Developing a SDR Testbed

Alex DolanMohammad Khan

Ahmet Unsal

Project AdvisorDr. Aditya Ramamoorthy

Presentation Overview

• Background Information • Project Overview • System Design • Progress and Plan

Background Information

• Software Defined Radio

• USRP-2

• DaughterBoard

Project Overview

Project Goal

1.Develop a Software Defined Radio network testbed, using MATLAB Simulink and USRP-2

2.Evaluate MATLAB Simulink’s Versatility as a SDR platform

Requirements

• Implement a SDR Testbed

• Use of Universal Software Radio Peripheral-2 (USRP-2)

• Use of MATLAB Simulink

• Implement digital modulation schemes like FSK, BPSK, DBPSK, QAM

• Implement simplified 802.11 MAC

Constraints

• USRP-2o Number of nodeso Frequency Rangeo Bandwidth o Transmission Power

 •  Processing

o CPU Cycles • Time

Assumptions

•Tested under reasonable conditions• Normal level of noise• Controlled transmission range

 

Resources

•  2 USRP-2so Sample rate of 100 MHz

•  2 Dell Optiplex 980 Computerso Intel Core i7 Processor

•  Daughterboardso Various daughterboards for different frequency bandso Able to transmit and receive up to 5 GHz

Design Process

• Design Physical Layer

• Design MAC Layer

• Testing and Logging

System Decomposition• Physical layer:

– USRP-2– Simulink – DSP and digital communications

• MAC:– Coordinates transmission among nodes.

• Testing and Logging:– The tools used to test the system.– Tracks progress and success.

System Block Diagram

Physical Layer

• Simulink signal processing• FSK, PSK, QAM modulation/demodulation• Synchronization and packetization• Error control

• USRP-2 hardware• Ethernet interface with 100 MSamples/s A/D conversion

Physical Layer (PHY) Block Diagram

MAC Layer

• Coordinate channel access between nodes

• Simplified 802.11 implementation• Carrier sense multiple access with collision avoidance (CSMA/CA)

• Written in C++ or embedded MATLAB.

MAC

• Design a MAC that allows simultaneous transmissions when both interfered messages can be decoded

  • Distributed Algorithm

o Similar to 802.11 distributed coordinate functiono Use RTS and CTS messages to coordinate interfering

transmissions

Testing and Logging

• Select logging/testing options  • Logging data to file from individual layers/components 

 • Scopes/Visualization of data from individual

layers/components  • Generation of statistics

 • Validation

Testing Procedure

• Design Physical Layer in Simulink.• Design each component in Simulink.• Test in controlled MATLAB environment.• Test using USRP-2 and Simulink.

 • Introduce MAC layer

• Move from point to point and introduce more nodes.

• Compare results to simulations and expected results.• Observe BER, data rates, etc.

Schedule

Questions?