6.03 Compare and contrast protocols for wireless networking

Introduction 

You’ve already learned about networking protocols and how they help devices communicate. Now, we’re going to dive deeper into the standards that make wireless networking possible. We’ll also explore some of the protocols used specifically for wireless communications, helping you understand how data moves through the air and how devices stay connected without wires. 

Access Points 

Wireless Technologies and Transmission 

Wireless networks use radio waves as the medium for transmitting data. These systems rely on transmission and reception antennas, tuned to specific frequencies to transfer signals. Most wireless LANs (Local Area Networks) follow the IEEE 802.11 standards, commonly known as Wi-Fi. 

Radio Tower

The name “802.11: comes from the Institute of Electrical and Electronics Engineers (IEEE)—a global professional association, founded in 1963 after the merger of the American Institute of Electrical Engineers (AIEE) and the Institue of Radio Engineers (IRE) organizations.  The IEEE is known for its highly cited publications, technology standards and professional and educational activities.  It has over 460,000 members in more than 190 countries and is dedicated to advancing technology for the benefit of humanity.

Infrastructure Mode 

Most Wi-Fi networks operate in what is known as infrastructure mode. Here’s how it works: 

  • Client Devices: Also referred to as stations, these devices connect to the network through an Access Point (AP). 

  • Basic Service Set (BSS): In the 802.11 documentation, this configuration is called a Basic Service Set. The MAC address of the AP's radio is known as the Basic Service Set Identifier (BSSID). 

Devices connected to the network through an AP

Functions of an Access Point 

  • Wireless Network: An AP can create a wireless-only network, allowing multiple wireless devices to connect. 

  • Bridge to Wired Networks: An AP can also act as a bridge, forwarding communications between wireless devices and a wired network. The wired portion of the network is called the Distribution System (DS). 

Connecting the Access Point 

  • Wired Network: The AP connects to the wired network using Ethernet cables, similar to how a regular computer connects to the network. 

  • Power over Ethernet (PoE): In enterprise networks, Power over Ethernet is commonly used. This allows the AP to be powered through the same Ethernet cable that carries the data, eliminating the need for a separate power source. 

Analogy: Imagine Wi-Fi infrastructure mode as a post office system: 

The Basic Service Set (BSS) is like a local neighborhood where everyone sends their letters (data) to a central port office (the Wi-Fi access point).  All houses (devices) in that neighborhood are part of the same BSS. 

The Basic Service Set Identifier (BSSID) is like the unique postal code for THAT neighborhood.  It ensures that mail from that specific area is handled by the correct post office (router).  Each neighborhood (BSS) has a different postal code (BSSID), so mail (data) doesn’t get mixed up with another area. 

98225

Now, the Access point (AP) is the post office itself.  Here is what it does: 

98225

98225

Sorting and Routing: The AP collects the data (letters) from all the houses (devices) and ensures it gets routed to the correct recipient, either within the same neighborhood (local devices/BSS) or to a faraway place (the internet or other networks). 

Handling External Communication: If a house (device) wants to send data to a different neighborhood (accessing the internet of other networks), the post office (AP) manages that as well, making sure that the data is properly addressed and sent through the correct channels. 

Managing Traffic: The AP ensures that no two houses send letters at the same time to avoid confusion or delays.  It schedules deliveries (within the millisecond range) and maintains order in the communication process, much like a post office would sort and manage a large volume of mail efficiently. 

Security and Access Control: Just like a post office only handles mail from verified addresses, the AP also controls which devices (houses) can send and receive data.  It makes sure only registered devices within the BSS can communicate, protecting the network from intruders. 

In summary, an access point serves as a crucial device for connecting wireless devices to a wired network, enabling smooth communication and data transfer in a Wi-Fi environment.  It serves as a central hub that manages, routes, and secures all data communication in a Wi-Fi network, ensuring smooth interaction between devices and external networks (the internet).  The BSSID (postal code) helps keep things organized by linking devices to the correct network. 

802.11a and the 5 GHz Frequency Band 

Understanding Frequency Bands 

Wi-Fi devices operate on specific radio frequency ranges within larger frequency bands, which are further divided into smaller ranges called channels. The two main frequency bands used by Wi-Fi networks are 2.4 Gigahertz (GHz) and 5 GHz, each with different characteristics.

A Hertz—named after German physicist Heinrich Hertz, who demonstrated the existence of electromagnetic waves—is the measuring unit of frequency, that represents the number of cycles per second of an oscillating or repeating wave pattern.  For example, when you hear a sound wave with a frequency of 440 Hz, it means that the sound wave completes 440 cycles in one second. 

So, a Megahertz (MHz) is equal to 1,000 times the frequency of a hertz.  A CPU clocked at 2.4 MHz performs 2.4 million instructions per second.  And a gigahertz represents billions of cycles per second—it is 1,000 times faster than a megahertz. 

   

2.4 GHz Frequency Band: 

  • Range: This wave frequency band has a better ability to propagate through solid surfaces, giving it the longest signal range. 

  • Challenges: 

    • It doesn’t support many individual channels, leading to congestion. 

    • Other wireless technologies like Bluetooth and devices like microwave ovens also use this band, causing interference. 

  • Performance: While it provides a longer range, the maximum data rates are lower than with 5 GHz. 

5 GHz Frequency Band: 

  • Range: The 5 GHz band is less effective at penetrating solid objects, meaning it has a shorter range than 2.4 GHz. 

  • Advantages: It supports more individual channels and experiences less congestion and interference, allowing for higher data rates at shorter ranges. 

  • Performance: The nominal indoor range is 30 meters (100 feet) for 5 GHz, compared to 45 meters (150 feet) for 2.4 GHz.

The lower frequency travels further, much like lower sound frequencies can be heard from further distances—think bass booming from a car from far away as opposed the higher pitched sounds.  Clients typically connect at full speed only within one-third to half of these distances, depending on the building features and interference.

IEEE 802.11a and 5 GHz Channel Layout 

The IEEE 802.11a standard operates solely in the 5 GHz frequency band and uses a data encoding method that supports a maximum data rate of 54 Mbps. 

  • Channel Setup: The 5 GHz band is subdivided into 23 non-overlapping channels, each 20 MHz wide. 

  • Regulatory Factors: The exact usage of these channels depends on regulations that vary by country. These regulations can also limit the power output, impacting the Wi-Fi device range. 

Dynamic Frequency Selection (DFS) 

Devices operating in the 5 GHz band must implement Dynamic Frequency Selection (DFS) to prevent interference with radar and satellite installations. This means that channels within the DFS range will be disabled if the access point detects radar signals. 

Channel Sub-Bands 

The 5 GHz band is divided into Unlicensed National Information Infrastructure (U-NII) sub-bands, which form the 20 MHz channels. Each sub-band is 5 MHz wide, and the Wi-Fi channels are spaced in intervals of four to allow for the required 20 MHz bandwidth. 

In summary, 802.11a operates in the 5 GHz band, providing higher data rates at shorter distances and using 23 non-overlapping channels. However, it faces limitations due to building interference, country-specific regulations, and the requirement for DFS to avoid radar signal interference. 

802.11b/g and the 2.4 GHz Frequency Band 

IEEE 802.11b Standard 

  • Frequency Band: 2.4 GHz 

  • Data Rate: 802.11b supports a nominal data rate of 11 Mbps, which is slower compared to 802.11a. 

  • Channel Layout: 

    • The 2.4 GHz band is divided into 14 channels, spaced 5 MHz apart, from 2,412 MHz to 2,484 MHz. 

    • Because Wi-Fi requires 20 MHz of bandwidth per channel, many 802.11b channels overlap, leading to potential interference. 

    • To avoid interference, users should select widely spaced channels like 1, 6, and 11. 

    • Regional Regulations: 

      • Americas: Only channels 1–11 are allowed. 

      • Europe: Channels 1–13 are permitted. 

      • Japan: All 14 channels can be used. 

Channel Overlap 

  • Issue: The 5 MHz spacing between channels in the 2.4 GHz band means that adjacent channels overlap, increasing the likelihood of interference. 

  • Solution: To reduce interference, widely spaced channels (such as 1, 6, and 11) are typically chosen. 

IEEE 802.11g Standard 

  • Frequency Band: 2.4 GHz 

  • Data Rate: 802.11g supports a nominal data rate of 54 Mbps, the same as 802.11a. 

  • Channel Layout: The channel layout remains the same as 802.11b, with channels spaced 5 MHz apart. 

  • Backward Compatibility: 802.11g was designed to be backwards compatible with 802.11b. This means devices that support 802.11g can also connect with older 802.11b clients, making it easier for users to upgrade without losing support for older devices. 

Summary of Key Differences 

  • 802.11b operates at 11 Mbps with significant channel overlap, making interference common unless widely spaced channels are used. 

  • 802.11g improves upon 802.11b by supporting 54 Mbps while maintaining compatibility with older 802.11b devices. 

In conclusion, 802.11b was an early Wi-Fi standard with slower speeds and channel overlap issues, while 802.11g provided a faster, more efficient solution on the same 2.4 GHz band, with backward compatibility for older devices. 

802.11n 

The IEEE 802.11n standard introduced several advancements to increase Wi-Fi bandwidth and reliability. This standard can operate on both the 2.4 GHz and 5 GHz frequency bands. 

  • Dual Band: Devices that support both 2.4 GHz and 5 GHz simultaneously are called dual band. However, many cheaper client adapters and smartphones only support 2.4 GHz. 

Channel Bonding 

  • Channel Bonding: 802.11n allows the combination of two adjacent 20 MHz channels into a single 40 MHz channel to increase data rates. This feature is more practical in the 5 GHz band due to its less restricted channel layout. 

    • 2.4 GHz Limitation: Due to limited non-overlapping channels in the 2.4 GHz band, channel bonding can cause interference, making it less practical in networks with multiple access points (APs). 

    • Radar Interference: In the 5 GHz band, certain channels may be blocked if the AP detects radar signals (using Dynamic Frequency Selection or DFS). 

MIMO (Multiple Input Multiple Output) 

MIMO technology was another significant improvement introduced with 802.11n. MIMO increases both reliability and bandwidth by using multiple antennas to send and receive data streams. 

  • Antenna Configuration: Antennas are represented as 1x1, 2x2, or 3x3, where the first number indicates the number of transmit antennas and the second represents the number of receive antennas. 

  • Improved Performance: MIMO can transmit multiple signal streams simultaneously, boosting data throughput. 

Data Rates 

  • Per Stream Rates: 

    • Nominal data rate is 72 Mbps per stream for a 20 MHz channel. 

    • For a 40 MHz bonded channel, the rate is 150 Mbps per stream. 

  • Marketing Designations: Access points are labeled with ‘N’ then a number variable (Nxxx) to indicate nominal bandwidth.

    For example: 

    • N600 refers to an AP that can achieve 300 Mbps per band (2.4 GHz and 5 GHz) using two streams in a bonded channel, resulting in a combined bandwidth of 600 Mbps. 

Renaming 

Wi-Fi 4: The 802.11n standard is now officially referred to as Wi-Fi 4 to make the naming convention simpler. 

This standard provided a substantial boost to Wi-Fi speeds and reliability, setting the foundation for modern high-speed wireless networks. 

Wi-Fi 5 and Wi-Fi 6 

Wi-Fi 5 (802.11ac) and Wi-Fi 6 (802.11ax) represent significant advancements in wireless technology, aimed at increasing data rates, improving efficiency, and handling larger numbers of devices in modern networks. 

Wi-Fi 5 (802.11ac) 

  • Frequency Band: Wi-Fi 5 operates exclusively in the 5 GHz band. 

  • Dual Band and Tri Band: 

    • Dual band access points use the 2.4 GHz band for legacy devices (802.11g/n) and the 5 GHz band for faster Wi-Fi 5 clients. 

    • Tri band access points have one 2.4 GHz radio and two 5 GHz radios. 

  • Streams: Wi-Fi 5 allows up to 8 streams, but most access points support 4x4 streams. 

  • Data Rates: A single stream over an 80 MHz channel has a nominal data rate of 433 Mbps. 

  • Channel Bonding: Supports 80 MHz and 160 MHz bonded channels to increase bandwidth. 

Multiuser MIMO (MU-MIMO) 

  • MU-MIMO allows access points to communicate with multiple clients at the same time. 

  • In Wi-Fi 5, downlink MU-MIMO (DL MU-MIMO) lets the AP send data to up to four clients simultaneously using multiple antennas. 

Wi-Fi 6 (802.11ax) 

  • Data Rate: Wi-Fi 6 improves the per-stream data rate to 600 Mbps over an 80 MHz channel. 

  • Bands: Works in both the 2.4 GHz and 5 GHz bands. The Wi-Fi 6e standard introduces support for the 6 GHz band, which offers more frequency space but shorter range. 

Key Enhancements: 

  • Support for 6 GHz: Wi-Fi 6e adds a new frequency band with less interference and more available channels. 

  • Increased Client Support: Wi-Fi 6 supports up to eight clients simultaneously, improving performance in congested environments. 

  • Uplink MU-MIMO: In addition to downlink, Wi-Fi 6 introduces uplink MU-MIMO, allowing clients to send data to the AP simultaneously. 

Orthogonal Frequency Division Multiple Access (OFDMA) 

OFDMA improves simultaneous connectivity by dividing a channel into smaller sub-channels, allowing multiple clients to send data at the same time. This works alongside MU-MIMO to enhance performance when many devices are connected to the same AP. 

Wi-Fi 6’s combination of higher data rates, support for more clients, and improved simultaneous connectivity makes it ideal for modern, high-density environments with multiple devices connected at once. 

Wireless LAN Installation Considerations 

When setting up a Wireless LAN (WLAN), various factors need to be considered to ensure optimal performance, compatibility, and security. Below are key aspects to focus on during installation: 

SSID (Service Set Identifier) 

  • SSID is the network name that clients use to identify the WLAN. It is configured on the access point. 

  • Length: Can be up to 32 bytes long. 

  • Best Practices: Use ASCII letters, digits, hyphens, and underscores for maximum compatibility. 

Channel Selection and Channel Bonding 

  • Channel Number: Select the channel number for each band to minimize interference. 

    • If multiple access points have overlapping ranges, they should be configured on non-overlapping channels. 

    • Autoconfiguration: An access point can auto-select the best channel, but this feature may not always work perfectly. 

Configuring the SSID for Dual-Band Access Points 

  • You have the option to use either the same SSID for both the 2.4 GHz and 5 GHz bands or separate names for each. 

    • Same SSID: The access point and client device will automatically select the band with the strongest signal. 

    • Different SSIDs: Allows users to manually choose between the 2.4 GHz and 5 GHz bands. 

Operation Modes for Frequency Bands 

  • The operation mode for each frequency band determines the compatibility with older wireless standards. 

    • Supporting legacy devices can reduce the performance for all clients. 

    • You should carefully choose the operation mode based on the mix of old and new devices in your network. 

  • Channel Bonding: This combines adjacent channels for more bandwidth (e.g., two 20 MHz channels into a 40 MHz channel). 

    • 5 GHz: Channel bonding is more practical in the 5 GHz band due to the availability of more channels and less interference. 

    • 2.4 GHz: Channel bonding in the 2.4 GHz band may cause interference with other networks, making it less practical. 

Wi-Fi Analyzers 

Wi-Fi analyzers are essential tools for measuring the signal strength of wireless networks and troubleshooting performance issues. These tools can be installed on a laptop or smartphone and help identify the access points (APs) in the area, as well as their channels and signal strengths. 

Measuring Signal Strength 

  • Signal strength is measured in decibel (dB) units, specifically in relation to 1 milliwatt (mW), where: 

    • 0 dBm equals 1 mW. 

    • A negative dBm value represents a fraction of 1 mW. For example: 

      • -30 dBm equals 0.001 mW. 

      • -60 dBm equals 0.000001 mW.

  • Signal strength closer to 0 dBm indicates better performance. 

    • -65 dBm is considered a good signal. 

    • -80 dBm or lower may lead to packet loss or a dropped connection. 

dB and Logarithmic Scale 

dB values are expressed on a logarithmic scale, meaning that small changes in value can represent significant changes in performance: 

  • +3 dB means the signal power doubles. 

  • -3 dB means the signal power is halved. 

Signal-to-Noise Ratio (SNR) 

  • The Signal-to-Noise Ratio (SNR) compares the strength of the data signal to background noise—both are measured in decibel-milliwatt (dBm). 

    • The SNR is expressed in decibels (dB) and represents the difference between the received signal strength and the noise level. 

    • Higher SNR values indicate better signal quality, reliability and performance. 

    • To achieve a reliable connection, the signal level must be significantly greater than the noise level. 

      • Background noise can come from various sources, including: microwave ovens, cordless phones, Bluetooth devices, wireless video cameras and fluorescent lights. 

Example: 

  • If signal strength is -65 dBm and noise is -90 dBm, the SNR is 25 dB, which is good. 

    • An SNR greater than 40 dB is considered excellent, ensuring efficient data transmission. 

  • If noise rises to -80 dBm, in the above scenario, then the SNR becomes 15 dB, significantly reducing connection quality. 

    • An SNR below 15dB may result in a slow, unreliable connection. 

Example Scenario 

In a Wi-Fi analyzer report: 

  • Two access points with the same SSID are using channels 6 and 11 on the 2.4 GHz band. The closer AP has a stronger signal on channel 6. 

  • On the 5 GHz band, the client detects a signal on channel 36 but with less range, as 5 GHz signals don't travel as far as 2.4 GHz. 

  • The client adapter supports Wi-Fi 6 (ax), but the access points are only running b/g/n/ac modes. 

Wi-Fi analyzers provide detailed insights into nearby networks and help optimize performance by selecting the best channels and analyzing signal strength. 

Long-Range Fixed Wireless 

Long-range fixed wireless is a cost-effective solution for connecting two networks without the need to lay cables. It is an ideal solution for providing broadband internet access to homes and businesses in rural or remote areas. It uses wireless technology to create a bridge between distant locations. However, the use of the radio spectrum is regulated, so the equipment used for long-distance communication must be carefully configured to comply with regulations. 

Point-to-Point Line of Sight 

  • Point-to-point fixed wireless uses high-gain microwave antennas that are highly directional. These antennas must be precisely aligned to ensure optimal communication. 

  • The antennas can transmit signals over distances up to 30 miles, provided there are no obstructions between them, such as buildings or trees. 

  • To avoid obstructions, these antennas are often mounted on tall buildings or poles. 

Licensed vs. Unlicensed Spectrum 

  • Licensed Spectrum: 

    • The network operator purchases exclusive rights to a specific frequency band for a geographic area. In the US, this is regulated by the Federal Communications Commission (FCC). 

    • If interference occurs, the operator can legally shut down the source of interference. 

  • Unlicensed Spectrum: 

    • The operator uses public frequency bands, such as 900 MHz, 2.4 GHz, and 5 GHz. 

    • Anyone can use these frequencies, making interference a risk. To reduce conflicts, power output is regulated. 

Wireless Signal Power 

A wireless signal’s power has three key components: 

  1. Transmit Power: The strength of the radio signal, measured in dBm. 

  2. Antenna Gain: The boost a signal gets from being directed in a single direction instead of spread over a wide area. This is measured in decibels isotropic (dBi). 

  3. Effective Isotropic Radiated Power (EIRP):The total power output of the signal, which is the sum of transmit power and antenna gain, also expressed in dBm. 

Power Limits and Frequency 

  • Lower frequencies, like 900 MHz, propagate over longer distances but have stricter power limits. 

  • Higher frequencies, like 5 GHz, allow for higher power output, especially when using highly directional antennas. 

  • For example, in the 2.4 GHz band, increasing the antenna gain by 3 dBi only requires a 1 dBm reduction in transmit power, allowing long-range fixed wireless systems to operate over much greater distances than standard Wi-Fi access points. 

Long-range fixed wireless systems use focused directional antennas and carefully managed power output to bridge networks over long distances, whether on licensed or unlicensed spectrum. 

Bluetooth, RFID, and NFC

While Wi-Fi is commonly used for networking computers, other wireless technologies such as Bluetooth, RFID, and NFC are used for personal area networking (PAN) and short-range communications. 

Bluetooth 

Bluetooth is a wireless technology used to connect peripheral devices like headphones, speakers, and wearables to PCs and mobile devices. It is also used for data sharing between devices. 

  • Data Rate: Up to 3 Mbps. Newer versions (Bluetooth 3.0 and 4.0) can reach 24 Mbps by leveraging an 802.11 radio link for larger file transfers. 

  • Range: 

    • Early versions: Up to 10 meters (30 feet). 

    • Newer versions: Up to 100 feet, though signal strength may weaken at this distance. 

  • Pairing: Bluetooth uses a pairing procedure for secure device authentication and data exchange. 

  • Bluetooth Low Energy (BLE): Introduced in version 4, BLE is designed for devices that transmit small amounts of data infrequently. It is used in battery-powered devices like fitness trackers and smartwatches. 

    • Key Feature: BLE remains in a low power state until a connection is initiated. 

    • Compatibility: BLE is not compatible with classic Bluetooth, but devices can support both standards. 

Radio Frequency Identification (RFID) 

RFID is used for identifying and tracking objects with specially encoded tags. 

  • Tags: RFID tags can be either: 

    • Passive: Unpowered, responding only when scanned at close range (up to 25 meters). 

    • Active: Powered, with a range of up to 100 meters. 

  • Uses: 

    • Passive RFID tags are used in stickers, labels, and tracking systems for parcels and equipment. 

    • RFID is also used in access control systems, such as security badges for electronic locks. 

Near Field Communication (NFC) 

NFC is a peer-to-peer version of RFID, allowing devices to work as both a tag and a reader for information exchange.

Range: NFC works at a very short distance—typically up to 2 inches (6 cm). 

  • Data Rate: It supports data rates of 106, 212, and 424 Kbps. 

  • Uses: 

    • NFC is commonly found in smartphones and is used for contactless payments, security ID tags, and shop labels for stock control. 

    • It can also be used to set up other connections, like Bluetooth pairing.  

Shopping Tag With Barcode To mange Stock

Contactless Payment With Mobile Device

Security Identification Tags

These technologies enable seamless communication and data exchange for short-range applications, such as device pairing, tracking objects, and contactless payments. 

Summary 

Great job diving into wireless technologies! You've learned how access points connect devices to Wi-Fi networks, the differences between frequency bands like 2.4 GHz and 5 GHz, and the improvements brought by standards such as 802.11n, Wi-Fi 5, and Wi-Fi 6. You also explored key considerations for wireless LAN installation and tools like Wi-Fi analyzers to optimize network performance. Plus, you now understand how technologies like Bluetooth, RFID, and NFC work for personal area networking. Keep up the fantastic work—you're building a strong foundation in wireless networking!