One of the traits of wireless networks is the way they work using radio frequency (RF) or radio techniques. This is both a strength and a weakness because it allows wireless transmissions to reach out in all directions, enabling connectivity but also allowing anyone in those directions to eavesdrop. As opposed to the transmission of signals in traditional media, such as copper or fiber, where someone must be on the “wire” to listen, wireless signals travel through the air and can easily be picked up by anyone with a device as simple as a notebook with a wireless card. This leads to a huge administrative and security headache and immediately makes clear the need for additional security measures.

Emanations of a wireless network can be affected by many factors that make the transmission go farther or shorter distances, including the following:

• Atmospheric conditions—Warm or cold weather will affect how far a signal will go because of the changes in air density that changing temperatures cause.

• Building materials—Materials surrounding an access point (AP), such as metal, brick, or stone, will impede or shield a wireless signal.

• Nearby devices—Other devices in the area (for example, microwaves and mobile phones) that give off RF signals or generate strong magnetic fields can affect emanations.

Wireless networks have become more and more common over the past few years, with the ability to connect to wireless networks being integrated into many types of devices and gadgets. From the early 2000s up to the current day, wireless technologies in the form of Bluetooth and Wi-Fi have become most common, with both features going from being an option to becoming standard equipment in notebooks; in mobile devices; and even in the growing number of smart sensors, smart devices, and smart appliances.

The widespread availability of wireless has made management and security much more difficult for the network and security administrator. With so many devices implementing wireless, it is now more possible that an employee of a company could bring in a wireless-enabled laptop or other device and attach it to the network without the knowledge of an administrator. In some situations, employees have decided that a company information technology (IT) department that has said “No wireless” is just being unreasonable and, oblivious to the security risks, have taken it upon themselves to install their own inexpensive wireless AP.

Wireless technologies aren’t new; in fact, wireless has been around for more than two decades for networks and even longer for devices such as cordless phones. The first wireless networks debuted in the mid-1990s with educational institutions, large businesses, and governments as early adopters. The early networks did not resemble the networks in use today because they were mainly proprietary and performed poorly compared with today’s wireless networks.

There are several options available when building wireless networks. The best option depends on how big the network needs to be and how it will be used. The most popular general purpose wireless networking standard is the Institute of Electrical and Electronics Engineers (IEEE) 802.11 family of standards, which range from 802.11a to 802.11ac. They are known collectively as Wi-Fi in standard jargon. In addition to the 802.11 family of wireless standards, other wireless technologies have emerged (Bluetooth, for example), each purporting to offer something unique.

When looking at wireless networking, it is easy to think of it as one standard, but this is not the case. Wireless networks have evolved into a family of standards over time, with each one including unique attributes. To understand wireless, it is worth looking at the different standards and their benefits and performance. The following sections discuss some of the most common wireless standards that you may encounter.

The 802.11 standard was the first wireless standard that saw any major usage outside of proprietary or custom deployments. It was used mainly by large companies and educational institutions that could afford the equipment, training, and implementation costs. One of the biggest problems with 802.11 that led to limited usage was performance. The maximum bandwidth was theoretically 2 megabytes per second (Mbps). In practice, it reached at best only half this speed. The 802.11 standard was introduced in 1997 and saw limited usage but quickly disappeared.

Its features included:

• Bandwidth—2 Mbps

• Frequency—2.4 gigahertz (GHz)

The first widely adopted wireless technology was 802.11b, introduced two years after the original 802.11 standard. It didn’t take too long to be adopted by businesses and consumers alike. The most attractive feature of this standard is performance; 802.11b increased performance up to a theoretical 11 Mbps, which translated to a real-world speed of 6–7 Mbps. This was a huge step forward because this speed approached traditional Ethernet wired speeds. Other attractive features of the standard include low cost for the consumer and the product manufacturer.

Its features include:

• Bandwidth—11 Mbps

• Frequency—2.4 GHz

One downside of 802.11b is interference. The 802.11b standard has a frequency of 2.4 GHz, the same frequency as other devices, such as cordless phones and game controllers, so these devices can interfere with 802.11b. Additionally, interference can be caused by home appliances, such as microwave ovens.

When 802.11b was being developed, another standard was created in parallel: 802.11a. It debuted around the same time as 802.11b but never saw widespread adoption because of its high cost and restricted range. One of the largest stumbling blocks that hampered its adoption was equipment prices, so the alternative 802.11b was implemented much more quickly and is seen in more places than 802.11a. Today, 802.11a is rarely seen.

The 802.11a standard did offer some benefits over 802.11b, notably much greater bandwidth: 54 Mbps over 802.11b’s 11 Mbps. Also, 802.11a offers a higher frequency range (5 GHz), which means less chance for interference because fewer devices operate in this range. Finally, the signaling of 802.11a prevents the signal from penetrating walls or other materials, allowing it to be somewhat easily contained.

The 802.11a standard is not compatible with 802.11b or any other standard because of the way it is designed. APs that support 802.11a and other standards simply have internal components that support both standards.

Its features include:

• Bandwidth—54 Mbps

• Frequency—5 GHz

In response to consumer and business demands for higher performance, the 802.11g standard emerged. The 802.11g standard is a technology that combines the best of both worlds (802.11a and 802.11b). The most compelling feature of 802.11g is the higher bandwidth of 54 Mbps combined with the 2.4-GHz frequency. This allows for greater range and backward compatibility with 802.11b (but not 802.11a). In fact, wireless network adapters that use the 802.11b standard are compatible with 802.11g APs, which allowed many businesses and users to migrate more quickly to the new technology.

Its features include:

• Bandwidth—54 Mbps

• Frequency—2.4 GHz

The 802.11n standard was developed to be the successor of 802.11g. This new protocol increased the amount of bandwidth that was available in previous technologies up to 600 Mbps in some configurations. The 802.11n standard uses a method of transmitting signals known as multiple input and multiple output (MIMO), which can transmit multiple signals across multiple antennas. The 802.11n standard offers backward compatibility with 802.11g, so it encouraged adoption of the technology by consumers.

Its features include:

• Bandwidth—up to 600 Mbps

• Frequency—2.4 GHz

The 802.11ac standard is currently the newest commercially available wireless standard. It advances wireless communication speed and reliability by using connections in the 2.4-GHz and 5-GHz bands at the same time. This dual-band technology allows 802.11ac to be backward compatible with 802.11b/g/n networks and offer superior performance. Although the successor of 802.11ac is still in development, 802.11ax is expected to offer four times the throughput while also raising WLAN efficiency.

Its features include:

• Bandwidth—up to 1300 Mbps on the 5-GHz band and 450 Mbps on the 2.4-GHz band

• Frequency—2.4 GHz and 5 GHz

For many years, we understood 802.11 as the one and only wireless technology. With 802.11 in common use, the variables were mostly in configuration, whether set as an AP with strong encryption or ad hoc “protected” by Wired Equivalent Privacy (WEP).

As discussed above, 802.11b and 802.11g offered big improvements in bandwidth. Still backward compatible with 802.11a, those two standards pushed wireless to become common and, for the most part, expected.

Still, there are continual improvements in new 802.11 protocol standards. Changes include the frequency used, bandwidth, compatibility, range, and technical data rate. Although it is risky to list proposed variants here, it is important to appreciate how many variants are currently in review. You can research current-day progress by searching “IEEE 802.11 standard variants.”

Although wireless networking in the form of 802.11 is probably the best known by the average consumer, other wireless technologies are in widespread use, including Bluetooth and WiMAX.