BOX 2.1 In-Home Networking Technologies Wired Ethernet      This is the industry-standard networking technology commonly used in office and business settings. Ethernet today routinely runs at 100 Mbps, which provides adequate performance for many applications, even video applications. (Quality-of-service management, which is not provided by standard Ethernet, may, however, be required for very-high-end applications.) The primary difficulty with using wired Ethernet is that most homes are not wired with the requisite category 5 wiring. There are long-term efforts aimed at promoting the installation of networking-compatible wiring in new construction;1 rewiring of existing dwellings is generally restricted to early technology adopters who are willing to deal with the cost and disruption associated with installing new wires within a house. With a wired infrastructure in place, Ethernet is a very inexpensive solution, with interface hardware available from many vendors and frequently incorporated into computers. It also offers ample headroom for future speed upgrades (1 gigabit per second [Gbps]s has been demonstrated over four category 5 twisted pairs of 150 feet). For the slowly growing set of users that have the requisite wiring, Ethernet is a likely technology of choice. Phone Line Networking      Phone line networking operates by using a high-frequency carrier superimposed over a home's existing analog voice telephone wiring, allowing any standard phone jack within the house to become a network port. For homes that have phone jacks already installed in locations where networked devices are likely to be located, as is the case in many U.S. homes, this is an attractive solution. An industry standards group, the Home Phoneline Networking Alliance (HPNA), has defined two standards: HPNA 1, which provides a 1-Mbps data rate, and HPNA 2, which increases the data rate to 10 Mbps while maintaining backward compatibility with the first version. The HPNA specification does not interfere with the normal voice operation of the phone line, and it operates in a different band from a G.992.2 asymmetric digital subscriber line (ADSL) (G.lite) so that it can coexist with that standard as well. HPNA products are currently offered by a number of vendors for attachment to existing computers via parallel port, universal serial bus (USB), or via a peripheral component interconnect (PCI) add-in card. Additionally, a number of PC vendors are shipping home PCs with HPNA integrated into the system directly. The technology is relatively inexpensive and HPNA is being bundled with home computers today, much as most home PCs include analog modems. HPNA has the drawback of interfering with broadcast radio and some, but not all, types of DSL. Wireless Networking      Wireless solutions are very attractive in that they require no wires to be installed. They allow networked computers to be located anywhere within the home, and they support mobility within the house. In the past, wireless technologies suffered from being too expensive for broad consumer acceptance, had lackluster performance, and were too power-hungry for use in battery-powered devices. More recently, two standards using the unlicensed 2.4-gigahertz (GHz) band that overcome these shortcomings have emerged: 802.11b and HomeRF. 802.11b has been defined by the Institute of Electrical and Electronics Engineers (IEEE) and supported by the Wireless Ethernet Compatibility Alliance industry consortium. It uses direct sequence spread spectrum rather than frequency hopping, and operates at up to 11 Mbps for data. A number of vendors have announced 802.11b products. 802.11b is also being widely supported in business environments and public access points and is also being used in a number of community access initiatives. With both standards, there are issues of interference with other uses and other technologies that make use of the same radio spectrum.      Products using a new standard from IEEE (802.11a), which use the 5-GHz band and promise data rates of 54 Mbps, are under development. Another wireless LAN standard operating in the 2.4-GHz band, 802.11g, would boost speeds to as much as 54M bit/sec while proving backward compatibility with the 802.11b. Another relevant wireless standard is Bluetooth. Currently Bluetooth targets data rates of less than 1 Mbps, although work is ongoing to define higher-speed versions. However, it focuses now and probably in the future on short-range "personal area networking," at less than 10 meters (m). While Bluetooth will likely have applications in the home, the range may restrict it from being a general-purpose solution for home networking. Also, because both Bluetooth and the current generation of wireless LANs use the same spectrum, there are still unresolved issues of how to efficiently share the spectrum and avoid interference. Powerline Networking      Because power outlets are ubiquitous in homes, there has been long-standing interest in technology that would provide high-speed networking over household AC power wiring. However, there is a great deal of interference present on power wiring, because these wires are used to supply power to motors and other very electrically noisy devices. In addition, many homes utilize both phases of the supply power in different circuits within the home; communicating across outlets connected to different phases requires installation of bridges between the phases, which may be difficult for consumers themselves to install.      In multidwelling units there are also potential interference problems, analogous to those faced in wireless networking, associated with multiple users using common lines. To date, the most common use of networking over the powerlines has been for X-10 home control devices that permit remote operation of lights and the like. In the year 2000, several companies began shipping, or announced, powerline-based data networking products, with claims of data rates up to 10 Mbps. The HomePlug Powerline Alliance available online at <www.homeplug.org> has been formed and is promoting its 10-Mbps baseline standard. Field trials and certification lab are reportedly approaching. 1 Wiring America's Homes, sponsored by the Home Automation Association.See <http://www.homeautomation.org/wah.html>.