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IntroductionDesignResults

TimelinePersonnel

Final PresentationImplementation Of A MIMO Transceiver

Using GNU Radio

Ethan Aebli ECEMichael Williams ECE

Erica Wisniewski CMPE

This research was supported by the MITRE Corporation as an independent research project. The views,opinions, and findings are those of the authors and are not intended to convey or imply an official position of

The MITRE Corporation.

April 14, 2016Ethan Aebli, Michael Williams, Erica Wisniewski Final Presentation Implementation Of A MIMO Transceiver Using GNU Radio


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Table of contents

1 Introduction

2 Design

3 Results

4 Timeline

5 Personnel

Ethan Aebli, Michael Williams, Erica Wisniewski Final Presentation Implementation Of A MIMO Transceiver Using GNU Radio


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Acronyms

MIMO Multiple Input Multiple Output

STBC Space Time Block Code

SDR Software Defined Radio

USRP Universal Software Radio Peripheral

BER Bit Error Rate

GNU GNU’s Not Unix



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Objective

MITRE conducts wireless communications research

Research often focused on improving existing technologies

Implement a MIMO algorithm on the SDR platform, GNURadio.

Facilitate testing of MIMO enhanced systems

Potential benefits of MIMO systems include increased datarate



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GNU Radio

Design and build MIMO encoder and decoder blocks

Provide functionality not currently available in GNU Radio



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Software Defined Radio

Typical hardware tasks performedby software

E.g., filtering, amplification,modulation

Works with USRPs

USRPs provide digital to analoginterface

SDR focused on baseband signalprocessing



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Advantages of MIMO Channel

Increase the diversity of the system

Increase the number of transmitted symbols

Channel capacity increases as number of antennas increase

Increased capacity results in increased data rate

Exploit multipath propagation



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Differential Alamouti STBC

Transmitted symbols related to information symbols throughrecursive process[

x1(n)x2(n)

]=

1√2

[x1(n − 1) −x∗2 (n − 1)x2(n − 1) x∗1 (n − 1)

] [s1(n)s2(n)

]Previously received symbols replace channel gains in decodingprocess[y1(n)y∗2 (n)

]=

1√2

[y1(n − 1) y2(n − 1)y∗2 (n − 1) −y∗1 (n − 1)

] [s1(n)s2(n)

]+

[w̃1(n)w̃2(n)

]Excellent choice when combating Doppler spread

Incurs 3dB loss in SNR compared to coherent Alamouti



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Tx BPSK Symbols for Antenna 0 and Antenna 1



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Received Symbols on Antenna 0



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Received Symbols on Antenna 1



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BER for BPSK with AWGN



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GNU Radio Flowgraph



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Input Data



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Output Data



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Test Plan

Software testing

LoopbackLeave channel simulation before sending signal to radioControl fading, channel changes slowly in time

Hardware testing

Use oscilloscope to look at transmitted signal prior to hookingup receiverClosed-loop environment, not over the air (wireless)Wireless experiment around campusInitially sending a text fileTime permitting, move to voice, video, etc.



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Remaining Tasks

Move design to USRP radio hardware

Field testing and review



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Corporate Sponsor And Faculty Advisors

Michael Wentz, Lead Communications Engineer, MITRE

Professor John Chandy

Professor Peter Willett



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References

[1] Hamid Jafarkhani, Space-Time Coding, Theory and Practice.Cambridge University Press, 2005.[2] Georgios Giannakis, Space-Time Coding For BroadbandWireless Communications. Wiley, 2007.



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Questions?


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