Pull everything out of the box.

Connect the power supply to AC power plug and the other end to DC plug on the back of the firewall.

Plug the 0/WAN port into your internet connection. Plug the 1/LAN port into your computer. You will configure your network adapter with a DHCP configuration.

Power up the firewall by turning the switch on. Located on the back.

When the firewall boots up, your computer should obtain a DHCP address.

IP:                        10.0.1.2
Subnet Mask:    255.255.255.0
Gateway:            10.0.1.1

Once this is complete, you will be able to manage the firebox by entering the following URL into your browser…

https://10.0.1.1:8080

Default credentials are…
admin
readwrite

Click Log In to access the web GUI.

Create a new configuration. Accept the License Agreement. Click Next.

The WAN interface might automatically connect with a DHCP address. If this is how your network will be configured, press Next. I will assign a static public IP in this case.

 Click the Static radio button. Click Next.

Enter the Static IP information. Click Next.

Enter the DNS information. Click Next.

Configure the trusted interface. Click Next.

Enter your status and admin credentials so that the device is not accessible with defaults. Click Next.

We will not worry about the remote management. Click Next.

Configure the Device Name, Device Location and Contact Person. Decide if you want to provide feedback and check the box accordingly. Click Next.

Select the Time Zone. Click Next.

Click Next.

Select some of the more advanced control features. Click Next.

Review your settings. Click Next.

The firewall will apply the new settings. You will be given a new IP address in the new subnet.

 

Overview

Ubiquiti switching – I am deploying the non-POE lite version on a current project. This appears to be an enterprise-grade switch at a SOHO price point. Steel case, DC power option and standard console cable. Specs are comparable to long-established equipment providers.

Console Connection

To access console terminal, connect console rollover cable to console port on the rear of the switch.

Settings
Speed                 115200
Data bits            8
Parity                 NONE
Stop Bits            1
Flow Control    NONE

You will need a USB to Serial adapter for most modern computers. Use Device Manager to determine COM port.

I received the following scrambled output while using an HL-340 USB to Serial Adapter…

CH▒▒
▒s[n▒▒H▒▒H▒7▒▒▒▒▒H▒▒H▒7▒▒▒▒▒

I used my Trendnet adapter and it worked.

User:ubnt
Password:ubnt
(UBNT EdgeSwitch) >en
Password:ubnt
(UBNT EdgeSwitch) #terminal length 0

(UBNT EdgeSwitch) #show run

default-config.txt

Show Interface Information

(UBNT EdgeSwitch) #show interfaces status all

Setup SSH

Generate the crypto key for SSH.

(UBNT EdgeSwitch) (Config)#crypto key generate rsa

(UBNT EdgeSwitch) (Config)#crypto key generate dsa

Make sure they are both present. Disable Version 1.

Here are some CLI commands for setting up SSH.

ip ssh server enable
ip ssh protocol 2

(UBNT EdgeSwitch) (Config)#show ip ssh

Administrative Mode: …………………….. Enabled
SSH Port: ………………………………. 22
Protocol Levels: ………………………… Version 2
SSH Sessions Currently Active: ……………. 1
Max SSH Sessions Allowed: ………………… 2
SSH Timeout: ……………………………. 5
Keys Present: …………………………… DSA RSA
Key Generation In Progress: ………………. None

CLI Write Memory To Save Config

(UBNT EdgeSwitch) #write memory confirm
Config file ‘startup-config’ created successfully .

Configuration Saved!

GUI Interface

The Edgeswitch comes with a default management IP address of  192.168.1.2

There is a cool tool for chrome that allows layer2 Ubiquiti device discovery. Ubiquiti Device Discovery Tool

Once installed you can access it from chrome by copying this into the URL… chrome://apps

You will need to set your network inteface IPV4 settings to 192.168.1.X (not 2) to reach the switch. (Or your can also use DHCP.) I like to know what switch I am working on by using the default IP directly connected.)

Make sure you can ping the switch.

Now you can access the management webpage from a browser by opening 192.168.1.2

Enter the username and password ubnt/ubnt and accept the terms if moved to do so.

GUI VLAN Setup

Add the new VLANs. I start by entering VLAN 3. Click Add.

Change the name once the VLAN is added. Click Submit. Repeat for the other VLANs.

Assign Untagged, Excluded or Tagged ports by toggling between U, E and T by clicking on the letter on the VLAN row. Make sure to leave your current management port untagged VLAN 1.

In this example, I am using port 23 and 24 for untagged VLAN 3 and tagged VLAN 4 backhaul traffic. Fiber ports 25 and 26 are tagged for potential future backhaul.

Setup Rapid Spanning Tree

I prefer to use Rapid Spanning Tree. The switch comes by default set to Multiple Spanning Tree. There is no need to run MST given our topology. Effectively MST will run like RSTP but what is the point? Just run RSTP to begin with.

Switching > Spanning Tree > Switch

Select IEEE 802.1w. Click submit.

GUI Management IP Setup

Finding the IP address in the legacy interface can be a challenge. The bread crumb to reach the interface configuration is…

System > Connectivity > IPv4

Enter the management IP address information. Select the Management VLAN ID. In this case we will use VLAN 3 for management.

WHEN YOU CLICK SUBMIT YOU WILL NEED TO CHANGE YOUR COMPUTER IP ADDRESS TO MATCH THE NEW SUBNET. YOU WILL ALSO NEED TO MOVE TO A PORT ON THE MANAGEMENT VLAN SETUP ABOVE.

Once you change your IP to the correct subnet. You will be able to log in on the new address.

Go back to the VLAN menu and program the original VLAN 1 management port to the VLAN it will used for.

Firmware Upgrade

Determine what the latest firmware revision is available on the site.

Ubiquiti Firmware

We will use ES-eswh.v1.8.2-lite.5192445.stk

Navigate to Basic>Firmware Upgrade

Select the Backup image upload by clicking the up arrow to load the firmware to the backup flash.

Navigate to the folder containing the firmware file and click Open.

Click Begin Transfer button.

Once the Transfer is complete, click close.

The new firmware should be in the backup location. Click the radio button to have the new firmware as Next Active. Click Submit.

Click on the Restart Switch tab. Basic > Restart Switch
Make sure that you have saved the configuration before reloading the switch.

Click Restart Without Core Dump

Once the device reloads, check to see if the firmware upgraded properly.

Through CLI you can issue the following…

(UBNT EdgeSwitch) #show version

Switch: 1

System Description……………………….. EdgeSwitch 24-Port Lite, 1.8.2-lite, Linux 3.6.5-1b505fb7, 1.0.0.4857129
Machine Type…………………………….. EdgeSwitch 24-Port Lite
Machine Model……………………………. ES-24-Lite
Serial Number……………………………. 18E8294A815A
Burned In MAC Address…………………….. 18:E8:29:4A:81:5A
Software Version…………………………. 1.8.2-lite

Make sure all your switches are running the same firmware.

Setting Up Time Servers

I tried using the default time servers. They did not work for me. I have always had trouble with name servers on switches. DNS resolution can be problematic even on the old school brands. I ended up loading resolved IP addresses for the servers and was able to get it working right away.

time-a-g.nist.gov…………..129.6.15.28
time-b-g.nist.gov…………..129.6.15.29
time-c-g.nist.gov……………129.6.15.30
time-d-g.nist.gov……………129.6.15.27

GUI Way
System > Advanced Configuration > SNTP > Global Configuration

System > Advanced Configuration > SNTP > Server Configuration

CLI Way

sntp unicast client poll-retry 10
sntp client port 123
no sntp server “1.ubnt.pool.ntp.org”
no sntp server “2.ubnt.pool.ntp.org”
sntp server “129.6.15.28”
sntp server “129.6.15.29”
sntp server “129.6.15.30”
sntp server “129.6.15.27”
clock summer-time recurring USA offset 60
clock timezone -8 minutes 0 zone “PDT”

Base Configuration

Base-Config

LLDP Configuration

LLDP is configured by the port on Ubiquiti switches.

To send all traffic…

interface 0/x
lldp transmit-tlv port-desc
lldp transmit-tlv sys-name
lldp transmit-tlv sys-desc
lldp transmit-tlv sys-cap
lldp transmit-mgmt

To prune LLDP traffic on port both directions…

interface 0/x
no lldp transmit
no lldp receive

To listen for LLDP packets and not transmit…

interface 0/x
no lldp transmit

Some helpful LLDP commands…

(UBNT EdgeSwitch) #show lldp remote-device all

LLDP Remote Device Summary

Local
Interface RemID Chassis ID Port ID System Name
——— ——- ——————– —————— ——————
0/23
0/24 3 18:E8:29:4A:81:5A 24 OtherSW
0/25
0/26

(UBNT EdgeSwitch) #show lldp remote-device detail 0/24

LLDP Remote Device Detail

Local Interface: 0/24

Remote Identifier: 3
Chassis ID Subtype: MAC Address
Chassis ID: 18:E8:29:4A:81:5A
Port ID Subtype: Local
Port ID: 24
System Name: OtherSW
System Description: EdgeSwitch 24-Port Lite, 1.8.2-lite, Linux 3.6.5-1b505fb7, 1.0.0.4857129
Port Description: Uplink
System Capabilities Supported: bridge, router
System Capabilities Enabled: bridge
Management Address:
Type: IPv4
Address: 192.168.0.21
Time to Live: 114 seconds

Thank you, everyone, who helped to make this possible.

Skål!

Link to Aruba’s white paper on 802.11ax.

The IEEE 802 family of standards deals with Local Area Networks and Metropolitan Area Networks. The first meeting of the 802 LAN/MAN Standards Committee (LMSC) was held in February of 1980. As a result, it is widely associated with 80-2.(1980-February) It was the next available number so this is more of a coincidence than anything.

The 802.11 working group is responsible for all aspects of Wireless Local Area Networks. The two layers at the heart of 802.11 are the medium access control(MAC) layer and the physical(PHY) layer.

This brings us to the topic of discussion. Why are there so many different letters associated with 802.11? It would seem that 802.11 would be 802.11. The letters at the end of the working group represent the version of the standard. Each subsequent revision will use the following letter in the alphabet. Some letters are not used. This is to avoid confusion with other standards or because they look like numbers. 802.11x is not used as it looks too much like 802.1X. It is also commonly used to identify all the 802.11 versions. 802.11l looks like 802.111 or 802.11i which would be confusing. 802.11o would also be confused with 802.110.

To make it even more confusing, there are roll-up standards. When there are a handful of letter-based standards the IEEE 802.11 working group will roll all the standards into a year based roll-up standard. This will often times include an earlier roll-up standard and an alphabet soup of some of the latest letter-based standards. See below for dated roll-ups and their associated standards.

802.11-2007
— 1999 edition
— 802.11a-1999 (Amendment 1)
— 802.11b-1999 (Amendment 2)
— 802.11b-1999/Corrigendum 1-2001
— 802.11d-2001 (Amendment 3)
— 802.11g-2003 (Amendment 4)
— 802.11h-2003 (Amendment 5)
— 802.11i-2004 (Amendment 6)
— 802.11j-2004 (Amendment 7)
— 802.11e-2005 (Amendment 8)

802.11-2012
— 802.11-2007
— 802.11k-2008: Radio Resource Measurement of Wireless LANs (Amendment 1)
— 802.11r-2008: Fast Basic Service Set (BSS) Transition (Amendment 2)
— 802.11y-2008: 3650–3700 MHz Operation in USA (Amendment 3)
— 802.11w-2009: Protected Management Frames (Amendment 4)
— 802.11n-2009: Enhancements for Higher Throughput (Amendment 5)
— 802.11p-2010: Wireless Access in Vehicular Environments (Amendment 6)
— 802.11z-2010: Extensions to Direct-Link Setup (DLS) (Amendment 7)
— 802.11v-2011: IEEE 802.11 Wireless Network Management (Amendment 8)
— 802.11u-2011: Interworking with External Networks (Amendment 9)
— 802.11s-2011: Mesh Networking (Amendment 10)

802.11-2016
— 802.11-2012
— 802.11ae-2012: Prioritization of Management Frames (Amendment 1)
— 802.11aa-2012: MAC Enhancements for Robust Audio Video Streaming (Amendment 2)
— 802.11ad-2012: Enhancements for Very High Throughput in the 60 GHz Band (Amendment 3)
— 802.11ac-2013: Enhancements for Very High Throughput for Operation in Bands below 6 GHz (Amendment 4)
— 802.11af-2013: Television White Spaces (TVWS) Operation (Amendment 5)

Once everything is rolled up into a dated standard, all of the previously published amendments and revisions are then retired.

Now that we have navigated by the global 802.11 map, let’s zoom in and take a look at some of the individual standards.

802.11-1997
Let’s start at the very beginning. A very good place to start, the 1997 standard. The original standard is sometimes referred to as 802.11 prime or 802.11 legacy. With this standard, the world was introduced to many of the foundational topics surrounding wireless local area networks. We are introduced to the contention mechanism carrier sense multiple access protocol with collision avoidance.(CSMA/CA) The standard includes the authentication, association, reassociation, encryption, power management and point coordination function(PCF has not ever been implemented) provisions.
We learn from the original standard many of the definitions we still use today when defining the various components of the wireless local area network. Some of these definitions include…
Access Point: A station that provides access to a distribution system through a wireless channel.
Association: The process by which an AP to Station mapping is created which allows the station to communicate with the distribution system services.
Authentication: The process by which a Station identifies itself as a member of a set of stations allowing it to associate with another station.
Basic Service Area: The coverage of a basic service set. In laymen’s terms, the AP coverage.
Basic Service Set: The set of stations controlled by a single coordination function. Think of this like the group of stations that are associated with a single AP on a single SSID.
Beacon: Transmission scheduled at specific interval which provides data about the device one each SSID and its capabilities. Also used for transmission synchronization.
Clear Channel Assessment: Function that detects whether the physical medium is clear or currently busy.
Distributed Coordination Function: The coordination function that is used by the various stations in a basic service set to coordinate access to the shared resource. A contention method.
There are many more terms that are still used in our modern 802.11 networks that are still commonly used.
Now that we have covered some of the ways the standard has remained the same, let’s consider some of the ways this standard offered some aspects that are no longer used.
The original standard was designed for infrared devices using baseband communications and radio transmissions in the 2.4 GHz band. The modulation techniques use for encoding data on the radio channel were frequency-hopping spread spectrum and direct sequence spread spectrum. Both of the different modulation techniques could yield a data rate of 1 Mbps and 2 Mbps. Infrared allowed 2 Mbps optionally.
Two types of authentication are available in the legacy standard. Open system authentication is the most basic form of authentication. Any station that requests authentication will be authenticated. The other method is shared key authentication. This method uses the deprecated Wired Equivalent Privacy (WEP) keys to establish a secured session. WEP is no longer a secure standard and should not be used on a modern Wi-Fi network. More recent standards will not even allow the faster modulations when WEP is used. Modern 802.11 networks no longer use FHSS with Gaussian Frequency Shift Keying or infrared. Direct sequence spread spectrum is still supported for legacy devices. There are significant performance drops by allowing DSSS devices to coexist on a modern network.

802.11-1999
This standard is also commonly referred to as 802.11 legacy or prime. It is a revision to the 1997 standard. As such, the documents are nearly the same with only slight variations and clarifications made between the two revisions. FHSS, DSSS, and infrared communications are all supported. Infrared communications are transmitted between 850 nm and 950 nm. Direct sequence spread spectrum operates within a 22 MHz wide channel bandwidth in 2.4 GHz. Differential binary phase shift keying (DBPSK) is used to obtain a data rate of 1 Mbps. Differential quadrature phase shift keying (DQPSK) is used to obtain a data rate of 2 Mbps. The early standards set the stage for the Wi-Fi Alliance certifications. There were so many different PHY layer options and so many varying implementations of the standard that equipment was not capable of interoperating reliably. This lead to Wi-Fi Certified certification to ensure that equipment was interoperable.

802.11-a
Now the alphabeterrific fun begins. The 802.11a standard was the first standard to allow devices to transmit in the 5 GHz frequency range. This standard is 5 GHz only. We are introduced to the unlicensed national information infrastructure (U-NII) bands. We were also introduced to a new modulation technique known as orthogonal frequency division multiplexing (OFDM). OFDM is a powerful way to stack individual carriers together allowing them to occupy the same bandwidth but not to interfere with each other. Quadrature amplitude modulation (QAM) is added to encode data on the carriers. Data rates of 6,9,12,18,24,36,48 and 54 Mbps are possible. These rates are achieved using BPSK, QPSK, 16-QAM and 64-QAM. This standard was not widely implemented at first. It was ahead of its time in many ways. The shortage of equipment capable of operating in this band and the added cost made it less attractive to many of the users. 802.11a was the foundation for the 802.11g standard that was very popular as the strengths of OFDM were adopted into the 2.4 GHz band.

802.11-b
This standard was one of the first to find widespread adoption. 802.11b introduced high rate direct sequence spread spectrum (HR/DSSS). In addition to the 1 and 2 Mbps, devices could now connect at data rates of 5.5 and 11 Mbps. This was done by adding complementary code keying (CCK). More data could be encoded on the 22MHz DSSS channel. A shortened preamble was also included. This standard only operated in the 2.4GHz band. An optional modulation of packet binary convolutional coding (HR/DSSS/PBCC) was introduced. It never found widespread adoption.

802.11-d
When learning about this standard, think domain-d. The 802.11d standard is concerned with conforming to the rules within each regulatory domain. Each country makes its own rules concerning how RF devices operate. Additional elements are added to existing frames, like the beacon frame, which tell devices what country the device is operating in. This allows devices to also meet the requirements of the regulatory domain and to roam between regulatory domains.

802.11-g
The extended rate phy (ERP) standard was very popular in the 2000s. This standard is a PHY amendment that operates in the 2.4 GHz band. 802.11g adapted OFDM from 802.11a into the 2.4GHz band with many of the same technical parameters ported over. The following data rates were available…
ERP-DSSS: 1 and 2
ERP-CCK: 5.5 and 11
ERP-OFDM: 6, 9, 12, 18, 24, 36, 48, and 54
ERP-PBCC: 5.5, 11, 22, and 33
DSSS-OFDM: 6, 9, 12, 18, 24, 36, 48, and 54
With so many different rates, this standard clarifies multirate support. Dynamic rate switching is where devices will change the modulation and coding scheme to increase throughput when signal is good and to decrease throughput when signals are not so good. The fact that all devices must be able to understand the broadcast traffic and management traffic, the lowest order modulations are typically used for transmitting. This significantly impacts throughput on a channel. This is why OFDM only is best practice for modern networks.

802.11-h
This amendment deals with spectrum and transmit power management. It prevents interference in the 5 GHz band to radar and satellites. From this standard we get the dynamic frequency selection (DFS) and transmit power control (TPC).

802.11-i
When I hear of 802.11i I think impenetrable. The standard increased the security using Wi-Fi Protected Access (WPA2) and the robust security network (RSN). It used the advanced encryption standard (AES).

802.11-j
When you see this lettered amendment, think Japan. This standard deals with the operation in the 4.9 to 5 GHz band in Japan.

802.11-e
When I see this standard, I think excellence. The e standard is used to define quality of service (QOS) on a Wi-Fi network. The standard created 4 separate access categories. AC_VO for voice operations requiring the highest QOS. AC_VI for video. AC_BE for regular data traffic and AC_BK for the lowest priority traffic. This form of QOS is probabilistic meaning that it does not guarantee a higher class will gain access to the medium first. It increases the likelihood that a higher class would gain access to the channel before the other classes.

802.11-k
Radio resource management (RRM) serves to facilitate the maintenance and management of the radios in a wireless network. Devices exchange information about the RF environment that allows them to make decisions about how best to operate the network. It also helps devices to roam.

802.11-r
Fast BSS Transition allows wireless clients to quickly roam from AP to AP without having to undergo a complete authentication exchange. This greatly improved the ability for devices to reduce latency or missed packets during a roam.

802.11-y
This amendment allows for high powered Wi-Fi networks to operate in the 3.65-3.7 GHz band in the USA. It operates using the 802.11a protocol. This band requires a light license. There is a nationwide non-exclusive license and a fee per base station fee.

802.11-w
This amendment deals with protected management frames. One of the problems with Wi-Fi is that the management information is passed without encryption. Even with the layer 2 encryption methods, only the payloads are actually encrypted. The open management frames allow attackers to hijack communications and can force clients to deauthenticate from the network causing service interruptions. By protecting the management frames, this prevents these types of attacks from occurring.

802.11-n
This is a PHY layer amendment that added multiple antenna support. MIMO was brought to the wireless networking world. This allowed for multiple spatial streams to significantly improve throughput and performance. This standard allowed for up to 4 spatial streams. The maximum modulation was 64QAM 5/6. There were 32 primary MCS index values and a whole bunch of mismatched modulations. Both the 2.4 and 5 GHz bands were included. RF channel width could increase to 40MHz by combining two 20MHz channels. Theoretical speeds up to 600 Mbps could be achieved.

802.11-p
This amendment adds wireless access in vehicular environments (WAVE). It is designed to provide roadside access via access points to devices in vehicles driving by. A way to remember this one is to think p for pavement.

802.11-z
Tunnelled direct link setup (TDLS) is a way for two devices that are associated with an AP to set up a direct link between each other without going through the AP to pass data directly. This keeps this traffic off the AP and theoretically increases system performance.

802.11-v
This wireless network management standard allows the configuration of a client device to be changed while remaining connected to the network.

802.11-u
When I think of the u amendment I think of ubiquitous. The idea behind Passpoint or Hotspot 2.0 is the idea that our devices can connect securely to networks spread far and wide. Information is exchanged before the connection that tells the device information about the network. Access network query protocol (ANQP) is used to exchange info between the AP and device. The device does not have to connect to the network to receive this information. The connection is also secured with WPA2 layer 2 encryption which is much more secure than connecting to an open network where hackers can listen in on your wireless traffic.

802.11-s
This amendment is the mesh networking amendment. When you think s think mesh.

802.11-ae
This amendment is about prioritizing management frames.

802.11-aa
When you see this amendment think of awesome audio. It allows for MAC Enhancements for Robust Audio Video Streaming. It is concerned with improving multicast traffic over Wi-Fi.

802.11-ad
The way I remember this one is to think almost deaf. This is the WiGig 60GHz standard. It allows for multi-gigabit speeds. The frequency band is really high and does not cover very far. It does have a lot of promise for delivering large amounts of data over short distances.

802.11-ac
This is a PHY layer amendment that only operates in the 5 GHz band. The very high throughput (VHT) PHY added 256 QAM modulation, multi-user MIMO (MU-MIMO) and support for up to 8 spatial streams.

802.11-af
The TV White Space amendment allows networks to operate in frequencies lower than 1 GHz. It is intended to be used in rural areas to provide wireless networks. It uses OFDM modulation. Stations are managed by a geolocation database (GDB) to ensure devices do not interfere with licensed TV operations.

Information about 802.11ax. MCS table for single stream device listed.

What is RF? Radio Frequency waves are an integral part of living in our modern world. The applications for wireless technology are vast. We use radio waves to communicate, cook our food, identify and track items, provide entertainment, triangulate positions, track weather, scan what lies below the surface of the earth and even scan the heavens.

So how is it that signals can be sent through space? Let’s start with the physics. Radio Frequency energy is composed of Electromagnetic waves. You might find the word strange. Can we take any concepts in physics and merge them together. Perhaps we could take gravity and mix it with energy to form grivitoenergy. All joking aside, the first physicist credited with making the connection between electricity and magnetism was Hans Christian Ørsted. It fills the Wifi Viking with pride to know that his gentleman was a good Scandinavian from Denmark.

As the story goes, Hans Christian Ørsted was discharging a current from a battery during a lecture when he noticed the needle of a compass move. He then went on to determine that magnetic lines of force circulate around a conductor as it carries a current.

This brings us to a principle referred to as the right-hand rule. The right-hand rules states that when current flows through a conductor, a magnetic field is created which circulates around the conductor at a 90 degree angle to the conductor. These magnetic field lines circulate in the direction of your fingers when the thumb is pointed in the direction of the conventional current flow. Physics? What? I thought this blog is about Wi-Fi. What does this have to do with wireless networking?

Let’s consider alternating current. It would seem that the right-hand rule only applies to direct current. (Current that only flows in one direction.) For a thought experiment, consider what happens if we start reversing the flow. As the current changes direction, the magnet field lines run in one direction and then the other.

These magnetic lines of force will travel away from the conductor as a wave. An electromagnetic wave is composed of an electric field and a magnetic field. We have discussed the magnetic field with our right-hand rule thought experiment. The electric field is transmitted in the same plane as the conductor and the magnetic field is oriented at a 90 degrees angle to the electric field.

An electromagnetic field is modeled using sine waves. A sine wave represents the voltage or current measured over time. A way to visualize a sine wave is to imagine tracing the perimeter of a circle with a pencil. If you were to look at the circle from the side while you traced it, you would see the tip of the pencil traveling up and down and up and down. It would not look like a circle. If you were to trace this up and down motion on a transparent strip of material that is moving at a constant speed, you would end up with a sine wave. Hooray! Another fun thought experiment.

When we are talking about electromagnetic waves or RF waves, there are several different terms that are used to describe the waveform.

Amplitude = The maximum departure of the value of an alternating current or wave from the average value. This is the strength or height of the wave. The maximum or minimum value of the amplitude is referred to as peak.

Wavelength = The distance between corresponding points of two consecutive waves. The distance over which the wave’s shape repeats. The is often referred to using the Greek letter λ (Lambda).

Frequency = The rate at which something occurs or is repeated over a particular period of time or in a given sample. Normally RF waves are measured in cycles per second or hertz. For the example below we will assume that each vertical division represents 125 ms. All eight squares represent one second. The frequency of this signal is eight cycles per second or eight hertz.

Phase = the relative position of two different waves at a specific point in time. The phase difference is measured on the zero axis between two corresponding points on the waveform. Here is an example of two waveforms 180 degrees out of phase. In this orientation, the waves will cancel each other out.

Now that we have gone over the different properties of waves, we can discuss how these different methods are used to encode data onto the waveform. Wireless communications have been accomplished using amplitude modulation, frequency modulation, and phase modulation. This process of encoding bits onto a waveform is known as keying.

Amplitude shift Keying = the amplitude of the waveform is varied over a set period of time to indicate either a 1 or a 0. One amplitude level is one state and another amplitude value is another state. The image below has a value of 01011010.

Frequency shift keying = the frequency of the waveform is varied over a set period of time to indicate either a 1 or a 0. One frequency represents a 0 and another frequency represents a 1. The image below has a value of 01011010.

Phase shift keying = the phase of the waveform is varied over a set period of time to indicate either a 1 or a 0. No phase shift represents a 0 and a phase shift represents a 1. The image below has a value of 01011010.

These different basic modulation keying methods can be complicated to include additional levels, frequencies and degrees of phase shift. Quadrature Amplitude Modulation (QAM) uses amplitude and phase modulation to encode data onto the waveform.

Thank you for watching my video today. Skål. Here’s to all you network engineers and anyone who is interested in Wi-Fi out there. Good luck building your wireless networks. This has been Bryan Noe. Have a wonderful day.