The Infrastructure Platform for Remote Learning_网络技术论文

3. HomeNet Logical Layer Architecture

Figure1 shows the HOMENET logical architecture, the whole system consists of five layers: physical media layer, protocol layer, API layer, APP layer (application program) and UI (user interface) layer. The specifications of the underlying two layers has been distributed and used in practices.

Figure 1 HomeNet architecture

The API layer is the key of HomeNet , the technologies of it is the hot issue of home network development, the Home API and Jini specifications distributed in 1999. The fourth layer APP is a set of applications over the third. The fifth layer is UI, it is a set of various interface tools, it is not limited to PC, but also includes emergent buttons, help switches, remote controlling devices and other visual interfaces.

The HomeNet protocols can be divided into three types: under layer protocols ( media ,protocol layers), API protocols and UI specifications. In UI layer, without proper distributed specifications, with the market enlarging and the increment of user requirement, it is necessary to standardize the UI design. From the view of zone, the HomeNet specifications are distributed by America, Europe and Japan, such as Japan’s HBS, Europe’s BatiBUS, Europe Home System and EIB, America’s X10, CEBus and lonWorks. Addition, some work group also distributed specifications such as HAVI’s IEEE 1394, Bluetooth, HPNP, Home API and Jini[4][5].

4. The Connect Scenarios and Media

There are several communication media at home as following: TP (twisted pair), TL (telephone line), xDSL, Cable Modem, FB (fiber), PL (power line) and wireless trsmission (IEEE802.11, HomeRF, Bluetooth). TP, TL and PL are current prevailing media in HomeNet, FB, xDSL, Cable Modem and wireless media will dominate in the f

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