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Distributed spectrum sensing in unlicensed bands using the VESNA platform. Seminar II. Student: Zoltan Padrah Mentor: doc. dr. Mihael Mohorčič. Agenda. Motivation Theoretical aspects Practical aspects Stand-alone spectrum sensing Distributed spectrum sensing Spectrum sensing testbed

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slide1

Distributed spectrum sensing in unlicensed bands using the VESNA platform

Seminar II

Student: Zoltan Padrah

Mentor: doc. dr. MihaelMohorčič

slide2

Agenda

  • Motivation
  • Theoretical aspects
  • Practical aspects
  • Stand-alone spectrum sensing
  • Distributed spectrum sensing
  • Spectrum sensing testbed
  • Experimental results
  • Conclusions
  • TODO: - slide number
  • - date
  • - location
  • headers somewhere

Seminar II

motivation
Motivation

Seminar II

motivation1
Motivation
  • Motivation
  • Theoretical aspects
  • Practical aspects
  • Stand-alone spectrum sensing
  • Distributed spectrum sensing
  • Spectrum sensing testbed
  • Experimental results
  • Conclusions

Seminar II

  • Introduction
  • Radio spectrum
    • Regulation
    • Usage
  • Using the radio spectrum more efficiently
    • Approach
  • Reusing radio frequency bands
    • Licensed
    • Unlicensed
slide5

Introduction

1

  • Radio spectrum1
    • Many systems use it: AM, FM, TV broadcast, GSM, UMTS, WiFi, GPS, satellite
    • Systems need to coexist
      • Avoid disturbance (interference)
  • Radio spectrum regulation
    • Frequency band allocation
    • Each system has its own frequency band

Seminar II

1image credit: Roke Manor reseach, 2004

slide6

2

Frequency band allocation

Seminar II

image credit: Roke Manor reseach, 2004

slide7

3

Usage of radio spectrum

  • Studies about radio spectrum utilization

Left: Cabric et al: Implemenation issues

In spectrum sensing

Bottom: Valenta et al: Survey in spectrum

utilization in Europe

Seminar II

slide8

Usage of radio spectrum

  • Studies about radio spectrum utilization

Terminal 2

Terminal 3

Left: Cabric et al: Implemenation issues

In spectrum sensing

Bottom: Valenta et al: Survey in spectrum

utilization in Europe

Terminal 1

Seminar II

slide9

Usage of radio spectrum

  • Studies about radio spectrum utilization

Terminal 2

Terminal 3

Left: Cabric et al: Implemenation issues

In spectrum sensing

Bottom: Valenta et al: Survey in spectrum

utilization in Europe

Terminal 1

Terminal 4

Seminar II

approach

4

Approach

Get information about radio spectrum

Take decision on the used frequency band

Seminar II

approach1
Approach

Perform database lookup

Get information about radio spectrum

Perform sensing with a radio

Take decision on the used frequency band

Seminar II

reusing radio spectrum

5

Reusing radio spectrum

In licensed bands

In unlicensed bands

Examples: ISM bands (868 MHz; 2.4 GHz)

Multiple equally threated users

Spectrum Sharing (SP)

  • Examples: TV VHF, UHF, GSM bands
  • Primary user(s)
  • Secondary user(s)
  • Dynamic spectrum access (DSA)

Seminar II

reusing radio spectrum1
Reusing radio spectrum

In licensed bands

In unlicensed bands

Examples: ISM bands (868 MHz; 2.4 GHz)

Multiple equally threated users

Spectrum Sharing (SP)

  • Examples: TV VHF, UHF, GSM bands
  • Primary user(s)
  • Secondary user(s)
  • Dynamic spectrum access (DSA)

Seminar II

theoretical aspects1
Theoretical aspects
  • Motivation
  • Theoretical aspects
  • Practical aspects
  • Stand-alone spectrum sensing
  • Distributed spectrum sensing
  • Spectrum sensing testbed
  • Experimental results
  • Conclusions

Seminar II

Problem formulation

Goals

Hidden terminal and exposed terminal situations

Spectrum sensing

Energy detection

problem formulation

6

Problem formulation
  • For solving the artificial spectrum scarcity problem, it is necessary:
  • Experimental-driven research
  • Experimental validation and improvement of sensing algorithms

We assume that either:

a radio communication experiment is prepared in an ISM radio frequency band

the radio activity in an ISM band is of interest at a given location

In both cases external interference might be observed.

Seminar II

Testbed is needed

goals

7

Goals

Seminar II

  • Defining the system architecture for a testbed
  • Developing software that allows performing spectrum sensing with the VESNA platform
  • Spectrum sensing:
    • Calibration of multiple VESNA devices
    • Evaluation of their performance
    • Performing experiments with them
  • Implementation of the functionalities needed for
    • Integrating multiple VESNA devices in a testbed
    • Communication system of the testbed, supporting experiments
  • Experimental evaluation of the performance of a VESNA-based spectrum sensing testbed.
slide18

8

Hidden terminal and exposed terminal situations

  • Idea: use multiple radios for observation
    • Each radio performs partial detection
    • Results are centralized
  • Resolves the problems:
    • Hidden transceiver
    • Hidden receiver
  • Relies on other methods for partial detection

Seminar II

slide19

9

Spectrum sensing

  • Detecting other radios
  • Spectrum sensing methods
    • Energy detection
    • Eigenvalue based detection
    • Cyclostationary feature detection
    • Matched filter detection
    • Collaborative sensing

Seminar II

slide20

10

Energy detection

  • Idea: measure the energy in frequency band and compare it to a threshold
  • Simple to implement
  • Needs correct threshold value: noise floor
  • Does not work well with spread spectrum signals

Seminar II

practical aspects1
Practical aspects

Todo, agenda style

  • Motivation
  • Theoretical aspects
  • Practical aspects
  • Stand-alone spectrum sensing
  • Distributed spectrum sensing
  • Spectrum sensing testbed
  • Experimental results
  • Conclusions

Seminar II

Used devices

VESNA platform

Spectrum sensing framework

used devices

11

Used devices

Seminar II

  • Sensor network based testbed
  • VESNA platform
    • Low-cost, low-complexity
  • CC1101 radio – 868 MHz ISM band
  • CC2500 radio – 2.4 GHz ISM band
  • The radios can only provide RSSI values
    • Only energy detection is possible
vesna platform

12

VESNA platform
  • Developed at Jozef Stefan Institute
  • ST ARM Cortex-M3, 64 MHz
  • JTAG, USB, USART PC interface
  • I2C, SPI, PWM, ADC, DAC, USART sensor and actuator interfaces
    • Code library: C/C++ (GCC)
  • 300-900 MHz, 2.4 GHz radio interface (all ISM bands);
    • TI CC1101, TI CC2500
  • Software tools: Open Source
    • Eclipse IDE
    • Tool-chain: GNU Compiler Collection
    • Cygwin, Linux environment for Windows
    • JTAG server: OpenOCD
    • JTAG hardware interface: Olimex ARM-USB-OCD

Seminar II

vesna platform1
VESNA platform
  • Developed at Jozef Stefan Institute
  • ST ARM Cortex-M3, 64 MHz
  • JTAG, USB, USART PC interface
  • I2C, SPI, PWM, ADC, DAC, USART sensor and actuator interfaces
    • Code library: C/C++ (GCC)
  • 300-900 MHz, 2.4 GHz radio interface (all ISM bands);
    • TI CC1101, TI CC2500
  • Software tools: Open Source
    • Eclipse IDE
    • Tool-chain: GNU Compiler Collection
    • Cygwin, Linux environment for Windows
    • JTAG server: OpenOCD
    • JTAG hardware interface: Olimex ARM-USB-OCD
  • Performance:
  • Comparable to other sensor node platforms, like TelosB or Sensinode
  • Lot less processing power than a PC

Seminar II

spectrum sensing framework

13

Spectrum sensing framework

Control system

Communication and control

On-line processing

Radio

VESNA

Data storage

Communication

interface

Off-line processing

Seminar II

standalone spectrum sensing1
Standalone spectrum sensing
  • Motivation
  • Theoretical aspects
  • Practical aspects
  • Stand-alone spectrum sensing
  • Distributed spectrum sensing
  • Spectrum sensing testbed
  • Experimental results
  • Conclusions

Seminar II

  • Goals
  • Experimental setup
  • Calibration results
    • CC2500
    • CC1101
goals1

14

Goals

Seminar II

Implementation of spectrum sensing functionality

Calibration of the prototype

experimental setup

15

Experimental setup

Coaxial Cable

Signal generator

VESNA

Generated signal level

Measured signal level

Offset value

Seminar II

calibration cc2500

16

Calibration – CC2500

Seminar II

Absolute error: < 6 dB

Nonlinearity: < 2 dB

calibration cc1101

17

Calibration – CC1101

Seminar II

Absolute error: < 8 dB

Nonlinearity: < 0.5 dB

calibration cc11011

18

Calibration – CC1101

Malfunction

Seminar II

distributed spectrum sensing1
Distributed spectrum sensing
  • Motivation
  • Theoretical aspects
  • Practical aspects
  • Stand-alone spectrum sensing
  • Distributed spectrum sensing
  • Spectrum sensing testbed
  • Experimental results
  • Conclusions

Seminar II

  • Goals
  • Demonstration
    • Devices
    • Environment
    • Representative results
  • Device comparison
    • Introduction
    • Environment
    • Results
goals2

19

Goals

Seminar II

  • Demonstrate the functioning of heterogeneous sensing system
  • Benchmark
    • Devices
    • Combinations of devices
demonstration devices

20

Demonstration – devices

Seminar II

  • eZ430-RF2500
    • Texas Instruments wireless development tool
    • MSP430 CPU
    • CC2500 radio
  • USRP2
    • Universal Software Radio Peripheral
    • SBX daugthterboard
    • Software defined radio device
    • GNU radio software
  • VESNA
    • CC2500 radio
device comparison

23

Device comparison

Path loss model with parameters

Measurement results from devices

Fitting

For each

device

Parameter values

Error relative to the model

Comparison

Seminar II

device comparison1
Device comparison

Path loss model with parameters

Measurement results from devices

Fitting

For each

device

Parameter values

Error relative to the model

Comparison

Seminar II

device comparison2
Device comparison

TODO intro

More text, because work has been done

  • One static continuous transmission
  • Multiple measurement locations

Path loss model with parameters

Measurement results from devices

Fitting

For each

device

Parameter values

Error relative to the model

Comparison

Seminar II

device comparison3
Device comparison
  • One static continuous transmission
  • Multiple measurement locations

Path loss model with parameters

Measurement results from devices

Fitting

For each

device

Parameter values

Error relative to the model

Mean Squared Error (MSE): average of squared error values for each data point

Comparison

Seminar II

environment

24

Environment

Seminar II

spectrum sensing testbed1
Spectrum sensing testbed
  • Motivation
  • Theoretical aspects
  • Practical aspects
  • Stand-alone spectrum sensing
  • Distributed spectrum sensing
  • Spectrum sensing testbed
  • Experimental results
  • Conclusions

Seminar II

  • Architecture
  • Goals
  • Requirements
  • Constraints
  • Measurements
    • Setup
    • Representative results
architecture

27

Architecture

Seminar II

architecture1
Architecture
  • Functionality abstracted in resources
  • RESTful design: GET and POST requests
  • All nodes addressable
  • Requests initiated by management and control part

Seminar II

architecture2
Architecture
  • Custom application layer protocol
  • Similar to HTTP

Seminar II

architecture3
Architecture
  • Management and control part
  • Access control
  • HTTP interface
  • Scriptable

Seminar II

goals3

28

Goals

Seminar II

  • Everything configurable remotely
    • No physical access
  • Unified control interface
    • Simple design and usage
  • Centralized control and data collection
    • Simplicity, reliability
  • Possibility of easily adding functionality in the future
requirements

29

Requirements

Seminar II

  • Spectrum sensing data collection
    • Performance level
    • Nodes  Control system
  • Reprogramming functionality
    • firmware image transmission performance level
    • Control system  Nodes
  • Reliability
constraints

30

Constraints

Seminar II

  • Availability of Internet access
    • for the gateway node
  • Location of light poles
  • Power connections to the light poles
  • Radio connectivity
  • Possibilities for experiments
measurements setup

31

Measurements – setup

Seminar II

  • Goal: measuring radio propagation
    • For the control network
experimental results1
Experimental results
  • Motivation
  • Theoretical aspects
  • Practical aspects
  • Stand-alone spectrum sensing
  • Distributed spectrum sensing
  • Spectrum sensing testbed
  • Experimental results
  • Conclusions

Seminar II

  • Scenario
  • Radio wave propagation in the testbed
    • Link quality categories
  • Experiment scenario
  • Results
scenario

33

Scenario

Seminar II

  • In the industrial zone
  • 2.4 GHz ISM band
  • Emulated behavior
    • Scripted
  • Observed by multiple nodes
link quality categories

35

Link quality categories

2)

1)

3)

Seminar II

Good link quality

Medium link quality

Bad link quality

node roles in the experiment

37

Node roles in the experiment

(c)

(n)

Seminar II

Node 17: terminal with cognitive radio capabilities (c)

Node 2: terminal without cognitive radio capabilities (n)

Rest of the nodes: observers

conclusions
Conclusions

Seminar II

conclusions 1

41

Conclusions (1)

Seminar II

  • Spectrum sensing: energy detection is suitable for low-complexity platform
  • Stand-alone spectrum sensing prototype
    • Developed
    • Calibrated
    • Integrated in a heterogeneous system
    • Accuracy has been determined
conclusions 2

42

Conclusions (2)

Seminar II

  • Spectrum sensing testbed
    • Architecture defined
    • Network planning performed
    • Developed, set up
      • Including HTTP like protocol
  • Spectrum sensing experiment
    • Prepared
    • Performed