What would we do without wireless? Because of the ever-increasing number of things that have the capability of connecting to the Internet using wireless technologies, most home networks include some type of wireless network functionality.
The Electromagnetic Spectrum (13.2.1)
Wireless technologies use electromagnetic waves to carry information between devices. The electromagnetic spectrum includes radio and television broadcast bands, visible light, X-rays, and gamma rays. Each of these has a specific range of wavelengths and associated energies, as shown in Figure 13-4.
Figure 13-4 Electromagnetic Spectrum
Some types of electromagnetic waves are not suitable for carrying data. Other parts of the spectrum are regulated by governments and licensed to various organizations for specific applications. Certain areas of the spectrum have been set aside to allow public use without the restriction of having to apply for special permits. These unlicensed sections of the spectrum are incorporated into consumer products, including the Wi-Fi routers found in most homes.
LAN Wireless Frequencies (13.2.2)
The wireless technologies most frequently used in home networks are in the unlicensed 2.4 GHz and 5 GHz frequency ranges.
Bluetooth is a technology that makes use of the 2.4 GHz band. It is limited to low-speed, short-range communications but has the advantage of communicating with many devices at the same time. This one-to-many communication has made Bluetooth technology the preferred method for connecting computer peripherals such as wireless mice, keyboards, and printers. Bluetooth also is a good method for transmitting audio to speakers or headphones.
Other technologies that use the 2.4 GHz and 5 GHz bands are the modern wireless LAN (WLAN) technologies that conform to the various IEEE 802.11 standards. Unlike Bluetooth technology, 802.11 devices transmit at a much higher power level, giving them a greater range and improved throughput.
Figure 13-5 shows where wireless technologies exist on the electromagnetic spectrum.
Figure 13-5 Wireless Frequencies in the Electromagnetic Spectrum
Wired Network Technologies (13.2.3)
Although many home network devices support wireless communications, in still a few applications, devices benefit from a wired switch connection that is not shared with other users on the network.
The most commonly implemented wired protocol is the Ethernet protocol. Ethernet uses a suite of protocols that allow network devices to communicate over a wired LAN connection. An Ethernet LAN can connect devices using many different types of wiring media.
Directly connected devices use an Ethernet patch cable, usually unshielded twisted-pair. These cables can be purchased with the RJ-45 connectors already installed, and they come in various lengths. In recently constructed homes, Ethernet jacks might already be wired in the walls. For those homes that do not have UTP wiring, other technologies, such as powerline, can distribute wired connectivity throughout the premises.
Category 5e Cable
Category 5e, shown in Figure 13-6, is the most common wiring used in a LAN. The cable is made up of four pairs of wires that are twisted to reduce electrical interference.
Figure 13-6 Category 5e Cable
Coaxial Cable
Coaxial cable, shown in Figure 13-7, has an inner wire surrounded by a tubular insulating layer that is then surrounded by a tubular conducting shield. Most coax cables also have an external insulating sheath, or jacket.
Figure 13-7 Coaxial Cable
Ethernet over Powerline
Existing power lines in a house can be used to connect devices to an Ethernet LAN, as shown in Figure 13-8.
Figure 13-8 Ethernet over Powerline
