Those who look at the home-networking market and see debate rather than development miss the point: The local-area networks of tomorrow's homes will require a mix of technologies with which to deliver a growing variety of bundled information and entertainment services, both into and throughout the home or small office.
Most of us are used to a fairly homogenous corporate network environment. But tomorrow's home LANs will connect more products over more fragmented networks via more physical-layer links than ever attempted before. Indeed, the question isn't which home-networking technology will "win;" neither is it how one can hedge one's bets in a seemingly fragmented market. More important is how those technologies can coexist to make next-generation voice and data services widely accessible using the broadest spectrum of consumer products in a diverse range of home and small-office environments.
Until now, Internet access has been the major focus of high-speed communications. Cable modems and asymmetric digital subscriber line (ADSL) technology have gained significant mind share and provide Internet access at rates far beyond what's available with analog POTS modems. But as these technologies begin to achieve market penetration, today's network equipment and service providers are beginning to offer a complete bundle of communications services for the home, including Internet access, local and long-distance telephony, cellular, paging and entertainment services, coupled with techniques for distributing these services throughout the home.
Clearly, it won't be possible to access all of these services using some sort of universal communications product or device. Tomorrow's home networks will have to accommodate multiple products, from desktop and portable PCs, handheld devices and "infotainment" appliances to telephones and imaging systems like printers, scanners and digital cameras. Similarly, no single home-networking technology can effectively accommodate all of these product platforms over the long term.
In the short term, though, the technology winner in the phone line segment has already been chosen: the Home Phoneline Networking Alliance (HomePNA) standard. HomePNA connects PCs via the same RJ11 cable that is used for connecting online with a modem. Users are familiar with this connection and it does not add any cables. Costs for HomePNA technology are low. In addition, it benefits from low noise, high speed, industry interoperability standards and the fact that multiple outlets exist in the home. Most of the leading PC manufacturers are now adding HomePNA networking capability to their product lines. Whether or not HomePNA prevails in the long term, it is considered by leading PC OEMs to be today's most viable candidate for mainstream home networking connectivity.
However, HomePNA is a tethered medium and, since there are a limited number of phone jacks in a home and they aren't in every room, users may need more connection points. For this reason wireless technology has emerged as the preferred home-networking option for untethered devices such as digital cameras, portable PCs, handheld terminals and digital toys.
Manufacturers of portable PCs are already offering wireless LAN technology. Apple Computer Inc. has endorsed IEEE 802.11b, an 11-Mbit/second variant of the original 1- to 2-Mbit/s IEEE 802.11 specification with the same 100-meter reach. The 802.11b spec is the most likely wireless LAN technology to be used in business applications, since it is the only wireless data LAN standard for business. If widely adopted for home nets, 802.11b would give users a single product that could provide connectivity both at home and in the office.
A group of companies has formed the Wireless Ethernet Compatibility Alliance (WECA) to promote interoperability among IEEE 802.11 products. The IEEE 802.11 High Rate Direct Sequence standard would help ensure global, seamless, high-speed wireless connections for the enterprise, small-office and home markets. It would also enable true multivendor interoperability by certifying that systems from different manufacturers can be used within the same wireless infrastructure.
Another option is HomeRF, which was designed to simultaneously support up to four quality voice channels, something 802.11 wasn't designed to do. So far, however, HomeRF hasn't been able to get much traction in the market, perhaps because a "killer app" requiring both voice and data support has not yet appeared.
Besides HomeRF another wireless LAN technology is being defined by several companies that supports packet and isochronous traffic simultaneously, giving preference to the isochronous. Although this would allow residential users to install a single wireless technology for both telephony and data applications, few consumers buy grand, all-encompassing solutions for their homes. Most tend to buy specific solutions for specific functions, knowing that the arrival of better technology will soon make today's purchase obsolete.
Other major players are backing Bluetooth, a cable-replacement technology based on a 2.4-GHz wireless radio that can be-and probably will be-embedded in notebook PCs, cellular telephones and handheld devices. Even though it was designed for communications over 10 meters at 1 Mbit/s, the addition of a power amplifier will enable greater coverage, perhaps up to 50 or 100 meters. Bluetooth's supporters believe it can evolve into an inexpensive home or small-office network capable of linking several machines at once. There is also discussion about extending Bluetooth to 10-Mbit/s data rates, which would position it as a significantly more attractive residential LAN component.
The future of home networking is likely to contain many technologies, services and products. Next-generation solutions will have to provide the convergence point for all these products and their associated services. One example of this direction is found in residential gateways for terminating high-speed multiservice communication links into the home. Cable, DSL and wireless local loop providers are all moving to provide Internet access and multiple lines of telephony to the residence. The residential gateway would interface to the high-speed communications pipe and distribute services via the most appropriate medium. For example, Internet access may be distributed via HomePNA, while telephony may be distributed via the copper wire pairs in the home.
Where a telephone jack isn't close enough to this residential gateway system-for instance, if implemented in a TV set-top box-cordless technology can be used to deliver telephony, especially since subscribers have proved to be wedded to cordless phones. Modems and faxes can be supported by using 64-kbit/s G.711 pulse code modulation (PCM) over the wireless path, or by implementing a "demod-remod" or "modem-fax relay" technique. And for Internet access via wireless devices throughout the home, one could incorporate wireless LAN technology into the gateway, along with a bridge or router to the HomePNA network.
Moving forward, residential home LAN technology is likely to develop in an ad hoc fashion. For example, consumers may purchase a PC that includes a HomePNA component and then add a HomePNA connection to their printers. Later, they may add a Bluetooth function to the LAN in order to connect between the primary PC and their PDAs.
Over time, this heterogeneous residential LAN will become the primary element of the digital home, with peripheral devices, including PCs, connected to it. Because of the networks' heterogeneous nature, it will be important that devices include multiple LAN technologies. For example, a supplier of residential gateways might include HomePNA and wireless LAN technology along with cordless phone technology to support demand for extended connectivity throughout the home.
Few OEMs will tolerate the cost or customer support burdens associated with connecting multiple cards in multiple slots to the single RJ11 jack in the wall. Combining all of that functionality into a single product will require system architectures that can integrate a PCI bus interface, buffering and an arbiter to manage all the interrupt handling for home networking, V.90 modem connectivity, DSL links and cable-modem and corporate-LAN operations or both. In that way, it will be possible for multiple functions to coexist on a single card, using a single RJ11 jack for input and output, or an RJ45 for cable-modem-to-corporate-LAN connections.
Easy upgrade path
This multifunction system architecture would also offer an easy upgrade path to incremental new communications capabilities, while enabling a wide variety of product feature sets and price points. For instance, an OEM could choose to offer a single-function home-networking product today and later integrate the necessary silicon to add V.90, ADSL and cable modem connectivity as required. That flexibility will be particularly important as OEMs begin to segment their product lines to include a variety of multifunction products for a home's main residential gateway "server" PC, as well as networking-only products for a home's secondary PCs.
As for the bridge-router product, it would provide the same functionality found in similar products for the corporate network, but in a scaled-down implementation. The bridge-router would facilitate internetworking between the HomePNA systems and a variety of Bluetooth-capable devices such as PDAs and digital cameras, enabling connectivity among a variety of both tethered and untethered devices.
Bluetooth promises to provide personal-area connectivity for devices such as cellular phones, PDAs and digital cameras. But Bluetooth at 1 Mbit/s may not be adequate for digital cameras, which is why the industry is looking closely at a 10-Mbit/s version. With a USB connection, users are accustomed to transferring images at about 12 Mbits/s. Dropping that to 1 Mbit/s would be painfully slow.
There are many options for combining these technologies at the silicon level into next-generation products and equipment. Initially, the physical-layer (PHY) portion is likely to stay separate, specific to the medium. Integration will happen at the upper layers where applicable. For instance, almost all of the solutions will use an Ethernet media-access controller (MAC) and a standard-whether HomePNA, 802.11, or HomeRF-and will require a media-specific PHY.
Integration can be done either with multichip modules or full silicon integration. MCMs offer an ideal option as the industry evolves. They significantly reduce component count while simplifying the test and integration process, yet they don't lock the silicon or equipment supplier onto a path that may have to be modified as technologies are adopted or abandoned. As market requirements solidify, full silicon integration then provides additional cost, space and power savings.
Clearly, tomorrow's challenge lies in how to address as many access and connectivity options as possible. A single product, such as a PC used for residential gateway functions, might support HomePNA, wireless networking, V.90 modem connectivity and broadband access with ADSL or cable. The coming tapestry of new voice and data services will require that multiple solutions be combined into a single seamless environment that gives consumers as many connectivity options as possible.