Network Coding Testbed Jeremy Bergan, Ben Green, Alex Lee

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

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

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

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

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

Constraints USRP Number of nodes Frequency Range Bandwidth Transmission Power    Processing CPU Cycles Time Alex USRP Frequency Range 2.4-2.5 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

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

Resources  14 USRPs All with daughter-boards able to transmit and receive between 2.4 - 2.5 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

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

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

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

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

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

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

Basic Network Implementation Physical Layer QPSK modulation MSK modulation MAC Layer Simplified IEEE 802.11 MAC (CSMA/CA) Network Layer Predetermined routing Similar packet format as 802.11 Host Layer Random data Predetermined patterns of data Ben

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

ANC Topologies Alice - Bob   Chain X Ben

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 802.11 DCF Nodes send information about packets in buffer Use RTS and CTS messages to coordinate interfering transmissions Ben

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

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

Schedule Alex

Questions?