1. Network Coding Testbed
Jeremy Bergan, Ben Green, Alex Lee

2. Presentation Overview
Background Information
Project Overview
Framework Design
Progress and Plan
Jeremy

3. Network Coding Overview
Intelligently combining packets at intermediate nodes to increase network throughput  
Jeremy
Framework will be used to implement and test Network Coding Schemes
Network Coding
Intelligently combining packets at intermediate nodes to increase network throughput
Butterfly Network
 Transmit A and B to both end nodes
Traditional methods require many steps
Network Coding increases throughput by combining A and B into A+B, then decoding at end nodes by subtraction

4. ANC: Decoding Interfered Signals
Node1 and Node2 simultaneously transmit
Signals interfere at intermediate node
Intermediate node amplifies and forwards combined signal
Node1 can decode Node2's message based on knowledge of the message it sent previously
Sachin Katti, Shyamnath Gollakota, Dina Kattabi, Embracing wireless interference: Analog Network Coding, in ACM SIGCOMM Computer Communication Review v.37, n.4, pp 397 – 408, October 2007
Jeremy
Analog Network Coding
State a form of network coding
Uses the physical layer
Example
Normal Network Example
Steps it takes
ANC Example

5. Project Overview Wireless Network Testing Framework
Use this Framework to implement and test Analog Network Coding 
Implement generalized MAC for arbitrary topologies
GNU Radio
Mature Signal Processing Libraries
Universal Software Radio Peripheral (USRP)
Alex
Wireless Network Testing Framework
Modulation Schemes
Wireless Protocols
Networking Protocols
Most importantly Network Coding
Mesh Networks
Educational Use
Research Use
Our goal is to implement and test Analog Network Coding
Signals deliberately interfered with a common intermediate node
router forwards interfered signal
receiver decodes interfered signal based on known packets
We plan on expanding upon previous research
Implement generalized MAC for arbitrary topologies
GNU Radio
Mature Signal Processing Libraries
Software Radios
Define/explain
Universal Software Radio Peripheral (USRP)
Modular Design
Modify and replace components to suit specific needs

6. Requirements Implement a testing framework for wireless networks
Implement a testing framework for wireless networks
Implement a Network coding scheme with equal or better throughput than traditional networks
   
Implement ANC MAC
   
Practical application to arbitrary network topologies
Use of Universal Software Radio Peripheral (USRP)
Use of GNU Radio signal processing libraries
Modular design
Alex
Modular design
simple enough for future students/researchers to use
Modify/replace components for particular purposes

7. Constraints USRP Number of nodes Frequency Range Bandwidth
Transmission Power
 Processing
CPU Cycles
Time
Alex
USRP
Frequency Range
GHz
Bandwidth
Limited by USB
Limited by Sample rate of USRP
DAC: 128 MS/s
ADC: 64 MS/s
Limited by Computation rate
Time
A lot of possible features, only so much time to implement

8. Assumptions Tested under reasonable conditions
Normal level of background noise
Global knowledge of routing at each node
Routing patterns will be pre-generated
Routing protocols outside scope of this project
Alex

9. Resources
 14 USRPs
All with daughter-boards able to transmit and receive between GHz
 5 Dell Optiplex Computers 
3 With the Ubuntu Operating System
2 With Red Hat Linux Operating System
 Various Daughter Boards
 Transmitters with different frequency range
 Receivers with different frequency range
 Transceivers
Alex

10. Design Process Functional Decomposition Prototype in Matlab
Test in Matlab
Jeremy 
Functional Decomposition
Understand individual subsystems
Define functionality of each subsystem
Define interfaces between subsystems
Prototype in Matlab
Test in Matlab
Simulation in controlled environment
Characterize system under various parameters

11. System Design Host: Generates and interprets data Network:
Packetizes and determines data route
MAC:
Arbitrates channel access. Coordinates
transmission among nodes
Physical:
Modulation/Demodulation
Testing and Logging:
Tools used in testing of system
Jeremy
Host
Stream audio and video
Play it through speakers
Network

12. Physical Layer Modulation / Demodulation Transmission / Reception
Carrier Sense
All signal processing functions
Jeremy
Layer interacts with the USRP for transmission and reception

13. MAC Layer Network Layer Coordinate channel access between nodes
Jeremy
Packetization of data
Routing Path is predetermined for each packet
Packet scheduling

14. Host Layer Generates data to send Receives and processes data
Several possible data types
Random data
Pre-determined pattern
Streaming media (audio/video)
Kernel network interface
Ben

15. Testing and Logging Layer
Select logging/testing options 
Logging data to file from individual layers/components 
Scopes/Visualization of data from individual layers/components 
Generation of statistics
Validation
Ben
Select logging/testing options
Logging data to file from individual layers/components
Scopes/Visualization of data from individual layers/components
Generation of statistics
Bit Error Rate
Packet Loss
Throughput
Comparison of multiple schemes
Validation
Verify Correctness of data
Verify correctness of statistics based on simulations

16. Basic Network Implementation
Physical Layer
QPSK modulation
MSK modulation
MAC Layer
Simplified IEEE MAC (CSMA/CA)
Network Layer
Predetermined routing
Similar packet format as
Host Layer
Random data
Predetermined patterns of data
Ben

17. Analog Network Coding Implementation
Physical Layer
MSK modulation
ANC algorithm for decoding interfered signals
MAC Layer
Modified CSMA/CA
Allows for simultaneous interfering transmissions if they will be able to be correctly decoded
Network Layer
Same as Basic network
Host Layer
Ben

18. ANC Topologies
Alice - Bob
Chain X
Ben

19. ANC: Generalized MAC
Design a MAC that allows simultaneous transmissions when both interfered messages can be decoded
Generalized algorithm that works for multiple topologies
Distributed Algorithm
Similar to DCF
Nodes send information about packets in buffer
Use RTS and CTS messages to coordinate interfering transmissions
Ben

20. Testing Procedure Implement each component of the design in Matlab
Simulation in a controlled environment
Implement each component with GNU Radio and USRP
Compare each component with simulation results
Test framework over air
Alex
Test each component in Matlab
Test each component in GNU Radio
Compare each component
Test Framework in Matlab
Test Framework in GNU Radio
Compare Framework results

21. Matlab Simulations Prototyping in Matlab has started QPSK Simulation
QPSK Simulation
Transmission and Reception
Alex
Practical Idea of Signals
Transmitting
Receving
Sampling theory
Synchronization
Channel Simulation
AWGN noise
Filters
Matched filter
Filter Design
Current Work ANC
Break into component in Matlab
Implement each component
Currently working on a full ANC implementation
MSK Modulation and Demodulation

22. Schedule
Alex

23. Questions?