Dr. Avril Salter – Interface Technical Training https://www.interfacett.com Wed, 21 Jun 2017 19:26:18 +0000 en-US hourly 1 3 Problems That Occur When Deploying in the 2.4 GHz Band in WiFi Networks https://www.interfacett.com/blogs/3-problems-that-occur-when-deploying-in-the-2-4-ghz-band-in-wifi-networks/ https://www.interfacett.com/blogs/3-problems-that-occur-when-deploying-in-the-2-4-ghz-band-in-wifi-networks/#respond Fri, 22 Jan 2016 20:45:44 +0000 http://www.interfacett.com/blogs/?p=?p=22325 The deployment of WiFi networks can be particularly challenging. We’re going to take a look at three problems that occur when deploying in the 2.4 GHz (Gigahertz) band. In the three examples we’re going to take a look at, they will be real life examples. For instructor-led Wireless training, see our 5-day course: WIRE400: Wireless Networking … Continue reading 3 Problems That Occur When Deploying in the 2.4 GHz Band in WiFi Networks

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The deployment of WiFi networks can be particularly challenging. We’re going to take a look at three problems that occur when deploying in the 2.4 GHz (Gigahertz) band. In the three examples we’re going to take a look at, they will be real life examples.

For instructor-led Wireless training, see our 5-day course: WIRE400: Wireless Networking for the IT Professional

We’re going to start by looking at the frequency Channels that you assign in the 2.4 GHz band, when you’re deploying WiFi access point.

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Then we’re going to look at a common misunderstanding that occurs when you’re deploying 802.11n in the 2.4 GHz band, in terms of the achievable data rate.

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Our third example is much more subtle.

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Our third example, we’ll be looking at common mistakes Engineers make when trying to assess the signal to noise level, as to whether or not they have good WiFi coverage.

Example 1 – Frequency Channels in the 2.4 GHz band

Let’s start with real life example, number one. A look at the frequency Channels in the 2.4 GHz band, and how to assign a Channel to a wireless access point. We’ll see in this list that in North America we can use Channels 1‑11.

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The mistake that most people make is they don’t distinguish between Channel numbers and Channel bandwidth.

Channel Numbers VS Channel Bandwidth

We need to understand how Channel numbers are assigned and then what is Channel bandwidth.

If we look at this list of Channels that we can deploy WiFi on, in the 2.4 GHz band.

Notice that Channel 1 is at 2,412 MHz.

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When we go to Channel two, it increases by 5 MHz. Then Channel 3, again increasing by five MHz.

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Each of these Channels is 5 MHz apart. In other words, the spacing between Channel numbers, for WiFi deployment in the 2.4 gigahert band is 5 MHz.

In this live deployment, in a hotel in Denver, they have decided that they will deploy the access point using all of these Channels.

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Here you can see one deployed on Channel 1, another access deployed on Channel 2, Channel 3, all the way up to Channel 11.

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You can see here is the central frequency of the access point deployed on Channel 1, Channel 2, etc.

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It’s a common misunderstanding, that when we look to configure our access point, and we’re given a choice of Channels 1‑11, that this IT professional had just gone ahead and deployed those different Channels to their access points.

You can see that Channel 1 indeed overlaps with Channel 2, overlaps with Channel 3, and in fact overlaps with Channel 4 and 5, as well.

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Which means that, if you deploy access points on Channel 1, 2, 3, 4, and 5, these will interfere with each other because they’re overlapping Channels.

To understand what’s going on, we need to understand what Channel Bandwidth is.

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Channel Bandwidth is the bandwidth that the signal occupies when it transmits.

Let’s say I’m transmitting on Channel 1. My signal will spread over a band.

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How wide is that band? That depends on the technology.

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In the case of 802.11b, it would be a 22 MHz Channel.

In the case of A and G, it would be a 20 MHz Channel.

In our hotel, in Denver, they were deploying 802.11g, which occupies a 20 MHz Channel.

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Because our Channels are actually spaced 5 MHz apart, what happens if you use Channel 1 and Channel 2 is that those allocations will therefore be overlapping.

If you’ve got an access point, here on Channel 1, that’s broadcasting out, and you have another access point that’s adjoining to it, that is broadcasting to Channel 2, then these are going to interfere with each other, because the Channels are overlapping.

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Therefore, for deployment in the 2.4 GHz band, you should use Channel 1, Channel 6, and Channel 11.

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By deploying them in a pattern, referred to as a One in Three Frequency Reuse Scheme, then you can reuse the channels some distance away.

Example 2

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Let’s go on to our second real-life example.

Have you experienced when you’ve gone out and bought an 802.11n device, this one is a 2×2 MIMO which can promise to go up to 300 Mb/s. Or maybe you’ve actually bought a 3×3 MIMO 802.11n which promises data rates of 450 Mb/s.

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But have you been disappointed that you can’t actually achieve these data rates? One of the reasons is if you’re deploying 802.11n and you want to achieve these higher data rates then you need to deploy it in a 40 MHz channel.

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You can see in this example, that I have indeed got a 40 MHz channel.

But you will also noticed that if I’ve deployed one access point in a 40 MHz channel then I don’t actually have any spectrum left to deploy a second 40 MHz channel.

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If you’re wanting to deploy more than one access point in the 2.4 GHz band, then there is simply not enough room to have two access points both operating on a 40 MHz channel without these channels overlapping and interfering with each other.

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In other words, unless you have a deployment that just has one access point then you need to deploy “N” in a 20 MHz channel in order to avoid interference between adjoining access points.

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If you “half” the bandwidth, then you “half” the data rate.

 023-Problems-when-deploying-the-2_4-gigahert-band-in-WiFi-Networks

In other words, if you buy a 2×2 MIMO 802.11n device and deploy multiple in the 2.4 GHz band, then your theoretical maximum data rate in good RF environments would be halved to just 150 Mb/s. And the 3×3 MIMO 802.11n that you thought would give you 450 Mb/s because you’re only deploying it in a 20 MHz band the maximum theoretical data rate gain will be halved to 225 Mb/s.

This can often result in people being rather disappointed with the equipment that they bought. Their expectations on what data rates they thought they were going to get has not been satisfied.

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Now if you do want to achieve the maximum theoretical data rates for an 802.11n device then your solution is to deploy it in the 5 GHz band.

In the 5 GHz band, you have a lot more spectrum available and you will be able to deploy multiple 40 MHz channels.

Example 3

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Real-life example number 3 is much more subtle and a very common mistake that very good IT Professionals will make.

When deploying a WiFi Network, it is important that you have enough signal strength over any interference and noise that is occurring within the band such that you can recover the signal.

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Many IT Professionals will look to measure the signal-to-noise ratio to determine what areas where they can get good WiFi signals and connectivity and what areas where they may not have enough signal strength or too much interference.

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This is a real-life deployment. The engineer was out looking at the signal strength of the network and you can see that in this particular RF environment, there was a significant amount of interference.

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When you look at this type of interference, it’s kind of a “hopping” across these different frequencies going backwards and forwards, they are like short spikes. Quite often, this is caused by Bluetooth radios that are also operating in the 2.4 GHz band.

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There are many different Bluetooth that we own and use. Even though all of this equipment is low powered, if you are close to this equipment while you are taking your measurements, you could see some very strong interference.

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The problem that this particular IT Professional had done he was taking his measurements when he was looking at the spectrum and the signal strength, he actually had his own personal equipment operating in a close proximity to the equipment he was using to sniff the WiFi network.

In other words, he was actually destroying his results. The results were showing significant Bluetooth interference whereas in reality, the amount of Bluetooth interference on this site was actually quite small.

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So when you are doing spectrum analysis and looking at signal strength, you need to make sure that you are not the source of interference. Particularly if you have devices operating very closely to the equipment that you are using to detect the signal and the noise.

So the message is, turn off your equipment.

I hope you enjoyed this short video of issues that can occur when deploying WiFi in the 2.4 GHz band.

I do hope you enjoyed it and if you did, please do come back and take our 5-day Wireless course WIRE400: Wireless Networking for the IT Professional at Interface Technical Training in Phoenix, Arizona. You will join me and we will go through a lot more detail and have a lot more fun about how you actually plan out a WiFi network, how you configure, deploy and then subsequently manage that WiFi Network. We get into a lot more detail going beyond “G” and “N” and looking at 802.11 ac and a lot of the antenna issues as well. I look forward to seeing you in our 5-day course.

 

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Planning your Wireless Network for IT Professionals. Can the Access Point Hear You? https://www.interfacett.com/blogs/planning-your-wireless-network-for-it-professionals-can-the-access-point-hear-you/ https://www.interfacett.com/blogs/planning-your-wireless-network-for-it-professionals-can-the-access-point-hear-you/#respond Fri, 15 Jan 2016 20:12:24 +0000 http://www.interfacett.com/blogs/?p=?p=22273 With IT professionals, I’m sure all of us have done things that we’ve been rather embarrassed about and would be considered to be rather silly. For instructor led wireless training, see our 5-day course: WIRE400: Wireless Networking for the IT Professional I’m going to share with you one of the funniest things that IT professionals do … Continue reading Planning your Wireless Network for IT Professionals. Can the Access Point Hear You?

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With IT professionals, I’m sure all of us have done things that we’ve been rather embarrassed about and would be considered to be rather silly.
001-Planning-your-Wireless-Network-for-IT-Professionals

For instructor led wireless training, see our 5-day course: WIRE400: Wireless Networking for the IT Professional

I’m going to share with you one of the funniest things that IT professionals do regarding planning their wireless networks.

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It is really common for IT professionals to use the smartphones, the “bars” that are shown on the smartphones, to actually assess whether or not there is WiFi coverage.

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We’re going to take a look at why that is a nonsensical thing to do.

Over the years we’ve all been trained by the cellphone industry that when we can’t make a phone call or can’t get data across on our cellphone, that we look at the bars and say, “Are we under coverage or not?” and, “Am I able to communicate with a base-station?” We’ve taken that awareness and started now to apply it to WiFi.

Deployment Scenario

I’m finding that WiFi professionals will take a look at their smartphone and say, “Yes, I have WiFi coverage, and therefore I should be able to connect.” Now, to understand why this doesn’t make sense, let’s look at a deployment scenario.

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Imagine if you would, you’ve deployed an access point, and in this example we’re going to assume that the access point has been deployed with a maximum transmit power of 800mW (milliwatts). Imagine that we have a laptop that we want to be able to communicate with this access point. When the signals come from the access point to the client, the client can hear the access point.

Laptops are designed to be utilized away from your desk, i.e., not plugged in to the main power. It is therefore fairly common for a laptop to be designed with a WiFi radio that minimizes the transmit power in order to conserve the battery power, and therefore the life which your laptop will continue to operate.

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In this example, I’ve set up a laptop and let’s assume that the maximum transmit power is 200mWs. It is still able to hear the access point, but when the laptop goes to respond to the access point and say, “Hey, it’s me. Please, can I connect?”

It cannot transmit at the high power level of the access point, and therefore even though it can hear the access point, when it transmits, the access point is unable to hear the signals from the laptop. It is therefore impossible to establish two‑way communication between the access point and the laptop.

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In other words, when you look at the “bars” on your device, what you’re looking at is how well you can hear the access point. What you haven’t done is determine whether the access point can hear your device. It may appear to you that you have WiFi coverage, but in reality you can hear the access point, but the devices cannot communicate with the access point.

What you might think your coverage looks like this:

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In reality your coverage is actually significantly less because your coverage is where devices can form two‑way communication.

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Not just hear the access point, but the access point being able to hear the device. Indeed, if you have devices, such as VoIP devices, some of those have a maximum transmit power as little as 40 mW or 50 mW.

For those devices to be able to connect, they need to be even closer to the access point. In other words, when you’re planning out a WiFi network, you need to know what the transmit power is of the devices that are connecting to it, and you need to plan around the weakest device that you have connecting to the network.

Just because you can hear the access point doesn’t mean the access point can hear you.

In order to do effective WiFi coverage planning, you must consider communications in both directions. The uplink from the client to the access point is typically always the weakest link because you can always raise the power level of your access point, but you cannot always raise the power level of your client.

If you enjoyed this and now find it quite amusing when you see people trying to do WiFi coverage planning using the bars on their cellphone, then please come and join me for one week of super‑fun wireless training class where you’ll really start to understand how wireless works, how to configure a WiFi network, and how to optimize and troubleshoot it and not make these rather amusing silly mistakes that many IT professionals make today.

WIRE400: Wireless Networking for the IT Professional
5-Day course at Interface Technical Training in Phoenix, Arizona.
Learn how to take control of your enterprises Wi-Fi network. In this 5-day hands-on course, you will learn how to plan, configure, deploy and manage a wireless network, secure and troubleshoot interference sources, identify and analyze Wi-Fi packets in Wireshark for data transfer. This course finishes with an overview of the latest next generation in Wi-Fi product enhancements for enterprise and end-users.

 

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Sources of Interference and When You Should Be Concerned https://www.interfacett.com/blogs/sources-interference-concerned/ https://www.interfacett.com/blogs/sources-interference-concerned/#respond Fri, 06 Mar 2015 15:53:16 +0000 http://www.interfacett.com/blogs/?p=?p=19889 What is interference? Wi-Fi operates in the license-exempt frequency bands. The main advantage of operating in these bands is that the network administrator does not need to pay a licensing fee to operate their equipment. The primary disadvantage of operating in these bands is that other equipment may also be transmitting in these bands, and … Continue reading Sources of Interference and When You Should Be Concerned

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What is interference?

Wi-Fi operates in the license-exempt frequency bands. The main advantage of operating in these bands is that the network administrator does not need to pay a licensing fee to operate their equipment. The primary disadvantage of operating in these bands is that other equipment may also be transmitting in these bands, and could cause interfere with the operations of your Wi-Fi system.

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Equipment that operates in the license-exempt frequency bands include Wi-Fi, Bluetooth radios, sensor networks such as ZigBee, microwave ovens, cordless phones, wireless Surveillance cameras, and satellites. Surveillance cameras can be particularly disruptive to Wi-Fi networks as they may be transmitting 100% of the time.

Interference negatively impacts performance

Before a Wi-Fi device transmits, it listens to the frequency channel.  If it detects noise on this channel above a threshold defined in the 802.11 standards it will not transmit.  When the wireless medium is free, the Wi-Fi device will then start its transmission procedures. Interference from devices operating on the same channel can therefore cause wireless transmissions to be delayed, resulting in a significant degradation to throughput and Quality of Service (QoS).

If the interference is bursty in nature, then a Wi-Fi device could transmit thinking that the medium is free, but the signal could be impacted while being transmitted over-the-air. This can lead to an increase in retransmission of lost packets, which in turn also detriments throughput and QoS.

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Interference reduces coverage

Most IP Professionals understand that interference impacts throughput and QoS, however they do not realize the impact of Wi-Fi coverage. A good analogy for understanding the impact on coverage is to consider a conversation between two people in a restaurant.

If the restaurant is quiet with little noise and interference, you can easily have a clear and error free conversation. If the restaurant is noisy, you have to shout to be heard over the noise and you have to repeat your words more often. It also helps if you get closer to the person you are trying to talk with. In other words, in a noisy high interference environment, cell coverage is reduced.

Detecting sources of interference

The best way to detect interference sources is to use a spectrum analyzer.  Spectrum analyzers display all received signals in a selected frequency.  Transmissions from Wi-Fi devices, microwave ovens, cordless phones and cameras have different transmission profiles.  Some of these transmission profiles are illustrated in figure 3.  By looking at the shape of the signals on the spectrum analyzer you can identify the probable type of interfering sources.

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A spectrum analyzer can range in price from a few hundred dollars to thousands of dollars depending on the functionality.  Indeed, many Access Points actually include spectrum analyzer capabilities. A simple low cost spectrum analyzer should enable you to both measure the received signal strength, and provide analysis on how the received signal strength changes over a period of time.  This is important as it will tell you now the received signal strength is fluctuating during the day.  Widely fluctuating signals warrant further investigation, as it is an indication that something is changing in the environment.

What is an acceptable level of interference

In order to successfully receive a signal, the transmitted signal must be heard above the interference.  One of the key measurements IT professionals who are managing Wi-Fi networks need to understand is the Signal to Interference Ratio (SIR).  The SIR is a measure of the received signal power level over the interference at the receiver. It indicates whether the received signal can be recovered at the receiver.

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Typically for data applications you will want to make sure your received signal strength does not drop below -70 dBm.  If you are implementing wireless phones, a higher threshold such as -67 dBm will be needed.

In most enterprise environments, interference is typically below -90 bBm. In other words, a SIR of 20 or 23 is generally considered good for data or voice applications, respectively.

Want to learn more?
Interface is offering a new course for IT professionals, to equip them with the skills necessary to plan, configure, troubleshoot and optimize Wi-Fi networks.

Register for this course today.

WIRE400: Wireless Networking for the IT Professional
5-Day course at Interface Technical Training in Phoenix, Arizona.
Learn how to take control of your enterprises Wi-Fi network. In this 5-day hands-on course, you will learn how to plan, configure, deploy and manage a wireless network, secure and troubleshoot interference sources, identify and analyze Wi-Fi packets in Wireshark for data transfer. This course finishes with an overview of the latest next generation in Wi-Fi product enhancements for enterprise and end-users.

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Should you wait for 802.11ac Wave 2? https://www.interfacett.com/blogs/wait-802-11ac-wave-2/ https://www.interfacett.com/blogs/wait-802-11ac-wave-2/#respond Wed, 04 Feb 2015 17:47:09 +0000 http://www.interfacett.com/blogs/?p=?p=19763 It is all about throughput: The IEEE 802.11n standard is called “high throughput”. The newer IEEE 802.11ac standard is called “very high throughput”. As the name suggests, 802.11ac enables higher throughput. Wikipedia defined throughput as “the rate of successful message delivery over a communication channel”, in other words, the number of bits per second successfully … Continue reading Should you wait for 802.11ac Wave 2?

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It is all about throughput:
The IEEE 802.11n standard is called “high throughput”. The newer IEEE 802.11ac standard is called “very high throughput”. As the name suggests, 802.11ac enables higher throughput.

Wikipedia defined throughput as “the rate of successful message delivery over a communication channel”, in other words, the number of bits per second successfully delivered from sender to the receiver. Throughput over a wireless 802.11ac network is being increased in two ways. Firstly, it increase bit rate over the air, and secondly it allows the simultaneous transmission of signals to multiple clients.

Wave 1 products increase the bit rate:
The 802.11ac products in the market today promise data rates of over 1 Gbps. The Wi-Fi Alliance certification of these products is referred to as Wave 1.
Wave 1 802.11ac products get to higher data rates by moving to a wider channel bandwidth, and increasing the modulation rate. Doubling the bandwidth from 40 to 80 MHz will more than double the data rate. 802.11ac also introduces 256-QAM, which increases the maximum number of bit per modulation symbol from 6 to 8. This results in an increase in the data rates by 8/6. These improvements can almost triple the maximum data rates.

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This alone may make you decide to upgrade your network to 802.11ac. However, it is important to consider other RF factors such as signal attenuation, interference, and antenna capabilities. The 802.11ac operates in the 5 GHz band only, and this band suffers greater attenuation than the 2.4 GHz band. This generally reduces coverage. Although the 5 GHz band typically suffers less interference than the over-crowded 2.4 GHz band, if there is interference the bandwidth will be reduced from 80 MHz to 20 or 40 MHz. This in turn reduces the transmitted data rate. In addition, 256-QAM can only be utilized in exceptional good RF environments. Typically 256-QAM with be implemented with beamforming, as beamforming increases the received signal strength. Beamforming is typically implemented on the more expensive enterprise Access Points.

Wave 2 products introduce MU-MIMO:
Wave 2 products extend the channel bandwidth to an optional 160 MHz. This provides the potential to further double the data rate. However, what is of particular interest, is that Wave 2 products introduce Multi-User MIMO (MU-MIMO).

In Wi-Fi networks today, if multiple stations transmit at the same time in the same channel, collisions can occur and data frames may become corrupted. MU-MIMO is a technique that leverages beamforming and the spatial separation between stations. By transmitting to different stations of different beams, MU-MIMO enables the transmitter to send multiple data streams at the same time in the same frequency channel. The 802.11ac standards specifies simultaneous transmissions to up to four stations at the same time, which has the potential to increase throughput 4-fold.

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Key influencing factors:
Wave 2 products will have wider bandwidths, a high number of spatial streams, and Multi-User MIMO (MU-MIMO). Deciding on whether you should transition to 802.11ac now or wait is a fairly complex question. In addition to the normal cost benefit analysis, there are three additional factors should be examined.

1. Growth of 802.11ac enable clients in your organization.
In comparison will legacy 802.11n enabled clients, 802.11ac almost triples the data rate for effectively the same handset power utilization. As a result, handset manufacturers are adopting 802.11ac in smart phone, tablet and laptop equipment at a much faster rate. Indeed, ABI Research predicted that 70% of mobile handset shipments will be 802.11ac enabled by the end of 2015.

In organizations that have high data rate applications but also require handheld devices to last a full working day, 802.11ac has significant advantages.

2. Interference in the 5 GHz band.
The underlying premise of all 802.11ac deployments is that you are able to transmit in 80 MHz channels. Similar to 802.11n devices, 802.11ac devices will perform a clear channel assessment prior to transmitting. If there is interference or noise it will reduce the bandwidth on which it will transmit. If there is so much interference and noise that the 802.11ac can seldom transmit on an 80 MHz channel, then you will not see the performance advantages of 802.11ac. It is really important that you perform a site survey and assess your interference levels before you commit to deploying 802.11ac.

3. MU-MIMO requires a hardware upgrade.
Upgrading from 802.11ac Wave 1 to Wave 2 requires a hardware upgrade. The introduction of MU-MIMO cannot be done as a firmware/software upgrade. Some vendors may provide a price break if you move to 802.11ac today, and subsequently upgrade to Wave 2 products.

Want to learn more?
Interface is offering a new course for IT professionals, to equip them with the skills necessary to plan, configure, troubleshoot and optimize Wi-Fi networks.

Register for this course today.

WIRE400: Wireless Networking for the IT Professional
5-Day course at Interface Technical Training in Phoenix, Arizona.
Learn how to take control of your enterprises Wi-Fi network. In this 5-day hands-on course, you will learn how to plan, configure, deploy and manage a wireless network, secure and troubleshoot interference sources, identify and analyze Wi-Fi packets in Wireshark for data transfer. This course finishes with an overview of the latest next generation in Wi-Fi product enhancements for enterprise and end-users.

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Three Common Mistakes IT Professionals Make When Planning Their Wireless Network https://www.interfacett.com/blogs/three-common-mistakes-professional-make-planning-wireless-network/ https://www.interfacett.com/blogs/three-common-mistakes-professional-make-planning-wireless-network/#respond Wed, 28 Jan 2015 17:24:26 +0000 http://www.interfacett.com/blogs/?p=?p=19699 Planning and deploying a wireless network for user access is considerably more difficult than implementing a wired network.  This is because every location has a unique radio frequency (RF) environment.  Even if you have offices or floors with the same physical layout, changes in construction material, the location of filing cabinets, the presence of microwave … Continue reading Three Common Mistakes IT Professionals Make When Planning Their Wireless Network

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Planning and deploying a wireless network for user access is considerably more difficult than implementing a wired network.  This is because every location has a unique radio frequency (RF) environment.  Even if you have offices or floors with the same physical layout, changes in construction material, the location of filing cabinets, the presence of microwave ovens, or differences in the way people congregate, will impact the ability for signals to travel over-the-air.

Dr.  Avril Salter has been helping IT professional understand and implement Wireless LANs for over 20 years.  In this blog she discusses the top three common mistakes made by IT professional when planning their wireless network.

Expected the maximum data rate to be achievable everywhere.

Whether you are purchasing a consumer or an enterprise-level Wi-Fi Access Point, the primary feature is the data rate that can be achieved. The new 802.11ac products promise data rates of over 1 Gbps.

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However, what many IT professionals do not realize that this a theoretical maximum data rates and it may not be practical to achieve these data rates in your environment.

Wi-Fi radios adapt the transmitted modulation and coding rate based on the RF conditions. A modulation rate of 256-QAM can be used in extremely good RF conditions, allowing 8 bits to be transmitted per modulation symbol. Users on the edge of cell coverage use a lower level of modulation. BPSK for example only transmits 1 bit per modulation symbol, reducing the date rate by 1/8th.

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This means that users that are in a better radio frequency (RF) environment, such as close to the Access Point and away from interfering sources, can transmit at higher data rates than users on the edge of coverage and closer to interfering sources.  As the user moves into more difficult RF conditions, such as moving towards the edge of cell coverage the data rates drop.

Deployed adjacent Access Points on overlapping channels.

In the 2400 MHz band (Also referred to as the 2.4 GHz band), there is 79 MHz of spectrum that can be used for the deployment of unlicensed radios such as Wi-Fi. The 802.11 standards define channels 1 to 13  in the 2.4 GHz band (Channels 12 and 13 cannot be used in North America). The separation between these channels is 5 MHz. For example, channel 1 is 2412 MHz, and channel 2 is 5 MHz higher at 2417 MHz.

Many IT professionals will configure their Access Points to operate on one of these eleven channels. The picture below shows an 802.11g,n deployment at a hotel in Denver, where all eleven channels have been utilized.

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The problem is that 802.11g,n equipment requires a 20 MHz channel. Therefore if two adjoining Access Points are deployed on channel 1 and 2, these channels overlap and they will interfere with each other. This can have a significant detrimental impact on throughput.

Deployments in the 2.4 GHz band should deploy adjacent Access Points on non-overlapping channels to minimize interference. In North America, you should use channels 1, 6 and 11.

Planned for coverage only.

Many IT professional focus on Wi-Fi coverage as their  top requirement. Then after they roll out the network they discover that network performance is not meeting their expectations.  When planning a network it is important to consider both coverage and capacity.

A coverage plan calculates the number of Access Points required to give you wireless coverage where you need it.  A capacity plan calculates how many Access Points will be required to achieve the desired minimum data rate.  The higher the minimum data rate you set for a cell, the smaller the size of the cell.  In other words a cell with a minimum data rate of 50 Mbps will be smaller than a cell with a minimum data rate of 6 Mbps.  This means that you will need to deploy more Access Points.

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There are several deployment scenarios where coverage plans are ideal.  For example free public hot spots or free guest access WLANs.  However, in most business situations you need to ensure that the users have sufficient bandwidth.  In these situations you should create a capacity plan.

Want to know more?

Interface is offering a new course for IT professionals, to equip them with the skills necessary to plan, configure, troubleshoot and optimize Wi-Fi networks.

Register for this course today.

WIRE400: Wireless Networking for the IT Professional
5-Day course at Interface Technical Training in Phoenix, Arizona.
Learn how to take control of your enterprises Wi-Fi network. In this 5-day hands-on course, you will learn how to plan, configure, deploy and manage a wireless network, secure and troubleshoot interference sources, identify and analyze Wi-Fi packets in Wireshark for data transfer. This course finishes with an overview of the latest next generation in Wi-Fi product enhancements for enterprise and end-users.

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Wireless Networking for the IT Professional. Now Available at Interface Technical Training https://www.interfacett.com/blogs/wireless-networking-professional-now-available-interface-technical-training/ https://www.interfacett.com/blogs/wireless-networking-professional-now-available-interface-technical-training/#respond Wed, 21 Jan 2015 15:56:45 +0000 http://www.interfacett.com/blogs/?p=?p=19680 Why IT professionals need to understand wireless Wireless networks are becoming increasingly more important to all organizations, from  mall mom and pop stores, to major corporations. It is forecasted that by 2018 wireless devices will account for 61% of IP traffic, greatly exceeding traffic from wired devices, which will reduced to a mere 39% of … Continue reading Wireless Networking for the IT Professional. Now Available at Interface Technical Training

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Why IT professionals need to understand wireless



Wireless networks are becoming increasingly more important to all organizations, from  mall mom and pop stores, to major corporations. It is forecasted that by 2018 wireless devices will account for 61% of IP traffic, greatly exceeding traffic from wired devices, which will reduced to a mere 39% of IP traffic. Cisco Visual Networking Index: Global Mobile Data Traffic Forecast Update, 2013–2018.  The growth in smartphones and tablets connected to Wi-Fi networks has taken the industry by surprise. Today, smartphones send over 4 times more data over Wi-Fi than cellular, and these figure are set to grow. This has led to many organizations implementing “bring your own device” (BYOD) policies, to allow employees to connect their personal devices to the enterprise network.

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As wireless networks become increasingly prevalent, it becomes critical that IT professional have a rudimentary understanding of wireless networks. With this in mind, Interface is offering a new course offering titled “Wireless for the IT Professional”.

What is exceptional about this new course offering?
There are three things that make this course exceptional: A world-renown instructor, a course syllabus that focuses on the IT lifecycle, and a unique opportunity to discuss and resolve real world problems

World-Renown Instructor:
Dr. Avril Salter has worked on Wireless LANs since 1992, five years before the first 802.11 Wi-Fi specifications were finalized. She developed her in-depth understanding of wireless while working for Motorola. Since then she has worked for Intel and Microsoft. She has taught Wi-Fi courses at Cisco since 2002, and has published an advanced wireless certification book with HP Press. Dr. Salter is well known for her ability to solve some of the most complex Wi-Fi implementation challenges.

What You Will Learn:
The course is focused around the IT lifecycle. This is distinct from other wireless courses which focus on certifications or how to implement a specific vendor’s wireless products.

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The course starts by making sure the learner understands the radio concepts essential for planning and designing a wireless network. Key concepts range from assigning channel frequencies to determining sources of interference and calculating link budgets. It takes the learner through Wi-Fi operations including Quality of Service (QoS), equipping them with the knowledge to enable them to effectively configure Wi-Fi for their specific work environment Wireless brings the advantage of flexibility, convenience and improved productivity to the organization, but it comes with risks such as eavesdropping, unauthorized access, and rogue Access Points. For that reason, learners will walk through the different security options available for Wi-Fi networks and discuss how to select the right security mechanisms for an enterprise’s unique needs. Students will experience different types of wireless attacks, such as eavesdropping, Denial of Service (DOS) attacks, and Rogue Access Points (APs). They will learn how the Wi-Fi mechanisms provide (or do not provide) countermeasures to obviate these attacks.

Students will learn the best practices for troubleshooting wireless networks. Learners are given real-life problems and will be expected to use the tools and techniques used in the course to troubleshoot and identify these problems. Tools include the use of Wireshark to analyze wireless packet captures and a spectrum analyzer to assess interference and physical layer activities.

The course ends with a discussion on how high data rates and high capacity networks can be achieved and sustained in a live environment. Both 802.11n and the newer 802.11ac technologies will be covered in depth.
Real-World Problems:
Students are encouraged to bring into the classroom their wireless issues, for discussion and resolution. The instructor, Dr. Avril Salter, will guide the student in taking the material they are learning through the week and applying it to these real-life problems.

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This technique not only reinforces the students learning, but most importantly enables the student to immediately be more effective in their job function.

Register for this course today.

WIRE400: Wireless Networking for the IT Professional
5-Day course at Interface Technical Training in Phoenix, Arizona.
Learn how to take control of your enterprises Wi-Fi network. In this 5-day hands-on course, you will learn how to plan, configure, deploy and manage a wireless network, secure and troubleshoot interference sources, identify and analyze Wi-Fi packets in Wireshark for data transfer. This course finishes with an overview of the latest next generation in Wi-Fi product enhancements for enterprise and end-users.

The post Wireless Networking for the IT Professional. Now Available at Interface Technical Training appeared first on Interface Technical Training.

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