A Low Power OOK Digital Transceiver: Moving Forward

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A Low Power OOK Digital TransceiverMoving
Forward

• Louise Crockett
• University of Strathclyde
• louise.crockett_at_eee.strath.ac.uk

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Summary

• Purpose of Manchester OOK Development System
• Tested design
• Area, data rate and power
• Planned experiments
• Testing with RF link
• Improvements and modifications
• Conclusions

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Glasgow / Strathclyde Development System

• Aims
• To achieve point-to-point communication over a
  wireless link
• To design for simplicity and low power
• To grab transmitted and received signals for
  use in simulation
• To identify the limitations of the system
• To estimate power
• Transmitted power
• Received power
• Power consumed by components

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Data flow
Output signal to RF
Packet data
Serial data
Manchester Encoding
1V
0V
XOR

Manchester encoding ensures a transition in the
middle of every bit period.
This signal is used to switch an oscillator on
and off
Packet details 32 bits preamble 8 bits SOF
delimiter 256 bits payload
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Manchester OOK Transceiver Test System
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Progress

• Proof of successful transmission and reception
  through a wire
• Visual inspection of oscilloscope trace
• SOF delimiter easily identifiable
• Pattern of data elsewhere in packet
• Next step is to quantify performance
• Signal to noise ratio (SNR)
• Bit error rate (BER)
• Develop method for making relevant measurements
• Can bit errors be counted on-chip?

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Test System Analysis

• Aspects to analyse
• Sample wordlength
• Hardware usage
• Data rates
• Clock speeds
• Power consumption (on-chip)
• SNR
• BER performance under various conditions

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Data rates
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Area Analysis
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Power Analysis
Assuming 30nW/MHz/gate
Data Rate 195kbps
Total Power Consumed 382mW Without Thresholder
46mW
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Power Consumption
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Inclusion of Differential Coding
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Differential Coding

• Tracks changes in signal level
• Can be combined with Manchester Encoding
• Either Biphase-M or Biphase-S
• Protection against inversion of signal
• Does this provide an advantage for certain
  channels?

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Integration of RF Link
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Planned Work Analysis of RF Link

• Signal degradation through RF link
• Want to quantify effects
• Vary link length
• Different types of channel
• Line of sight
• Multipath with line of sight component
• Non line of sight, with severe multipath
• Vary transmit power
• Vary data rate
• Short term SNR
• Longer term BER

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BER Analysis

• Useful to collect BER information
• Via simulation
• On chip

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What happens next?

• Area and power analysis
• Change to Biphase-M or Biphase-S encoding
• Connect to RF hardware
• Collect and analyse data
• Feed back into SystemView simulations
• Incorporation of Faisals work on channel
  estimation
• Discussion regarding packet formatting

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Conclusions

• DSP transceiver designed and tested
• Shortly to integrate with RF section
• Area and power analysis
• Low power design
• Potential for further reduction
• Planned experiments

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Review

• Context
• Test system
• Area, data rate and power
• Planned improvements and experiments
• Useful information to inform future design