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Embedded Systems November 2000 Vol13_12

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I :II :II c. Phoneline networking is an attractive option because it does not require any new cabling within the home and operates like the familiar Ethernet system. FIGURE 6 Bluetooth protocol stack Application Programs Data transport-focused standards Table 1 captures some of the compet- ing technologies vying to be the domi- nant data transport provider in the home network. These technologies are best grouped by media type. ' Radio - FIGURE 7 Phoneline The Home Phoneline Network Association (HomePNA) has adopted Tut Systems' technology to provide a 1Mbps data rate over existing phone lines in the home. The system uses the spectrum in the 5MHz to lOMHz range, well above analog phones, modems, and xDSL. This allows the systems to co-exist on the same wiring. Phoneline networking is an attractive option because it does not require any new cabling within the home and operates like the familiar Ethernet sys- tem. While 1Mbps is not a tremen- dous amount of bandwidth, the HomePNA has adopted Epigram's lOMbps solution as their version 2.0 standard, which will be backward compatible to the Tut Systems solu- tion. In addition, lOOMbps is planned for a future version. Another significant advantage to Manager lso. Resource Manager Transaction Layer the HomePNA is the support within the industry. There is no fragmenta- tion because no other proprietary protocols are vying for market share. Backwards compatibili ty is also a big plus for the faster versions of the pwtocol. HomePNA addresses only the phys- Node Controller ical layer of the intewperability proto- col stack. In fact, HomePNA simply sends standard Ethernet packets over their physical layer. things easier and more flexible for the end user. Of the many contending protocols and transport mechanisms vying for the top spot in the home net- working arena, none of them provide a complete top to bottom stack defini- tion. The focus of each protocol seems to be in one of two areas. Some focus on the lower layers involved in data uĀ·ansport while others concenuĀ·ate on the services and data representation layers. 70 NOVEMBER 2000 Embedded Systems Programming RF RF technology is attractive because it allows mobility and requires no cabling. Three potential candidates are the IEEE 802.llb protocol, Bluetooth, and the HomeRF. IEEE 802.11 b is a standard for RF LANs that provides up to llMbps through- put, with extensions to 50Mbps and beyond in the works. The standard is

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