00180 Helsinki, Finland
Tel: +358-20-743 5910
Fax: +358-20-743 5919
On February 10, 2006, I interviewed Antti Korhonen, President and CEO of Ekahau, Inc. I discovered a series of products and technologies that address the where is it and where are they problem in elegant ways. Ekahaus products address the need to track assets and people.
Have you seen me? Do you know where I am?
Korhonen provided the example of a hospital, a setting with many customers and lots of movable, expensive equipment. A hospital has considerable capital invested in movable assets, from video monitors to gurneys to wheelchairs. Not knowing where these assets are can mean problems with critical care, redundant ownership and poor use of resources.
Ekahau sells three products (which are further described below):
- Site Survey
- Positioning Engine
- Wi-Fi Location Tag.
- They use existing Wi-Fi infrastructure no proprietary hardware
- Active Wi-Fi tags allow rapid deployment
- They permit rapid mapping of the enterprise for Wi-Fi propagation assessment.
The site survey product allows rapid mapping of the enterprise workspace (it typically takes an hour for every 10,000 sq.ft.). A map is generated showing signal strength by Wi-Fi node, network coverage, and signal to noise ratio. The map can handle queries such as show me the areas of signal level greater than 70 decibels. It allows for precise mapping of the workspace so that location can be determined down to one meter. This means items can be tracked by building floor.
The positioning engine works in real-time and combines signal strength with site calibration to display positions on a map of the workspace. The engine can show the position of any device connected to the Wi-Fi network, such as laptops, PDAs or Wi-Fi tags.
Wi-Fi Location Tag
This tag is similar to an RFID tag except it is active (battery powered) and works on a Wi-Fi network. It has a call button feature that lets the person wearing the tag identify that they need assistance by pushing a red button.
Have you seen the Doctor? Where is the patient?
A feature of the Ekahau solution is the way it establishes position. A simple method of triangulation is used for locating any radio transmitter, cell phone, or Wi-Fi enabled device. It measures signal strength or decay of the signal received at three or more points. This establishes a set of bearings and triangulation, and looks like this.
In a Wi-Fi environment there is also signal overlap (bearing to the location) and position can be determined in the same way. However, there are other factors that make the process more complicated. Network coverage may not be uniform and the frequencies are prone to reflection and refraction, making the signal path and the resultant signal strength measurement more complex. In the example below, it would appear that there are three nodes that are the paths to the target location (sources #1, #2 and #4).
But the actual case may be more like the image below, with multiple paths due to the nature of the environment. Multiple paths provide more signal sources and a more complex set of problems for determining location.
One of the advantages of the Ekahau system is that in surveying the site, measurements are made across the workspace that allow for a form of what is called radio finger printing. It uses three factors. First, the location signal source -laptop, PDA or Wi-Fi tag- has unique characteristics. Second is the IP address of the location (target) signal source. Third, the signal characteristics of the target source itself have unique fingerprints, as do the Wi-Fi access points collected by the site survey.
Site Survey Map
These three factors allow for creation of a database of unique characteristics. The result is that the target signal source (laptop, PDA or Wi-Fi Tag) can be located with 1 meter and its location can be displayed on a map in real-time.
Not only does this work well for finding assets, it works especially well for locating the nurse who is having problems with a patient and needs help, because the Wi-Fi location tag has that assistance needed button.
Ekahaus products move beyond merely measuring signal strength at a point they provide more definitive location information. Using the technology in a building, you can track an asset to a specific floor and determine its location on that floor. When you need to find people and assets, the ability to know their locations within a minimal range is very important.
These products offer a degree of elegance. If you need to know where things are in your facility and would like to start by seeing your existing Wi-Fi coverage, you can download the trial Site Survey software.