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The Definitive Guide to Wireless Networking (Wi-Fi)
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A wireless network is essentially the same as a wired data network. However, the link between networked devices is – as the name suggests - wireless. As the devices aren’t tethered by a cable, they have the ability to be mobile. The wireless devices can also roam to different parts of the network, making connections to new devices along the way.
For Wi-Fi, the wireless connection is usually only linked to the user device. The users wireless device joins the network via an access point, which provides a bridge between the wired and wireless parts of the network. Wireless networks can also link access points, such as in a wireless mesh network and mobile phone networks. There are also point-to-point links, which are great for connecting neighbouring buildings and forming long-range links, like those used to connect mobile phone cell towers.
The most basic Wi-Fi network is made up of a single wireless Access Point (AP) and is connected to some wireless client devices. This is known as a Basic Service Set (BSS). An AP is likely to be configured with more than one service set, each with its own identifying name know as a Service Set Identifier (SSID).
The AP will periodically send out beacons, which provide basic details of each SSID. When a wireless client wants to join a BSS, it can either scan all available channels, listening for these beacons or send out a probe request. The probe request will detail the capabilities of the client device and, sometimes, which particular SSID it would like to join. This request is received by the AP, which sends a probe response to the client providing details of the SSID.
If the two are compatible, the client will attempt to authenticate to the SSID. This is only an 802.11 authentication. Proper client authentication involving user credentials will happen later. Once the client is authenticated, it will send an association request. Again, if the details are compatible, the AP will respond with an association response and data transfer can begin. This is basic association of the client with the access point. If specific network access is required, further authentication will take place. This will be in the form of a Wi-Fi password, user credentials or client machine authentication.
When there’s a meeting, several people will often have something to say at the same time. If more than one person talks at the same time, usually neither can be understood. The same is true with wireless networks. Wi-Fi uses a technique known as CSMA collision avoidance (CSMA/CA). This technique defines a process that ensures only one wireless device can talk at a time. When a device wishes to transmit, it first listens for any other transmitting device. If a transmission is detected it will back off for a random amount of time before trying again. If a transmission isn’t detected, the device will reserve the air space by telling all other devices to be quite for a set amount of time, before transmitting its data.
Often several APs will exist within the same network. This type of network is known as an Extended Service Set (ESS). These APs will likely have the same SSIDs configured and as a result, clients will be able to roam from one AP to another, whist staying connected to the same SSID. As the client moves between BSS’s, a re-association process takes place. This should be transparent to the user - they shouldn’t be able to notice when a roam happens. There have been several recent advances to improve this process. They involve sharing information between APs and clients, so that a client knows which AP to roam to, and the AP knows the client details, so it can authenticate quickly and seamlessly.
When creating a wireless network, you can choose between three types of deployment: centralised deployment, converged deployment and cloud-based deployment. Each of these suits different types of applications. Forfusion is here to provide guidance on which will best fit your business needs.
Centralised deployments are the most common type of wireless network system. They’re traditionally used in campuses where buildings and networks are in close proximity. This deployment consolidates the wireless network, facilitating advanced wireless functionality and making upgrades easier. Controllers are based on-premises and are installed in a centralised location.
For small campuses or branch offices, converged deployments offer consistency in wireless and wired connections. This deployment converges wired and wireless on one network device—an access switch—and performs the dual role of both switch and wireless controller.
This system uses the cloud to manage network devices deployed on-premises at different locations. The solution requires Cisco Meraki cloud-managed devices, which provide full visibility of the network through their dashboards.
In September 2020, the IEEE celebrated 30 years since the start of the 802.11 project. This was essentially the conception of Wi-Fi. Over the following years, the standards developed, making Wi-Fi the most popular wireless technology used for data transmission. The first Wi-Fi standard from the IEEE was 802.11-1997. This standard used a relatively basic form of modulation known as Frequency Hop Spread Spectrum (FHSS). In FHSS, the transmitter and receiver will hop between frequencies to reduce the chances of eavesdropping the conversation.
Bluetooth technology currently uses FHSS. This is why - although Bluetooth uses the same 2.4GHz spectrum as Wi-Fi - interference between the two is generally minimal. The next development for Wi-Fi was 802.11b, which used Direct Sequence Spread Spectrum (DHSS) as a way of spreading the signal using a code. The signal effectively gets lost amongst the noise in the spectrum, so that only the intended receiver who has the code can reconstruct the signal. This technique added security against eavesdropping, while making the signal resistant to interference.
802.11a brought Orthogonal Frequency Division Multiplexing (OFDM), which improved on the previous coding techniques. Since then, the modulation techniques have continuously improved, essentially allowing more and more data to cram into the available bandwidth. Each generation has brought better performance. Compare the 2Mbps available with 802.11-1997 to the 9.6Gbps available with 802.11ax. 802.11ax is also known as Wi-Fi 6. This renaming was brought in by the IEEE to make the 802.11 standards more accessible.
802.11b, 802.11a, 802.11g, 802.11n, 802.11ac and 802.11ax don’t have any logical sequence and it’s therefore not immediately apparent which supersedes which. These standards have been renamed in this order as Wi-Fi 1 to Wi-Fi 6, making the marketing of each new standard much more accessible.
Each generation of Wi-Fi has developed from the last. Reliability and security have been big drivers for change, but the main headlines have always been the big jumps in performance. Data rates have continuously increased in line with the insatiable demands of ever more data-hungry applications. Each iteration brings more complex modulation techniques, more radios and the ability to use more of the available spectrum - all with the goal of greater data rates.
However, the most recent generation of Wi-Fi 6 has gone in a slightly different direction. Instead of going all out for more performance, the focus has been more on efficiency. Previous generations have allowed more and more channels to bond, in order to increase bandwidth.
Wi-Fi 6, however, goes the other way. It allows the slicing of a single channel, reducing bandwidth but serving multiple clients on the same channel at the same time. This technology is known as Orthogonal Frequency Division Multiple Access (OFDMA). Think of it like car sharing. Bonding channels is like pooling all resources for that ultimate performance, a bit like using all your budget to buy a Ferrari. This is great for boasting high performance stats, but how often do you need all that performance?
Even when you do want to go for a blast, there are all the other slow cars you have to contend with. Efficient use of resources makes more sense in the real world, hence why most of us have a sensible hatchback. Going one step further and car-sharing in that sensible hatchback is what OFDMA in Wi-Fi 6 brings to the table. See the OFDMA section for further details on how this works.
Another example in this analogy is voice traffic and Quality of Service (QoS). Voice traffic is like a push bike. It doesn’t have high performance but does require consistency. Stopping and starting on a bike makes it really hard work. This type of traffic is very different from the motorised type, which can cope with regular stops and starts. The solution here is bike lanes. They use the same infrastructure as the rest of the traffic, but use a narrow lane that allows the bikes to keep a consistently moderate pace with minimal effect from other traffic. In this way, QoS enables voice traffic to pass through the network with less imposition. QoS is particularly important when implementing Voice over WLANs, due to the traffic being so affected by latency and jitter.
Wi-Fi 6 brings with it the following enhancements:
One of the most significant challenges with wireless networks is that only one device can transmit on a channel at any one time. Each device must listen and wait for the channel to be clear before transmitting. When clear, the device reserves the channel for a set amount of time to allow the data to be transmitted. Often, the overhead involved with this process takes significantly longer than the transmission of the actual data payload. This is because the management and control messages need to be sent at a low data rate to allow for backwards compatibility with legacy standards.
OFDMA aims to improve the efficiency of this process by segregating the data payload so that multiple clients can use the same reserved time slot at the same time. OFDMA achieves this by segregating the base 20MHz channel into smaller 2MHz segments. This means that the data portion of the packet can be split between several clients and therefore serve multiple clients at the same time. This data segmentation works in both the uplink and downlink direction, controlled by the AP. The following graphic provides an excellent analogy similar to the car sharing analogy discussed earlier. Highlighted here is that the management overhead, represented by the truck’s cab, is amortized between the clients. With standard OFDM, used in previous standards, each client has a separate management overhead, adding delay to the network. OFDMA combines this overhead for multiple clients, in turn reducing the channel reservation time. This improves efficiency, increases capacity, as well as reducing latency and jitter.
As discussed earlier, a challenge with wireless networks is that only one device can transmit on a channel at any one time. So, when a wireless device wants to transmit and they listen for a clear channel, how clear does the channel need to be?
What level of signal represents a busy channel? This is known as the Signal Detect (SD) level and it is very low at only 4dB above the noise floor (4dB SNR). Compare this to the 25dB level that is typical for the edge of an access point signal cell. In free space loss, the 25dB level will typically be around 20 meters from the access point. But, due to the exponential decrease in signal strength, the 4dB level can be as much as 250 meters away. Also used is the Energy Detect (ED) level. This refers to non-Wi-Fi signals and can be much higher at 20dB above the SD level.
The problem here is that there are only so many channels, so they often need to be re-used in the same RF environment. If an access point won’t transmit if it can hear another Wi-Fi device at only 4dB above the noise floor, this can cause significant problems. This and other limitations of Wi-Fi is why it’s essential to get the RF environment configured as efficiently as possible. See our Wireless Network Assessment section for more details.
Basic Service Set (BSS) colouring provides a solution for this in that access point - and its associated clients in a BSS - will tag their RF traffic with a colour. BSS is essentially an access point and its associated clients. If a wireless device is waiting to transmit and it detects a signal on the same channel, normally it would back off and wait for the channel to clear. However, with BSS colouring, the transmitting device can see that the signal is from a separate BSS and can use the ED (24dB) level rather than the SD (4dB) level to decide whether to transmit at the same time or not. This makes the spectrum much more efficient for re-use.
OFDMA and BSS colouring are excellent enhancements for the 2.4GHz band. Due to its exclusion from Wi-Fi 5 (802.11ac), it was thought that there would be no use for the 2.4GHz band. However, with the recent developments in Wi-Fi 6, the band is very much back in use again. This is great news, as the 2.4GHz has many advantages such as greater signal propagation - unaffected by weather radar and DFS events – and is perfect for inexpensive devices such as IoT.
Wi-Fi security also made significant advancement in Wi-Fi 6 with the introduction of WPA3. WPA3 provides enhancements over WPA2 is the following three areas:
WPA3 Personal solves the problem of having to use complex passwords that are difficult to remember. The new robust replacement for PSK is resistant to dictionary attacks. Even if a password is compromised after the data is transmitted, the data remains protected.
WPA3 Enterprise offers an enhanced suite of cryptographic tools, which build upon WPA2 and ensures the consistent application of security protocols across the network.
One enhancement we particularly like with WPA3 is the encryption of open networks. Currently, with WPA2, all open wi-fi networks are unencrypted, so anyone can easily capture your passwords, credit card details and all sorts of other personal data that you may be unwittingly sharing. WPA3 brings secure encryption while still having the convenience of an open network.
It’s expected that Wi-Fi 6 devices will become more prevalent throughout 2020 and 2021. Wi-Fi 6E is also on the horizon, which has a significant improvement of having access to the 6GHz spectrum. This is highly significant as the last increase in spectrum was Wi-Fi 2 in 1999 when the 5GHz spectrum was made available. Devices are already being developed with increased numbers of radios to allow the use of the three radio bands.
Ofcom officially made the statement regarding the release of the 6GHz spectrum in July 2020. A total of 500MHz of RF spectrum is being made available.
"Make the lower 6 GHz band (5925-6425 MHz) available for Wi-Fi and other RLAN technologies."
Opening this band will make an additional 25 20MHz channels available. Bonding of these channels will also be possible with up to 3 160MHz channels, each providing theoretical peak data speeds of 9.6Gbps. This will increase capacity and reduce congestion across the existing frequency bands.
"The release of this spectrum will also enable very low power (VLP) outdoor use."
This will enable the development of new and exciting innovative applications.
"Remove the Dynamic Frequency Selection (DFS) requirements from channels used by Wi-Fi in the 5.8 GHz band (5725-5850 MHz)."
The DFS requirement has long been a significant inhibitor of performance and reliability for Wi-Fi devices in the 5GHz band. The DFS requirement forces an access point to scan for radar signals and to switch channel if suspected radar transmissions are detected. All clients connected to the AP also have to change channels, causing significant disruption. Although this restriction will only be removed in the UNII 3 band at the top end of the 5GHz spectrum, this is still great news and will undoubtedly improve performance.
Although the UK won’t get as much spectrum released as the US, this is still a significant development. We should remain optimistic that 6GHz Wi-Fi devices will be available soon, as they will use an enhanced version of the existing Wi-Fi 6 standard. No doubt vendors will be racing to take advantage of this fantastic boost to Wi-Fi performance.
Wi-Fi 6E will bring data rates of up to 9.6Gbps. This is the same as the maximum available with Wi-Fi 6, meaning 6E is more about spectrum capacity than speed increases. However, if 9.6Gbps is not enough Wi-Fi 7 (802.11be) is due in 2024 with data rates expected of up to 30Gbps!
A possibility for Wi-Fi 7 is the removal of the legacy management overhead. This has not changed for over 20 years but is necessary for backwards compatibility.
A note on data rates: Those rates quoted above are the maximum available. The data rate you can realistically achieve depends on the access point type, client type, signal strength and spectrum available. The actual data throughput will be less than half of the data rate and will be divided by the number of clients per AP radio. In reality - due to the legacy management overhead and the high number of low performing mobile devices - even a well-designed Wi-Fi 6 enterprise wireless network will only average around 80Mbps of throughput per AP. It’s important to note this when considering dual-cabling or multi-gigabit switching.
The Cisco Enterprise Wireless Solution brings the benefits of Wi-Fi 6 and applies them to an enterprise network environment. The solution has the following Wi-Fi 6 technology components combined with next generation networking technologies found in Software Defined Access (SD-A).
The Wi-Fi 6 components and their benefits are as follows:
Programmable RF application-specific integrated circuits (ASICs). This is a fantastic addition. Previously this had to be done with a dedicated tool or by removing an AP from service to use the spectrum analysis functionality. The additional functionality is ideal for managing Wi-Fi networks in congested RF environments; particularly where the environment has several external influencers such as neighbouring networks, non-Wi-Fi interference and DFS events. It provides you with real-time analytics, as well as a platform for future innovation and capabilities. Combined with Cisco DNA Assurance, this gives you radiofrequency visibility and the intelligence to help you run your networks better.
Cisco offers multilingual support and application hosting of IoT protocols to better support IoT service and expansion.
Built-in Intelligent Capture provides enhanced issue detection, root cause analysis, real-time troubleshooting and in-service access point monitoring with over-the-air packet capture.
Cisco DNA Assurance with Active Sensor is a compact wireless device that lets you test real-world client experiences to validate wireless performance for any situation.
Cisco's Flexible Radio Assignment provides a better mobile user experience for high-density networks by automatically detecting when a large number of devices are connected to a network and adjusting its dual radios to serve more clients.
Cisco CleanAir® technology provides proactive protection against radio frequency interference and takes automatic action to avoid current and future interference.
Next-generation wireless networks integrate into the software-defined access model. This provides a single network fabric from edge to cloud and allows you to set identity-based policy for users, devices and ‘things’.
The SD model provides access to any application, without compromising on security, while also gaining insight into any attempt to access your network. Automatic segmentation of users, devices, and applications means you can deploy and secure your services faster.
The network is creating new opportunities for changing the way we work and helping us become more efficient. Forward-thinking organizations are investing in a wireless network to facilitate those opportunities for productivity, innovation, and growth. As they transition to digital-ready networks, they subsequently require advanced features and security.
The approach of Wi-Fi 6 is creating anticipation for what’s possible. And we want you to be able to tackle all of the excitement head-on. When you upgrade your wireless network to the latest Cisco solutions, you’ll be prepared for Wi-Fi 6 so you can support more bandwidth-intensive applications, more IoT devices and more clients. You’ll also be able to offer advanced wireless capabilities that go well beyond traditional networking.
For those with investment in wireless. Cisco DNA Spaces takes it one step further to combine wireless connectivity with location-based insights. Cisco DNA Spaces provides a simple, scalable and standardized approach to support wireless users with location analytics, business insights, customer engagement toolkits, asset management, Bluetooth Low Energy (BLE) management and location data APIs.
Cisco is a founding member of the OpenRoaming consortium. OpenRoaming will let mobile users automatically and seamlessly roam between Wi-Fi and cellular networks, including Wi-Fi 6 and 5G. OpenRoaming is part of efforts by Cisco, together with other industry leaders to break down the barriers between Wi-Fi 6 and 5G to support connection everywhere, seamless onboarding, more choices for access and more secure connections.
How does an intent-based network support mission-critical deployment? Cisco DNA Center is the network management and Command Center for your intent-based network- both wired and wireless. Combining management, automation, analytics and security, Cisco DNA Center simplifies network management and speeds up innovation.
Your network is full of all the data you need to optimize it and manage it better. Cisco DNA Assurance lets you put that data to work without a complete network overhaul. While Cisco DNA Wireless Assurance gives you full network visibility, troubleshooting, time savings, efficiency, and insights based on real-time as well as historical data to make predictions and resolve issues.
Some technology experts have tried to compare Wi-Fi 6 and 5G, with some even saying that one will negate the need for the other. Vendors, however, are looking to find ways of combining these technologies so that they complement each other. As discussed in the previous section, industry leaders including Cisco have formed the OpenRoaming consortium. The goal of OpenRoaming is to seamlessly integrate these two technologies.
The integration of data networks and telecoms networks has long been an aspiration of technology vendors. Unfortunately, the challenges stem from the two technologies being born with two very different goals in mind.
All data networks use the same 7-layer model. Each layer performs a different function but all with the same purpose. The goal is to package the data is such a way that - no matter what happens over the network - the data can be unpackaged and read reliably at the receiving end.
There’s a lot of overhead with this model, but it does mean that it’s very rugged. For instance, the data can be received in sudden bursts or even in the wrong order, but it doesn’t matter because the higher-level protocols can sort everything out. This is ideal for the Internet, as there’s no way of knowing what sort of network the data will have to traverse to reach its destination.
One significant advantage of Wi-Fi data networks over telecoms networks is that you own the data. This would be significant if you want to perform any traffic management or data analytics. Over a 5G network you may have the situation where you have to buy back your data in order to analyse it.
Telecoms networks, on the other hand, are very different as they’re all built and managed by telecoms companies. Therefore, the performance of the network is much better controlled, and less technology is required to ensure reliable performance. Telecoms networks are like a racetrack, very well maintained and highly predictable. Race cars are designed to match their environment and perform well within it. Whereas, the Internet is more like the outback of Australia, completely wild and unpredictable. Roads are likely to be built by each local farmer with varying levels of quality. The 7-layer model is like an off-road truck, designed to cope with any terrain and still deliver its occupants comfortably and safely to their destination.
Despite their differences, Wi-Fi 6 and 5G both have the same fundamental goals of high throughput, low latency and high capacity. They both provide higher data rates to support new applications and increase in network capacity to connect more users and devices. So, can they co-exist? Well, the vision is uninterrupted wireless access with Wi-Fi 6 and 5G being dominant in disparate environments. Wi-Fi 6 is ideal for indoor environments like your home, the office, conference centres and stadiums. 5G, on the other hand, is suitable for outdoor environments such as cities, towns and on the road in your car. The goal is that wireless network access is always available and devices are always connected, providing the same service in all locations.
A significant part of your wireless network is the RF environment. Getting this right ensures that your network has the fundamentals to perform to your expectations.
A good RF Design considers the existing environment including external factors such as neighbouring networks and any potential interference sources. The applications planned for the network will define the requirements of the RF design. A correctly designed and managed RF environment is essential for good wireless network performance.
Network monitoring tools such as Cisco DNA centre and 7 Signal can provide visibility of any problems on your wireless network. However, it’s often a deep dive analysis that’s required to unearth the root causes. This is where specialist tools and knowledge come in to analyse traffic flow and examine how the data is actually being passed through your network.
Wireless networking is unique among other networking technologies as you have very little control over what type of devices enter your network environment. Wireless networks are often open to guests or even the general public. Sometimes the devices in your network environment may not even be networking devices (non-WiFi) however, they can still have a significant effect on it.
If you find that you have poor performance on your wireless network, the only way to get a full picture is to analyse the three main components of the network: the configuration, the RF environment and the client devices. At Forfusion, we offer a full wireless network assessment which consists of an analysis of the three main components.
The wireless network assessment offered by Forfusion is a service that provides a full analysis of your wireless network based on industry standard best practices and many years of professional experience.
The Assessment focuses on the three components of the wireless network.
The wireless network configuration is analysed, and your infrastructure is audited to ensure that it follows the best practices and is optimised for your network and applications.
RF data is captured for all wireless devices in the area. This includes both Wi-Fi and non-Wi-Fi devices.
Details of the type of wireless clients on the network are captured and analysed. Often poorly performing clients can cause the whole network to run slower.
The wireless network assessment will be bespoke for your network. We’ll discuss your requirements, any current issues with your network and your plans for future developments. Generally, the assessment comprises the following components:
A capture of all network components and their configuration. Also included is an audit of AP placement and orientation.
An RF survey consists of RF data gathering of the current wireless network coverage, including signal strength, noise floor, capacity and interference. An audit of user density and expected application usage is also included.
Wi-Fi Analysis captures all of the Wi-Fi environment, including neighbouring networks and rogue networks. Identification of problem areas, for example, high utilisation, poor performance and sources of interference. Wi-Fi Client analysis.
If issues are identified from the assessment components, further analysis may be required using the following.
Protocol analysis involves a deep dive data gathering of wireless traffic, focusing on the identified problem areas. Wireless packets are captured and analysed. Problem areas are analysed to ensure efficient network performance, such as data capture of the client roaming process.
Spectrum analysis is the deep dive data gathering of non-Wi-Fi signals. Those that are causing performance degradation on the network are identified. Further data gathering of spectrum utilisation for both Wi-Fi and non-Wi-Fi devices is also completed.
After the data is gathered and analysed, the results are collated into a report and presented in the following format.
The network audit will provide an update to your current documentation. This has time-saving value for your support teams. Having a detailed and up to date picture of your network will allow your support teams to be more efficient in resolving issues and administration.
Identifying issues in advance of them occurring will save the time and effort of troubleshooting down the line. There’s also the advantage of user perception. A few simple issues can cause users to perceive the network as poorly performing and unreliable.
The remediation plan will provide several options for improvement. Often these will be inexpensive ‘quick wins’. The plan will also identify the most cost-effective ways of improving your network, so that expenditure is focussed on the areas that provide the most efficient returns in performance.