Using a GPS to perform a Wi-Fi survey

It is important to perform a wi-fi survey so that you can determine not only the perfect place to locate your access point or bridge but to gain an understanding of the channel co-existence challenge you may face.  With wireless access points in surrounding neighborhoods and businesses, you will need to  perform a survey by walking around and mapping out the BSAs (Basic Service Area) of wireless that surrounds you and your organization.

Below is an example of our school’s perimeter.  Matt, Chris and James, students in the Computer Information Technology, class performed a survey using a Microsoft GPS and Vistumbler.  This survey revealed access points and their channels of current wireless at our institution and  includes APs in surrounding businesses and neighborhoods.  These were mapped using Google Earth after exporting their KML file from Vistumbler.

This type of survey allows IT professionals to analyze data exported to ensure the correct channels can be used at their organization.

Miller Goodroe Felts

After exporting the wireless information, you can analyze each access point or wireless device by clicking on it.  Below is an example of the information exported into Google Earth.   Each device shows SSID, Network Type, Mac Address, Channel, Security, Encryption Type, Data Rates, Latitude, Longitude and Manufacturer information.   Analyst using this information can also determine the best placement of wireless devices along with channel information.

ESSID Expanded

Channel co-existence is when access points share channels that are very close to one another.

802.11 wireless on 2.4 Ghz has three non-overlapping channels.  These channels are 1, 6 and 11.  The closer channels are, the more likely interference will take place.  With the amount of wi-fi in use today, IT professionals have to chose between 2.4 Ghz and 5 Ghz and and try to select channels that are not in use if possible.   Professional access points and bridges can also adjust power as necessary.   A dense population can make this very challenging.

If you look at the students’ survey by zooming out to see how many access points can be seen, this is what you are looking at!  Now you can see why site surveys are important at your organization.

Exploded

In addition to this survey, a secondary survey using a spectrum analyzer is very important to search for interference from other sources.  (See our review of the Airview Spectrum Analyzer)

analyzer-software

Channel information (Chart from Wikipedia)

NonOverlappingChannels2.4GHzWLAN-en.svg

Here’s another look at a wireless survey showing vertical lines and signal strength.  (James M. KML survey)

Another view James Miller KML

Enable NetBIOS over TCP/IP

If you have several computers on your network and would like to see the computers on your network, Enable NetBIOS over TCP/IP to speed this process up.  NetBIOS allows computers to be seen by name on your network.  Enabling NetBIOS allows your computer to find other computers in your network (Network or Network Places).

To enable NetBIOS over TCP/IP on Windows 7:

  1. Click Start, and then click Network. (click Start, type ncpa.cpl into the search box for Windows 7 or Vista, hit ENTER).
  2. Click on the Network and Sharing Center
  3. Click Manage Network Connections.
  4. Right click on the Local Area Connection select Properties.
  5. Select Internet Protocol version 4 (TCP/IPv4)
  6. Click the Advanced button under the General tab.
  7. Click the WINS tab.
  8. Click Enable NetBIOS Over TCP/IP.
  9. Click OK and Exit the settings.

Improve Your Internet Speed – Read the Article
Are you IPv6 Ready?

Setting up WINS

AMD vs Intel Quad Core Shootout

Want to optimize your computer? See our checklist!

See our review of Windows 8 and see how you can run 90% of your programs, virtualize other operating systems, use your network and more.

Now Tweak your wireless!!

Scan your network with SoftPerfect’s Network Scanner

Best Free Wi-Fi Tools

One of the best wi-fi tools you have on your Windows based computer is netsh.   Netsh can be used to find out information about wi-fi.

Open a command prompt and you can use these tools…

netsh wlan show networks

Netsh One

netsh wlan show networks mode=bssid

Netsh Two

inSSIDer

- Uses your current wireless card and connection software
– Works with Windows XP, Vista and 7 (32 and 64 bit)
– Compatible with most GPS devices
– Track the strength of received signals in dBm over time
– Sort by MAC address, SSID, Channel, RSSI, and Time
– Export Wi-Fi and GPS data to a KML file in Google Earth

Inssider

Vistumbler  (GPS Capable)

  • Find Wireless access points
  • GPS Support
  • Export/Import access points from Vistumbler TXT/VS1/VSZ or Netstumbler TXT/Text NS1
  • Export access point GPS locations to a google earth kml file or GPX(GPS eXchange format)
  • Live Google Earth Tracking – Auto KML automatically shows access points in google earth.
  • Speaks Signal Strength using sound files, windows sound api, or MIDI

Vistumbler

NetSurveyor

  •  6 graphical, diagnostic views:
    *Timecourse of Beacon Qualities For Each Access Point
    * Differential Display of Beacon Qualities for Each Access Point
    * Usage of Each of the 802.11 Channels
    * Timecourse of the Usage of Each of the Channels
    * Heatmap / Waterfall Chart of the 802.11 Channels
    * Channel Spectrogram of the 802.11 Channels. The more (and different) ways you have at looking at data then the greater the chance something will catch your eye that you might otherwise miss if only a single type of chart were used.
  • Generates reports in Adobe PDF format
  • Powerful and innovative logging and recording capability.NetSurveyor’s playback mode is unique in that it shows you all the recorded data

NetSurveyor

Xirrus

  • Find Wi-Fi networks
  • Managing and troubleshooting Wi-Fi connections
  • Verifying Wi-Fi coverage
  • Locating Wi-Fi devices
  • Detecting rogue APs

Xirrus

What GPS have we used successfully and easily installs in Windows for the GPS Wi-Fi finders above?  The Microsoft GPS Receiver.   The receiver is small, light weight and installs easily.

Microsoft
Our class uses a scientific method of studying wireless and security.  With hands-on during every term (not in a closed lab like a majority of higher-ed institutions), the classes we teach really enjoy the study of wireless and analyzing signals.   During a recent study we found over 380 access points of which 50% were unsecure.

WiGLE has a global map drawn up by wardrivers.   Viewing the maps is scary – really, really scary.  These online GPS maps show secured and unsecured networks.

How to secure your access point- Linksys Belkin Netgear 2wire DLink

Attaching to unknown networks that are unsecured and not public is both dangerous and illegal.   Actually connecting to wireless  hotspots can be dangerous (See our article on attaching to HotSpots).   You should always use a vpn when connecting to a hotspot.   There are now applications that allow laptops, netbooks and droids to be setup as hotspots.  With packet capturing software, your data can be intercepted if you don’t use a vpn.

Improving your wireless signal is actually is easy.  For as little as $40, you can gain (from 30mw) to 1000mw or even 2000mw with the Alpha Antenna.  With a standard laptop, we see approximately eight access points.  With the Alpha we see approximately 14, and with a large antenna we were able to see 44 access points.

So what if you get a larger antenna?  There is a balance of antenna type vs. antenna gain.  A larger antenna can be better,  if it is not too large.


Decibels in relation to power gain:

20 dB is an increase of 100X in power
10 dB is an increase of 10X in power
6 dB is an increase of 4X in power
3 dB is an increase of 2X in power
2 dB is an increase of 1.6X in power
1 dB is an increase of 1.25X in power
0 dB is no increase or decrease in power

Decibels/dB, how to understand their relationship to power loss:

1 dB loss: 80% of power remains.
2 dB loss: 63% of power remains.
3 dB loss: 50% of power remains.
6 dB loss: 25% of power remains.
9 dB loss: 12.5% of power remains.
10 dB loss: 10% of power remains.
12 dB loss: 6.25% of power remains.
20 dB loss: 1 percent of power remains.
(Therefore professional wireless cards have to be used for larger antennas)

(Calculators)

If you add an antenna (yagi, omnidirectional) and need to add cable, make sure the total attenuation or loss is no more than about 3 db at 2.4 GHz or you could lose half of your total transmit power before it even reaches the antenna.

Specs on the Alfa Antenna ~

* Compatible with IEEE 802.11n, 802.11b/g/n wireless standards
* 2.4GHz frequency band, MIMO (Multiple Input Multiple Output)
* Complies with Universal Serial Bus Rev. 2.0 specifications
* High speed transfer TX data rate up to 150 Mbps
* Supports WPS by S/W
* Supports wireless data encryption with 64/128-bit WEP, WPA, WPA2, TKIP, AES
* Wide Range coverage
* Compliant with FCC Part 15.247 for US, ETS 300 328 for Europe
* Works with Windows 2000, XP 32/64, Vista 32/64, Windows 7 32/64.

Specifications:

- IEEE 802.11b/g/n standard
– USB 2.0 standard
– Up to 150Mbps for 802.11n connections
– Frequency Range: 2.412~2.483 GHz
– Receive sensitivity 11b: -92dBm, 11g: -76dBm, 11n: -73dBm@HT20, -70dBm@HT40

Want to further analyze signals? Use a Spectrum Analyzer ($40+).

If you are looking for an economical solution the 2.4 Ghz Spectrum Analyzer by  Ubiquiti  is an excellent buy and is around $40+ – with an external antenna (AirView software is free)  My recent purchase for our class (personal purchase) is an excellent production and teaching tool.

A Spectrum Analyzer normally cost several hundred dollars.  This solution is an excellent solution for viewing the distribution of RF energy in the 2.4GHz band.   By viewing the analyzer, you can determine which channel has the least interference and select an appropriate channel for maximum performance.

See How it works- Link

Product Information

You must purchase the hardware in order to use the software.

Excellent Product for the money.

Xirrus Wi-Fi Inspector

My two personal favorite Wi-Fi Inspectors are NetSurveyor and inSSIDer. Another great application is Xirrus Wi-Fi Inspector which is a powerful tool for managing and troubleshooting the Wi-Fi on a Windows XP, Vista, or 7laptop. Built in tests enable you to characterize the integrity and performance of your Wi-Fi connection. Applications include:

  • Searching for Wi-Fi networks
  • Managing and troubleshooting Wi-Fi connections
  • Verifying Wi-Fi coverage
  • Locating Wi-Fi devices
  • Detecting rogue APs

Don’t forget about Vistumbler which offers GPS information.

Over-Provisioning and SSDs

Over-provisioning is the allocating of a specific amount of free space on your SSD.  Over-provisioning improves SSD endurance and performance.   Many SSDs are packaged with software that helps the end user install the drive and to plan for OP.  (More advanced drives are doing away with OP).

The SSD controller manages all of the data that is stored on the drive.  While these drives are really fast, data writes are not just placed on the drive.  Data is moved around and the controller on the drive is programmed to use the drive evenly across the NAND blocks.   By moving the data around, the controller can use the free space (OP) to swap information as needed.     This in turn adds life to your SSD.  Always update your SSD firmware, use the manufacturer’s software for OP if your drive recommends it and don’t forget to trim your hard drive.  TRIM allows for the removal of junk or old data.  How? Easy – Open a command prompt (as Admin)

Type the following - fsutil behavior set DisableDeleteNotify 0

Over-provisioning in Samsung Magician’s software.

OP

Always load the drivers – Below is Intel Drivers on my laptop vs. Windows 8 generic drivers

drivers

Windows 8.1 SSD Optimization

If you have install an SSD to Windows 8 or 8.1, and you aren’t sure if the OS is optimized for an SSD. Here’s the fastest way to make sure it is optimized.

Open a CMD prompt as an Administrator
Run winsat formal
Defrag will remain on, that’s right, on. After ‘seeing’ the SSD, this tool (defrag) will become optimize and will trim your SSD.
Of course AHCI should be on, over provisioning accounted for and the proper chipset drivers loaded.