Wireless Access

What is a Wireless Site  Survey?

A really fast definition and  straigh to the point would be  the design and planning of a Wireless Network

Types of Wireless Site Survey

1. Passive Site Survey
   
2. Active Site Survey
   
3. Predictive Site Survey
   

Passive Site Survey

What is?
This is the most usual type of site survey, or at least is what i think.  Its done on site, and what you do its collect data of the radio frequency enviroment,  you dont need to connect to any AP in this type of Site Survey

What type of Data you can collect with it?

• Signal Level
• How much interference is on the Area
• How many APs
• Placement of APs
• Requirements such as BW per Device
• Etc

Example of Tools Used

• Wifi Testers for example a Fluke AirChecker( One of my favorites!)
• Wifi Analyzer

Active Site Survey

What is it?
This type of site survey does a more indeep study than the passive one, as you will be connecting a device or deveices to get more specifc infomration

What type of Data you can collect with it?

• TCP Troughput(uptream/downstream)
• UDP Trhoghput(Uptream/downstream)
• Get an idea of the performance of the AP in expected scenarios
  

Example of tools used

• Application that generates network traffic
• Devices(laptops, smartphones etc)
• Applications that can measure thoughput rate
  

Predictive Site Survey

What is it?
In this type of site survey you simulate with a program where should be placed the APs,  how many APs you need and all this is done by inputing some building plans in the soflware

What type of Data you can collect with it?

• Number of APS
• Placement of APS
• Etc

Example of tool used

• Visual RF(In our case)
• Vendor specific simulator( Mosf of Wifi vendors got their own simulator)
• AirMagnet
• Etc

Survey Requirements:

You see that i have mention before Requirements? well when i say requirementes i mean things that you need to ask the client to take in mind for your design

• Bussiness REquirements: Why is the bussines asking for Wifi? asnwering this can give you the idea of the wifi architecture you will need
  
• Coverage vs Capacity:  Here you need to take in mind or ask the client how many devices will be connected to the wifi in a specific areas, so you know if you need more than one AP(Lately you will notice that most of the client are starting to pick capacity over coverage).  But still you will see some clients which just need coverage as they just want wifi for some random users and high level users like managers, owners, and other type of users like guest.
  
• Devices Requirements: How much BW does the devices need? what kind of deivces are expected? there would be a lot of cellphones? if so you migh be thinking then that you need no less than an RSSI of -65 even -60 for those.
  
• Cell Planning: Yes when you are doing High Density you need a Cell planning.  You will be using 20mhz or 40mhz channels on 5ghz? how many channels you would need?  Are you using dual band dual radio APS? then you should be thinking in surveying for 5ghz as well
  

This small techincal guide will give you an idea of what site survey is about i mean an overivew of it.

Cheers

Carlos

Carlos

Being new to the industry I'm unsure what a good RSSI should be when doing a site survey and when to add/move AP's due to area's under performing RSSI. When surveying an area, what RSSI should you aim for and does this change depending on the devices that connect to the network. E.G. laptops, tablets, phones. You mentioned in your message a RSSI value of -60 to -65 if there is a lot of cell phones. I imaging the device reading the levels would affect your readings or are the RSSI values an absolute level irespective of the receiver.

Thanks again

Wayne

Hello StoneWall

Yes it depend on the reciver  :)

My fluke would give me something else different than someone using a crappy cellphone with wifi analyzer :)

Cheers

Carlos