Powerline Communications

• Home Networking: A Detailed Overview
• Using Your Home Network
• Comparison Chart of Home Networking Technologies

Home Networking: A Detailed Overview
Are you tired of having to compete with a family member or roommate for access to the Internet or the printer? Well, problems like this are becoming common in the United States. Currently, about 30 million households in the United States have some kind of Internet access (Jupiter Communications, 1999). According to Dataquest, 15 million homes have more than one PC, and in 1999, 60% of new home computer purchases will be by families that already have at least one computer.

High-speed Internet access is also spreading. Currently, over 1.5 million homes have cable modems or DSL, and that number is expected is grow to 9 million in 2002 (The Yankee Group). Homes that used to have little communication technology now have multiple computers, peripherals like printers and scanners, televisions, radios, stereos, DVD players, VCRs, cordless telephones, PDAs, and other electronic devices. How can a household manage all of these often-disparate technologies? Home networking is the answer.

Home networks link the many different electronic devices in a household by way of a local area network (LAN). The network can be point-to-point, such as connecting one computer to another, or point-to-multipoint where computers and other devices such as printers, set-top boxes, and stereos are connected to each other and the Internet. It is estimated that by 2002, 15.3 million households in the United States will have some kind of home networking (Jupiter Communications).

There are many different applications for home networking. They can be broken into five categories: resource sharing, communications, home controls, home scheduling, and entertainment/information.

Resource Sharing
Home networking allows all users in the household to access the Internet and applications at the same time. In addition, files (not just data, but also audio and video depending on the speed of the network) can be swapped, and peripherals such as printers and scanners can be shared. There is no longer the need to have more than one Internet access point, printer, scanner, or in many cases, software packages.

Communications
Home networking allows easier and more efficient communication between users within the household and better communication management with outside communications. Phone, fax, and e-mail messages can be routed intelligently. Access to the Internet can be attained at multiple places in the home with the use of terminals and Webpads.

Home Controls
Home networking can allow controls within the house, such as temperature and lighting, to be managed though the network and even remotely through the Internet. The network can also be used for home security monitoring with network cameras.

Home Scheduling
A home network would allow families to keep one master schedule that could be updated from different access points within the house and remotely through the Internet.

Entertainment/Information
Home networks enable a plethora of options for sharing entertainment and information in the home. Networked multi-user games can be played as well as PC-hosted television games. Digital video networking will allow households to route video from DBS and DVDs to different set-top boxes, PCs, and other visual display devices in the home. Streaming media such as Internet radio can be sent to home stereos as well as PCs.

The speed of home networks is also important to consider. Most home networking solutions have speeds of at least 1 Mbps, which is enough for most everyday data transmission (but may not be enough for bandwidth-intensive applications such as full-motion video). With the development of high-speed Internet access and digital video and audio comes a need for faster networks. Several kinds of home networks can operate at speeds of 10 Mbps and up. Digital video networking, for example, requires fast data rates. DBS MPEG-2 video requires 3 Mbps and DVD requires between 3 and 8 Mbps. HDTV requires more speed than current home networks have but that should change in the future, as home networks get faster and as technology develops and adapts to new Internet appliances and digital media.

There are currently four major categories of home networking: conventional Ethernet, phoneline, wireless, and powerline.

Conventional Ethernet
A home network using conventional Ethernet is just like the LAN at an office or school. This kind of networking requires special wiring called Category 5 wire as well as a server, hub, and/or router to direct network traffic. Each device on the network must be connected to the Ethernet. Ethernet networks have not been popular because they often require new wiring as well as a hub (a central connection point) and Ethernet add-in cards for older computers. The expense of wiring a home and the inconvenience of opening up the PC are the drawbacks to a conventional Ethernet home network. Ethernet does have a high-speed transmission rate from 10 Mbps up to 100 Mbps.

Phoneline (HomePNA or HPNA)
While conventional Ethernet requires special wiring, home networking can use existing phone lines. The Home Phoneline Networking Alliance (HomePNA) has standardized two open standard specifications for phoneline networking: 1.0 and 2.0. HPNA 1.0 has a data transmission rate of 1 Mbps. HPNA 2.0 greatly increases that rate to 10 Mbps.

HomePNA uses the existing wiring typically found in homes. You may be wondering how this can occur when the phone line is also carrying POTS (Plain Old Telephone Service) and perhaps DSL? HomePNA uses frequency division multiplexing (FDM) to allow the phone line to carry multiple services without interference.  Each service is assigned a different frequency, so they do not interfere with each other. The graphic below illustrates how your phone line can carry these multiple services.

Figure 1

Compatible with Voice and xDSL

One pair of telephone wires acts as 3 separate 'channels' for simultaneous voice, Internet access and home networking

Because HomePNA uses existing phone lines, tests indicate that the service can work in over 99% of the homes in the United States. In addition, the network can support up to 25 devices up to 500 feet apart in homes up to 10,000 square feet. The following graphic shows how different devices can be connected in a HomePNA network.

Figure 2 - A HomePNA Network

HomePNA is interoperable with other home networking technologies such as Ethernet and HomeRF and is compatible with high-speed Internet access technologies such as cable modems and DSL. Unlike conventional Ethernet, HomePNA does not require hubs or Category 5 wiring, nor termination filters or splitters.

HomePNA can also work with Macs and older PCs. If the computer has an Ethernet port, it can be linked with an adapter. There are stand-alone adapters for use with any device having a 10Base-T interface, and PC Network Interface Cards (NICs) will be available to connect a PC directly to a telephone jack. The cost for one HomePNA NIC is less than $100 per device.

Wireless
If the idea of having a flexible, mobile, and cable-free home network appeals to you, then wireless home networking might be the answer. There are currently three types of wireless networking services/standards being developed and sold today: IEEE 802.11 (wireless Ethernet), HomeRF, and Bluetooth. Each one works a little differently and has its own strengths and weaknesses.

A wireless home network or LAN uses electromagnetic waves to transmit and receive data over the air. These electromagnetic waves are actually low frequency radio signals which use a portion of the spectrum called the Instrumentation, Science, and Medical (ISM) bands. These bands are around 2.4 GHz, are not currently licensed by the FCC and are used mainly for microwave ovens and cordless telephones.

A wireless home network is configured with an access point that acts as a transmitter and a receiver connected to the wired network at a fixed location using a conventional Ethernet cable. The access point then transmits to end users who have wireless LAN adapters with either PC cards in notebooks, ISA or PCI cards in desktops, or fully-integrated devices.

A wireless home network allows real-time instant access to the network without the computer having to be near a phone jack or power outlet. Installation is easy because there is no cable to pull as with conventional Ethernet. The devices do not have to be in line-of-sight but can be in different rooms or blocked by walls and other barriers. Finally, all of these services are secure as they use encryption technologies.

Wireless Ethernet, also known as IEEE 802.11, is a wireless networking protocol that is quickly being adopted by the computer industry. Used principally by businesses, medical, manufacturing, and academic areas, wireless Ethernet has thus far not been a huge player in home networking.

HomeRF was developed as an open industry specification for wireless digital communication between PCs and consumer electronic devices. HomeRF uses the Shared Wireless Access Protocol (SWAP) and operates at 2.4 GHz on the ISM band. HomeRF has a range of up to 100 meters. SWAP 1.0 has data transmission rates of 1 Mbps, while SWAP 2.0 can transmit data up to 10 Mbps. As with other wireless networking technologies, HomeRF allows users to roam within the home and is interoperable with other home networking services such as HomePNA and powerline networks. HomeRF costs are considerably less than 802.11, and its developers claim that SWAP was designed for voice and data and thus handles voice better than 802.11 which was developed for data only. 

Bluetooth was developed for short-range wireless communication (around 35 feet). This means that Bluetooth is useful for cable replacement, data and voice access points, and ad hoc networks. A person at home could surf the Web on the sofa with her laptop computer without any cable, or that same person could be on a picnic in the park and surf the Web using a cellular phone dialed up to a high-speed Internet access provider. Products are being rolled out with Bluetooth chips such as cellular phone headsets. A home network user would not set up a Bluetooth network in their home: rather, the user obtains Bluetooth electronic devices that communicate with each other and create an ad hoc network.

Bluetooth can be described as creating point-to-point networks, while HomeRF and Wireless Ethernet are used for an entire home network. Bluetooth uses a multi-piconet structure and frequency hopping spread spectrum technology. Because Bluetooth uses fast hops and shorter packets, interference from other devices that use 2.4 GHz such as microwave ovens, is limited.

Powerline
Powerline networking uses existing power lines within the home. Enikia, Intellon, and Intelogis are three companies working on powerline networking systems.

Enikia's new chip set will allow networking in a home at speeds up to 10 Mbps in regular 2 phase power environments. Up to 256 devices can be connected in homes up to 5,000 square feet in size. The system uses Enikia's gateway product that is plugged into an outlet and a high-speed modem. The household electrical wires then essentially become a network for accessing the Internet. Network interface adapters are then attached to electronic devices through USB or parallel ports so they can communicate with each other and connect to the Internet.

The network is relatively secure as the signal is encrypted before transmission. In addition, the signal reduces quickly, so it will not leave the home. However, some powerline technologies are more secure than others; an unencrypted household network may be accessible to neighbors sharing the same transformer.

Power lines are often called hostile environments for networks because of the flux and change that can occur such as power surges, lightning, and brown outs. A power surge usually slows data transmission, and a brown out will affect the network devices much like it affects other electrical appliances in your home. Lightning is viewed as noise by the system. Further, you risk permanent damage to your PC, printer, and other appliances connected to the powerline network from lightning and power surges, since several powerline networking technologies do not permit you to plug into a surge protector or power strip first.

Current powerline home networks support the Ethernet standard, so all software that is network compatible is also compatible with this technology.

Chart 3: A comparison of advantages and disadvantages of networking technologies.

Conclusion
All these networking technologies might seem intimidating to the average family. There is no need to worry, though, as home networking is user friendly. Users have described setting up a home network as "almost as easy as flipping a light switch." With HomePNA, wireless, and phoneline networks, there is no new wiring to deal with. All the technologies discussed here involve not much more than plug-and-play. If you already have a computer with a modem and peripheral such as a printer, then you probably have the computer know-how to operate a home network.

Each of the home networking technologies available today has its own special characteristics, advantages, and disadvantages. The two charts will help you compare these technologies. Chart 1 examines the advantages and disadvantages of each technology, and Chart 2 compares their characteristics.

Considering your specific needs, budget, and home environment should enable you to make an intelligent choice of home networking technology.

Using Your Home Network

Imagine the Possibilities
You are relaxing on the beach with your family. You take a group picture with a digital camera, and you automatically send it via e-mail to some friends using your cellular phone to dial-up your ISP.

You have gone out of town for the weekend and a cold front has moved in. You can dial-up and connect to your home network to make sure the house is comfortable and well lit by the time you arrive.

You want to watch a movie from your DBS service, while one roommate wants to watch a Web-enhanced basketball game and your other roommate wants to watch a documentary. Using your home network and an entertainment service, you can route each digital video signal to television set-top boxes and PCs in your house. Everyone is happy. All services are coming through a single high-speed Internet service.

The applications of home networking discussed here are just the beginning! Even as you are reading this, faster and more robust networking technology is being developed, and new Internet appliances designed for use with home networks are being rolled out. Some of the applications you can look for include:

• Small, inexpensive, wireless Webpads that can be taken anywhere in the house for convenient Web browsing.
    
• Small, portable, wireless viewing devices for Internet and DBS digital video and audio.
    
• Bluetooth enhanced cellular phones, PDAs, and laptop computers for mobile anytime Web surfing.
    
• Internet enhanced televisions and telephones.
    
• Automatic communication between PCs, peripherals, PDAs, home appliances, consumer electronics, and Internet appliances.

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Chart 4: A comparison of home networking technologies

Applications: RS = resource sharing, C = communications, HC = home controls, HS = home scheduling,
EI = entertainment & information

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