems, in general, can be divided into the following five points.
First: their own power and thermal effect.
Own power and thermal effect is very easy to understand, mainly through Power over Ethernet switches, routers, gateways and set-top box equipment, power supply modulation. The device itself is a big power. If using Ethernet, then bound to create its own power consumption of such equipment. Second, the thermal effect is difficult, because the power to control the multi-port, these devices increase in number of voltage regulation. Therefore, the thermal effect on the re-bound, handled properly, this type of equipment their most important data exchange and processing of damaged a bit more harm than good. Therefore, control and design requirements of power supply is high.
Second: how to provide stable and high voltage.
Is because of the thermal effect and the use of five types of transmission lines by heat, the impact of issues such as transmission distance, whether the issue to the terminal voltage is a problem. In addition, due to a variety of new equipment to provide integrated services, such small devices often requires a higher voltage, then the use of Power over Ethernet can provide a high-power voltage is difficult.
No. 3: How to maximize the transmission distance, and reduce energy consumption.
Though power LAN, but it is precisely distance, the lack of AC-powered devices need to use more direct power over Ethernet.
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