Stevens Institute of Technology Wireless Research Laboratory

Summer Research

Final Report

Distributed Frequency Access and Networking Wireless Testbed

May 2005 – August 2005 This research is sponsored by the Department of Defense, United States Army

Name: Shamim Akhtar Advisor: Professor Ufuk Tureli Email: sakhtar@stevens.edu Cell: 646.239.1054

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Table of Contents

Summary …………………………………………………………………………... 3 Introduction ……………………………………………………………………….. 4 Comblock Definition ……………………………………………………………… 5 Previous Work …………………………………………………………………..…. 5 Hardware …………………………………………………………………….…..… 8 Existing 1-Antennae Design ………………………………………………... 8 Modified 2-Antennae Design ………………………………………………. 9 Software ……………………………………………………………………….……11 Comblock control center …………………………………………….….…..11 Comblock Console …………………………………………………….……12 Spectrum Stats ………....………………………………………….….…….. 13 Conclusion ………………………………………………………………………… 14 Reference …………………………………………………………………………... 15 Appendix …………………………………………………………………………... 16

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Summary

Research on Distributed Frequency Access and Networking Wireless Testbed is ongoing and currently in the development phase. This testbed can be utilized for diverse wireless experiments and for analyzing the waveforms of radio frequency (RF) signals. The testbed employs comblock modules as the building blocks for the research. Various component comblock modules are being tested and built into comblock assemblies during summer research. These assemblies include Transmitter and Receiver (Tx/Rx) setups which are being researched and developed. These Tx/Rx nodes will be deployed around the Stevens campus and will be ultimately powered over an active network connection. We would be able to control the nodes, change settings and capture and analyze data sent from one transmitter and collected by one or more receivers. Different engineering methods are being employed to design more efficient and economically viable Tx/Rx arrangements. During this research various programs have been developed and modified making it possible to control the comblocks from anywhere on a Local Area Network (LAN). Some of these programs have been built by previous groups working on research, while others have been developed by the manufacturer of comblock.

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Introduction

Innovations are not limited to discovering new things, exploring new horizons and going where no man has gone before. Engineering innovations also include making efficient and effective use of already existing technology in a cost effective manner. The most widespread of these modern technologies is the use of wireless equipments. It has brought to light how the frequency spectrum is being used by various devices. The spectrum has been licensed and fragmented with various companies using different sections of it. However to use it more effectively schemes have to be developed so that the same frequencies can be utilized for multiple uses. In order to achieve that goal the frequency must be analyzed; its power aspects as well as its waveform. The current research project employs various methodologies to analyze and explore the waveforms. It is currently in the development phase and the wireless testbed is being constructed. This report discusses the various methods and engineering practices used to choose the best product to develop the testbed and the different designs considered before deciding on the best design.

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What is a Comblock?

According to the Comblock website ComBlock modules can be described ae small commercial off-the-shelf modules which are pre-programmed with essential communication processing functions. These functions include modulation, demodulation, error correction encoding and decoding, digital to analog/RF, RF/analog to digital, formatting, data storage and baseband interface. They are used for rapid prototyping of complex communication equipment. When software simulations are no longer fast enough nor representative enough, ComBlock offers a real-time cost-effective alternative. Communication Block modules support processing speeds of up to 120 MHz and I/O speeds of up to 40 Msamples/sec. The following figure shows a typical comblock module and it also displays its size with respect to the finger of the person holding the wires.

Figure 1 - Typical Comblock Module

Previous Work Distributed Frequency Access and Wireless Testbed is an ongoing project and various other Summer Research groups, as well as Senior Design groups, have worked on it in previous semesters. However due to lack of documentation, an organized file structure and working directories, as well as uniformity in programming language use, their work could not be used in a constructive manner. In the end much of the time was spent debugging their code and achieving the same level of experimental results. The first two weeks were spent collecting and organizing previous material, as well as familiarizing ourselves with the project, the equipment and the programming languages involved. The existing Matlab and Visual Basic code were modified and our group worked on advancing already completed tasks. Once the Matlab code was functional we obtained various graphs on specified frequencies. Some of these graphs are presented below.

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Figure 2 - Single Frequency Graph

By specifying a single frequency in the Matlab code the above graph was obtained. The Matlab code had the capability of specifying two (2) or even multiple frequencies. We could also specify the number of samples we wished to consider. But collecting and analyzing a large number of samples had a drawback. The increase in the number of samples results in an increase in the time needed to run the simulation. The following figure shows a graph obtained by specifying multiple frequencies in the simulation.

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Figure 3 - Multiple Frequencies

If we zoomed into any of the above “vertical lines” we would be able see an image similar to Figure 2 with the single frequency graph.

These graphs look promising and initially they were thought to represent signals that the receiver was picking up from the air. However after careful consideration and extensive discussions with Professor Tureli they were determined to be carrier signals.

A Graphical User Interface (GUI) was also made to demonstrate how the Tx/Rx

setup can be used to analyze frequency channels. This GUI was called Spectrum Stats and it displayed the frequencies that the receiver could detect and the free frequencies among them. It is discussed in greater details in the Software – Spectrum Stats section of the report.

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Hardware Existing 1-Antennae Design:

TRANSMITTER

RECEIVER

Workstation

COM-5001LAN/IP

NETWORK INTERFACE

COM-8001WAVEFORM GENERATOR

COM-2001D/A

CONVERTER

COM-4001DUAL BAND

2.4GHZMODULATOR

RF

Workstation

COM-5001LAN/IP

NETWORK INTERFACE

COM-8002HIGH SPEED

DATA ACQUISITION

COM-3001DUAL BAND

2.4GHZ MODULATOR

RF

Figure 4 - Existing Setup

The existing setup can be seen in the above figure. The transmitter is shown at the

top and the receiver at the bottom. The transmitter is broken down into the different component comblocks. COM 5001 – LAN/IP Network Interface acts as the network port for the Transmitter. It can be assigned a specific IP address (static) and the IP and the Default Gateway must be defined in the registers of the COM 5001. It provides the means of communication between the computer attached to the setup and the Transmitter. The comblocks have to be initially defined using a serial cable. The comblocks are controlled by a group of register settings which are set in Hex. These registers are set using the Comblock Control Center and after all the registers have been set, the comblock assembly can be accessed via the LAN module. From then onwards the comblocks and effectively the whole setup can be accessed and changed via LAN connection to which the Tx/Rx setup is connected. As is evident from the figure above for the Transmitter the layout of the comblocks is: Com 5001 LAN/IP Network Interface Com 8001 Waveform Generator Com 2001 D/A Converter Com 4001 Dual Band 2.4GHz modulator RF

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As is evident from the figure above for the Receiver the layout of the comblocks is: Com 5001 LAN/IP Network Interface Com 8002 High Speed Data Acquisition Com 3001 Dual Band 2.4GHz modulator RF Modified 2-Antennae Transmitter-Receiver Design:

During the course of summer research it was decided to have a 2-Antennae transmitter/receiver design. Thus each node would consist of a receiver with 2 antennae or a transmitter with 2 antennae. As this kind of an assembly had never been constructed or designed before, the group had to consult with MSS, the manufacturers of comblock, and Professor Tureli. After careful consideration of several Tx/Rx designs, it was decided to have two (2) parallel transmitter and receiver assemblies. These assemblies would be synchronized and thus they can start and stop collecting data samples at the same instant of time. Each transmitter and receiver would be assigned individual IP addresses and they can be controlled using these IP addresses.

The new Tx/Rx design are shown below.

Modified Tx/Rx setup:

Figure 5 - Modified Design for 2 Antennae Receiver

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Figure 6 - Modified Design for 2 Antennae Transmitter

The individual comblocks of the modified Tx/Rx assemblies had been ordered and

they are currently being tested. After completion of the tests they will be deployed around the Stevens campus. Then they will form the wireless testbed for various research experiments.

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Software Several different programs have been written to control various aspects of the experiments that can be conducted using the wireless testbed. Each of the comblock setups obtains data that the receiver collected, sends signals via the transmitter and also analyzes the data collected are controlled by the programs. These programs have been written using an array of programming languages including Matlab, Visual Basic, and Visual C. A discussion of the different software used to modify and control the comblock Tx/Rx setups is provided below. Comblock Control Center: A screenshot of the Comblock Control Center is provided below.

Figure 7 - Comblock Control Center

The above figure shows the Comblock Control Center connected to the Comblock setup. This program is made and distributed by Comblock manufacturers to act as an interface to the comblocks. The left of the picture shows the list of comblocks attached to each other and the order in which they are connected; starting from the LAN/IP network interface, moving on to the Arbitrary Waveform Generator and so on. The right side of the picture shows the values of the registers for the highlighted comblock (Arbitrary Waveform Generator). Each of the registers hold a specific value and their detailed descriptions can be obtained from the datasheets for that comblock from the comblock website (http://www.comblock.com ). Before the comblocks can be connected to the LAN the registers have to be set. The first four (4) registers set the IP and the next (4) sets the default

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gateway and other registers reflect the DNS, clock synchronization (internal or external), transmission mode and other settings. Comblock Console:

Figure 8 - Comblock Console

The comblock console is a program developed by Stevens students. In this program

the receiver and transmitter can be chosen via the drop down menu at the upper left corner. After connecting to the transmitter and receiver this program can be used to generate and receive RF signals at particular frequencies. The frequencies can be defined in the text boxes in the main body of the GUI. It can also be used to upload and download small files using the Upload/Download functions to the right side of the GUI.

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Spectrum Stats:

Figure 9 - Spectrum Statistics

This program has been developed by Stevens students and it has been modified

during this current summer research term. This program has been written in Matlab and the main program calls on several small Matlab functions for its execution. All these functions and their associated library and dll files need to be present in the working directory of the Matlab program for Spectrum Stats to work properly. This program can be used to analyze the RF signals detected by the Receiver. This program can determine the whole range of frequencies that the receiver identifies and then establishes which of these frequencies are free. The left side of the GUI shows all the frequencies and the right side shows the free frequencies. It also displays the Signal to Noise ratio (SNR) of the signal and the access pattern of the wave generated by the signal.

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Conclusion

The Wireless Research Testbed is one of the pioneering advances in wireless technology that is currently going on at Stevens. This research implements cutting-edge technology combined with innovative programs written in a variety of programming languages. The testbed, once completed, will allow students to perform diverse and extensive wireless experiments. Funded by the Department of Defense, this project is currently meeting or exceeding the milestones set so far and is expected to be used for various purposes.

This research involved a variety of challenges, both hardware and software, which

together provide an invaluable learning experience. Developing the testbed is an extremely challenging and complicated task as it involves a range of engineering techniques and disciplines. Initially there were a variety of issues facing this project. But over the course of research these problems were solved, issued resolved and the project advanced smoothly. As this year’s summer research ends new groups can continue working on the testbed and develop and deploy the wireless nodes.

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Reference

1.) Comblock website: http://www.comblock.com/ Datasheets:

a) 5001 – http://www.comblock.com/download/com5001.pdf b) 8001 – http://www.comblock.com/download/com8001.pdf c) 8002 - http://www.comblock.com/download/com8002.pdf d) 2001 - http://www.comblock.com/download/com2001.pdf e) 4001 – http://www.comblock.com/download/com4001.pdf f) 3001 - http://www.comblock.com/download/com3001.pdf

2.) Sofware Defined Radio:

http://www.ettus.com/ 3.) Senior Design Groups

a) http://panda.ece.stevens-tech.edu/sd/grp5/ b) http://panda.ece.stevens-tech.edu/sd/grp20/ c) http://panda.ece.stevens-tech.edu/sd/grp23/ d) http://koala.ece.stevens-tech.edu/sd/archive/02F-

03S/websites/grp15/public_html/

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Appendix The appendix section consists of the weekly progress reports submitted and presented during the course of summer research. They are presented below in chronological order. Week – 1:

Researched on Digital Signal Processing Collected, categorized and prioritized previous work done on this topic Determined research goals and procedures how to achieve them Familiarized with equipment Tested Transmitter and Receiver with default configurations and made necessary

changes Week – 2:

Tested Transmitter and Receiver Researched on Matlab coding Looked at previous Matlab and Visual Basic programs done by other groups Analyzing existing source code for the GUI used for changing RF frequencies Continuing discussions with MSS (Comblock) and Flex Radio Systems for enhancing

the Transmitter/Receiver setup Week – 3:

Compared technical specifications of Comblock assembly and Ettus product to determine more efficient and cost effective product

Debugging existing source code for the GUI used for changing RF frequencies

Gave presentation to Picatinny official about progress of project

Presentation attached:

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Summer ResearchSummer Research

Transmitter Transmitter –– Receiver Receiver

Shamim AkhtarShamim AkhtarShaina DohertyShaina Doherty

Under supervision of:Under supervision of:Prof. Prof. TureliTureli

Tasks CompletedTasks Completed

Got familiar with the current Got familiar with the current ComBlockComBlock setup.setup.Located and reviewed previous Located and reviewed previous MatlabMatlab and VB and VB code prepared by previous groups.code prepared by previous groups.Contacted MSS/Contacted MSS/ComBlockComBlock to solve to solve troubleshooting problems.troubleshooting problems.Contacted MSS, FlexContacted MSS, Flex--Radio, Radio, EttusEttus to explore to explore more efficient productsmore efficient products

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Existing Setup

Future PlansFuture Plans

Locate and test unused channels in the spectrumLocate and test unused channels in the spectrumDevelop a distributed radio Develop a distributed radio testbedtestbed for testing crossfor testing cross--layer algorithmslayer algorithmsPlace 10 Transmitter & 10 Receiver network nodes at Place 10 Transmitter & 10 Receiver network nodes at suitable locationssuitable locationsEach node should be a 2Each node should be a 2--antennae antennae transmitter/receivertransmitter/receiverDevelop GUI using existing Develop GUI using existing MatlabMatlab and VB codeand VB code

Picture of actual Comblock assembly:

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Week – 4: Compared and tested the programs/code that has been done so far on the software

aspects of the project.

Compiled Matlab source code obtained in the previous week.

Full program has an included ‘pnet.c’ file which is supposed to call Matlab functions from within Visual C++. But VC++ is unable to execute ‘matlab.exe’. Trying to work around that problem which might be due to difference between various versions of VC++ (versions used are VC 6.0 and Visual C++ .NET 2003).

This week trying to compile/simulate existing Comblock Console application in

Visual Basic. This is an existing GUI which works on a particular set of comblocks, but due to lack of documentation and fragility of the application it is extremely hard to work with. If the existing source code is run then the following empty GUI is obtained:

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Picture of graph obtained from running Matlab program:

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Week – 5:

Modified Matlab code so that the graph does not refresh every 30 seconds. Could modify the “tic-toc” function to refresh the graph every few minutes instead of seconds.

Trying to use the “gui.m” file developed by a different group in conjunction with the

rest of the Matlab files that we modified.

Existing GUI that we are trying to debug and run should look like the following:

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Using the above GUI the following graph was obtained by previous group:

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Practiced with demos for Matlab GUIs: Week – 6:

Debugged Matlab code and Matlab functions Graphs obtained are presented below:

◙ Graph obtained from using first set of frequencies:

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◙ Graph showing the zoomed view of the previous graph:

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◙ Graph obtained from using second set of frequencies:

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◙ A zoomed view of the previous graph. Concentrating on 1 of the 2 vertical spikes seen above:

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◙ Graph obtained from using third set of frequencies:

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◙ A zoomed view of the previous graph. Concentrating on 1 of the multiple vertical spikes seen above:

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◙ Increasing the zoom the following picture is seen:

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◙ Further zooming on the graph does not reveal any more features.

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◙ GUI:

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◙ GUI demonstration follows. Notice the “Access Pattern” changing when a different frequency is plotted.

Week – 7:

Researched various comblock Tx/Rx configurations

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Ordered new Comblocks from MSS

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Currently working with borrowed Tx/Rx comblock setups. Registers need to be set correctly to match the new IP and Default Gateway.

Waiting for new Comblocks to arrive. They will be modified with 2 antennae.

Week – 8:

Installed Linux Mandrake version 10.2 on computers. Tested stability of OS after installation.

Installed Matlab on Linux and turned off unnecessary features of Matlab.

Contacted MSS/Comblock to discuss viability of Transmitter/Receiver setup

designs.

Preparing presentations for Army Research group from Picatinny. Week – 9:

Worked with Comblock assemblies borrowed from WinSec Lab.

Setting the registers to conform with new network setup to which they are now connected.

Presented summer research progress to Army Research Lab group from Picatinny.

Presentation is attached:

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Summer Research

Comblock Transmitter – Receiver

Undergraduate Students:

Shamim AkhtarShaina Doherty

Under supervision of:

Professor Uf Tureli

Tasks Completed

• Reviewed previous work done with ComBlocks.• Modified existing Matlab and VB code.• Collected initial graphs from Receiver which display

selected carrier signals.• Recreated a GUI which was not previously functional.• Ordered new parts for ComBlock testbed.

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Existing Setup

Pictures – Transmitter

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Pictures – Receiver

Receiver – boxed setup

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Receiver – open box

Working Matlab Graph

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Matlab - GUI

Comblock Control Center

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Design Proposal

Design Proposal … cont

• Discussed various design options with Prof. Tureli. • Contacted MSS/Comblock regarding feasibility of

design proposal.• Received guidance from Comblock technical

support.• Continue working on resolving hardware and

software issues.

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Future Plans

• To further develop the ComBlock testbed.• Develop a distributed radio testbed for testing

cross-layer algorithms• Place 10 Transmitter & 10 Receiver network

nodes at suitable locations• Each node should be a 2-antennae

transmitter/receiver

Questions - Comments

Thank you!