Introduction to Wireless

Introduction to Wireless!

This probably should have been my 2nd post after the "Intro" post but its never too late to create a post on introduction to wireless.

Quick overview of what you will learn:

*         What is Wireless?

*         WPAN/WLAN/WMAN/WWAN

*         Standalone AP and Controller based AP

*         802.11a/b/g/n and 802.11a/c

*         2.4 GHz

*         5.0 GHz

*         Interference

*         Why Wireless Skills Matter

*         Different Types of Cisco Access Points

Lets define wireless:

       Wireless is: Not using wires to send and receive electronic signals: sending and receiving electronic signals by using radio waves.

Lets define Radio Waves:

Radio Waves are: An electromagnetic wave that is used for sending signals through the air without using wires.

4 Common Types of Wireless Networks you will hear about:

*        WPAN – Wireless Personal Area Network

•      Works in a very small area (5 to 10 meters)

•      Mice, keyboards, headsets that connect to your computer

•      Think of Bluetooth

*        WLAN (Wireless Local Area Network)

•      Works typically around an area of under 100 meters

•      Think of the wireless network you have at your house or office

*        WMAN -Wireless Metro Area Network

•      Low budget, bridging network.

•      Alternative to T1 or 3 point to point leased lines. 

*        WWAN (Wireless Wide Area Network)

•      Cellular service providers – Example: AT&T nationwide GSM cellular Network.

2 types of access point modes you will hear about:

v  Access Point in:

•       Standalone Mode – No WLC

•      Router (layer 3)

•      Switch (layer 2)

•      Wireless Access Point standalone

•      End Devices (Wireless phone, ipad, laptop, etc)

•      Access Point – Lightweight Access Points –
(LWAPP/CAPWAP – Controller Mode)

•      Router (layer 3)

•      Switch (layer 2)

•      Wireless Access Point (LAP)

•      Wireless LAN Controller

•      End Devices (Wireless phone, ipad, laptop, etc)

We still need the wireless NIC on the client side for everything to complete the list of component
for a wireless network.

Be familiar with the following terms:

v  IBSS (Independent Basic Service Set) – Ad Hoc

•      Wireless NICs and other devices can communicate directly without the need for an AP.

•      Peer to Peer

v  BSS (Basic Service Set) – The area/cell defined by the wireless signal served by the AP.

•      It might be referred to as BSA.

•      Single AP

v  ESS (Extended Service Set) –

•      Most common in a corporate environment

•      All access points to the same SSID

•      Roaming ability takes place

v  SSID (Service Set Identifier ) – Unique 32-character identifier

Now lets go over 802.11a/b/g/n:

*         Narrow band and spread spectrum are the two main ways of sending a signal

*         802.11a operate at:

*         5.0GHz band

*         Uses OFDM with modulation formats that are available: BPSK, QPSK, 16-QAM, 64-QAM

*         802.11b operate at:

*         2.4GHz band

*         Uses DSS (Direct-sequence spread spectrum) with CCK or PBCC modulation formats.

*         802.11g operate at:

*         2.4GHz band

*         Uses either OFDM or DSS and the modulation formats are set according to the data rate.

*         802.11n operate at:

*         Can operate at both 2.4GHz and 5.0GHz band

*         Uses DSSS but prefers OFDM (Orthogonal frequency division multiplexing)

*         MIMO + OFDM

*         802.11a/c operate at:              

*         5.0GHz band with support for backwards compatibility with other 802.11n technologies operating in the same band. MIMO + OFDM

*         802.11ac AP Support up to 8 data streams (Each stream at 433Mbps)

*         Max speed 1.3Gbps

*         Samsung Galaxy S4 chipset only supports 1 single stream (up to 433Mbps in speed)        

Its always a good idea to understand the basics above. Don't worry too much about the modulation 
techniques just yet!

Now lets take a look at 5.0Ghz

2 terms that you should understand are:

v  RSSI – Received signal strength indicator

•       The measure of signal strength that arrives at the receiving device.

•       The lower the number to 0dBm would indicate a stronger signal

•       Grade value from 0 to 255 with each grade value is an equivalent dBm (decibels to a milliwatt) value.

•       The scale will be different from one card vendor to another.

•       Anything above SNR of -72dBm would mean the client is far away or signal is weaker

v  SNR – Signal to Noise Ratio

•       Comparison of the amount of signal as compared to the surrounding noise.

•       The higher the SNR the better. (Anything between 25dB to 40dB SNR is very good signal)

Now lets talk about types of interference's that can weaken or disrupt your wireless signal:

*         Types of signal interference:

•       Physical interference – Easier to see.

•       A cordless phone sitting next to an AP.

•       Plants and Trees

•       Microwave ovens

•       Hidden physical interference – difficult to mitigate. Think about: What is inside those walls?

•       An Exterior wall that consists of brick and thick insulation can cause interference and its not easy to see.

•       Lead paint

•       Bulletproof glass (you might think nothing of it but the degree of attenuation is high )

•       Channel interference – Other wireless devices on an overlapping channel.

•       Neighbor APs using channels that is interfering with the AP channel that ones own is on. 

So what happens when there is interference? Well, the wireless signal range is degraded, 
data throughput decreases and you may end up having complete signal drops or intermittent signal 
drops.

Why do wireless skills matter?

Wireless as grown tremendously over the years. Not many people know how to properly design, 
configure and manage a wireless infrastructure. It is an advantage to be not only good but great
with managing a wireless network. As more and more wireless devices come into a network, it
will be up to you as a wireless engineer to train, maintain, support your staff with ease if you
take the time to learn and understand the art of wireless!

I highly recommend going with Cisco because when it comes to wireless deployments because
Cisco gets the job done! Feel free to correct any mistakes I've made or ask me any questions. 
Please check out my twitter and instagram! Most images are courtesy of Cisco, Apple, Wiki,
Ciscolive. I strongly encourage you to visit and register for free at www.ciscolive.com if you 
want to learn more. The site offers free resources from industry experts like myself. 

Thank you for visiting!!!


Cisco 3700 Access Points (802.11ac)

Cisco 3600 Access points (support for 802.11AC with module)

Cisco 2700 Access points (3x4, 802.11ac)

Cisco 1600 Acces points (entry-level)