The Location-based WiFi Services system: A Complete Open Source Solution for Wi-Fi Beacon Stuffing Based Location-based Services

0. What is LoWS?

Omnipresent Wi-Fi access points (APs) periodically broadcast beacon frames to inform potential stations (STAs) about their existence. Beacon frames can be extended by adding additional information (so-called beacon stuffing) making it pos- sible to deliver this information to mobile devices (smart-phones, tablets, etc. equipped with 802.11 interfaces) without the need for their association with the local infrastructure. This feature can be used to support location-based information services (LBS) related for e.g. to advertising local opportunities, temporary obstacles and traffic disturbances or emergency notifications. The Location-based WiFi Services system is the technical solutions for LBS support of using 802.11 beacon stuffing. LoWS supports an original, highly efficient way to encode the delivered information. The LoWS system can be integrated in an existent 802.11 infrastructure while the receiver application can be installed on commercial off-the-shelf Android devices. The LoWS system is modular with well-defined interfaces making it to an attractive tool for modifications, changes and improvements.

1. Repository Description

1.1 LoWS-Receiver-Application (Sources in Subfolder LoWS-Receiver-Application)

• Here the Android source code is stored, the complete Eclipse projects can be found in the subfolder "Source", the javadoc for the Android source can be found in the subfolder "javadoc".
• In the Source subfolder the folder "release_apk" the apks which can be used to install the LoWS-Receiver-Application and the broadcastreceiver example are stored.
• The "Backups" folder contains the sources as .zip file.
• The "LoW-S" folder contains the eclipse project for the LoWS Receiver Application including the complete source code.
• The "lowsbroadcast" folder contains the eclipse pro- ject for the lowsbroadcast receiver example which shows how to receive LoWS messages within an external application.

1.2 LoWS Control / LoWS-Control-DB (Sources in Subfolder lows-control and lows-control-db)

• This is the LoWS Control Program prototype, realized using PHP and MySQL, the corresponding MySQL database can be initialized by importing the file "create-lows- control-db.sql" in the subfolder "lows-control-db".
• An apache with PHP plus an MySQL server is needed.
• It is also useful to run an DHCP server on the same machine but not necessary, for our experiments we used the address space 192.168.68.0/24 while the LoWS-Control used 192.168.68.1

1.3 Local Codebookserver (Sources in Subfolder codebookserver)

• This is the local codebookserver implementation, also realized using PHP. For our experiments we ran the codebookserver on the same server as the LoWS-Control, therefore the access from the codebookserver to the LoWS-Control-db worked locally, if the local codebook server should run separately, the connection to the LoWS-Control-db has to be adjusted.

1.3 Global Codebook Address Server (Sources in Subfolder gcbas)

• This folder contains the Global Codebook Address Server also implemented using PHP, we ran this code on a separate machine using apache with PHP and a MySQL server. The Global Codebook Address Server DB can be installed by importing the file "gcbas-database.sql" from the MySQL server. The access to the database requires login credentials these have to be modified within the "address-handler.php" file.

1.4 OpenWRT Files (Sources in Subfolder OpenWRT)

• This folder includes all source code which was used on the OpenWRT access points. The subfolder "hostapd-add-ie/openwrt" contains the patch for enabling the additonal setting of IEEE 802.11 IEs within hostpad via the hostapd_cli daemon. The folder "hostapd-add-ie/hostapd-2.2" contains the full hostapd source with enabled IEEE 802.11 IE adding support via hostapd_cli which can be used on a standard x86 machine.
• The subfolder "beaconspammer" includes the beaconspammer" source code with a Makefile for OpenWRT. The paths in the Makefile have to adjusted to allow crosscompiling.
• The subfolder "mac80211-radiotap-rates-set" includes the mac80211 patch to enable beaconspammer the access to the IEEE 802.11 rates via the radiotap header.
• The subfolder PA_Python_script contains a python script which accesses the waiting ticket numbers from the TU Examination Office via the Freitagsrunde website The script parses the website and uses the modified hostapd_cli to send WTN LoWS messages including the current waiting ticket numbers from the TU examination office.

9. Contact

• Sven Zehl, TU-Berlin, zehl@tkn
• Niels Karowski, TU-Berlin, karowski@tkn
• Anatolij Zubow, TU-Berlin, zubow@tkn
• Adam Wolisz, TU-Berlin, wolisz@tkn
• tkn = tkn.tu-berlin.de

10. How to reference LoWS

Please use the following bibtex :

@inproceedings{Zehl16lows,
Title = {{LoWS: A Complete Open Source Solution for Wi-Fi Beacon Stuffing Based Location-based Services}},
Author = {Zehl, Sven and Karowski, Niels and Zubow, Anatolij and Wolisz, Adam},
Booktitle = {{9th IFIP Wireless and Mobile Networking Conference (WMNC 2016)}},
Year = {2016},
Location = {Colmar, France},
Month = {July},
Url = {http://www.tkn.tu-berlin.de/fileadmin/fg112/Papers/2016/zehl16lows.pdf}
}