CHANNEL SOUNDING USING USRP2 & GNU-RADIO

Channel Impulse Response And Coherence Bandwidth Estimation

By:- Rohit Sharma Jay Prakash

Under :- Prof S.N Merchant SPANN LAB,IIT Bombay

Channel Sounding UsingUSRP2 & GNU-RADIO

Increased Use of Wireless DevicesIncreased Use of Wireless Devices

Data-Intensive High Bandwidth ServicesData-Intensive High Bandwidth Services

Strain in capacity of RF SpectrumStrain in capacity of RF Spectrum

Most Communication becomes impractical above 10GHZ in Microwave Region.

Why?:- Motivation

Channel Sounding UsingUSRP2 & GNU-RADIO Multipath Effects of Channel

Multiple propagation paths:Line-of-Sight (LoS) and NLoS Invites Multipath invites:-Scattering, Reflection, Diffraction. Channel Becomes:-Frequency dependent,Time dependent and Position dependent.

Ultimately Coherence Bandwidth is adversely affected.

Channel Sounding UsingUSRP2 & GNU-RADIO

Flow Model

Channel Sounding UsingUSRP2 & GNU-RADIO

Apparatus

Channel Sounding UsingUSRP2 & GNU-RADIO

Host PC

PN code

Tx Gain

BPSK Modulation

USRP(Tx)

FPGA

DAC

RF Boar

d

RFX2400Up-

Conversion

TransmitterAntenna

Interpolation Filters , Cordic

DUC

Our Transmitter side Flow-Design

Channel Sounding UsingUSRP2 & GNU-RADIO Our Receiver side Flow-Design

USRP(Rx)

Daughter Board

ADC

FPGA

FPGA Cordic.

DDC

Data Flow

USRP(RX) Motherboard

Rx Host PC

Channel Sounding UsingUSRP2 & GNU-RADIO Host PC(Tx) Flow-chart

USRP2 Gb Ethernet Host Pc

(Transmitter)

Digital_bert_tx.py

GNU-RADIO

UHD-DRIVER

PN Sequence Vector Source

Unpack_to_pack

BPSK Differential gray coded Modulation

Uhd_Transmitter USRP2

Channel Sounding UsingUSRP2 & GNU-RADIO Host PC(Rx) Flow-chart

File Sink(.dat)

File SinkHost Pc (Receiver)

Gb Ethernet I

Q

Data Processing I

USRP2

Read Complex_to_Binary

Window/Seq

Windowing on Data-Stream Per PnSequence

Channel Sounding UsingUSRP2 & GNU-RADIO

Data Processing II

Window/Seq

Local Pn-Seq Channel Impulse

Response

Cross Correlated Data

Cross_Corr

Averaged Over Windows Average CIR

Power Delay Profile

Frequency Correlation Function

FFT

Coherence Bandwidth Estimation

Channel Sounding UsingUSRP2 & GNU-RADIO

Host PC(Rx) Flow-chart

Host Pc (Receiver)

GNU-RADIO

UHD-DRIVER

Demodulator

Stream Converter

Uhd_Receiver

Digital_bert_rx.py

Octave Based Post-Processing

File Sink(.dat)

Channel Sounding UsingUSRP2 & GNU-RADIO

Requirements:-

Our Automated-Sounder APPLICATION

Software

Gnu-Radio 3.6.0PythonOctaveUHD_Driver (Latest stable)

Hardware

USRP2(Tx,Rx)Two PCsGb Ethernet

Channel Sounding UsingUSRP2 & GNU-RADIO Our Automated-Sounder APPLICATION

Channel Sounding UsingUSRP2 & GNU-RADIO

Impulse Response of a window

Channel Sounding UsingUSRP2 & GNU-RADIO

Power Delay of the window

Channel Sounding UsingUSRP2 & GNU-RADIO

Channel Impulse Response

Channel Sounding UsingUSRP2 & GNU-RADIO

Power Delay of the window

Channel Sounding UsingUSRP2 & GNU-RADIO

Power Delay Profile

Channel Sounding UsingUSRP2 & GNU-RADIO

Frequency Correlation Function