Cooperative Communication Protocol on Software Defined Radio Howard T. Huang Prof. Hamid Jafarkhani...
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Transcript of Cooperative Communication Protocol on Software Defined Radio Howard T. Huang Prof. Hamid Jafarkhani...
Cooperative Communication Protocol on Software Defined Radio
Howard T. HuangProf. Hamid JafarkhaniProf. Homayoun Yousefi’zadehLun Dong (Postdoctoral)
SURF-IT 2010
Diversity Schemes
Diversity schemes mitigate effects of multipath fading
Transmit redundant signals over independent channels
Well known schemes:MIMO – multi-input multi-outputCooperative Communication
Cooperative Communication
Trans
mitte
d sig
nal
Transmitted signal
Retransmitted signal
relay
destinationsource
Differences From Repeaters
Repeaters are dedicated base stations (infrastructure)Have “unlimited” power resources
Relay radios belong to other usersAre generally mobile and run on batteriesHave their own data to transmit
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)
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)
Our SDR Test Platform
GNU Radio Software on regular PC’s running Linux + Universal Software Radio Peripheral (USRP)
GNU Radio is open source softwareDoes bulk of signal processing
USRP contains only ADC/DAC converters and RF frontendDoes only baseband processing
Transmission Errors
Bit error
Sent: 01101101|01101101|00101110Received: 01111101|01101001|01001100Errors: X X XX X
Packet error Any bit error in the packet results in packet error
Sent: 01101101|01101101|00101110Received: 01111101|01101101|00101110Errors: X
Results: BER vs. Transmit Power
0
1
2
3
4
5
6
7
2.5 3 3.5 4 4.5 5 5.5 6
Tx power (mW)
BE
R (
%)
Direct Tx Coop
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
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