I recently purchased a Wi-Fi 6 device (Samsung Galaxy S10), and when I checked which date rate it was using over the Wi-Fi, this is what I got:

I wanted to find out which MCS index and which modulation was used but after doing some research online, I couldn't find any easy resources that could give me the new data rates available with 802.11ax (Wi-Fi 6). So I decided to create that resource myself.

This blog presents the results of the new MCS table updated to include all the new 802.11ax data rates. It also presents how these data rates are calculated.

The following table includes all the MCSs data rates defined by the 802.11n (HT), 802.11ac (VHT) and 802.11ax (HE) amendments:

Here is a link to the full MCS Table: ​http://bit.ly/2G0DIcD

​As you can see, the table is getting very big. In fact, 802.11ax is introducing 2880 new data rates. However, not all data rates will be used in the real world. In order to focus on what will be most useful to Wi-Fi Engineers, I have created some smaller tables which only focuses on sections of the complete table.

This table presents 802.11n (HT), 802.11ac (VHT) and 802.11ax (HE) data rates for up to 3 spatial streams:

Here is a link to the spreadsheet: http://bit.ly/2KksViN

This table only presents the data rates for 802.11ax communications up to 3 spatial streams:

Here is a link to the spreadsheet: bit.ly/2Ia1Pc2

This table only presents the data rates for 802.11ax communications when OFDM is used:

Here is a link to the spreadsheet: http://bit.ly/2VwYNSk

This table only presents the data rates for 802.11ax communications when OFDMA is used:

Here is a link to the spreadsheet: ​​http://bit.ly/2VztdmU

First we need to understand how the MCS data rates are calculated prior 802.11ax. I am only going to focus on 802.11n (HT) and 802.11ac (VHT) here. 

Here is the formula we can use to calculate which data rate is used for both 802.11n and 802.11ac:

Let's detail each of these variables and which value they can have for both 802.11n and 802.11ac:

Now, the formula doesn't change much with 802.11ax. However, some new features will impact the way we calculate data rate for 802.11ax:

• A new symbol duration is used: 12.8µs
• Different Guard Intervals are used: 0.8µs, 1.6µs and 3.2µs
• The size and number of data subcarriers is not the same (especially with the different RU sizes introduced by OFDMA.

Even though the formula doesn't change much, the IEEE does define 2 different formulas depending on if OFDMA is used or not. When OFDMA is not used, we can used the formula previously presented above.

Here is the formula we can used when OFDMA is used (it is pretty much the same except that we define the number of data subcarriers per RU and not per channel):

Let's now details each of these variables and which values they can have when HE (802.11ax) is used. The first table details the parameters used when OFDMA is not used. The second table details the parameters when OFDMA and resource units are used.

Due to the addition of a new modulation technique (QAM-1024), 2 new MCS indexes are now available with 802.11ax:

• Index 10: when the 1024-QAM modulation is used with a coding of 3/4
• Index 11: when the 1024-QAM modulation is used with a coding of 5/6

So now that we have this information, let's try to understand the data rate that my phone was using.
The phone is a Samsung GS10 which supports 802.11ax and up to 2 spatial streams. The AP used is an Aerohive AP630. I have configured it with an 80MHz wide channel. OFDMA is not used here because ODFMA was not activated at the time of this capture.

So based on this information, we can determine some of the variables required to calculate the data rate and narrow down the data rates that will be used by this device:

• Number of Data Subcarriers for an 80MHz wide channel: 980
• Number of Coded bit per subcarrier (Modulation): we don't know yet
• Coding: we don't know yet
• Number of Spatial Streams: 2
• OFDM Symbol Duration: 12.8µs
• Guard Interval: we don't know yet

So here is the list of possible data rates used by this device when connecting to this AP:

Because we know that the data rate used was 1200.95 Mbps (as indicated on the picture above), we can now determine that:

• MCS 11 was used
• 1024QAM with a coding of 5/6 ​was being used
• A guard interval of 0.8µs was used

As always, comments and feedbacks are welcomed! Let's make it better together :)
​

Here are some related resources used to create the timeline:

• Wi-Fi Alliance Security Page: https://www.wi-fi.org/discover-wi-fi/security
• Wi-Fi Alliance WPA3 Specifications: https://www.wi-fi.org/download.php?file=/sites/default/files/private/WPA3_Specification_v1.0.pdf
• Wi-Fi Certified Enhanced Open delivers data protection in open Wi-Fi networks: https://www.wi-fi.org/news-events/newsroom/wi-fi-certified-enhanced-open-delivers-data-protection-in-open-wi-fi-networks
• OWE Specifications: https://www.wi-fi.org/download.php?file=/sites/default/files/private/Opportunistic_Wireless_Encryption_Specification_v1.0_0.pdf
• RFC 8110 - Opportunistic Wireless Encryption: https://tools.ietf.org/html/rfc8110
• RFC 7664  Dragonfly Key Exchange : https://tools.ietf.org/html/rfc7664
• IEEE 802.11 Timeline: http://www.ieee802.org/11/Reports/802.11_Timelines.htm

​I am really excited about 2019. The Wi-Fi technology is always evolving, bringing new challenges along the way. And this year is no exception. I am looking forward to the challenges that I will face this year and I am looking forward to the new learning experiences that 2019 will bring.

In this article, I talk about some of the important trends that I think will be quite popular in the discussions we will have among the community or with our customers.

​Last year, we talked a lot about the theory behind Wi-Fi 6 (or 802.11ax). We saw a couple of enterprise vendors coming out with 802.11ax access points (Aerohive, Aruba Networks). We also saw a few consumer 802.11ax access points being released. However, we still haven’t heard about any 802.11ax client devices yet.

So this year, I really hope that we will start seeing some Wi-Fi 6 client devices being release so we can start playing with it. I would like 2019 to be the year of Wi-Fi 6 in practice and not only in theory. I would love to see the future iPhone supporting Wi-Fi 6.

Nevertheless, from an Engineer point of view, I believe that we will have to keep educating ourselves on the technology. First, because we need to apprehend it better. Second, we need to be able to advise and educate our customers. We are going to see a lot of false positive messages around the Wi-Fi 6 technology and we need to be able to guide and help our customers.

​As we will see more and more service providers deploying 5G this year, we will continue to talk about it among the Wi-Fi community. The question is always: will 5G replace Wi-Fi in the long run? It might have the potential to do so in some cases. However, I still think that Wi-Fi will still stick around for a long time. I don’t really see the two technologies necessary competing with one another. I believe they will be complementary in most cases.

In the enterprise space, I have seen a couple of companies in Europe using alternative wireless solutions when Wi-Fi was not perfectly applicable to their use case. So I do see the use of alternative wireless solutions, such as CBRS/private LTE, being used more this year. On that note, Ruckus is coming to market with a set of CBRS LTE access points and the FCC has reserved some spectrum in the 3.5GHz band to be used for CBRS.

I have personally started to see automation changing my work and the way I see my work. I believe that it is becoming more and more part of our work today and will continue in 2019. Automation requires us to learn about programming (or at least scripting). So this is not going to be an overnight transition. This is definitely something that will help us and that we can take advantage of.

With more and more vendors offering APIs to interact with their equipment, it becomes part of the technical solution and can help us configure and monitor our infrastructures. On that note, I have seen a couple companies hiring programmers to add to their networking team in order to program additional services which will interact with the Wi-Fi infrastructure using APIs. From the point of view of a VAR or consultant, it is a good way to perform the work faster and, therefore, be more competitive.

Cisco released their new WLAN controller (Catalyst 9800 Wireless Controller) at the end of 2018. They have completely re-written the code and the new OS looks promising. One of the features is that it can now be installed on a public Cloud (such as AWS). We have also seen very good results from Meraki in 2018 (compared to traditional Cisco WLC). Mist started to really take up being involved with Fortune 10 companies. Aerohive launched their own NAC platform in the cloud (A3).

All of this leads to making me think that Wi-Fi solutions will leverage more and more cloud services in 2019. The cloud clearly allows the systems to be more intelligent, more flexible and we can all appreciate a little fewer bugs (or at least, faster ways to fix them).




What are your thoughts for 2019? Feel free to leave a comment to start the discussion.

Cheers'

François Vergès

This article presents the regulations around the use of the unlicensed 5GHz frequencies for Wi-Fi communications in Canada. It provides an update and consolidation of our previous articles and includes the changes made by ISED (Innovation, Science and Economic Development Canada) in 2017. We are also talking about the future outlook presented by ISED earlier this year.

In May 2017, ISED published a document announcing new regulations for the UNII1 band in Canada. Previously, this band was reserved for indoor use and the maximum EIRP was set to 200 mW. The new regulations now allow the use of these frequencies to be used both indoor and outdoor with a higher power. However, a license is required if you want to use UNII1 outdoor with an EIRP greater than 200 mW. The license is valid for 1 year and is free (for now).

​The new requirements to meet are presented in this table:

Source: ISED

If the equipment you are planning to use is located within 25km for a licensed earth station, you will have to coordinate the earth station operator to determine potential exclusion zones.
Users operating for personal use should not be eligible for that license. The reason is that it would involve too much administration and monitoring work.

DFS (Dynamic Frequency Selection) is a mechanism that allows wireless LANs to coexist with radar systems. It automatically selects a frequency that does not interfere with the radar systems. In Canada, any Wi-Fi devices operating on the channels 52-64, 100-116 and 132-140  have to employ a DFS radar detection mechanism. The use of DFS while implementing a Wi-Fi network is the choice of the Engineer. It allows you to use more channels for sure, however, the frequency change might bring some instability in the network. Moreover, the client devices are not always certified for DFS band operation which is the case for many portable devices. Therefore, many engineers prefer implementing their network without the use of these "DFS" channels.

If you want to learn more about DFS, feel free to take a look at the DFS Operations Infographic we have created:

ISED received comments proposing that some portions of the band become available for license-exempt devices (eg. Wi-Fi). However, they did not propose any specific changes to this band in 2018 pending potential outcomes of the WRC-19 (World Radio Conference).  There will most likely be some changes in the next few years. Since ISED is involved in the WRC-19 conference that will be taking place in Oct/Nov 2019, we could be expecting some changes as early as late 2019. Here are the potential changes:

• Use of the 5600-5650 MHz Band for license-exempt use. Channel 120, 124, 128
• Use of the 5350-5470 MHz Band for license-exempt use. Channel 68, 72, 76, 80, 84, 88, 92, 96
• Use of the 5850-5925 MHz Band for license-exempt use. Channel 169, 173, 171. This is unlikely as ISED prefers to reserve this band for connected vehicle applications. They will only allow Wi-Fi to share this band if they know for sure that it won’t be disruptive.

It feels good to be able to do what you like, it feels even better when there is a purpose in doing it. That is often something I ask myself when working on different projects for different customers. Am I making a difference? Who will benefit from my work? Who am I designing or installing Wi-Fi for?

I have found that our main purpose is to help the end users, perform their work in an easier way. This could be; helping a nurse providing care, a banker moving money around, a school teacher sharing  knowledge, a journalist reporting news, a warehouse worker moving goods or even sport fans supporting  their team.

The end users will be the ones using the Wi-Fi, enjoying the Wi-Fi, taking advantage of the Wi-Fi and maybe sometimes cursing the Wi-Fi. They are the reason why we do what we do. This is why, as a Wi-Fi Engineer, I always try to keep them in mind while designing, installing and troubleshooting a Wi-Fi network.

Focusing on the end user experience helps me to put the human factor back into the game. I consider it a very important part of my work.

François Vergès

The FCC and the EU has been talking about releasing more spectrum for unlicensed use in the 6GHz frequency band (5925 MHz to 7125 MHz). The focus was specifically to release more spectrum that could be used by technologies such as Wi-Fi, LTE-U and LTE-AAA.

This would give access to an impressive number of additional Wi-Fi channels:

• In the US:
  • 59x 20MHz channels 
  • 29x 40MHz channels
  • 14x 80MHz channels
  • 7x 160MHz channels
• In the EU:
  • 24x 20MHz channels
  • 12x 40MHz channels
  • 6x 80MHz channels
  • 3x 160MHz channels

As a Wi-Fi Engineer and seeing channel related problems every day, I get very excited knowing that more channels could become available. It could solve a lot of our issues and improve the overall performances of our Wi-Fi networks.

However, in Canada, the ISED does not have current plans of opening up the 6GHz band for licence-exempt use.

Currently, here is how the 6GHz band is used in Canada:

• 5925-6425 MHz: Two-way Backhaul. Uplink communication for FSS (Fixed Satellite Service) (delivery of broadband services + distribute TV programming) 
• 6425-7125 MHz: two-way Backhaul + TV auxiliary services and studio transmitter links.

​Also, the ISED mentioned that they were « not aware of commercially available equipment that would operate in a licence-exempt fashion in the 6GHz band ». This state might change has these bands might be embraced in the US and in Europe. More and more manufacturers might be interested in producing devices able to operate in the 6GHz band in the near future for these markets.

​n the near future, it does not look like the ISED will be releasing more spectrum in the 6GHz band for Wi-Fi use. The technologies using this band are not going anywhere and are still heavily using the band. Therefore, ISED has classified it as a priority 3 during their Outlook Consultation, earlier this year. This means that nothing much is going to happen in the next few year (between 2018 and 2022).

Here is the spectrum outlook priorities set by ISED for the next 5 years (2018 to 2022). As you can see 6GHz has been assigned a priority of 3:

​They did mentioned, in their Spectrum Outlook 2018 to 2022 document, that they will keep monitoring what is happening in the US and in the rest of the world to see if they could work on a solution where the current technologies using the 6GHz band would co-exist with new services (aka. Wi-Fi). This will probably require some coexistence mechanism to be put in place (The Wi-Fi industry is proposing a mechanism called Automated Frequency Coordination (AFC) that could be used in Canada as well).

​If we look at the FCC timeline, it looks like they will be starting permitting Wi-Fi operations on the 6GHz band by 2021. So, it’s hard to say what will be happening past 2022 but I would think that, at that time, they would have a plan to release some spectrum in the 6GHz band.

In parallel, the IEEE could potentially decide to only allow certain amendment to be used on the 6GHz bands which would strongly push ISED to release these frequencies for Wi-Fi use. It is already being said that the 802.11ax wave 2 devices will be able to operate on the 6GHz band.

•  ISED Spectrum Outlook 2018 to 2022: 
  •  https://www.ic.gc.ca/eic/site/smt-gst.nsf/eng/sf11403.html
• Wi-Fi Trek Présentation from Chuck Lukaszewski « Opening the 6GHz band for unlicensed operations » :
  • https://doc-08-ac-docs.googleusercontent.com/docs/securesc/ha0ro937gcuc7l7deffksulhg5h7mbp1/diabgngrluu0j1ruolmbvtq7odhjdja7/1541109600000/13899844155198599612/*/1S5wZbFJrre4_NoD2X3mBUxHpeZQRIkPl?e=download
•  FCC Notice of Proposed Rulemaking « UnLicensed Use of the 6 GHz Band »
  • https://docs.fcc.gov/public/attachments/DOC-354364A1.pdf
• ​ EU Radio Spectrum Committee Working Document « Commission paper on a draft Mandate to CEPT on RLAN in the 6 GHz band (5925-6725 MHz) »
  • https://circabc.europa.eu/d/d/workspace/SpacesStore/d63ea67f-8171-4619-a53d-8feb57387c27/RSCOM17-40_RLAN%206%20GHz.pdf

Written by François Vergès

This infographic was inspired by the work of Nigel Bowden and Devin Akin. Nigel wrote this really good article on DFS that you can find on his website wifinigel.blogpost.com. Devin presented a really detailed webinar on DFS in partnership with Netscout. You can find the recording here.

I would encourage you to go and take a look at their ressources.

Note: there are a lot of disparities in the way DFS operations work between the different ​Wi-Fi vendors. It was a challenge to try to standardize it into one graphic. Please perform detailed testing of your own WLAN solution to find out what the actual DFS operations are in your environment.

​Click on the image below to download the infographic in the PDF format:

​Feel free to look at these ressources if you want to learn more about DFS operations:

• Nigel Bowden's Blog post on DFS: http://wifinigel.blogspot.com/2018/05/the-5ghz-problem-for-wi-fi-networks-dfs.html
• Devin Akin's webinar on DFS: https://www.brighttalk.com/webcast/5522/279895/designing-with-dfs-channels
• DFS Regulations in Canada: http://www.ic.gc.ca/eic/site/smt-gst.nsf/eng/sf10971.html
• IEEE 802.11-2016 Standards Clause 11.9

I would like to thank Devin and Nigel for their help in reviewing the infographic and providing feedbacks. If you ​think of a way we could improve this infographic, do not hesitate to let me know in the comments below. 

Thank you!

Cheers,
François Vergès

This is a video showing you how to retrieve the scale of a floor plan in AutoCAD in order to scale it in Ekahau. 

This video follows the one we published to explain how to export PDF floor plans from AutoCAD: www.semfionetworks.com/blog/preparing-floor-plans-for-ekahau-in-autocad

Written by François Vergès

Floor plans are very important for us WLAN professionals. We need them to do our designs and surveys. Sometimes, the quality of the floor plans we receive from our customer (when we receive some) is not always the best.

Just like a baker needs quality flour to produce good bread. As Wi-Fi Engineers we need quality floor plans in order to produce accurate designs.

In this article, I will show you how to export good quality PDF files from an AutoCAD .dwg file. You could then import this PDF file into Ekahau (or other preferred site survey software) to perform your design.

When receiving floor plans in a .dwg file format from a customer, you have the choice to import it directly into Ekahau. Ekahau has the ability to parse the different views and layers and gives you the ability to pick and choose the view and layers you want to incorporate into your project. It even draw the walls for you!

However, there are some limitation to this process. Here are examples:

• The views define in the CAD file don't represent what you want to see in Ekahau (for example, it is dividing the building into multiple areas when what you want is to see the full building on one view)
• The floor plan is not centred on the view and there is a lot of white space around it. It won't look good in the report.
• There is only one view in the CAD file when you actually need to divide the building into multiple section.

In all of these situations, I like to open the CAD file with AutoCAD and export exactly the views I want into different PDF files.
I use AutoCAD LT on macOS and I pay the monthly subscription when I need it (67$ a month).

Once I am done, I go back to Ekahau and import the PDF files to start working on my design.
And yes, this means I am drawing the walls myself! I care about providing a quality document to my customers, that's why I take the time to make sure, the input floor plan file is good.

This video clip shows how to export different views of a floor plans from AutoCAD:

You can also find this video on youtube: youtu.be/mdL-Wi-vaKM

As WLAN Engineers, do you think we should spend more time learning about AutoCAD?

​
Written by François Vergès

​Free Space Path Loss (or FSPL) represents the amount of energy that a given radio wave loses as it travels through the air away from its source.  Understanding FSPL will help us understand how far a Wi-Fi signal can go. It is also widely used by Wi-Fi survey tools to predict Wi-Fi signal propagation.

It is something that we can calculate by applying this mathematical formula (d in km and f in GHz):

FSPL is not specific to Wi-Fi waves, it can be applied to any other waves using other frequencies.

In a Wi-Fi environment, FSPL refers to the amount of power a Wi-Fi signal losses as it travels away from the transmitter (it can be an AP or a station).

This loss is relative to 2 main components:

• Frequency
• Distance

The following diagram shows exactly how much energy a Wi-Fi wave will lose as it travels away from an AP:

Let’s start with frequency. Here, we are talking about the frequency of the radio wave.  As you can see in the formula above, the higher the frequency is, the higher the loss will be. In Wi-Fi, this means that a 2.4GHz signal is less prone to loss than a 5GHz signal. We commonly say that 2.4GHz travels further away than 5GHz.

Another factor is affecting « how far » a Wi-Fi signal is travelling. And this is related to a specific receive characteristic. Any dual band receivers will need 1 antenna to listen to 2.4GHz signals and another one to listen to 5GHz signals. Because the wavelength of a 2.4GHz signal (12 cm) is longer that the one of a 5GHz signal (6 cm), the size of the antenna needs to be bigger. This means that the 2.4GHz receiver will have a larger receive aperture and will be able to better "hear" the incoming signal.

The FSPL formula in Wi-Fi defines that, in the first meter:

• A 2.4GHz signal is loosing about 40dB
  • Calculation for channel 1: 20log(0.001) + 20log(2.412) + 92.45 = 40.09dB
  • Calculation for channel 11: 20log(0.001) + 20log(2.462) + 92.45 =  40.28dB
  • Calculation for channel 13: 20log(0.001) + 20log(2.472) + 92.45 = 40.31dB
• A 5GHz signal is loosing about 47dB
  • Calculation for channel 36: 20log(0.001) + 20log(5.180) + 92.45 = 46.74dB
  • Calculation for channel 52: 20log(0.001) + 20log(5.260) + 92.45 = 46.87dB
  • Calculation for channel 100: 20log(0.001) + 20log(5.500) + 92.45 = 47.26dB
  • Calculation for channel 149: 20log(0.001) + 20log(5.745) + 92.45 = 47.64dB
  • Calculation for channel 165: 20log(0.001) + 20log(5.825) + 92.45 = 47.76dB

​Here, we are talking about the distance travelled by the Wi-Fi wave away from the source. Common sense tells us that it would make sense if the signal was to lose power as it travels away from its source.
The FSPL formula tells us exactly by how much following the inverse square law.

The inverse square law, developed by Isaac Newton, tells us that as the distance from the source doubles, the energy is spread out over 4 times the area. This results in the signal loosing 4 times it's original amplitude. In other words, the Wi-Fi signal is loosing 6dB every time the distance from the source is doubled (This is represented in red in the diagram above).

​
So, if we know the power of our signal leaving the access point, we can calculate how far this signal will go. This is assuming there is no source of attenuation between the transmitter and the receiver.

What happens when we introduce a wall between the transmitter and the receiver?

As expected, the wall will attenuate the signal. The FSPL will be applied to the signal as it travels to the wall and away from the wall as explained on this following diagram. The amount of attenuation will depend on the structure of the wall.

If we know the amount of power that the Wi-Fi signal will have leaving the AP (Equivalent Isotropically Radiation Power or EIRP), we can calculate the size of our desired cell.

Here is an example if we have an AP using an EIRP of 14dBm (or 25mW) for band frequency bands:

It is now easy for us to see that the 2.4GHz cell will be twice as big at the 5GHz cell if the same EIRP is used.

​In order to obtain the same cell size for both frequency bands, we can offset the EIRP of the 2.4GHz by 7dB. The way we can do it is by decreasing the 2.4GHz transmit power by 7dB. Most Wi-Fi system will only let us increase or decrease transmit power by an increment of 3dB. Therefore, the best we can do it decreasing the 2.4GHz transmit power by 6dB:

• Wikipedia article on Free Space Path Loss: https://en.wikipedia.org/wiki/Free-space_path_loss
• Effect of Transmit power changes on AP by Nigel Bowden: http://wifinigel.blogspot.ca/2014/11/effect-of-transmit-power-changes-on-ap.html
• Wi-Fi Free Space Loss Calculator by Nigel Bowden:  http://wifinigel.blogspot.ca/2014/05/wifi-free-space-loss-calculator.html
• FSPL diagram by Devin Akin: http://divdyn.com/so-called-ghost-frames-not-exist/

written by François Vergès