Multiple Home Network Options Keep Designers Guessing

Most of you define a home network as a system that links two or more PCs in the home. Yet that's only part of the picture. Home control networks have existed for years, but interest has recently been rekindled. Furthermore, there's a growing interest in and need for home entertainment networks.

However you define it, home networking is definitely not just a fad. Current estimates say that about 3% to 5% of U.S. homes already have some kind of home network. These are the high-tech early adopters, but the real consumers are expected to join the home networking movement as products become available and prices decrease. Several major magazines now cover this field at the consumer level. Check out Home Automation, Electronic House, and Penton's Connected Home magazines at your local newsstand.

The Wired Home LAN: The most common reason for a home network is sharing some major resource like a printer or high-speed Internet connection. A server-like device called a residential gateway accomplishes this by connecting to your high-speed cable TV line or DSL line. The gateway then distributes the signals to the various PCs on the network via the chosen communications medium—cable, wireless, or power line.

The most direct approach is to just wire up a simple 10- or 100-Mbit/s Ethernet LAN using category 5 (CAT5) twisted-pair cable. Cheap Ethernet network interface cards (NICs) for PCs are readily available. Most new PCs and laptops have a 10/100-MHz Ethernet port built in. Buy an inexpensive four-port Ethernet hub to connect the gateway to the PCs. Running the cable is the hard part. Even the serious do-it-yourselfers won't find it easy. Or maybe you're lucky enough to own one of the many new homes prewired with CAT5.

Another option is to use the house electrical wiring to carry the data from computer to computer. Because every room has multiple outlets, network connections are available everywhere. The data signals are superimposed on the 120-V, 60-Hz sine wave. The data is carried to all outlets simultaneously.

Also known as carrier current communications, power-line networking has functioned in the electrical power industry for years. But power lines are extremely lossy and noisy. Both conditions severely limit data rate and distance.

Over the years, several different power-line networking technologies have developed, including X10, CEBus, and LonWorks. Most are used for telemetry and control operations rather than for carrying high-speed data.

But the latest technology really overcomes the problems of power-line networking. Named HomePlug 1.0, it's supported by over 80 companies. Gateways and interfaces are just now becoming available. This standard tolerates up to a 14-Mbit/s data rate using orthogonal frequency division multiplexing (OFDM) implemented in DSP.

A typical power-line network system is the new NeverWire 14 QX-201 from Phonex Broadband (Fig. 1). According to Brad Warnock, director of marketing for Phonex, the unit runs at 14 Mbits/s, but protocol overhead drops the actual transfer rate to about 8 Mbits/s. Up to 16 units may be connected on the network. As for distance, Phonex says you can wire up to about 1000 ft of ac power wiring.

Therefore, you can easily network the average house. You can even network between nearby buildings, apartments, or offices. When networking in an apartment, security becomes important. The Phonex units have a built-in Digital Encryption Standard capability using a 56-bit encryption key.

The heart of the Phonex units is the Intellon INT51X1 chip, which implements the HomePlug 1.0 standard. You will undoubtedly see this chip in other power-line interfaces, or use it yourself. Both Ethernet and USB interface options are available.

Another company making HomePlug 1.0 chips is Cogency Semiconductor Inc. Its new Piranha chip set consists of the CS1102 Ethernet MAC/PHY implemented in firmware that can be customized to the application, and the companion AD9875 mixed-signal front end made by Analog Devices. A version for USB is available too, as are reference designs.

Cogency also makes power-line networking end products, specifically wall adapter units that plug directly into an ac outlet. Both Ethernet and USB versions are available. Figure 2 shows the basic block diagram of the USB interface.

Another wired option is the existing home telephone wiring. While most homes don't have as many telephone jacks as power outlets, the available telephone wiring is typically sufficient to eliminate the need for installing other wiring. Several companies supporting the Home Phoneline Networking Alliance standard make NIC cards that plug into any nearby RJ-11 modular jack. The data is then available at all other phone jacks. The current standard moves 10 Mbits/s, but future versions will feature up to 100 Mbits/s.

Wireless Options: Wireless devices are the most popular home networking medium right now. The network interface card in each PC contains a short-range microwave transceiver and antenna. The most popular version is based on the IEEE 802.11b wireless Ethernet standard. It uses direct-sequence spread-spectrum in the 2.4-GHz industrial, scientific, medical (ISM) band. The range reaches up to 150 ft, even through walls. The maximum data rate is 11 Mbits/s, but it drops back to 5.5 or even 2 or 1 Mbits/s, based on the distance between units and the ambient noise level.

The 802.11b radio modems are inexpensive and widely available. An industry support group, the Wireless Ethernet Compatibility Alliance (WECA), sponsors an interoperability testing standard called WiFi (wireless fidelity). It ensures that each manufacturer's radio modem works with all other manufacturers' units. The IEEE's standards group recently approved an updated version of this standard, 802.11g. The update provides data rates from 22 to 54 Mbits/s with backward compatibility.

One of the original home wireless options is called HomeRF. This standard uses frequency-hopping spread-spectrum with frequency-shift keying (FSK) in the 2.4-GHz ISM band as well. The data rate is 10 MHz. Although this standard is less widely used and supported than 802.11b, it's an option. HomeRF is typically much lower in cost than 802.11b modems, but that difference is quickly disappearing. A recent change in Federal Communications Commission (FCC) Part 15 regulations now permits HomeRF to achieve 20-Mbit/s speeds.

Two other wireless standards that may eventually find their way into home networking are Bluetooth and IEEE 802.11a. Bluetooth is a super-cheap, low-power wireless system that transmits data at up to 1 Mbit/s in the 2.4-GHz band. Products using Bluetooth are just now reaching the market, and this technology is expected to grow in use. But the low speed and limited range will keep it from seeing much action in home networks, though higher-speed versions are in the works.

The IEEE 802.11a Ethernet standard defines a wireless LAN connection that operates in the 5-GHz band with OFDM and produces data rates up to 54 Mbits/s. Modems and chip sets are now available, but they're a bit more expensive than 802.11b units, and the range is more limited. These modems are overkill for most home applications, except perhaps for video or fast computer games.

While power-line and phone-line interfaces have sufficient speed for most data and audio applications, they don't handle video very well. Video is possible if heavy compression is used, but home entertainment systems require high-definition video. The 802.11a modems will give you that speed.

A newer high-speed wireless option is ultra wideband (UWB). This exotic technology, recently approved by the FCC, can exceed 100-Mbit/s data rates. Few products are currently available, but you can now get Xtreme, Spectrum's Trinity UWB four-chip set. It consists of the XS1102 transceiver; the XS1112 LNA, along with a 1-in.² planar pc-board antenna; the XS1141 MAC, based upon the forthcoming IEEE standard 802.15.3; and the XS1122 baseband processor integrated with an analog-to-digital converter.

The data rate can be set to 25, 50, 75, or 100 Mbits/s, and the range is about 10 m. While no UWB end products are available yet, expect to see some soon using this chip set in home-entertainment networking systems.

Wireless is by far the easiest of all choices because you don't have to do anything other than plug the units into your computer and go. Your best bet is the 802.11b Wi-Fi units that are readily available and fully interoperable. Prices continue to drop as they become more widely adopted in enterprise networks nationwide.

Entertainment Networks: Entertainment networks link consumer electronic equipment, especially digital video and audio units. While no formal systems exist today, manufacturers and independent organizations are working on standards based on existing technologies like IEEE 1394 and wireless.

Some examples of current interconnection problems include:

• Distributing the cable TV signal, like the forthcoming HDTV signals, to multiple sets around the house without multiple set-top boxes.
• Connecting personal video re-corders, the digital hard-disk-based units by TiVo and SONICblue, to the cable box, TV set, or satellite TV receiver.
• Connecting video games to the TV and the Internet for game downloads.
• Integrating VCRs and DVD players.
• Providing convenient connections for camcorders and digital cameras to the TV set.
• Simplifying the multiple IR remote control nightmare.
• Downloading, storing, and distributing digital music to MP3 players and the stereo system from a broadband connection.
• Distributing surroundsound to speakers and handsets, and to speakers in other rooms.
• Providing a link to the home local-area network (LAN) gateway for Internet access to facilitate video on demand (VOD) and music downloads.
• Simplifying interconnections in a home theater.

Right now we have many different mini or micro networks, or individual connections between units using multiple protocols and media, rather than some integrating standard. Is a collective standard necessary or even possible? Video requires a very high-speed link, unlike audio. Yet both are isochronous data that need quality-of-service capability for reliable communications. Ethernet—wired or wireless—and power-line carrier don't currently provide for this, so standards like IEEE 1394 may supply the ultimate solution.

Some semiconductor companies are working on various solutions to the entertainment network quandary. For example, LSI Logic's latest products address the key component in most home entertainment systems, the set-top box. Figure 3 shows LSI Logic's concept for a digital home network. The set-top box acts as the main gateway and is based on the company's available cable, terrestrial, satellite, and DSL modems, the new DoMiNo Network Media Processor, and the SC200X decoder/demodulator chips for the individual products.

DoMiNo is a one-chip programmable, multistream, multiformat MPEG audio/video/system codec. It includes dual RISC processors and supports both MPEG-2 and MPEG-4. Interfaces include YUV video, four- and eight-channel audio, 32-bit PCI bus at 66 MHz, smart cards, hard disk and DVD, IEEE 1394, UARTs, SPI, and IR.

Another positive development is Royal Philips Electronics' recent demonstration of digital transmission on an IEEE 1394 interface over IEEE 802.11a wireless. This demo is the first to conform to the existing and new industry standards under the IEEE 1394 Trade Association, including IEEE 1394a-2000 and the 1394.1 bridging technology. The 1394 standard solves the isochronous data problem, while the 54-Mbit/s 802.11a standard takes care of the speed necessary to distribute video, including HDTV. Watch for products in the near future.

Another effort at entertainment networking is the Home Audio Video Interoperability (HAVi) initiative. This joint effort by eight leading consumer electronic companies seeks to establish a seamless interoperable interconnection architecture based on the IEEE 1394 standard. Available now, version 1.1 of the specification covers authentication, graphical user interface, remote controls, and application program interfaces (APIs).

A more ambitious effort is the Open Services Gateway Initiative (OSGi). This is a specification for network delivery of a variety of services and applications to consumer equipment. It starts with a broadband Internet connection, but it also manages the home PC LAN and the entertainment and home automation networking functions. The OSGi system incorporates a secure gateway managed by Java software that supports different types of downloads. The specification is broad and extensible.

Other standards efforts covering consumer entertainment networks include Microsoft's .Net; the Multimedia Home Platform, based upon digital video broadcasting equipment; and the Internet Home Alliance. Obviously, there's no lack of effort to develop some kind of standard. Hopefully one will emerge.

Home Automation Networks: A home automation network permits organized monitoring and control of lights, electrical appliances, security systems, heating and air conditioning, and other equipment. Home control networks have been around for years in an attempt to create the "smart home." Most use power-line networking. Still popular, the X10 home control system was introduced in the 1970s. It maintains its widespread use for turning lights and appliances off and on, light dimming, and security system access.

The X10 system transmits binary control pulses as 1-ms bursts of 120-kHz sine waves on the 60-Hz line voltage. It overcomes the noise spikes, surges, and other power-line glitches by using slow data (no more than 360 Hz) and repeating the control messages three times. X10 also has a wide range of other home-control and networking devices, including wireless and infrared.

A more recent home control system is the CEBus, originally developed by the Electronics Industry Association. Now the CEBus Industry Council supports and sponsors that standard (ANSI/EIA 600). Industry members develop and market products known as HomePnP (plug and play).

This standard also uses power-line networking with a spread-spectrum scheme that helps to overcome the losses and noise of the power line. This method im-plements a frequency sweep or chirp in the 100- to 400-Hz range, instead of more traditional frequency-hopping or direct-sequence spread-spectrum. The Consumer Electronics Association continues its research with its R-7 standards, including the Versatile Home Network (VHN) for secure data and the Audio Video Network (AVN).

Another long-time player in the home control field is Echelon. Founded in the late 1980s, this company developed a spread-spectrum power-line networking system, LonWorks. Initially, LonWorks was used to monitor and control lighting, HVAC, security systems, and elevators in large buildings. Echelon also makes home monitoring and control products based on the same technology for operating lighting, heating, air conditioning, security, water sprinklers, and home entertainment. The i.LON 1000 Internet server lets users monitor and control their home, office, or plant via the Internet.

A number of companies have ex-plored the remote control and monitoring of home appliances, lights, and other systems through Internet access. One of these is Connect One Semiconductor Inc. The company's iChip contains a built-in dial-up modem as well as an embedded controller that interfaces with the device to be controlled or monitored. AT+I protocol software facilitates the customization of the chip to the application. This system is widely used in remote control, data collection, remote diagnostics, remote metering, and medical telemetry.

Just recently, Connect One added Wireless Application Protocol (WAP) support to its iChip Internet Controller. This permits industrial or home monitoring or control from WAP-enabled cell phones or PDAs. The iChips are also available to work with General Packet Radio Service-enabled 2.5G GSM cell phones.

The big question about home control networks is if they will remain separate from the home PC data network and home entertainment network, or merge with them. Can we expect any convergence? Right now it seems like the home will have three separate networks, although the potential certainly exists for convergence. Just don't hold your breath.