The WatchMe Project Presented by: Elad Weiss Nir Maoz Supervised by: Edward Bortnikov

Problem Description What is "WatchMe”?

Location Awareness You Are Here Until today… ?

Location Awareness You Are Here Until today…The WatchMe way ? And Going Home

Project Goals 1. A Server-Client Application 2. Static Location Recognition 3. Dynamic Location Recognition 4. Implementation Over SIP

Implementation Algorithms & System Operation

Figuring out your location: Get the strengths of the access points’ signals. Calculate the distance to each access point. Use the triangulation technique to find your true location using as many access points as possible. Location Pinpointing

Location Pinpointing cont.  A plot of real signal strengths and their corresponding distances from the access point.

Location Pinpointing cont.  A plot of real signal strengths and their corresponding distances from the access point.  We used the equation from another project, and changed the constant multiplying the exponent, to a function of the signal strength (determined by many tests & measurements).  This was later realized to be very much like a polynomial curve fit, as shown above.

Path Recognition 0%20%40%60% Path Completion Percentage: 50% Path Required Activation Percentage: Path X is now active. Your status is: X.

And for your friends:

Communication Server Communication Handler Client Communication Handler INVITE SIP/2. Via: SIP/2.0/UDP :1103 Max-Forwards: 70 From: "Alice W." To: "Bob G." Call-ID: CSeq: 1 INVITE Contact: Content-Type: application/sdp Content-Length: 105 The server acts as a bridging unit between the RTC and SIP protocols.

Communication cont. SIP messages content  in XML! ADD_STATUS <signal ap=“ D- <signal ap=“ REMOVE_STATUS <location x=“5” y=“4” z=“3” map=“floor3.jpg” />

Server structure Server Communication Handler Server Application 1Server Application 2 Server Application n Server Data SIP method = “…” WatchMe header = “…” Synchronized Database SQL

Request 1: SIP method = “…” WatchMe header = “…” Thread Assignment Call Flow Server Communication Handler SIP Request Request n … Request 3 Request 2 Request 1 Work Queue Server Application X running on the assigned thread

The Development Process Difficulties & Solutions

Difficulties  The RTC client implements the SIMPLE protocol, which has not been officially published yet.  Documentation is poor.  There is no standard for the specifications.  Some examples:  Offline (SIMPLE) = Away (RTC)  RTC sends SIP MESSAGE requests through a session. In SIMPLE, these SIP requests are not bound to a session.  Some headers are critical for RTC to work, but RTC seems to forget sending them himself.  Solution:  Trial & Error.  Some more Trial & Error.

Difficulties cont.  The RTC Client doesn’t run on an iPAQ.  Solution:  Switching to a laptop.

Difficulties cont.  Wireless signal detection  Packages only available for Windows CE and Java™.  There exists a Win32 C++ package that uses a method, which won’t be supported in the future.  Solution:  Writing our own package (WirelessNet.dll).  We used WMI for accessing the driver.  Microsoft encourages the use of WMI over other methods – such as device IOCTL (which we had tried).

The Development Process Conclusions & Acknowledgements

Accomplishments  What we’ve learned:  Dealing with new environments: iPAQs / Laptops with wireless adapters.  Programming close to the driver level (this was not planned).  New communication protocols:  SIP, SIMPLE (RTC).  New MIME formats:  XML, SDP, PIDF.  Programming in various environments and languages: .NET Framework.  Java™  C#  SQL  Working with several packages:  JAIN-SIP, RTC, OpenNetCF (though we did not use it eventually).

Remaining Problems  The use of signal amplitudes (a.k.a. RSSI) for distance determination is highly inaccurate.  Some interfering factors are:  Background noise.  Obstacles (such as walls, doors etc…).  Angle confronting the AP.  Each NIC has its own accuracy.

Proposals for the Future  AM is known to be more prone to interference and distortion. Possible solutions: I.Arranging the APs in such a way, as to get a better signal from as many APs as possible. II.A GPS guided laptop, would make the program much more realistic, improving the accuracy of location & path recognition to a great degree. III.Adding a third dimension could help improve location determination by a small factor.

Proposals for the Future cont. iPAQ issues:  WinXP  WinCE will require the client program to use a different GUI, since the one already employed, uses a lot of WinXP features, not to be found in WinCE.  The benefit, of course, will be the increased mobility.  Signal detection should be easy to convert since WinCE allows you to use OpenNETCF’s wireless interface.

Software We Used  Microsoft Visual Studio.NET 2003  Eclipse  Microsoft Office Visio 2003  Microsoft PowerPoint 2003  Microsoft Word 2003  Adobe Photoshop 7.0  Notepad  …

Related Links  - RTC  - JAIN SIP  - RFC’s, documents…  - The SIP Protocol  - DDK  - Google

Acknowledgements  We would like to thank:  Victor Kulikov  Yoram Yihyie, Hai Vortman  Yoel Davidson  Orit Shteif  Palram Industries