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Twisted Copper-Pair or Coaxial-Based Transport Systems (Ethernet)
The typical topology of these systems is demonstrated in Figure 2.
Figure 2. Typical Ethernet System
This technology is based on the Institute of Electrical and Electronic Engineers (IEEE) 802.3 standard, which has undergone many revisions since its conception to enable interoperability between many manufacturers. Copper-pair or coaxial-based transport systems are bidirectional, typically have a high degree of reliability, and are thus widespread among businesses as the standard choice for networking office PCs and printers. They require the use of bulky Category 5 (CAT5) cabling, and are typically expensive to install. Some home networks have Ethernet, but because of its expense and difficulty to install, few have chosen to use it.
Twisted Copper-Pair-Based Systems (Phone Line)
The typical topology of these systems is demonstrated in Figure 3.
Figure 3. Typical Phone Line System
This technology uses the existing phone wiring found in most homes today. In some cases, CAT3 wire elements transport at a date rate of 1 Mbps, and many speculate that it will support up to 10 Mbps in the near future. This technology claims to work simultaneously with regular phone service, without attracting the user's notice. The Home Phone Network Alliance (HomePNA) is one organization dedicated to the development of standards and specifications for interoperable, home-networked devices that use existing twisted-pair phone wiring. Although solid progress has been made toward enhancing the usefulness of this embedded asset, inflexibility and capacity limitations will limit its success. A typical home does not contain many RJ–11 jacks; they are rarely in every room or in the location where access by additional phones, computers, and other devices is required.
In addition, selection of signal characteristics for data transport over this medium is critical to resist interference from other shared devices. These devices include answering machines, fax machines, modems, telephone sets, and other data-transport devices such as the integrated services digital network (ISDN) and digital subscriber line (xDSL) equipment that use the twisted pair simultaneously.
Two-Way Coaxial Cable–Based Transport Systems (Broadband)
The typical topology of these systems is demonstrated in Figure 4.
Figure 4. Typical Coaxial System
This technology uses the same type of coaxial cable that is used by cable TV. It provides a reliable medium for data transport and has long-distance capability. Typically used by cable operators to send data into the home, it terminates near the television and is thus an uncommon means of distributing data through the home.
Selected suppliers of bidirectional coaxial cable–based systems do, however, use coaxial cable to distribute data through the home. One such supplier is Canada Ltd., which offers IBM Info-Structure Wiring™ components. IBM Info-Structure Wiring components consist of three CAT5 and two RG–6 coaxial cables. These start at the basement of a home at a distribution panel similar to the electrical box, connecting the services into a home and routing or directing them to several locations throughout the home. Each location in the home that connects to these services has an info-port. The info-port allows four telephone connections: one connection for a data network within the home and an extra outlet for future fiber-optic cable, distributed cable TV, and distributed satellite services.
In order for the IBM system to allow PC–to–PC networking, a combination of coaxial cable and twisted pair are used. There are no systems that allow for PC–to–PC communications using only coaxial cable.
These home-network transport systems require preplanning with homeowners, builders, or developers, because the systems are limited to network access by well-placed jack locations. Specific applications are best accommodated with a room-use plan before installation. Postinstallation upgrades for new access locations have limited success or flexibility without surface wiring and jack installation and add substantial additional expense.
Alternating Current Powerline-Based Transport Element
The typical topology of these elements is demonstrated in Figure 5.
Figure 5. AC Powerline-Based Transport Element
Alternating current (AC) powerlines are readily available as network transport elements throughout a home. They are used as transport facilities to send and receive discrete frequency-based control, monitoring, and communications messages to smart devices that manage lighting and environmental systems ("turn off," "turn on," and "dim"). They also are used as voice-communication elements for telephone extensions, computer-modem access, and intercom devices through standard electrical outlets. Throughput for any application requiring higher data rates can be a challenge. In addition, no standards exist to ensure interoperability between manufacturers.
