Designing MIMO-OFDM Wireless Communication Systems Designing MIMO-OFDM Wireless Communication Systems

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  • 1© 2015 The MathWorks, Inc.

    Designing MIMO-OFDM

    Wireless Communication Systems

    Dr. Amod Anandkumar Senior Application Engineer

    Signal Processing and Communications

  • 2

    Outline

     Designing MIMO-OFDM baseband algorithms

     Modelling RF frontend for system-level design

     Working with SDR and live radio signals

  • 3

    Outline

     Designing MIMO-OFDM baseband algorithms

     Modelling RF frontend for system-level design

     Working with SDR and live radio signals

  • 4

    Why look at MIMO-OFDM systems?

    and many more…

  • 5

     Need to design/model

    • Advanced baseband algorithms

    • Channels with multipath and fading

    • Non-linearity and impairments of RF front-end

    • Antenna arrays

    • Various types of antennas

    Challenges in designing MIMO-OFDM systems

  • 6

    Demo – Transmitting digital video in a multi-

    actor scenario

  • 7

    Processing Chain of MIMO-OFDM Systems

    Input

    bits

    ModulationChannel

    coding MIMO ..

    ..

    Transmitter

    Channel

    Large-scale

    fading

    (path-loss …)

    Small-scale

    fading

    (Multipath,

    Doppler

    effects)

    Interference

    Noise Receiver

    Channel

    decoding

    De-

    modulation

    MIMO

    Receiver

    (Equalizer)

    Channel

    estimation

    OFDM

    receiver

    OFDM

    receiver

    Output

    bits

  • 8

    Incrementally Develop a MIMO-OFDM System Version 1: Baseline - Modulation and Coding

     Start with a SISO transceiver with modulation, coding, scrambling

     Channel modeling (Interferer + path loss)

     No multipath fading yet

     Isotropic (non-directional) antenna

    Signal

    Source (S)

    Interference

    Source (I)

    𝜃𝑆

    𝜃𝐼

    𝑑𝑆

    𝑑𝐼

  • 9

    Perform Link-Level Simulations

    • Use algorithms in

    Communications System

    Toolbox

    • Quickly build and run fast &

    reliable simulations

    • Simulate dynamic changes

    of systems (such as

    modulation scheme)

    • Perform measurements

    and examine performance

    metrics during simulation

  • 10

    Version 2: Model OFDM link with Pilot Symbols

    • OFDM modulator and

    demodulator from

    Communications System

    Toolbox

    • Gold or PN Sequence

    generators to generate

    pilots (reference signals)

    • System objects make

    exploring with system

    parameters easier

    • Explore a wide range of

    center frequencies and

    bandwidths

  • 11

    Version 2: Baseline + OFDM

     Introduce OFDM transmission

     Transceiver with modulation, coding, scrambling & OFDM

     Channel (Interferer + path loss) modeling

     No multipath fading yet

    Signal

    Source (S)

    Interference

    Source (I)

    𝑑𝑆

    𝑑𝐼

  • 12

    Version 3: Beamforming with Multiple Antennas

    • Antenna arrays and beamformers

    from Phased-Array System

    Toolbox

    • 2-D and 3-D spatial array

    responses and directional gains

    • Implement beamforming

    algorithms with a few lines of

    MATLAB code

    • Easily quantify interference

    mitigation gains provided by

    beamforming

  • 13

    Version 3: Baseline + OFDM +

    Transmit-side beamforming

     Introduce Transmit-side beamforming

     Transceiver with modulation, coding, scrambling & OFDM

     Channel with Interferer + path loss

     Transmitter has multiple Antennas (1 to 8)

    Signal

    Source (S)

    Interference

    Source (I)

  • 14

    Version 4: Introduce Multipath Fading Channel

    • MIMO fading channels from Communications System Toolbox

    • Channel estimation and equalization with received values of time-

    frequency grid

    • Experiment with ideal and pilot-based channel estimation algorithms

  • 15

    Final Version: Baseline + OFDM +

    Transmit-side beamforming + Multipath fading

     Transmit-side beamforming with Multipath fading

     Transceiver with modulation, coding, scrambling & OFDM

     Channel with Interferer + path loss + multipath propagation

     Transmitter has multiple Antennas (1 to 8)

    Signal

    Source (S)

    Interference

    Source (I)

  • 16

    Simulation example – application domains

    Video read

    and coding

    Video decoding Demodulation

    Channel and

    interferer model

    Antenna array,

    Beamforming

    Image Processing,

    Computer Vision Communications,

    Signal Processing Antennas,

    Phased Arrays

    Modulation

  • 17

     Communications & Phased Array System Toolbox

    – Modulation, Coding, OFDM

    – MIMO Fading Channels

    – Beamforming

     MATLAB & DSP System Toolbox

    – Dynamic & interactive MATLAB test benches

    – Change system parameters on-the-fly with tunable parameters

    – Spectral Analysis

    – Visualizations and Measurements

     Computer Vision System Toolbox

    – Read telemetry video data as transmitted bit stream

    What we learned in this demo

  • 18

    Outline

     Designing MIMO-OFDM baseband algorithms

     Modelling RF frontend for system-level design

     Working with SDR and live radio signals

  • 19

    Why Consider RF in System-Level Simulation?

     RF causes imperfections that cannot be neglected

    Digital

    baseband

    Digital to

    Analog

    Converter

    RF Digital

    baseband

    Analog to

    Digital

    Converter RF

    Transmitter (TX) Receiver (RX)

  • 20

    SimRF Demo

    Link to demo

    http://www.mathworks.com/help/releases/R2015a/simrf/examples/executable-specification-of-a-direct-conversion-receiver.html

  • 21

    SimRF Libraries:

    Circuit Envelope Equivalent Baseband

  • 22

    What Can You Do With SimRF? Fast Simulation for Link Budget Analysis of RF Cascades

    Link to Webinar

    http://in.mathworks.com/videos/design-and-verify-rf-transceivers-for-wireless-communication-systems-81982.html

  • 23

    What Can You Do With SimRF? Estimate the Impact of Interference and Spurs

    Link to Webinar

    http://in.mathworks.com/videos/design-and-verify-rf-transceivers-for-wireless-communication-systems-81982.html

  • 24

    CW test signal

    LTE or custom test signal Multi-rate finite-precision

    programmable decimation filters

    Analog continuous-time

    programmable filters

    Tunable

    RF receiver

    What Can You Do With SimRF? Model Highly Tunable RF Architectures

    Third order

    Delta-Sigma ADC

    RSSI

    AGC

    Link to demo

    http://www.mathworks.com/adi-rf

  • 25

    What Can You Do With SimRF? Test the RF Front-End with Real-Life and Reference Signals

    MATLAB Testbench

    RF Receiver

    Simulink Simulation in the Loop

    Link to demo

    http://www.mathworks.com/company/newsletters/articles/measuring-the-impact-of-rf-impairments-on-an-lte-system.html?refresh=true

  • 26

    SimRF

     System-level simulation including RF

     Architectural design of RF transceivers

     Tradeoff simulation time and modeling

    fidelity

  • 27

    Outline

     Designing MIMO-OFDM baseband algorithms

     Modelling RF frontend for system-level design

     Working with SDR and live radio signals

  • 28

    Test Your Radio with Over-the-air Communication

    Transmit and receive radio signals over the air

     Transmit and receive waveforms

     Configure hardware parameters

    – centre frequency, sampling rate and more

     Analyze acquired I/Q baseband signal with configurable

    measurement tools

     Verify and validate your designs based on live radio

    signals

  • 29

    Numerous Platforms Supported

    RF Signal Generator

    Zynq/FPGA SDR

    USRP SDR

    RF Spectrum Analyzer

    Zynq/FPGA SDR

    USRP SDR

    RTL SDR

    Transmitter Receiver

    Discover more here

    http://in.mathworks.com/discovery/sdr.html http://in.mathworks.com/discovery/sdr.html

  • 30

    Summary

     Designing MIMO-OFDM baseband algorithms

     Modelling RF frontend for system-level design

     Working with SDR and live radio signals

  • 31

    Channel fading, interference, noise

    Antenna, Antenna arrays type of element, # elements, configuration, positio