1. Connecting To Several Access Points Simultaneously In IEEE 802.11 Networks Students: Nadav Dawidowicz, Dvori Yossi Instructors: Dr. Omer Gurewitz Dr. Yehuda Ben Shimol Mr. Itzik Kitroser

2. Contents 802.11 Background Motivation Project goal Possible solutions The Platform The selected solution Results Future Work

3. 802.11 Introduction The IEEE 802.11 is a wireless technology based on random access Providing connectivity between wireless stations and wired networking infrastructures Enable stations to travel to various places and still have access to the network

4. 802.11 Standards 802.11 - 2 Mbps, S-Band ISM, FHSS 802.11b - 11 Mbps, S-Band ISM,DSSS 802.11a - 54 Mbps, C-Band ISM, OFDM 802.11g - 54 Mbps, S-Band ISM, OFDM 802.11n – 600 Mbps, S/C – Band ISM, OFDM

5. Current Behavior Station Connects to a Single AP ◦Power inefficiency ◦No roaming while connected ◦Break before make

6. The project goals: Allow connection to several APs ◦green transmission (power efficiency) ◦Reduce the amount of retransmissions ◦Extend the coverage of the network ◦Reduce the amount of handovers

7. General Architecture

8. Possible Solutions

9. A. Creating Several Virtual WNICs ApplicationManager MadWIFI Virtual WNIC #1 Physical WNIC Requirements: The driver should support multiple station instances Routing is controlled by the server application

10. B. Working As AP In WDS Mode Requirements: The topology should be known from advance The driver should support WDS mode

11. C. Duplicating the APs

12. Requirements: Duplicating the MAC address Open network

13. The Platform - Hardware WNIC based on Atheros 5213 chipset Intel Atom CPU on low power pc platform Trendnet 7dBi antennas 160GB hard drive

14. Software And Tools OpenSuse MadWifi Wireshark Macchanger Iperf

15. The MadWifi Project “Multiband Atheros Driver for Wireless Fidelity” MADWIFI is a driver for WNIC Open source Linux driver Configurable and flexible Version MadWifi 0.9.4

16. The Selected Solution A. Creating Several Virtual WNICs ◦MADWIFI does not support multiple station instances (IOCTL error) B. Working as AP in WDS Mode ◦Known topology – limited mobility C. Duplicating the APs

17. The Selected Architecture : Duplicated APs. The following parameters should be identical in the wireless interface : MAC address ESSID Channel

18. The Selected Architecture : Duplicated APs. The APs is composed of: Wireless NIC NIC Bridge between both of them

19. The AP Duplicate Script macchanger –m 00:25:86:ce:ac:6b wifi0 iwconfig ath0 essid “project” chan 6 Wlanconfig ath0 create wlandev wifi0 wlanmode ap

20. The Network Diagram

21. Results Outdoor Measurements APs

22. Results Outdoor Measurements

23. Results Indoor Measurements

24. Summary The goal to connect to several APs was achieved. The improvements: Power efficiency increased Extended AP coverage Less retransmissions But… Network overloading The improvements are case specific

25. Future Work Finalizing the client server application to measure properly the improvements