Spectrum%20Etiquette%20Rules%20for%20Shared%20and%20Unlicensed%20Bands

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Spectrum Etiquette Rules for Shared and
Unlicensed Bands

• Amer Hassan, Microsoft
• Jan Kruys, Cisco
• Jim Raab, Dell
• Stefan Mangold, Philips

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Purpose

• IEEE 802.18 SG1 is approaching the FCC with
  recommendations regarding the unlicensed use
  ofTV-bands and other fallow spectrum
• A task group was formed in summer 2003 in the
  Wi-Fi Alliance to address spectrum sharing
• Ensure license exempt spectrum usable with good
  user experience with the rapid increase of
  licensed exempt devices across all market
  segments products
• It is very important that such recommendations
  have a solid basis in research and modeling
• Industry should provide the right direction to
  international regulators in this early stage of
  discussion
• Simple sharing rules are discussed in the
  following

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Solutions in Four Domains

• Frequency, Space, Time, Information

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Possible Solutions to Spectrum Etiquette

• Improving Receivers
• Filtering
• Modulation and Coding
• Antenna Diversity, MIMO
• Improving Transmitter
• Modulation Coding
• Power Constraints
• Antenna Pattern
• Listen-before Talk (LBT)
• Sample spectrum etiquette rulesare discussed in
  the following

• Improving Wireless System
• Power/Time constraints
• Frequency selection
• Feedback from the receiver
• Hybrid Methods

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Be Nice and Efficient

• Non-Greedy Occupancy
• No user may occupy the channel with rate 0 (no
  data to send)
• RULE1 A device shall only transmit when it has
  data to send
• Channel Selection
• A channel is deemed accessible at a node if the
  aggregate interference power at the intended
  receiver is less than ITH
• RULE2 A device shall only transmit on a channel
  if the aggregate interference power for that
  channel as measured at the intended receiver is
  less than ITH

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RULE1 Simulation Results (Out/Indoor)

• average number of blocked nodes, as function of
  number of greedy nodes
• ?even 1 greedy node blocks the channel at an
  average of 4 nodes outdoors and 24 nodes indoors
• ?10 of the nodes greedy blocks an average of 41
  of the nodes outdoors and 98 indoors
• number of nodes blocked at least 90 in time, as
  function of number of greedy nodes
• ?10 of the nodes greedy blocks 33 of the nodes
  outdoors and 93 indoors at least 90 of the time
• ?a small fraction of greedy nodes can block
  channel access for the majority

indoor
outdoor
indoor
outdoor
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RULE2 Simulation Results

• ? a new active link with RULE2 results in a
  slight reduction in clear links compared to the
  background case
• ?a new active link w/o RULE2 results in a more
  significant reduction in clear links compared to
  both the background and the RULE2 cases

• average number of clear (not blocked) links for
  four scenarios
• Outdoor propagation model with low background
  interference
• Outdoor propagation with high background
  interference
• Indoor propagation with low background
  interference
• Indoor propagation with high background
  interference
• ?For each scenario the average number of clear
  links is shown with background interference only,
  with new active link, with and w/o channel check
  (RULE2)

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Frequency Selection

• Left without etiquette, right with etiquette
• Apparently, it would be beneficial to the
  broadband radio systems if the narrowband radio
  systems would select channels according to the
  etiquette

Uncoordinated channel selection Spectrum efficient behavior (etiquette)

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Conclusions

• It is important that we work together as industry
  to improve the usage of unlicensed spectrum
• We demonstrated simple rules that significantly
  improve the usage of such spectrum
• Thorough evaluation is already under way at
  802.18 SG1 and Wi-Fi Alliance
• Such evaluation is needed prior to approaching
  regulators