Software Radio Network Testbed

Transcription

1 Software Radio Network Testbed Senior design student: Ziheng Gu Advisor: Prof. Liuqing Yang PhD Advisor: Xilin Cheng 1

2 Overview Problem and solution What is GNU radio and USRP Project goal Current progress Summary Future plan References Budget 2

3 Problem and Solution Traditional radio High cost Fixed function Hard to implement Software radio Low cost Flexible function Easy to implement 3

4 What is GNU Radio and USRP GNU Radio: A free and open-source software development toolkit Provides signal processing blocks Can implement signal processing in the physical layer Can be used with USRP (Universal Software Radio Peripheral) to create software radio Blocks written in C++ Blocks connected by Python GNU Radio Companion helps to save time like Simulink 4

5 What is GNU Radio and USRP USRP: Million Gate FPGA (Field Programmable Gate Array) Digital up and down conversion, sampling, Interpolation Transmitter and receiver front end ADCs (Analog to Digital Converter) and DACs (Digital to Analog Converter) 5

6 What is GNU Radio and USRP USRP N MS/s dual ADC and 400 MS/s dual DAC Can operate signals from DC to 6 GHz Supports MIMO configuration (Multiple Input Multiple Output) 6

7 Project Goal What do we have? Two USRP N210 Two computers to implement software defined radio on USRP N210 Two GPS disciplined clocks to provide synchronization What system do we want to build? Set up the connection between computer and USRP Use GNU Radio to implement software defined radio communication between two USRPs 7

8 Project Goal Final design requirement: Implement OFDM communication (Orthogonal Frequency Division Multiplexing) in the system Each hardware can transmit and receive packets consisting of OFDM symbols Text, voice, video and other types of data can be transmitted by this system Test and compare different prototypes of underwater communication 8

9 Current Progress Completed Tasks: Set up connection between computer and USRP Install Linux system on each computer Install GNU Radio Set up network Download and load frameware 9

10 FM Transmitter and Receiver Build FM transmitter and receiver Transmitter can transmit wav music file to specified carrier frequency modulated FM signal Receiver can receive specific carrier frequency modulated FM signal and demodulate the signal to voice signal. GRC program of our FM transmitter and Receiver 10

11 Spectrum in the Processing of FM Transmitter and Receiver 11

12 OFDM Transceiver OFDM transceiver Orthogonal frequency division multiplexing Transmit many narrow-band signals in parallel on orthogonal sub-bands A good way to transport digital data Widely used in LTE, Wi-Fi, etc. Physical Layer of our OFDM transceiver 12

13 GRC Program of our OFDM transceiver 13

14 OFDM Transceiver Use the OFDM transceiver to transmit repeated random digital stream, we get following OFDM signal in time domain and frequency domain at RF end. Spectrum of OFDM Real time value of OFDM 14

15 Results We use virtual sink and source to connect the transmitting and the receiving part. Transmit unrepeated random digital stream. Record the digital stream from random source and receiver sink, store in SourceBit and ReceiverBit. Read data from SourceBit and ReceiverBit with Matlab and compare Virtual connection, no real wireless channel No bit error occurs Data at the tail of stream are lost because of the delay of signal transmitting (will correct this issue in future) Num Increasing of TX( of the number of transmitted bytes leads to Byte) decreased packet loss rate. Packet Loss rate(%) M

16 Summary So far, we have set up the connection between USRP and computer, completed the FM transmitter and receiver. Also, we built the basic OFDM transceiver prototype which can transmit and receive OFDM byte data in virtual wireless environment. What I learned: Analog communication theory OFDM communication theory Linux system Python and C++ programming GNU Radio 16

17 Future Plan Implement decoding part and encoding part of various types of files Implement virtual channel of wireless environment Implement channel estimation Implement BER/SER Computation Set up communication between two USRPs Fix the packet loss problem Test and compare different prototypes of underwater communiciation 17

18 Budget Item Amount USB2.0 Gigabit Ethernet Adapter $24 GPS Disciplined Clock $ GPS Disciplined Clock $ Total $

19 References B. P. Lathi and Zhi Ding, Modern Digital and Analog Communication Systems, 4th Edition, Oxford University Press, 2009 GNU Radio Manual and C++ API Reference M. Braun, OFDM Packet Receivers in GNU Radio t_transceivers/attachments/slides/383/export/events/attachments/tut orial_ofdm_packet_transceivers/slides/383/martinbraun_gnuradio _OFDM.pdf X. Cheng, M. Wen, X. Cheng, D. Duan, and L. Yang, ``Effective Mirror-Mapping-Based Intercarrier Interference Cancellation for OFDM Underwater Acoustic Communications, Elsevier Ad Hoc Networks,

20 Thank you! 20