Learn the terminology, protocol and methods to work with the highest quality WiFi.
Establish a proven foundation in WiFi technology with this guide for beginners and intermediate learners.
Understanding the fundamentals of WiFi will make you successful every time you configure wireless for yourself or your customers. WiFi routers are very easy to purchase and turn on, but knowing the fundamentals when installing, operating.or troubleshooting will make the difference between a lousy performance and quality wireless service.
Quality IT Engineers are constantly in demand, but so few who manage WiFi do it with a Real Grasp of the Dynamics Involved. As a result, many fail with unclear excuses for the WiFi’s poor performance. When a manager has to find a long Cat5 cable to do a presentation for a national or international audience, the WiFi is a liability, and a threat to a network engineer’s job!
The ability to command Mission Critical Skills such as WiFi, Antennas, Propagation, Site Surveying and RF Technologies will set you apart and make you the WiFi expert in your field.
WiFi 100: The Complete Wireless Guide was created and developed by Scott Yates and Branding Tools (eLearning consultant/producer) partnering to create the most effective structure and content to help learners get the most from the the WiFi Wizard training system. Stay tuned on our Udemy page and website for the latest.
Thank you for signing up for this course, I invite you to enjoy the complete series today.
INTRODUCTION TO WIFI - 101
WiFi is Everywhere...in your BluRay Player, your Cable or Satellite Box, your PC, Laptop, Tablet, Cellphone. And Just as the devices are ubiquitous, so are all the ways that WiFi-based devices can be configured....OR, Misconfigured.
This Course will give you a thorough grounding in the technologies that make Wireless Networking Fast, Reliable, and Break-Proof.
So, Who Am I? Where does Scott Yates come off saying things like, "Radio is my Life"...
• I have spent A Lifetime in Radio
• I got my FCC General Radiotelephone Licensee at the age of 26, my Ham Radio License at 28, and attained my Amateur Extra Class Radio License later that same year, and have 276 Radio Countries Confirmed, and 42 countries worked mobile.
• I have been expert in Ham Radio Emergency Operations, and in Navy-Marine Corps and Army Military Affiliated Radio Systems.
• I love training students as yourself, and I've helped hundreds become WiFi Masters
I train at expert level in the fundamentals of WiFi, and in this course I help students like you understand and apply concepts in WiFi to become WiFi masters. WiFi is an essential part of today's technology and your career IT or the Computer Technology. The content in this course will help you get a hands on understanding of what WiFi is and how to use it and become a WiFi Master in your company.
This course 101 of the 100 series goes from history to high end wireless designs in the span of a few lessons. so be prepared to take notes, study and be on path to being the local WiFi Wizard with your clients.
Just as Samuel F.B. Morse and Alexander Graham Bell changed the world forever, by allowing the transmission of communications at the Speed of Light, Their WIRES Still Tethered Users of Communications and Computers to an office, a Warehouse or Plant, or a desk, or some PLACE.
WiFi Freed these Users from the Need for Physical, Layer 1 Connectivity. Suddenly, the Wire was a Radio Wave, and BarCoders, Tablet, Laptop, and Other Users were able to escape that LEASH, and Break Free. In many ways, WiFi LIBERATED Users to a New Level, and Scope, of Productivity.
The Basics of Connectivity…
Now, you use and understand regular Ethernet…it is the IEEE 802.3 Standard, and uses the topology called CSMA/CD, or Carrier Sense Multiple Access with Collision Detection. So, for it to work, it detects a signal, or Carrier, allows multiple users to access the medium, with Collision Detection. So picture a data signal traveling on a wire, someone else wants to talk at the same time, that signal, added to the other signal, causes a doubling of the voltage and the interface judges a collision has occurred. The two stations back off for a randomly generated time, and both stations are allowed to pass their traffic.All that happens in mere MICROSECONDS.
Wifi is different….it is IEEE 802.11, and uses CSMA/CA….just like traditional Ethernet, it listens for a carrier, it is Multiple Access, but the CA tells all you need to know about the difference…
It is Collision Avoidance.. In the Radio and WiFi world, once a signal is launched into the ether, the air, the transmitter has no way of knowing if another station has transmitted. The radios assume the worst of all situations, and since they have no way of detecting if the entire frame was delivered, if it was truncated or interfered with, so If another signal is detected, the transmitter, and the interferer BOTH BACK OFF!
So, WiFi is Polite….in many cases, it is way too polite. It may be functioning flawlessly, exactly as designed, but NO TRAFFIC is passed. What you need to know is that in the ISM bands, you are expected to tolerate interference. Unlike the licensed frequencies which are enforced by the FCC, these are like the Wild West…it is every one for themselves, so if your wireless service doesn’t work, you have no recourse, other than make sure you’re working with a Wireless Expert.
While Wired Networks usually use the standard MTU (Maximum or Media Transmission Unit) mandated by Ethernet of 1500 to 1512 Bytes, as WiFi has evolved, with larger desired payloads and data rates, the MTU, or Frame Size, has pushed upwards to 4500 bytes, or greater. In a Physical Medium, like Ethernet, these would be rejected by the transceiver chipset on the Ethernet Interface as a GIANT Frame, and discarded. Wireless can, and will, tolerate these large frames, so that as fewer checksums are needing calculation, greater transfer rates are very possible.
Knowing the history is the best way to understand the future. Take this quiz to ensure your understanding of the origins of WiFi.
Conclusion to the History of WiFi.
The Federal Government, through the FCC, established the Industrial, Scientific and Medical frequency allocations. They are, in brief, 900 MHz, 2.4 GHz, and 5 GHz. Just to put these into perspective, 900 MegaHertz is roughly twice the frequency of the little FRS Handy-Talkies you see being used at sporting events, during camping, or in retail stores.
As I mentioned earlier, the 2.4 GHz band was convenient, simply because it required relatively small antennas. In fact, with a little bit of smarts, if you look in your laptop, you’ll see a very small module with a little squiggly copper trace that is the 2.4 GHz antenna for the Bluetooth Radio.
So for this, and the relative availability of 2.4 GHz radio modules, 2.4 was the first WiFi Band. It was broken into channels, 22 MHz wide, with a 3 MHz “Guard Band” between channels. In the US, the FCC authorized 11 channels, and in other areas, called “Regulatory Domains” i.e., Government Regulations, some places had 13 channels, and Japan had 14 channels allocated. But there was a problem…
Here, in the US, you had 11 channels…Why Not USE THEM ALL? It sounded great, but there were practical considerations…
The radio signals are not just on, in this instance, Channel 3. You’ll notice that there is still a sizable signal present on channels 1 and 5. You’ll notice that the signal is shown as -30 dB….that is 1,000th the signal strength, but we require these radios to be sensitive so we’re not constantly losing contact, so really, 30 dB is not a great weakening.
Radio and Antenna Math will explain these things.
Radio and Antenna Math…
You will hear, in your WiFi-Expert work, the Term of DeciBEL. This was originally a standard developed by Alexander Graham Bell to measure signal power. The unit of measurement was the Bel, or in our case, 1/10 as much, or decibel, or dB.
DeciBels are ratios. Simply put, if the antenna ports were directly connected, the perfect, loss-less signal, the Signal would be 0 dB, Zero dB.
As the antenna ports become separated, possibly with wires or antennas connected, every signal is less than perfect, and in WiFi, all signals are expressed as NEGATIVE Numbers, or LESS than perfect. In Air, the loss is predictable.
In buildings, the losses are much greater. They can be predicted by the characteristic loss figures in Sheet Rock, Concrete Blocks, Reinforced Concrete, etc.
In the RF Power World, power is expressed in dBm, or Decibels related to Milliwatts. In the normal consumer world, 100 milliWatts is a strong radio.
Related to power, 20 dBm is the same as 100 milliWatts, the normal highest output power of a WiFi Radio. DeciBels are on a logarithmic scale. 10 dBm is 10 milliWatts, and 1 dBm is 1 milliWatt.
1 dBm = 1 mW
10 dBm = 10 mW
20 dBm = 100 mW
30 dBm = 1000 mW, or 1 Watt
These are obviously in powers of 10, 102 = 100, 103 = 1000, etc.
It is obvious in the above example that an increase of 10 dB is TEN TIMES MORE. Conversely, a decrease of 10 dB is a decrease to 1/10###sup/sup### .
The other important number to remember is 3dB. An increase of 3dB is a doubling, and a decrease of 3 dB is a half. These numbers are additive, so an increase of 6 dB is twice times twice.
These can also be intermixed and added and subtracted.
If your power is increased by 16 dB, that is 10 x 2 x 2. So if your power is 100 mW, and you have 16 dB antenna gain, it is 100 mW x 10 = 1 W, 1 x2 = 2, 2 x 2 = 4, or an effective power increase to 4 Watts.
As a WiFi Expert, one of the things you'll need to understand in any indoor installation is that you need to not only understand that signals decrease by the Inverse Square Law, but also the attenuation, the Loss of Signal, imposed by the materials through which the radio signal must pass. If the signal in question must pass through 4 walls, between the Access Point and the receiver, and those walls have an attenuation factor of 3 dB each, then you know that you will see a loss of 3dB times 4 walls of 12 dB. Lets say you're starting with a signal of 100 mW, or 20 dBm,
Based on our knowledge that each wall gives a loss of 3 dB, we understand that this means that loss through wall #1, makes the signal 1/2 of the 100 mW, or 50 mW, or 17 dBm.
Wall #2 gives you a signal of 14 dBm, or 1/2 the 50 mW, or 25 mW.
Wall #3 gives you a signal of 3 dBm less, or 11 dBm, or 12.5 mW.
Wall #4 gives you a signal or 3 dBm less, or 8 dBm, or 6.25 mW.
The point of this exercise is that the distance between radio and receiver may only be 30 feet, but the 4 walls separating them can take a huge signal of 100 millWatts and reduce it to only 6.25 milliWatts.
Writing in dB math, this shows why deciBels makes so much sense, and "de-Complicates" the issue...since you need only add and subtract the numbers.
If your signal starts at 20 dBm, your losses are 15 dBm, but your receiver has a 12 dBm Gain Factor, the simple dB Math tells you that ...
20 -15 = 5, 5 + 12 = 17 dBm
A Simple web-based dB Calculator can be found at
So, if we’ve been allocated 11 channels, why not use them all? It is all about bandwidth…
So remember this as your GREAT RULE OF WiFi # 1
GREAT RULE OF WiFi # 1 – on 2.4 GHz, there are ONLY 3 CHANNELS USABLE! Channels 1, 6, and 11!
Now, over the years, there have been plans to try channels 1,4,8 and 11. Even in the early days, channel availability was already a concernDidn’t work…..but this WiFi that everyone seems to need more than anything else is not all that old…
The original 802.11b was adopted in 1997….that’s just 19 years ago….but the 802.11b at 2.4 GHz was just ratified by the IEEE in 1999, as was 802.11a at 5 GHz.
The 54 Mbps Data Rate did not become the standard in 802.11g until 2003…that’s just 13 years ago, and 802.11n was just 7 years ago, in 2009.
Quick question…Why develop newer standards? They had 802.11b & g at 2.4 GHz, 802.11a at 5 GHz….it was for only one reason…..SPEED!
With the arrival of 802.11n, it became possible to “BOND” Channels….the signal would start at a base channel, like channel 153 in the 5GHz band, and then EXTEND Up or DOWN. So Channel 153 with a secondary channel of 149. This is represented as 153- (153 Minus).
The Standard 20 MHz Channel now has the capability of becoming a 40 MHz Channel. Why does this matter? It is simply because that nice 3 channel layout in the 2.4 GHz band just became almost a 1 channel band. Why?
If you set an 802.11 b/g/n radio on channel 1, in actuality, the signal becomes centered on Channel 3, extends way down below channel 1, and up above Channel 8. Maybe, just maybe, if you use channel 11, and it extends 2 channels above and below…..if the signal strength is not too great, you might be able to use 2 radios, a big wide 802.11n (40 MHz) on 1, and a nice narrow 802.11g (20 MHz) on channel 11
Why the History Lesson? It is because the things that people think today are so important, so pervasive, SO NECESSARY….haven’t been around all that long. The Availability of WiFi Gear has far out-paced the knowledge of how to deploy them successfully, with repeatable success.
But every store, every device, seems to have WiFi capability. This leads us to the next subject, Antennas:
To master WiFi, knowing how the math works is critcal
The Antennas for a WiFi system can be the simplest of things, like a bent paper clip inserted into an "N" Connector (yes, I've done it a number of times) to a very high gain directional Parabolic Grid Antenna or a Panel Antenna.
In the Real World of Radio Electronics, all antennas are Dipoles, meaning a Dual-Pole Antenna. Electronically, One side of the Antenna is being fed with RF Energy, and the other half is fed "At or Against Ground".
You can see this in the attached video. If you see a CB Radio antenna, or a 2-way radio antenna on a police car, it looks like only the vertical radiator, or 1/2 the antenna is there, and half is missing. And what about that enclosed coil on the bottom....what does it do?
The main thing you have to understand as an antenna user is that the missing part of the antenna is actually the body of the car. It is called a "Counterpoise". If you are holding a handy-talkie, your hand, your body, is the counterpoise.
And that gray or black coil at the bottom is just for the purpose of impedance matching, a device that makes the transmitter in the Radio Happy. Happy Radio equals cool output stages, and therefore, stable, full power operation.
You have seen the very simplest antennas, like the little plastic antennas that come on the consumer grade routers and access points.
I have also shown you larger, or Gain, Antennas. These are still basically Omni-Directional Antennas, antennas that radiate their power in all directions. They create "GAIN" by taking multiple antenna elements, and stacking them one on top of another. They made the pattern FLATTER so made the signals greater, in their preferred "at the horizon"
I was able to show you antennas that had Directional Gain, by using metal reflectors, or parabolic grid dishes. Their design eliminates signals in the non-desired directions, once again, producing GAIN.
RF ANTENNA MATH
We, as network and RF Wireless Engineers typically speak in terms of “DB this and that”…here are some rules of thumb to remember…
The small antennas shown on the previous slide are generally considered to be Zero, or Unity, Gain. They are rated as 2.2 dBi Gain, where dBi is deciels related to an Isotropic Radiation Source, an extremely small point source of RF Energy. In reality, since they have an actual radiating surface, they actually have a small gain.
If additional antenna elements are stacked one above the other, you can effectively achieve Antenna Gain. The power is the same, however. The pattern changes from a big, fat doughnut pattern around a little dipole as shown in slide 10, to a pattern that is narrower in the vertical plane, but more focused at the horizon. The power is the same, but it is more concentrated where it can do the most good, thus giving the apparent result of Antenna Gain.
Additionally, if you place multiple driven elements against a metal backplane, and maintain a good phase relationship, you can get up to 24 dBi gain from a Panel Antenna. A Solid Dish Antenna can give you up to 30 dBi, or higher, Gain.
The small antennas shown on the previous slide are generally considered to be Zero, or Unity, Gain. They are rated as 2.2 dBi Gain, where dBi is deciels related to an Isotropic Radiation Source, an extremely small point source of RF Energy. In reality, since they have an actual radiating surface, they actually have a small gain.
You can buy larger antennas for your consumer grade WiFi Router. They are longer, often larger in diameter, and employ the exact same principles as the commercial market gain antennas.
As you can see, there is a large amount of technical engineering goes into the design of WiFi Antennas.
Antenna Companies, and the Designers that work for them, spend large fortunes on the designs of their antennas. Very Large ANECHOIC Rooms, with walls covered with Radio Energy Absorbing materials, test these antennas as they are built and fine-tuned.
They also have large outdoor Antenna Test Ranges so that they can test these designs in open air, over various ground surfaces, and with varying feed methods.
The main thing I want you to design is that the Antenna Pattern that is advertised does not occur 2 feet from an antenna....it takes, in many cases, many multiple wavelengths away from the antenna to actually develop into a real pattern.
I have actually had to connect a building with the antenna 5 stories up to a building only 1 story tall, a mechanical building. They were about 300 feet apart. I had at my disposal a line of Omni Antennas with a "5 Degree Downtilt" meaning that the pattern was stronger 5 degrees down instead of at the horizon.
Therefore, I decided to use a very low-gain antenna on both ends of the path. The lower gain antennas had much "FATTER" radiation patterns, and saw each other quite well. Since these antennas were part of a Radio Mesh, it was still important to use Omni antennas when possible.
Being able to create a predictive design can be very useful, and is a great Resume Bullet Point.
Let's say you have been asked by a large church to help them create a WiFi network inside and outside their building. Do you just start hanging Access Points? What do you base your decisions on? If you install the network, and the coverage, or wireless access is not what they wanted...How do you fix that?
Upon what information did you decide to place an Access Point there, or there?
Let's look at the Process to make a quality Predictive Design:
1. You need a set of Building Plans, preferably electronc. And you need to be able to read them.
2. You need to, and this is VITAL, walk the site. Make note of wall constructions, ceiling heights, cable plant accessibility, and mounting locations and options. TAKE LOTS OF PICTURES, Before and After.
3. Ideally, the AP's should be Injected, i.e., powered via network cable and a POE (Power Over Ethernet) injector, or a POE Enabled Switch.
4. Using a tool like Airmagnet Survey Pro, or Ekahau Site Survey, you import the building plans into the software, and begin the long process of drawing in all the walls, interior and exterior.
5. Once done, the software will take into account the attenuation added by the various wall constructions. It goes without saying that a Poured Solid 8 inch Concrete Block wall, with Reinforcing Rods in the voids has much more attenuation than a simple sheet rock wall with wooden studs on 16 inch centers.
6. Once you've done your advance work, you turn the software loose, and let it do its magic.
Attached you will see a Predictive design done in Ekahau on a site that spanned 6 floors and over a thousand six hundred feet, end to end.
Signals degrade according to very simple, straight-forward rules...
The Inverse Square Law says that 2 Times the Distance equals 1/4 the RF Signal.
Coax has predictable Losses per foot and increases with frequency. One of the best calculators is available on TIMESMICROWAVE.COM. You just plug in the Cable type, the Footage, the Frequency, and you'll have an exact figure for the Loss.
Never use the power output claimed for a radio unless you can verify it yourself. A Microwave milliWatt Meter will cost between $1100 and $1300.
I recommend that you design around 17 dBm (50 mW) for 5 GHz, and 14 dBm (25 mW) for 2.4 GHz.. The 2.4 GHz signals travel about 30% better than 5 GHz, and the antenna elements are slightly larger, ie., greater capture surface.
Whenever you are in doubt, MEASURE the Loss for yourself. For instance, if an elevator tower is present, it will usually have 4 reinforced concrete walls. The same for Vault areas.
Walls surrounding an X-Ray or MRI Area will frequently have RF or Magnetic shielding in the walls, and very powerful magnetic fields.
These situations are best measured with the "AP ON A STICK", an AP Mounted on a stand, preferably non-ferrous, and powered via a POE Injector.
In a Warehouse or Factory environment, you can hang an AP on a beam
clamp, powered from the floor with an injector, and if mobility is
important, use a battery pack, portable car booster/air pump, or UPS to
provide power. Also, a battery with Inverter will provide your needed
There is a great dichotomy in in the WiFi World....it is Fat versus Thin.
To put that in simpler terms, some of the Access Points have their own operating systems, they boot up when powered up, and they load their own saved settings. These are the Fat, or Autonomous Access Points. Power them up, and they just work. They have saved configurations, Encryption Keys, and come up pretty quickly. They know how they're configured, and they run without further attention. They usually have their own web interface and can be easily configured.
One problem is that the device contains the Security Definitions of the parent network...It has the passwords, the encryption methods, everything needed to break into the host network.
Steal one, get outside the building or enterprise, power it up, break into it, and you have the keys to the castle. You would be shocked if you realized HOW MANY devices use the Default Passwords.
However, there is one more great weakness to this topology. It might be fine in an environment with 10 or 20 access points, but what if you are in a University, with Hundreds or Thousands of AP's, or a large multi-national company, with dozens of offices, in multiple countries?
The answer to that was the Thin, or Light-Weight, Access Point, These are often called LWAP's. They are a Software Defined Radio....they don't know what they are, and what functions, they are to perform, until they have talked with their Wireless Controller.
The LWAP is typically powered over a POE (Power Over Ethernet) connection, via a POE Enabled Switch, or via a POE Injector. These use the unused conductors in a CAT5 Cable to supply 48 VDC to the AP.
Conductors 1,2,3 and 6 are the Ethernet Conductors,
Conductors 4,5,7 and 8 are the Power Over Ethernet wires.
If your wires are punched down correctly, and your cable installer knows his stuff, you will not hurt anything by plugging a POE Cable into a non-POE Device.
The LWAP Will power up, and look for a DHCP Server. Once it obtains an IP Address, it will start looking for a Wireless Controller, usually via a Sub-Function of DHCP, or a well-known MAC Address, or a DNS Name Resolution, i.e., Wireless Controller = 22.214.171.124.
Once the controller is located, the controller loads an image to the AP, i.e., sends it a copy of its' operating system, the AP Boots the newly installed OS, and then loads its' Configuration. Some of the Config parameters may be global, others may be specific to one AP.
The Obvious Advantage is that you can have Networks, Multiple SSID's (the Wireless Network Name, or Service Set IDentifier), different (or the Same) Encryption Keys and Methods, Channel, Power...They can all be administered from one single administrative console.
If the Controller is smart enough, it can also modify channel
numbers, power, control interference....ALL ON THE FLY. If a user brings
in a "ROGUE", i.e., an unauthorized Access Point, like a MiFi, or a
small router, these devices can be detected, avoided, or in an Intrusion
Prevention or Detection situation, actually kill the rogue, either on
the wire by killing it at the Switch Port, or in the Air, by
impersonating the Device or Devices, and sending Disassociation Frames
to the Client, so it simply quits trying to connect. Other methods can
be employed as well, either manually, or automatically by the Controller
or an Enterprise-Grade Intrusion Detection System.
To get the best wireless setups, the correct predictive designs need to be worked out.
The Dynamics of a Predictive design can be plagued with dozens of "unknowns".
One of the first things you need to understand in doing a Survey or a Predictive design is the construction materials used in the building being surveyed. This is most important in Predictive Designing, because you are having to Forecast how the RF propagates in a building, through walls, floors, glass...all these things, including the Antennas, Powers, channels, frequency bands, RF modes.....many things will govern the success, or failure, of an installation.
Ultimately, if you're dealing with an unusual construction type, measure the signal at a standard distance, like 10 feet, then position yourself so that the signal has to travel through that material, at the same distance from Signal Source to receiver. In that way you have established the Attenuation Factor for that material.
Some commonly accepted loss figures are:
Thin Window 2 dB
Windowed Office 3 dB
Plasterboard Wall 3 dB
Light Door 4 dB
Dry Wall 4 dB
Cinderblock Wall 4 dB
Glass Wall, Metal Frame 6 dB
Brick Wall 8 dB
Metal Door 11 dB
Concrete Wall 12 dB
Heavy Security Door 15 dB
I will attach several examples of examples of surveys I have taken personally. You will notice the RED TRACK...
That is the path that was walked. You mark your starting point, walk straight until you have to turn, click on that, and continue to mark your walking path. The entire time that is taking place, so is your Survey Laptop constantly listening, measuring, and searching the wireless environment. If you have a Spectrum Analyzer attached to your survey laptop, you'll be able to look at not just the WiFi Frequencies, but also NON-WiFi Signal Sources, like MicroWave Ovens and Flash Dryers, Door Opening Systems, Radars, and other signal sources.
The Site Survey is hard science, but it is also an Art...you will develop a sense for how a type of construction. However, your sense of the survey can sometimes lead you astray...
Once I was surveying in a Small University's Science Building. The Lab areas had a second internal wall, where they ran all the drains, air, vacuum, gas for bunsen burners, etc.
The signals which usually travel extremely well horizontally were terrible, but the floor to floor signal leakage was tremendously high, as if the normal reinforced concrete floor were paper instead of concrete. Making too many assumptions can burn you if you don't test thoroughly. Be diligent...it is your reputation as an Expert on WiFi on the line.
I once had to provide outdoor coverage, from the inside! This would require me to position the placement of APs directly inside a window to allow signal leakage outside. I did these on the second floor, thereby angling the signal downwards. I tested by mounting an AP on a stand on a desk inside the building, then measuring the signal FROM THAT ONE AP. This proved my method to be workable, and was eventually installed in that same way.
In the cafeteria area, I had to do the same, and by placing the radio 10 feet back from the windows, measuring the signal 1 foot inside the window, then 1 foot outside the window, I was able to compare the signals, and as it turned out, the windows were not aluminized, and the attenuation was minimal.
Here are some easy to follow do's and don'ts for surveys.
One of your most valuable tools, as a surveyor, is a camera, or a good camera in your phone. Take pictures in the Closets, take pictures of the potential AP or Antenna Locations, and in the cases of a long distance shot, use Google Earth and Good Pictures to see these paths for yourself. If you're using WiFi frequencies, it MUST BE LINE OF SIGHT.
You must also consider the Fresnel Zone, the Cigar-Shaped path between two widely separated points. If anything (trees, buildings, etc.,) impinges, obstructs, this path more than 40%, the reliabilty can be considerably degraded.
In a situation that is less than optimum, you may want to test with a fixed transmitter (AP) and use a movable receiving antenna.
In such a situation, I took a 24 dBi Panel antenna and duct taped it to an extendable Painters Pole, and used a long LMR-240 cable and was able to move the receiving antenna until I got an acceptable Signal to Noise Ratio (SNR).
Since I was using a MESH Enabled Radio, once it joined the mesh, I had only to move the Panel until I got the best signal.
There are many uses for the Science of the Survey.
First, it is to Analyze the environment in which you are to install a system. This is often described as an RF Site Survey, and I typically did this with both a quality Survey Tool, like Airmagnet Survey, or Ekahau. This lets you know what is there when you start
Secondly, you can use your Site Survey software to create a predictive design, based on the building layouts, walls and floors, dimensions, and AP types.
Finally, you can use the software to confirm, or validate, the results you designed for. Are there any holes you did not expect? What about over-covered areas, areas with interference?
Your Survey software is essential to your design success.
I will include, on the Wizard Website, some URLs and links to download the software, evaluate it, and possibly purchase.
Troubleshooting and best setup practice require a fundamental understanding of taking effective surveys.
Conclusion of WiFi 101
The WiFi-Wizard WiFi Rules of Thumb:
1. NEVER NEVER NEVER Use 802.11n or 802.11ac on 2.4 GHz.
2. Always use 5 GHz when possible
3. Set 2.4 GHz AP’s to lowest power, 5 GHz to Highest Power
4. Set Laptops to Prefer 5 GHz
5. 802.11n or 802.11ac is ONLY for 5 GHz
6. Never set AP’s to use “Least Congested Channel” or AUTO. This is
selected at boot up and will not reflect current conditions. Channel Changes require a reboot.
7. Most consumer-grade Router/AP’s are factory set to Ch. 6.
Usually Ch. 1 or 11 is a safer bet, but run inSSIDer first to be sure.
8. If the Signal Graph in inSSIDer or Acrylic show breaks, those are
representative of the radio Backing off under interference.
9. You can only sample signals your adaptor allows you to. If your Laptop supports only 802.11a, you’ll show an 80 MHz channel as 54 mbps on a single channel, like Ch.100. If your adaptor supports 802.11ac, you’ll show, as in my house, Channels 100+104+108+112
I want you to understand how the rules and standards and practices came to be...
In my most recent large engagement, I was tasked with creating a worldwide network, probably 99% or which was of which was installed outdoors. Ultimately, there were over 5800 radios running around the world. There were many lessons to be learned from that, especially for the novices in my group. The important thing, most of all, was that the standards developed over many years were proved to be completely correct. Lightning Protection and water-proofing are ESSENTIAL to making an outdoor system survive.
The techniques used made for a completely stable, reliable, and secure system. It did its job, and the Intrusion protection, and intrusion prevention technologies employed worked exactly as desired.
Those experiences, plus many installations in the Corporate Enterprise space, helped me derive the Rules of Thumb that you can apply to any system.
You have just completed the first of a Series called the WiFi-Wizard WiFi Training System.
It is indeed a system. I have learned the lessons about Radio, RF, Antenna Design, and WiFi over a 40 year career as a licensed RF Engineer, 38 years as an Amateur Radio Operator, and 18 years as a user and designer of WiFi Networks.
I would like you to benefit from my lifetime of experience in the Radio World.
There are other courses available, what we consider a full suite of very specialized training.
UPCOMING TRAINING SESSIONS:
WiFi-Wizard Video Training Presents: WiFi-102 – HANDS-ON WiFi Configuration and Design Considerations
WiFi-Wizard Video Training Presents: WiFi-103 – The ART of the Survey – Fact-Finding Before the Design, The Design, and Validation AFTER the Install
WiFi-Wizard Video Training Presents: WiFi-104 – Finding and Identifying WiFi Problems, using “Over the Counter” and Professional Tools
WiFi-Wizard Video Training Presents: WiFi-105 – Wireless Security, Intrusion Detection and Prevention, making your systems bulletproof
Please feel free to email me if you have questions, firstname.lastname@example.org
Most of All, NEVER FEAR WiFi. It is completely fact-based, BUT....it also requires a love for, and feel for, the technology.
You will distinguish yourself immediately when you apply the WiFi-Wizard System. Over time you will develop your own tools and preferences, but when based on facts and science, and the most valuable asset of all....YOU, the Field Engineer and Master of WiFi, you will excel in a market space that most people avoid.
Congratulations, WiFi-Wizard in Training!
My name is Scott Yates, aka the WiFi Wizard, and I'm passionate about the wireless world. My decades spent mastering WiFi technology and equipment and my years training others to also master it has only fueled my passion through the years, and why I'm here on Udemy.
I offer quality WiFi training, consultation and top notch resources from both my Udemy content and my website, but here's a little about my history...
In my Computer Networking Career, I have been fortunate to be involved in some of the most fascinating projects imaginable. In the mid-90’s, I assisted, as SE-Team Leader, with the Network Upgrade and Infrastructure Buildout at Pinellas Co, Fl. As part of this, we implemented Switch and Router replacements, and upgraded the mobile classrooms to WiFi Point-to-MultiPoint links from the classrooms to the central administrative building at each school. This gave me some invaluable “lessons-learned” as we implemented 1000 Wireless systems in the Classroom infrastructure upgrade.
I spent 4 ½ years as Regional Service Manager for Cabletron Systems / Enterasys Networks, and consulted with both Customers and Sales on the designs of Enterprise-grade Networks.
Other high profile networks included the design of the wireless network in the Vertical Assembly Bldg. at Cape Canaveral, and the Networking Centers at Wake Forest University and in the Network Core at University of Memphis.
Recently, I was contracted to redesign a wide-area network for 9 banks in a small banking group, clearing the Cisco 2611 and 2811 Router Configs, moving the WAN Links from an older carrier to an AT&T Switched Ethernet topology. I also was tasked with the provisioning of some small to medium VMware VSphere Servers.
I have made an effort to capsulize my life-experience in networking. I have been honored to work in some of the most exciting environments imaginable, and have always made decisions and recommendations based on that which is in the best interest of the customer, and the customer’s mission.
Wireless is the last great mystery in networking. While many do it, few do it well. My goal is to take the mystery out of it, replacing suspicion and uncertainty with time-tested techniques and industry standard best practices.