Location Based Services (lecture 4)
Written by: Jonathan Briggs
February 22, 2007 [1523 views]
Let us start by considering the following results from last week’s activity.
You were asked which of the following applications could make use of the tracking technology described in the articles provided. Here is the percentage of respondents that thought the technology would support each application.
- Tracking your teenage daughter 81%
- Alert me when my friends are nearby 74%
- Marking the area in which the tracked phone is located on a map 73%
- Tracking a member of your sales staff 69%
- Finding a lost phone 67%
- Sending out targeted advertising to customers in the area 62%
- Finding the quickest route between your current location and the location of a phone being tracked 50%
Each of these is a location-based application and the possibility of each is dependent on a number of factors:
1. The technology being used to measure location
2. The additional technologies are being used
3. Business models to provide the service
4. Privacy and security issues
Technologies to measure location
1. Cell position
- available as standard to mobile phones
- relies on network to record which mast is communicating with the handset
- accurate only to the size of a cell (500m – 12km)
2. Cell triangulation
- possible but not available through standard “track me services”
- expensive for the networks to implement
- relies on measuring position (through distance estimation) from 3 masts and computing the intersecting location
- accurate to about 100m (but may not be 3 masts in range in rural areas)
3. GPS (radio receiver!)
- not built into most phones yet
- also works on triangulation by measuring distance from satellites in known orbits around the earth
- does NOT communicate with the satellite, only receives timed signal. Computes the delay in the signal to work out the distance
- accurate to about 10m in areas with clear view of the sky
- Japanese combine GPS, LBS and a compass!
4. Assisted GPS
- combine the power of GPS and mobile
- GPS provides the basic positioning information
- mobile channel provides access to servers with huge processing power and ability to predict position from limited GPS data
- may also provide location specific information for the customer or application
- accurate to about 10m in most areas (where implemented)
Now consider each of the applications above
Tracking your teenage daughter
- many services available to provide cell level tracking
Alert me when my friends are nearby
- would need friends to register as friends (MySpace perhaps)
- would need a server based application to monitor cell positions of each phone and alert “friends” when others entered the same cell
- would need all participants to opt-in
- not clear how it could be offered as a 3rd party service: would require the colloboration of the networks
Marking the area in which the tracked phone is located on a map
- standard part of most tracking services
- could be easily built using Google or Yahoo! Maps
- would not allow you to follow a journey in detail without a GPS
Tracking a member of your sales staff
- exactly the same as your teenage daughter
- tracking sales reps cars would be better done using a dedicated GPS tracking device
Example of a vehicle tracking device
Finding a lost phone
- think carefully about this one! cell area accuracy would be useless
- even with GPS the maximum accuracy is about 10m
- try and spot your phone in a crowded room!
Sending out targeted advertising to customers in the area
- needs the collaboration of networks to provide information on cell location
- expensive (and forced opt-in) if using LocateMe services
- might be easier with Bluetooth
Finding the quickest route between your current location and the location of a phone being tracked
- straightforward add on to LocateMe services (or GPS services) but needs route-finding and mapping application
Privacy and security
Here are the results from your answers to this week’s survey…
- Want to track other people 40%
- Do not want to be tracked 70%
- Think employers should be able to track 27%
- Believe tracking could solve crimes 84%
- Think police should be able to track 48%
- Think parents should be able to track 60%
- Think consent should be required 81%
- Want tracking to be more accurate 74%
- Would avoid being tracked 51%
- Want local content 59%
- Want improved “find my nearest” services 85%
These results appear (as expected) to contradict each other. How can we use LBS to solve crime if everyone has to opt-in to being tracked? How can you be offered improved LBS services when you want to avoid systems knowing where you are? People want the service but not the lack of privacy.
Recent comments:
What do you think?
On March 1, 2007 at 10:12 PM, sk wrote:
this lecture got me really thinking last week in reference to how GPS works, as you said they have receivers and listen for signals from the satellite, u said it's not possible to trace via gps,
wot i was thinking more along the lines was that a satellite sends signals down and waits for the signal to dissappear when a gps picks up the signal,
would this be possible?
Jonathan replies: No! Think radio. A radio transmitter does not know that it has been listened to! Indeed the signal does not reduce in strength just because someone is listening. It is not consumed!