Doc.: IEEE 802.11-14/1335r1 Submission October 2014 Jim Arnold, US DoTSlide 1 IEEE 802.11 Regulatory...
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doc.: IEEE 802.11-14/1335r1 Submission October 2014 Jim Arnold, US DoT Slide 1 IEEE 802.11 Regulatory SC DSRC Coexistence Tiger Team DSRC Band Plan Rationale Date: 2014-10-03 N am e A ffiliations A ddress Phone em ail Jim Arnold US D epartm entof Transportation 1200 N ew Jersey A ve, SE, W ashington, DC 20590 +1 202 366 0278 [email protected] Authors:
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Transcript of Doc.: IEEE 802.11-14/1335r1 Submission October 2014 Jim Arnold, US DoTSlide 1 IEEE 802.11 Regulatory...
doc.: IEEE 802.11-14/1335r1
Submission
October 2014
Jim Arnold, US DoTSlide 1
IEEE 802.11 Regulatory SCDSRC Coexistence Tiger Team
DSRC Band Plan Rationale
Date: 2014-10-03
Name Affiliations Address Phone email Jim Arnold US
Department of Transportation
1200 New Jersey Ave, SE, Washington, DC 20590
+1 202 366 0278 [email protected]
Authors:
doc.: IEEE 802.11-14/1335r1
Submission Jim Arnold, US DoT
AbstractThis presentation is a summary of issues in the DSRC
band plan
October 2014
Slide 2
doc.: IEEE 802.11-14/1335r1
Submission
Background
• Material from a report prepared March 14, 2006, by TechnoCom (now part of Kapsch) for ARINC (now Rockwell Collins ARINC).
• Is available as part of history of DSRC standards development.
• Formed foundation for several decisions by IEEE DSRC standards Task Group
Jim Arnold, US DoT
October 2014
Slide 3
doc.: IEEE 802.11-14/1335r1
Submission
DSRC Band Overview
• Control Channel (178) used for short messages and directing OBEs to appropriate Service Channels
• 10 MHz channels (6 Mbps data rate)
• Option for 20 MHz channels (combining CH 174+176, and 180+182)
Channel178
(CCH)
5.855 GHz 5.925 GHz
Channel180
(SCH)
Channel182
(SCH)
Channel184
(SCH)
Channel176
(SCH)
Channel174
(SCH)
Channel172
(SCH)
Jim Arnold, US DoT
October 2014
Slide 4
doc.: IEEE 802.11-14/1335r1
Submission
DSRC Band Plan Overview
These were first adopted by ASTM(1) and then the FCC in 2003(2)
Jim Arnold, US DoT
October 2014
Slide 5
doc.: IEEE 802.11-14/1335r1
Submission
Receiver Performance• Minimum DSRC receiver sensitivity defined in 802.11 standard(3)• Doubling channel bandwidth (10 to 20 MHz) also doubles receiver
noise power– Receiver noise floor raised by 3 dB
Jim Arnold, US DoT
October 2014
Slide 6
doc.: IEEE 802.11-14/1335r1
Submission
Receiver PerformanceWith the same received signal power, a DSRC receiver with a 10 MHz channel has better performance than the one with a 20 MHz channel. To have the same signal coverage as a DSRC radio with a 10 MHz channel, a DSRC radio with a 20 MHz channel needs to double transmission power in free space propagation, even more in multipath fading. Channel bandwidth of a DSRC receiver
Guard interval in the OFDM scheme
Maximum allowed delay spread
20 MHz
800 ns 800 ns
10 MHz
1600 ns 1600 ns
Jim Arnold, US DoT
October 2014
Slide 7
doc.: IEEE 802.11-14/1335r1
Submission
Channel Capacity
• Control Channel
• With the same transmission power in free space propagation, a DSRC radio with a 20 MHz channel has 50% less signal coverage than the one with a 10 MHz channel. Combining the impacts of the raised noise floor and multipath fading, a DSRC radio with a 20 MHz channel needs to more than double the transmission power in order to have the same signal coverage as a DSRC radio with a 10 MHz channel. The higher signal power a transmitter is required to generate, the stronger interference it generates to nearby co-channel transmitters. As a result, the channel capacity is reduced.
• Service Channels
• The control channel capacity with a high message receipt rate (95%) for a 10 MHz channel can meet the requirements of most traffic situations. Using a 20 MHz channel does not help.
Jim Arnold, US DoT
October 2014
Slide 8
doc.: IEEE 802.11-14/1335r1
Submission
Channel Re-Use
Frequency reuse with four10 MHz service channels
1st 10 MHz SCH
2nd 10 MHz SCH
3rd 10 MHz SCH
4th 10 MHz SCH
Jim Arnold, US DoT
October 2014
Slide 9
doc.: IEEE 802.11-14/1335r1
Submission
Channel Re-Use
Frequency reuse with two 20 MHz service channels
Jim Arnold, US DoT
October 2014
Slide 10
doc.: IEEE 802.11-14/1335r1
Submission
Summary
• Doubling channel bandwidth requires doubling transmit power for same coverageo Even more in multipath fadingo Channel capacity reduced due to co-channel interference
• 10 MHz Service Channels = more Service Channels available in an areao 10 MHz channels at least 50% more efficient than 20 MHz
channels
• Using 20 MHz Control Channel does not aid message success rate
• Existing DSRC channel plan is optimized for balancing performance and capacity
Jim Arnold, US DoT
October 2014
Slide 11
doc.: IEEE 802.11-14/1335r1
Submission
Footnotes and other reference material• 1. ASTM E2213 (2003): 5.9GHz DSRC PHY and MAC Specification.
• 2. FCC CFR47 Part 90, Subparts I and M.
• 3. IEEE Std. 802.11-2005 (REVma/D4.0), Information technology—Telecommunications and information exchange between systems—Local and metropolitan area networks—Specific requirements—Part 11: Wireless LAN Medium Access Control (MAC) and Physical Layer (PHY) specifications.
• Additional reference material:
• http://www.standards.its.dot.gov/Factsheets/Factsheet/66
• https://mentor.ieee.org/802.11/documents?is_dcn=DCN%2C%20Title%2C%20Author%20or%20Affiliation&is_group=0reg
• Look under DSRC SG, TGp, and WAVE SG
• Lin Cheng ; Carnegie Mellon Univ., Pittsburgh, PA, USA ; Henty, B.E. ; Cooper, R. ; Stancil, D.D. , A Measruement Study of Time-Scaled 802.11 waveforms over the Mobile-to-Mobile Vehicular Channel at 5.9 GHz, IEEE Communications Magazine, Volume 48, Issue 5
Jim Arnold, US DoT
October 2014
Slide 12
