1. Cooperative Communication Protocol on Software Defined Radio Howard T. Huang Prof. Hamid Jafarkhani Prof. Homayoun Yousefi’zadeh Lun Dong (Postdoctoral) SURF-IT 2010

2. Multipath fading

3. Diversity Schemes Diversity schemes mitigate effects of multipath fading Transmit redundant signals over independent channels Well known schemes:  MIMO – multi-input multi-output  Cooperative Communication

4. Cooperative Communication Transmitted signal Retransmitted signal relay destinationsource

5. Differences From Repeaters Repeaters are dedicated base stations (infrastructure)  Have “unlimited” power resources Relay radios belong to other users  Are generally mobile and run on batteries  Have their own data to transmit

6. SURF-IT Project Implementation and Testing of A Cooperative Communication Protocol on a Software-Defined Radio Platform Verify performance of cooperative protocol by measuring bit error rate (BER) and packet error rate (PER)

7. What is Software-Defined Radio? Software-Defined Radio (SDR) is programmable by…software!  Can be easily reconfigured to users’ needs  Example: Qualcomm’s Gobi SDR can switch between HSPA (AT&T) and EV-DO (Verizon) Traditional radios can only operate as one type of radio  Function is hard-coded and cannot be changed  Example: AT&T phones (GSM) do not work on Verizon network (CDMA2000)

8. Our SDR Test Platform GNU Radio Software on regular PC’s running Linux + Universal Software Radio Peripheral (USRP) GNU Radio is open source software  Does bulk of signal processing USRP contains only ADC/DAC converters and RF frontend  Does only baseband processing

9. GNU Radio + USRP Photo by Jason Tran, SURF-IT 2009

10. The USRP Photo by Jason Tran, SURF-IT 2009

11. Transmission Errors Bit error Sent: 01101101|01101101|00101110 Received: 01111101|01101001|01001100 Errors: X X XX X Packet error  Any bit error in the packet results in packet error Sent: 01101101|01101101|00101110 Received: 01111101|01101101|00101110 Errors: X

14. Conclusions & Future Work Cooperative protocol is actually extension of Load-Adaptive MAC protocol (LA-MAC) proposed earlier  MAC protocols allow devices to share a transmission medium (the air)  LA-MAC is designed to improve efficient usage of wireless medium Part of larger project using GNU Radio/USRP as MANET (mobile ad-hoc network) testbed for developing network protocols and algorithms

15. Acknowledgements Prof. Hamid Jafarkhani (mentor) Prof. Homayoun Yousefi’zadeh (mentor) Lun Duong (Postdoctoral) Xiaofang Liu (MSEE graduate) Weihong Hu (Ph.D candidate) Jason Tran (SURF-IT 2009 fellow) And of course the SURF-IT sponsors, Calit2 and UROP And the Boeing Corporation

16. Questions?