802'11k Radio Resource Measurements

1
802.11k Radio Resource Measurements

• Kai Törmä

2
Outline

• Introduction
• 802.11k measurements
• How it works
• Conclusions
• Current status of 802.11k
• References

3
Introduction

• Task group k launched in late 2002
• Define radio resource measurement (RRM)
  parameters for network management and performance
  enhancement
• provide mechanisms to higher layers for radio and
  network measurements

4
802.11k Measurements

• Make measurements from layer 1 and 2 of OSI
  protocol stack
• Statical Measurement
• Characterize the radio environment in long-term
  statistical sense
• Identity Measurements
• Identify stations that affect each others
  performance

5
802.11k measurements

• Channel Load
• Noise
• Histogram
• Beacon Frame
• Hidden Node
• Medium Sensing
• Time Histogram
• STA Statistics
• Transmit power control (802.11h)

6
Roaming decision

• APs can provide a site report to clients
• APs collects data with beacon frames and will
  analyse it
• AP generates an ordered list of access points,
  from best to worst service, called a site report

7
Channel selection

• Currently APs and clients cannot share channel
  information
• With 802.11k
• Noise histogram
• Channel load
• Time histogram
• -gt AP will know is the channel quality good
  enough

8
Hidden nodes

• Clients or APs that other clients or access
  points cant hear
• With 802.11k
• Clients track hidden nodes and access points
  query clients with those lists
• APs knows now about clients who are on the edge
  of their cells

9
Client statistics

• Currently are limited to statistics APs maintain
• With 802.11k
• 802.11 MAC statistics
• Counts of MSDUs/MPDUs received/transmitted
• Counts of Channel utilization in rx tx
  direction
• Data rate modulation of last rx and tx
• RSSI, RCPI, and signal quality
• Etc.
• -gt More complete view of network performance

10
How it works
AP1
AP2
1
2
4
AP3
Client
3

• Client is moving away AP1, so AP1 informs the
  client prepare to move to another access point
• The Client asks the AP1 to provide it with a list
  of preferred access points nearby
• AP1 responds with a site report
• Client moves to the channel of best access point
  listed in the site report and connects it

11
Benefits

• Simplify WLAN radio configuration
• Enable better diagnostics of problems
• Using info that is easy and cheap to gather
• Enable new services
• Location based services
• Voice Over IP (VOIP)
• Enable better frequency planning, optimize
  network performance
• Enable automatic frequency planning
• Better traffic distribution

12
Changes to STAs

• Wireless MAC message protocol
• Build upon 802.11h mechanisms and measure frames
• add RRM capability bit and RRM action frame type
• MAC firware
• Handle new management frames in the wireless MAC
  protocol
• Compute measurement payloads form PHY registers
  and traffic

13
Conclusions

• Better wireless performance and management
• Better Observation of Access point
• Better Client performance
• Take Environmental data into consideration

14
Conclusions

• Measurements necessary for future wireless growth
• Future technologies require more measurement
• Once ratified, 802.11k would help IT build a
  better WLAN

15
802.11k status Mar 05

• 2nd Letter Ballot in Progress Currently
• Expect to go to Sponsor Ballot Summer or Fall 05
• Expect to be a standard by the end of 05 or early
  06

16
References

• Radio resource measurements (11k) intro IEE
  802.11-05/0184r0 ftp//ieeewireless_at_ftp.802wirel
  essworld.com/11/05/11-05-0184-00-000k-radio-resour
  ce-measurement-11k-intro.ppt
• Technical article Demystifying IEEE 802.11 for
  industrial wireless lans http//wireless.industri
  al-networking.com/articles/articledisplay.asp?id2
  25
• Searchmobilecomputer.com 802.11k
  http//searchmobilecomputing.techtarget.com/sDefi
  nition/0,,sid40_gci999671,00.html
• 802.11k makes WLANs measure up http//www.nwfusio
  n.com/news/tech/2004/0329techupdate.html
• Which 802.11 standards will actually make a
  difference? http//www.techworld.com/mobility/fea
  tures/index.cfm?fuseactiondisplayfeaturesfeature
  id1065page1pagepos1
• Developements of IEEE 802.11 technology
  http//www.electronics.dit.ie/staff/mdavis/EI_tal
  k_summary.pdf
• An adaptive approach to wireless network
  performance optimization http//www.intel.com/tec
  hnology/magazine/communications/wi02043.pdf