The Case of User Cooperation
Transcription
The Case of User Cooperation
Developing Next-Generation Wireless using WARP: The Case of User Cooperation Chris Hunter, Ashutosh Sabharwal Patrick Murphy {chunter,ashu}@rice.edu Rice University [email protected] Mango Communications Outline • • • • WARP Overview Research Examples Case Study: User Cooperation Demonstration Wireless Open-Access Research Platform • Cross-layer design • • Completely programmable, from PHY through networking Fast timescales and wide bandwidths • • 40MHz bandwidth per radio Turn-around-Times in ~20µsec Wireless Open-Access Research Platform • WARP refers to two things • • The Hardware The Support Packages • Xilinx Virtex-4 FX100 FPGA (XC4VFX100-11FFG1517C) • • • All processing is local to the board (no host PC required) FPGA fabric to handle PHY processing PPC (inside FPGA) to handle MAC processing • Up to 4 radio interfaces • • • MAX2829-based RF front-end (2.4/5GHz, 40MHz BW) All frequency locked for MIMO applications Slots can be used for other daughterboards Platform Support Packages Inter-FPGA Board Links MGTs Hardware Description Logic Logic-Bus Interface PPCs Xilinx FPGA FPGA Board Peripheral Interfaces Radio Video Analog I/O Daughtercards WARP Hardware warp.rice.edu WARP Repository Research Applications WARPLab rapid PHY prototyping WARPLab Ethernet links WARPLab • One PC controls many WARP nodes • MATLAB for signal processing • Non-real-time processing • WARP for wireless interfaces • Real-time channel use WARP real-time host-free processing OFDM Reference Design MAC Research Application PPC Code WARPMAC WARPPHY PHY Driver DMA Driver Timer Driver Misc. Drivers Ethernet MAC Driver Custom PHY Packet Buffers Timer Radio Controller Ethernet MAC PLB MIMO OFDM MIMO OFDM Transmitter Receiver Digital I/Q AGC Digital I/Q I/Q & RSSI Radio Bridges Radios FPGA Logic Packet Detector RSSI Control Ethernet Hardware WARPnet enables experiments with networks Channel Controlled: Node position, Tx Power, etc. Uncontrolled: Multipath fading, interference, etc. Was observed effect due to my controlledChannel parameters or due to causes beyond my control? Controlled: Node position, Tx Power, etc. Uncontrolled: Multipath fading, interference, etc. Channel Observations Control Real-time Network Monitoring with WARPnet WARPLab WARP real-time WARPnet Examples: Directional Mobility Examples: Directional Mobility Examples: Directional Mobility ,*-.%)/$."#'&*'#$)##'0 3.2 cm 3.2 cm 1*"+#.2-.%)/$."#'&* '#$)##' 3456 7'8$"8 !"#$%"&&'(&)*+"$"% 3-5 dB link gain, higher with more antenna patches (Amiri, Zhong @ Mobicom 2010) Examples: Directional Mobility Video of Real-Time Directional Mobility Testbed Examples: Full Duplex Examples: Full Duplex • 2 WARP nodes, each with 3 Radios (2 Tx + 1 Rx)! • 10 MHz OFDM! • Inter-node distance 10m.! • 80dB self-interference suppression! • 50-70% throughput gain! • Duarte & Sabharwal, 2010! ! R R S S R D R R S S R D R R D S R R R D S R R R D S R R R D S R Examples: User Cooperation Broadcast Phase Relay Phase R S R D S D Examples: User Cooperation Initial Transmission N Header R Payload Header Payload S D X Examples: User Cooperation Initial Transmission NACK Transmission Header R Header Payload Header Payload S R D X S Header D C Examples: User Cooperation NACK Transmission Coop. Retransmission Header R R X Header Payload S Header D S D only cooperates when retransmission On-demand: would happen anyway Y Loc −10 −5−5 User 00 55 1010 1515 −10 Examples: Cooperation X Location (m) 00 5 −15 −15 4 4 4.5 X Location (m) Y Location Y Location (m) (m) Y-Location (m) Y Location (m) ! !Throughput (Mbps) Throughput (Mbps) Throughput Improvement over CSMA/CA 0 −15 −10 −5 0 5 10 15 15 X Location (m) (Mbps) 15 ! Throughput (Mbps) 1010 10 15 5 x 10 1 10 10 15 .55 5 10 55 5 10 00 50 -15 −15 −15 4 55 x x1010 1.5 15 15 -10 −10 −10 S D 00 -5−5 55 −5 0 5 X XLocation Location(m) (m) X-Location (m) 1010 10 1515 15 0 50 0 Relay Transmission Rate Relay Transmission Rate a) In0 DOC, the relay provides maximal amount of assistance 0when −15 −10 −5 0 5 10 15 15 15 ocated between the source and the destination. X Location (m) warp.rice.edu/papers • • WARP hardware provides resources for next-generation wireless WARP platform support provides high-level access to resources • • • WARPLab for PHY prototyping Real-time implementation for real-world timescales WARPnet for network testing warp.rice.edu