Regulatory Information for Low Latency Scanning in 5 GHz bands

1
Regulatory Information for Low Latency Scanning
in 5 GHz bands

• Amjad Soomro, Zhun Zhongand Javier Del Prado
• Philips

2
European Regulations in 5 GHz Bands

• For any STA, before transmitting on a channel
• Detect radars
• Know maximum transmit power levels
• Apply transmit power mitigation, if applicable
• However, STAs are allowed to rely on measurements
  and Mitigation requirements announced by AP

3
Situation

• STAs are forced to do passive scanning while
  roaming in 5 GHz bands in European regulatory
  domains
• Similar requirements might become applicable in
  US in upper 5 GHz bands
• Limits on maximum transmit power might be
  desirable for administrative reasons where
  regulatory requirements do not exist
• Passive scanning may result in wait times of up
  to one beacon period per scanned channel
• 5 GHz bands has at least twelve channels
• Many more to be available in future (US)

Results in long scan times
4
Proposal 1

• Include regulatory information in Site Report
• Enables active scanning
• Specifically, include additional four bytes
• Maximum Transmit Power Level
• Local Power Constraint
• Map field (as defined in 802.11h amendment)
• Information supplied by neighboring APs

Maximum Transmit Power Level Local Power Constraint Map
Octets 1 2 1
5
Proposal 2

• Site Reports may not be always available.
• No neighbor information available
• APs may choose to not include neighbor
  information

6
Proposal 2

• Add capability for APs to transmit regulatory
  information in between beacons
• Define new Regulatory Domain Information frame
• The frame to be transmitted, autonomously, by an
  AP in between beacons, zero or more times.

Category Action Dialog Token Regulatory Domain Information Element
Octet 1 1 1 5
Figure 0-6 Regulatory Domain Information frame
body format

Element ID Length Maximum Transmit Power Level Local Power Constraint Map/Detected Signal Map
Octets 1 1 1 1 1
Figure 1 Regulatory Domain Information Element
field format
7
Field Definitions

• The definitions for Maximum Transmit Power Level,
  Local Power Constraint and Map are the same as
  defined in IEEE 802.11h amendment.

8
Benefits

• Beacons have lots of other information
• Regulatory Domain Information frame keeps the
  frame length small
• Efficiently announces regulatory domain
  information, making it easier to transmit it
  multiple times within a beacon interval
• Reduces Passive Scanning Times
• By enabling on-demand active scanning
• Measurements Results/Information already exists
  in AP/neighboring APs
• No additional measurement burden just reporting
• No hardware changes required

9
Comparison Table for Two Proposals
Site Report Regulatory Domain Frame
Benefit at Initial Start up while passive scanning No Yes
Dependent on Neighbor Information Available Yes No
Channel Information Supplied Current Channel Other Channels
Benefit while operating in the same channel No Yes
Benefit when moving to a different channel Yes Yes
The two proposals are complementary
10
Conclusions

• Only passive scanning possible with the current
  protocol in 5 GHz European bands
• The proposal
• Enables active scanning
• Reduces time spent in passive scanning
• Simple additions in the protocol
• Without hardware changes

11
Straw Poll 1

• Would you support including regulatory
  information in Site Report to enable active
  scanning

YES
NO
12
Straw Poll 2

• Would you support adding a protocol frame to
  report regulatory information/measurements

YES
NO
13
Motion 1

• Instruct the editor to incorporate changes
  submitted in the document 11-04-0753 in the next
  TGk draft

14
Motion 2

• Instruct the editor to incorporate changes
  submitted in the document 11-04-0754 in the next
  TGk draft