Physical Layer Testbed Components

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Physical Layer Testbed Components Michael
Fitz fitz_at_ee.ucla.edu Babak Daneshrad babak_at_ee.ucl
a.edu University of California, Los
Angeles Urbashi Mitra ubli_at_ceng.usc.edu University
of Southern California, Los Angeles
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Overview of Effort

• Narrowband Testbed (Fitz)
• MIMO Wideband Testbed (Fitz/Daneshrad)
• Ultrawideband Testbed (Mitra)
• Note as one would expect testbed network utility
  today is inversely proportional to bandwidth
• The Whynet goal is to bring these capabilities to
  roughly equivalent levels

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Narrowband Testbed - Executive Summary from
Kickoff Meeting

• Goals in Year 1
• Establish infrastructure based testbed
• Establish ad-hoc long range testbed
• Produce physical layer interface and overview
  document
• MIMO feedback communication experiments
• Eventual network capabilities
• Full infrastructure network (10 nodes)
• Full ad-hoc network (10 nodes)
• Integration with 802.11 network for configuration
  management applications
• MIMO limited (1-2 nodes)

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Narrowband Network Accomplishments

• API for modem and base stations complete
• Linux based
• Appears as a standard network port
• Demoed during PI meeting
• 5 node network established
• Developed an efficient physical layer
  synchronization architecture for ad-hoc operation
• Bandwidth efficient CPM modulation
• Carrier sense and complete synchronization of phy

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Narrowband Network System Configuration
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Narrowband Near Term Goals

• Document the network
• Software interfaces for networking community
• Realistic deployment
• Transfer an FCC license (could use NSF help here)
• Factor building (cover entire West side of LA)
• Write a magazine article to advertise the
  capability and invite the communitys
  participation

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MIMO Wideband Testbed - Executive Summary from
Kickoff Meeting

• Functional in Year 2
• Nodes for MIMO enable network testing
• Produce physical layer interface and overview
  document
• MIMO feedback communication experiments
• Eventual network capabilities
• Full ad-hoc network (10 nodes)

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Wideband Network Accomplishments

• Established an automated infrastructure for
  realistic channel data acquistion
• Established a testbed for .11n applications
• Calibrated and tested wideband radios/modems at
  2.4GHz and 5.4GHz
• Performed an extensive field test at 5.4GHz

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Goal is to Automate Radio Testing

• Automated to minimize labor in testing
• Remotely accessible
• Acquire data remotely
• Control experiment remotely
• Share data across the internet
• Construction must be by an untrained labor force
• NSF does not give much money

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Solution - Lego Robot
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Measurement Setup

• Remote terminal could be anywhere
• Demoed at PI meeting

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Remote PHY Testing - Channel Emulator

• 4 Channels were able to be purchased
• Future proposals for more channels in the works
• Demoed running 2x2 at the PI meeting

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Asteriod The Phase-1 Testbed
Graphical User Interface (GUI)
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Practical Impairments Calibration-
Calibration to 25 dB SNR floor- Fix known issues
to deliver a stand alone robust platform
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Testbed calibration in perfect timing mode
Implementation Loss with Perfect timing
Implementation Loss with Non-Perfect timing
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Most Recent Measurement Campaign- Inside same
room- Between 2 rooms- From Lab to Hallway-
Inside of cubicle area- Results to be added to
WHYNET repository
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Capacity curves in EE54-114
Keep received power Constant for all cases By
referring back to the Tx.
Theoretical channel Capacity
Capacity measured using slicer SNR
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MIMO2x2 Overhead analysis
As training symbols and continuous pilots
increase SNROUT increases, but throughput drops
due to increased overhead.
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Wideband Goals

• Automated test environment
• Robots
• Channel emulator
• Make this environment available on the web
• FPGA/DSP platform
• Algorithm development and testing
• ASIC/FPGA platform
• Networking development and testing

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Ultrawideband Radios - Executive Summary from
Kickoff Meeting

• Functional Point to Point Year 2
• Physical layer experiments
• Point to point networking with interference
• Eventual network capabilities
• Stationary local area networking
• Limited network scenarios

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Second derivative of Gaussian pulse as tx template

• Left Measured template in anechoic chamber
• Right Measured received signal due to a single
  template in the typical environment.
• Note to the very dense multipath effects on the
  received signal
• Note to the differentiation effect of
  transmission in the single template

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WHYNET test bed

• UWB physical layer simulation
• Link with network simulator (NS) environment
• C programming
• Different settings and parameter selection
• Simulate different typical environments
• (IEEE 802.15 four UWB channel models)
• Different parameter selection in transmitter,
  receiver and employed techniques
• Wireless development kits (WDK) from
  XtremeSpectrum

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Channel models and timing recovery

• Channel model (IEEE 802.15)
• CM1 LOS, 0-4m channel measurement
• CM2 NLOS, 0-4m channel measurement
• CM3 NLOS, 4-10m channel measurement
• CM4 Extreme NLOS multipath, 25 nsec rms delay
• Synchronization levels
• UWB Frame timing recovery
• Symbol timing recovery

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Mode parameters block diagram
De-spreading RAKE receiver/ TR receiver
(standard/optimized) Decoder
IEEE UWB channel model (CM1/CM2/CM3/CM4) Narrow
band interference Gaussian Noise Propagation
effects on template waveform
Sync. symbols Error correction codes Spreading
codes (TH/DS) No. of frames/bit
Template waveform Power/Energy
UWB Frame maker
Receiver front-end
Modulator (PAM/PPM)
CHANNEL
Detector/decoder
Data blocks to higher layer
Data blocks From higher layer
Effects of antenna on template Channel
estimation Clean algorithm/efficient search
algorithms Synchronization
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UWB Future Goals

• Majid to add

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Some basic parameters (adjustable)

• Nsy Number of data symbols/observed interval
• Nd Number of transmitted symb/data symb
• Tsam Template sampling time
• Nu Number of users
• Ts Symbol time
• Nf Number of frames/symb
• Nc Number of chips/symb
• Nh Time hopping seq. max value
• Nr Number of reference symbs
• Delta-samTime of RAKE fingers
• Alpha Fraction of transmitted energyspent for
  training and data symbs
• Np period of spreading sequence (DS case)
• Bcode Block code being used

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Using Testbeds in the Classroom
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EE233B Wireless Communications Research

• Simulation Component
• Students simulate a complete end to end QAM
  system with DFE and smart antenna processing
• Experimental Component
• Experimental system transmits 10 Mpbs real time
  and incorporates both DFE and smart antenna
  system
• Students carry out field measurement campaign and
  collect data
• Analysis and Conclusions
• Compare filed data and simulation data
• Draw conclusions and explain discrepancies

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EE233A Wireless Communication Theory

• Used the narrowband infrastructure to teach
  wireless communication theory
• Gave the students journal papers and they were
  required to implement the papers algorithm in a
  real-time system
• EX - BLAST
• 4bits/antenna