Wireless Wizardry: Exploring the Mysteries of Wifi Design and Network Integration (Part 3)

Welcome back to my LinkedIn series, where today we'll be exploring some advanced Wi-Fi concepts. As wireless technology continues to evolve at an unprecedented pace, understanding the intricacies of Wi-Fi becomes essential for IT professionals, network engineers, and tech enthusiasts alike. In this article, we'll delve into the more complex aspects of Wi-Fi, shedding light on features and techniques that can help you optimize your wireless network's performance, security, and efficiency.

Over the years, Wi-Fi has evolved from a luxury to a necessity in both personal and professional settings. The continuous development of new standards, protocols, and technologies has significantly enhanced its capabilities, making it crucial for those in the industry to stay up-to-date. By understanding the advanced concepts and techniques we'll be discussing in this series, you'll be better equipped to tackle the challenges of today's highly connected world.

We'll cover a range of topics, including:

1. Wi-Fi Standards and Protocols: A closer look at the latest Wi-Fi 6 and Wi-Fi 6E standards, as well as their impact on network performance and device compatibility.
2. Beamforming and MU-MIMO: Explore the advanced techniques that improve wireless network efficiency, range, and throughput by making better use of available radio frequency (RF) resources.

As we delve deeper into these advanced Wi-Fi concepts, empowering you to unlock the full potential of wireless networking. Whether you're an IT professional, network engineer, or simply a tech enthusiast, this article series will equip you with the knowledge to stay ahead of the curve in the ever-evolving world of Wi-Fi. So let's get started.

Non-overlapping Channels

The concept of non-overlapping channels is important because it allows multiple access points (APs) to operate in the same area without causing self interference, which can slow down or disrupt the network's performance. In densely populated areas with many wireless devices, the use of non-overlapping channels becomes even more critical to prevent channel contention.

Non-overlapping channels are channels that do not overlap in frequency, meaning they can be used simultaneously without causing interference. For example, in the 2.4 GHz band, there are 11 channels available, but only channels 1, 6, and 11 are non-overlapping channels, which means they can be used without interfering with each other. This is because these channels are spaced 5 MHz apart and have a bandwidth of 20 MHz, with a 2.4 GHz center frequency.

However, achieving non-overlapping channels in WiFi networks can be a challenge. The main reason for this is the limited number of available non-overlapping channels in the 2.4 GHz and 5 GHz frequency bands. In the 2.4 GHz band, there are only three non-overlapping channels, as previously mentioned however, the number of non-overlapping channels in the 5 GHz band depends on the channel width being used.

The 5 GHz band provides more channels and is less congested than the 2.4 GHz band, resulting in better performance. Here's a breakdown of non-overlapping channels based on different channel widths:

1. 20 MHz channel width: With 20 MHz channel width, there are 24 non-overlapping channels available in the 5 GHz band (23 channels in the U-NII-1, U-NII-2, and U-NII-3 bands, and 1 additional channel in the U-NII-2e band).
2. 40 MHz channel width: Using 40 MHz channels effectively doubles the bandwidth, allowing for higher data rates. There are 12 non-overlapping 40 MHz channels in the 5 GHz band (11 channels in the U-NII-1, U-NII-2, and U-NII-3 bands, and 1 additional channel in the U-NII-2e band).
3. 80 MHz channel width: The 80 MHz channel width is a key feature of the Wi-Fi 5 (802.11ac) and Wi-Fi 6 (802.11ax) standards, allowing for even faster data rates. In the 5 GHz band, there are 6 non-overlapping 80 MHz channels.
4. 160 MHz channel width: Wi-Fi 6 (802.11ax) introduced support for 160 MHz channel width, which provides even greater throughput. However, there are only 2 non-overlapping 160 MHz channels in the 5 GHz band.

Keep in mind that the availability of these channels may be subject to local regulations and restrictions. Always ensure you are operating within the guidelines set forth by your country's regulatory authority.

Self Interference

One of the big challenges in WiFi is that neighboring access points can interfere with each other even if they are using non-overlapping channels. This is because the signals transmitted by APs can spill over into adjacent channels, causing interference. This can be particularly challenging in densely populated areas, where there may be many APs operating in close proximity to each other.

To mitigate these challenges, WiFi network engineers often use techniques such as channel planning and power management. Channel planning involves carefully selecting channels for each AP to ensure that they do not overlap with neighboring APs. Power management involves adjusting the transmit power of each AP to reduce interference and ensure that the signal does not spill over into adjacent channels however power reduction can come with an increase in latency.

Latency is not a good thing in Wi-Fi networks.

Latency refers to the delay between when a request is made and when a response is received, and it can be caused by a variety of factors, including co-channel interference. In Wi-Fi networks, co-channel interference can occur when multiple access points are broadcasting on the same channel in close proximity to each other. This can lead to collisions and turn-taking, which can result in increased latency and reduced network performance.

High latency in a Wi-Fi network can have several negative effects, including slower data transfer rates, increased buffering and loading times, and decreased network responsiveness. This can be especially problematic for applications that require real-time communication, such as video conferencing, online gaming, and VoIP. To minimize latency in Wi-Fi networks, it is important to optimize the network for performance and minimize sources of interference.

Reducing power can also reduce interference however this can come at a cost.

Reducing the power output of an access point can cause the signal-to-noise ratio (SNR) to decrease, which can have a negative impact on throughput for clients. SNR is the ratio of the signal strength to the level of background noise, and a lower SNR means that the signal is weaker and more prone to interference and errors. When the power output of an access point is reduced, the signal strength received by clients may be lower, which can result in lower data rates and increased packet loss. This is because the client devices may need to use lower modulation rates or retransmit packets more frequently to maintain a reliable connection, which can reduce overall throughput. Additionally, reducing the power output of an access point can increase the distance between the access point and the client devices, which can further reduce signal strength and increase interference from other sources.

As you can see the RF (Radio Frequency) engineers face a multitude of challenges when designing and implementing wireless networks to achieve a specific signal strength, like -65 dBm, while ensuring high performance. Factors such as attenuation, channel allocation, transmit power, user density, client devices, and unique facility requirements must all be taken into account.

New for WiFi 6e - Spectrum Allocation Service (SAS)

Spectrum allocation service (SAS) is a crucial component in the deployment of WiFi 6E in the 6 GHz band. The SAS is responsible for managing the use of the 6 GHz band to avoid interference with incumbent users, such as radar systems and satellite communication services.

One of the primary reasons why the SAS is necessary is to manage the power levels of access points (APs) that are operating in the 6 GHz band. The SAS allocates specific channels and power levels for each AP, taking into account the location of the AP and the potential for interference with incumbent users. The SAS ensures that APs operate at a power level that will not interfere with incumbent users, while still providing optimal coverage and performance.

Another reason why the SAS is necessary is to manage the locations of the APs. The SAS allocates specific channels for each AP based on its location, ensuring that there is no interference with incumbent users. The SAS also monitors the use of the 6 GHz band in real-time to detect any potential interference and adjust the allocation of channels and power levels as needed.

Digging Deeper - Advanced Concepts

Devices sharing a WiFi network take turns using WiFi through a protocol called Carrier Sense Multiple Access with Collision Avoidance (CSMA-CA).

In CSMA-CA, each device listens to the wireless medium before transmitting data. If the medium is idle, the device begins to transmit data. However, if the medium is busy, the device waits for a random amount of time before trying again. This random backoff time helps to avoid collisions and ensures that multiple devices do not try to transmit data at the same time.

The WiFi access point (AP) also plays a role in managing turn-taking in the network. The AP manages the network and allocates time slots for each device to transmit data. The AP also controls the power level of each device to ensure that the devices do not interfere with each other and that each device has a fair chance to transmit data.

Furthermore, the use of Quality of Service (QoS) in WiFi networks can also help devices to take turns using WiFi. QoS allows the network to prioritize traffic based on the application, so that critical traffic like voice and video are given higher priority than less critical traffic like email and web browsing. This ensures that time-sensitive applications are given priority and have a higher chance of successful transmission.

All of these factors work together to ensure that each device has a fair chance to transmit data and that the network operates efficiently and effectively. Carrier sense multiple access with collision avoidance (CSMA-CA) is a protocol used in WiFi networks to minimize collisions and maximize efficiency. The protocol works by allowing multiple devices to share the same wireless medium and take turns transmitting data.

Multi-User Multiple Access MIMO (MU-MIMO) is a technology used in WiFi networks to improve wireless performance by allowing multiple devices to simultaneously transmit and receive data.

In early WiFi networks, only one device could communicate with the access point (AP) at a time, even if there are multiple antennas on both the device and the AP. With MU-MIMO, the AP can communicate with multiple devices at the same time, using multiple antennas on both the AP and the devices.

MU-MIMO works by dividing the wireless channel into multiple sub-channels, with each sub-channel allocated to a specific device. The AP then sends data to multiple devices simultaneously, using different sub-channels and different antennas. This allows multiple devices to transmit and receive data at the same time, improving overall network performance.

There are two types of MU-MIMO: downlink MU-MIMO and uplink MU-MIMO. With downlink MU-MIMO, the AP sends data to multiple devices simultaneously. With uplink MU-MIMO, multiple devices can send data to the AP at the same time.

MU-MIMO requires both the AP and the devices to support the technology, and not all devices are MU-MIMO compatible. Additionally, the number of devices that can use MU-MIMO at the same time is limited by the number of antennas on the AP and the devices, as well as the number of sub-channels available.

Overall, MU-MIMO is a technology that improves wireless performance by allowing multiple devices to simultaneously transmit and receive data using multiple antennas, which helps to reduce network congestion and improve overall network efficiency.

How to figure out the speed..

The MCS (Modulation and Coding Scheme) index is a parameter that is used to evaluate the performance of a WiFi client device. It is a value that represents the level of modulation and coding that is being used by the device to transmit and receive data.

Higher MCS index values generally correspond to higher data rates and better performance, as they indicate that the device is using more advanced modulation and coding schemes to transmit data. Conversely, lower MCS index values indicate lower data rates and potentially lower performance, as the device may be using less advanced modulation and coding schemes.

The index is a parameter used in wireless communication systems to determine the data rate for a specific link. It defines the combination of modulation techniques (how the data is encoded onto the radio wave) and Forward Error Correction (FEC) coding rates (used to correct errors that may occur during transmission). The MCS index is crucial for optimizing the data rate and, in turn, the overall performance of a wireless network.

The MCS index is calculated based on factors such as signal-to-noise ratio (SNR), channel bandwidth, the number of spatial streams, and the Guard Interval (GI). In general, a higher SNR allows for more complex modulation schemes and higher coding rates, resulting in a higher MCS index and data rate.

Here's an example of an MCS index chart for the 802.11n standard with a 20 MHz channel bandwidth and a 400 ns Guard Interval:

MCS Index | Modulation Scheme | Coding Rate | Data Rate (Mbps)

In this example chart, the MCS index ranges from 0 to 7. Each index corresponds to a specific combination of modulation scheme and coding rate, which determines the achievable data rate (in Mbps). For instance, MCS index 4 uses 16-QAM modulation with a 3/4 coding rate and yields a data rate of 39 Mbps.

Note that this is just one example of an MCS index chart for 802.11n. Different charts will apply to other Wi-Fi standards, such as 802.11ac and 802.11ax, which have more MCS indexes and can accommodate higher data rates, wider channel bandwidths, and more spatial streams.

By evaluating the Wi-Fi equipment, access point (AP), and client capabilities, along with the Wi-Fi standard they support, you can predict the likely top-end throughput in the communication link. The number of spatial streams supported by the devices (e.g., 2x2, 3x3, 4x4, or 8x8) plays a crucial role in determining the maximum achievable throughput.

To estimate the top-end throughput, consider the following factors:

1. Wi-Fi standard: Determine which Wi-Fi standard the AP and the client device support (e.g., 802.11n, 802.11ac, or 802.11ax). Each standard has different maximum data rates and features that impact throughput.
2. Spatial streams: Check the number of transmit and receive antennas (e.g., 2x2, 3x3, 4x4, or 8x8) supported by both the AP and the client device. The actual number of spatial streams used in the communication link will be determined by the device with the lowest number of supported spatial streams. For example, if an AP supports 4x4 and a client device supports 2x2, the communication link will effectively operate as a 2x2 system.
3. Channel bandwidth: Identify the channel bandwidth supported by both the AP and the client device (e.g., 20 MHz, 40 MHz, 80 MHz, or 160 MHz). The actual channel bandwidth used in the communication link will be determined by the device with the lowest supported channel bandwidth.
4. Guard Interval (GI): Determine the Guard Interval used by the devices (e.g., 400 ns or 800 ns). A shorter Guard Interval can increase the data rate but might be more susceptible to interference.
5. MCS index: Based on the Wi-Fi standard, channel bandwidth, spatial streams, and Guard Interval, find the highest MCS index supported by both the AP and the client device. Refer to the corresponding MCS index chart to determine the maximum data rate.

Once you have gathered all this information, you can calculate the top-end throughput by multiplying the maximum data rate (obtained from the MCS index chart) by the number of spatial streams in use.

Keep in mind that these calculations provide an estimate of the maximum achievable throughput under ideal conditions. Real-world performance may be lower due to factors such as interference, signal attenuation, network congestion, and client device capabilities.

Looking forward

As you may have deduced, the over-saturation of Wi-Fi access points can lead to interference, channel congestion, increased noise, increased power consumption, and increased complexity. To avoid these issues, it is crucial to properly plan and design Wi-Fi networks, taking into account the specific requirements and characteristics of the environment in which they will be deployed. In the next few articles, we'll start exploring the essential steps and best practices for designing high-performance Wi-Fi networks.

To create a high-performance Wi-Fi network that meets the needs of users while minimizing potential issues, it's important to follow a systematic approach. We'll cover the key aspects involved in designing such networks, including:

1. Site Survey: Understanding the physical layout and characteristics of the deployment environment is essential. We'll discuss the importance of conducting a thorough site survey, the various survey methods, and the tools that can help you obtain accurate and valuable information about the environment.
2. Radio Frequency Planning: Learn how to effectively plan the use of RF resources to minimize interference, channel congestion, and noise. We'll delve into strategies for choosing the right channels, channel widths, and transmit power settings for your specific environment.
3. Access Point Placement: The strategic placement of access points (APs) is crucial for ensuring optimal coverage, capacity, and performance. We'll explore the factors to consider when determining AP locations, including signal propagation, attenuation, and user density.
4. Network Capacity and User Density: Understand the importance of designing a Wi-Fi network that can handle the demands of various user densities and types of applications. We'll discuss techniques for estimating required network capacity and accommodating diverse user needs.
5. Scalability and Future-Proofing: With the rapid evolution of wireless technologies, it's essential to design networks that can adapt to future requirements. We'll cover best practices for building scalable and future-proof Wi-Fi networks, including the adoption of the latest Wi-Fi standards and the use of software-defined networking (SDN).

By following the guidelines and best practices discussed in this article, you'll be better equipped to design and deploy high-performance Wi-Fi networks that provide robust, reliable, and efficient connectivity for a wide range of environments. Stay tuned as we delve deeper into the fascinating world of Wi-Fi network design, helping you unlock the full potential of wireless technology.