CompTIA A+ Core Certification: A Simple Guide To Networking - Compare and Contrast Wireless Networking Protocols

220-1101: Objective 2.3: Compare and contrast protocols for wireless networking.
Computer networking protocols are generally accepted procedures and rules for communication between devices. Different protocols are used for communication, security, data, and so on. When computers communicate on any network, they must follow these strict rules and conventions, to minimize errors. Wireless network protocols are developed by the Institute of Electrical and Electronics Engineers (IEEE), and understanding them and how they have evolved will help you service wireless networks.

Frequencies
Wireless routers use either the 2.4GHz band or the 5GHz band. Each band offers advantages and disadvantages. The 2.4GHz band has a longer range but can perform at slower speeds. The 5GHz band can provide faster rates but has a shorter range. A couple reasons account for the differences. First, lower frequencies travel better through obstacles such as floors and walls. Second, the 5GHz band is less used and has more channels than the 2.4GHz band, and its channels do not overlap. This means that 5GHz devices do not contend with other devices for bandwidth, as do devices in the more popular 2.4GHz range.
Many wireless routers offer both the 2.4GHz and 5GHz bands, and each can be configured separately; some routers are capable of switching between the two frequencies if a signal becomes weak. 

Table: 2.4GHz vs. 5GHz Wireless Bands

The latest Wi-Fi generation, Wi-Fi 6E, supports not only the 2.4GHz and 5GHz bands, but also a new 6GHz frequency. The 6GHz band allows for higher throughputs and lower latency.

MIMO
The number of antennas supported by the router and the adapters (either built-in or add-on devices) is one reason for different performance levels in a given 802.11n, 802.11ac, or 802.11ax device. Multiple input multiple output (MIMO) devices are available in the following configurations:
1x1: One transmit, one receive antenna
2x2: Two transmit, two receive antennas
2x3: Two transmit, three receive antennas
3x2: Three transmit, two receive antennas
3x3: Three transmit, three receive antennas
The number of transmit antennas generally corresponds to the number of spatial streams (data streams) the device can support. In the case of a router that supports both 2.4GHz and 5GHz signals, the specifications include this information for each band.
Two types of MIMO exist: single-user MIMO (SU-MIMO) and multiuser MIMO (MU-MIMO). SU-MIMO allows wireless routers to communicate with multiple devices, but the router can communicate with only one device at a time. This means that SU-MIMO operates on a first come, first served basis. SU-MIMO was used with 802.11n devices. MU-MIMO allows multiple wireless devices to communicate with a wireless router at the same time. MU-MIMO offers significant improvements over SU-MIMO because it breaks up the available bandwidth into individual streams that are shared equally. MU-MIMO was supported in 802.11ac, but only for downlink transmissions. In 802.11ax, MU-MIMO is supported for both the uplink and downlink transmissions. MU-MIMO routers come in 2x2, 3x3, 4x4, and even 8x8 configurations.
When a device has different numbers of receiving antennas and sending antennas, the device can be identified by the number of spatial (data) streams it can send and receive. For example, a device with a 2x3 antenna configuration can also be identified as having a 2x3:2 configuration (two send antennas, three receive antennas, and send/receive support for two spatial [data] streams). Some smartphones and tablets simply use the term MIMO (multiple input multiple output) if they support two or more 802.11n or 802.11ac streams.

Channels
Because frequencies within the radio frequency spectrum exist everywhere, making them available to practically anyone, regulatory bodies were formed to standardize and control how they are used. The United Nations created the International Telecommunication Union Radiocommunication Sector (ITU-R) to manage the international radio frequency spectrum. However, each country can have its own regulations that govern what radio frequencies, channels, and transmission power are allowed. In the United States, the Federal Communications Commission (FCC) regulates what channels and frequencies are allowed and can be used for Wi-Fi LANs.

The two frequency ranges that apply to the wireless spectrum are 2.4GHz–2.5GHz and 5.725GHz–5.825GHz. On a 2.4GHz wireless network, the wireless spectrum is divided into 11 channels. Installing a router involves selecting an appropriate channel for the signal. For best results, avoid overlapping channels. Only channels 1, 6, and 11 do not overlap with other channels, so it is best to use one of these three channels.
Some routers feature an Auto setting that enables the router to use the least-active channel, but if you prefer to (or must) select a channel manually, use a Wi-Fi diagnostic utility (discussed later in this guide) to find the least-used channel. (More information on channels follows in the next section.)

To change the channel used by a wireless network, follow these steps:
Step 1. Log into the router.
Step 2. Navigate to the wireless configuration dialog.
Step 3. Select a different channel (typically 1, 6, or 11 when using 2.4GHz networking because they have less interference than other channels).
Step 4. Save your changes and exit the wireless configuration dialog.
shows a typical wireless channel configuration dialog on a dual-frequency (2.4GHz and 5.0GHz) Wireless-N router from Western Digital. Most SOHO routers have similar options.



Configuring Wireless Frequencies and Channels

Bluetooth
Bluetooth began as a short-range, low-speed wireless network technology primarily designed to operate in peer-to-peer (or ad hoc) mode between PCs and other devices, such as printers, projectors, smartphones, mouse devices, and keyboards. Bluetooth runs in virtually the same 2.4GHz frequency that wireless networks use, but Bluetooth uses a spread-spectrum frequency-hopping signaling method to minimize interference. Bluetooth devices connect to each other to form a personal area network (PAN).
Some systems and devices include integrated Bluetooth adapters; others need a Bluetooth module connected to a USB port to enable Bluetooth networking.
Bluetooth version 1.2 offers a data transfer rate of 1Mbps. Version 2 offers 3Mbps. Bluetooth version 3.0 + HS can reach speeds of up to 24Mbps because it uses Bluetooth only to establish the connection; the actual data transfer happens over an 802.11 link. This feature is known as Alternative MAC/PHY (AMP). Bluetooth 4.0, also known as Bluetooth Low Energy, is designed for use with very low-power applications, such as sensors. Bluetooth 4.1, a software update to 4.0, enables Bluetooth to perform multiple roles at the same time and to work better with LTE and 5G cellular devices.
Bluetooth 4.2 includes additional features to support the Internet of Things (IoT), and Bluetooth 5.0 was designed with the IoT in mind. IoT devices can be spread around a home, factory, or farm and can send a day’s worth of stored data back to a network. Bluetooth 5 can provide up to twice the speed and up to four times the range of Bluetooth 4, while keeping power consumption low. As IoT growth continues at a rapid rate, Bluetooth 5 is a common solution for IoT gateway devices.
Bluetooth is divided into classes, each with a different range. Table 2-5 shows these classes, their ranges, and the amount of power their corresponding antennas use to generate signal.

Table: Bluetooth Classes
 

As you can see, Class 1 generates the most powerful signal and, as such, has the largest range. The most common Bluetooth devices are Class 2 devices, with a range of 10m (for example, portable printers, headsets, and computer dongles).
The Bluetooth radios that are built into mobile devices and some laptops can be used for many devices, including headsets, printers, and input devices such as mouse devices and keyboards. By default, Bluetooth is usually disabled on Android devices, but it is enabled on iOS devices such as iPads and iPhones. To connect a Bluetooth device to a mobile device, Bluetooth first needs to be enabled; then the Bluetooth device needs to be synchronized to the mobile device. This is known as pairing, or linking, and it sometimes requires a PIN code. Once synchronized, the device needs to be connected. Finally, the Bluetooth connection should be tested.

Wi-Fi Standards
Six Wi-Fi standards are in use:
802.11b has a maximum speed of 11Mbps and can fall back to 5.5Mbps or slower, if necessary. It uses the 2.4GHz frequency band with 20MHz-wide channels.
802.11a has a maximum speed of 54Mbps and supports slower speeds, from 6Mbps to 48Mbps, as needed. It uses the 5GHz frequency band.
802.11g has a maximum speed of 54Mbps and supports slower speeds, from 6Mbps to 48Mbps, as needed. Unlike 802.11a, 802.11g uses the 2.4GHz frequency band, so it is backward compatible with 802.11b.
802.11n (Wi-Fi 4) has a maximum speed of 150Mbps when using a single 20MHz channel, or it can run at up to 300Mbps with channel bonding (40MHz channel). All 802.11n devices use the 2.4GHz frequency by default, but 802.11n can optionally support 5GHz frequencies as well. 802.11n supports MIMO (multiple input multiple output) antennas to improve performance and range, although not all devices include multiple antennas.
802.11ac (Wi-Fi 5) uses only the 5GHz band and supports up to 80MHz-wide channels, compared to 20MHz for 802.11b/g and 40MHz for 802.11n using channel bonding. It supports multiuser MIMO (MU-MIMO). The speed of 802.11ac is up to 433Mbps per stream when 80MHz-wide channels are used.
802.11ax (Wi-Fi 6 & Wi-Fi 6E) has important improvements over Wi-Fi 5 and others. Wi-Fi 6 uses both 2.4GHz and 5 GHz bands, with increased speeds up to 9.6Gbps. Wi-Fi 6E improves upon Wi-Fi 6 by supporting the 6GHz band. Benefits include increased capacity, with up to seven channels at 160MHz wide, better performance, and improved power efficiency.
Beginning with Wi-Fi 4, the Wi-Fi Alliance (www.wifi.org) now uses Wi-Fi version numbers so that users can identify newer and better devices. These versions appear in the wireless user interface information on the device so that users can identify the type of connection they have.

Table: Comparison of six wireless Ethernet standards.

* Non-overlapping channels; exact number varies by country. ** Non-overlapping channels. *** Up to four streams supported.

Most devices have up to three antennas but can receive/transmit only two streams at a time. Wi-Fi certified hardware is 802.11-family wireless Ethernet hardware that has passed tests established by the Wi-Fi Alliance. Most, but not all, 802.11-family wireless Ethernet hardware is Wi-Fi certified.

Long-Range Fixed Wireless
Cable modems and DSL have been the traditional method for homes and businesses to connect to the Internet. In cases where physical access to an ISP was not possible, such as rural areas, satellite access has been an option, although it is a slower, less reliable, and more expensive solution. In recent years, another option has emerged: fixed wireless Internet.
Fixed wireless providers send a signal from a wireless tower to customers who have a small antenna in their home or business. For best results, the antenna is placed in direct line of sight to the tower, sometimes aimed out a window or mounted on a rooftop. The antenna is connected via a cable to a router for wired and wireless access to the home or office.
Data rates can be very fast and the service is competitive with wired access, although the ISP usually sets the data rate to coincide with the customer’s subscription rate.

Figure depicts a wireless Internet antenna on the wall of a home.



A Home Antenna for Long-Range Wireless

The majority of the radio spectrum is licensed by the Federal Communications Commission (FCC) for specific uses or organizations such as radio and television broadcasters. An organization can purchase a license for exclusive rights to transmit on a specific frequency within a specific geographical area. This means that no one else is allowed to use or interfere with that frequency. However, certain spectrums can be used without a license. For instance, the wireless spectrum is unlicensed and does not require permission or a license from the FCC to use.
Wireless power transfer (WPT) is the process of using electric power to wirelessly charge a device. Two categories of WPT exist: near field and far field. Much like it sounds, near field transfers power over short distances, such as charging an electric toothbrush or using a wireless charging pad for a smart phone. Far field transfers power over longer distances and has potential application in powering unmanned aircraft and vehicles or solar-powered satellites. The FCC regulates WPT, and any device that uses frequencies above 9kHz is subject to FCC rules.

NFC
Near-field communication (NFC) is a feature included in many mobile devices such as smartphones and tablets for data transfer and shopping. When NFC is enabled and a suitable payment system (such as Apple Pay or Google Pay) is installed on a mobile device, the device can be used for secure payments at any retailer that supports NFC payments.
NFC can also be used to automatically turn on Bluetooth and transfer files between devices (a feature sometimes referred to as “tap and go” or, on Android devices, Android Beam). It can be enabled separately from NFC for payments. Apple uses NFC for purchases and other limited functions that require secure data. The technology is widely used and continues to proliferate as the world moves toward contactless transactions.

RFID
Radio frequency identification (RFID) technology consists of an RFID tag that can broadcast information about an item, as well as an RFID reader to accept the broadcast information and deliver it to a computer system for use. An example is RFID security badges that allow doors to be unlocked in a secure environment, granting access to some while denying use to others. In some retail environments, an item for sale has an RFID badge identifying the item name and price. The badges on the items in a shopping cart broadcast their information to a checkout reader, and customers can simply walk out the door with their purchases: The items are counted, priced, and paid for just by passing the reader. Passports and other identification documents might also have RFID information embedded in them.