doc.: IEEE 802.11-10/0533-02-0wng Submission Roberto Aiello, Stefan Mangold Slide 1 carrier-grade 802.11 operating in paired spectrum Date: 2010-05-18 N am e A ffiliations A ddress Phone em ail Roberto A iello D isney Research D isney Research, G lendale CA , U SA [email protected]Stefan M angold D isney Research D isney Research, Zurich, CH [email protected]Authors:
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Doc.: IEEE 802.11-10/0533-02-0wng SubmissionRoberto Aiello, Stefan MangoldSlide 1 carrier-grade 802.11 operating in paired spectrum Date: 2010-05-18 Authors:
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• previously, we described desire for Frequency Division Multiplex (FDM) in 802.11 [ref: 11-10-0287-03]– for operation in paired spectrum, or TVWS
• we presented at WNG because the idea seems long term and of broader interest– with FDM, new (licensed) spectrum becomes available
– regulators often allocate different downlink and uplink spectrum
• here, we illustrate candidate spectrum, and discuss pros and cons of FDM for 802.11– we share evaluation results and collect feedback
Roberto Aiello, Stefan MangoldSlide 2
doc.: IEEE 802.11-10/0533-02-0wng
Submission
outline
• summary of 11-10-0287-03
• scenarios in which 802.11 FDM may be beneficial– 802.11 FDM in TVWS
– 802.11 in licensed paired spectrum
• pros and cons of various approaches for FDM– half-duplex and full-duplex
– feedback channel & collision detection
• conclusion and outlook
Roberto Aiello, Stefan MangoldSlide 3
doc.: IEEE 802.11-10/0533-02-0wng
Submission
a modification of 802.11 wasdiscussed in 11-10-0287-03
• objective: to connect wireless devices in theme parks– including toys & consumer products (hence chosing 802.11)– with full coverage, carrier-grade quality, at low-cost
• 802.11 is our natural choice, but still has shortcomings– larger number of APs is difficult to install in theme parks– low-frequency TVWS regulation is complex: not enough channels available
• we argued that modifying 802.11 towards FDM enables a new type of 802.11 that meets our needs
– FDM enables paired spectrum operation with uplink / downlink separation– any paired spectrum, e.g., much of licensed LTE / WiMAX becomes available– also beneficial for TVWS secondary spectrum usage– larger 802.11 cell sizes and cellular-like network deployment become feasible
Roberto Aiello, Stefan MangoldSlide 4
doc.: IEEE 802.11-10/0533-02-0wng
Submission Roberto Aiello, Stefan MangoldSlide 5
carrier-grade 802.11 deployment areacarrier-grade 802.11 deployment area
outdoor coverage in theme park
unwantedantennas
unwantedantennas
indicator for quality per user
indicator for quality per user
large number of devices in hotspotlarge number of
devices in hotspotThis is jemula802.This is jemula802.
doc.: IEEE 802.11-10/0533-02-0wng
Submission
frequency division multiplex
Base Stations (fixed TVWD)
Stations(portable TVWDs)
“uplink“
“downlink““backhaul“
time
backhaul
downlink
uplink
backhaulmesh
mesh
...
...
... ...
“direct / mesh“ACK
ACK
ACK
ACK
ACK
ACK
mesh spectrum usage
Roberto Aiello, Stefan MangoldSlide 6
doc.: IEEE 802.11-10/0533-02-0wng
Submission
802.11 FDM in TVWS - regulation
• FCC regulation separates fixed and portable channels– example: TV channel 14: downlink only, no uplink
Roberto Aiello, Stefan MangoldSlide 7
rules for fixed (downlink)
rules for fixed (downlink)
rules forportable (uplink)
rules forportable (uplink)
exampleexample
doc.: IEEE 802.11-10/0533-02-0wng
Submission
802.11 FDM in TVWS - Disneyworld
• In Disneyworld, FDM helps TVWS operation– example: use TV channel 9 for fixed/downlink and use TV
channel 28 for portable/uplink (assuming no Part 74 devices around)
• advantageous to separate downlink and uplink
Roberto Aiello, Stefan MangoldSlide 8
TV channel 9 could be used for fixed (downlink)TV channel 9 could be
used for fixed (downlink)TV channel 28 could be used for
portable (uplink)TV channel 28 could be used for
portable (uplink)
doc.: IEEE 802.11-10/0533-02-0wng
Submission
802.11 in LTE paired spectrum
• preferred harmonized frequency arrangement for the band 790-862 MHz [ref: CEPT (2009)]
– “technology neutral“ regulation: there is no reason for regulators to mandate a standard 802.11 might as well be deployed
Roberto Aiello, Stefan MangoldSlide 9
doc.: IEEE 802.11-10/0533-02-0wng
Submission
uplink: stations to AP
DATA
downlink: from AP to stations
DATA
ACK(1)
stations defer in UL while receiving from AP
(2)AP cannot transmit in DL while receiving frames from station
(3)UL and DL frames
may collide
ACK
freqtime
DATA
RTS
simple half-duplex with single radio(CCA on both channels, separate rx and tx)
• advantages:– low-cost & simple to implement
• disadvantages:– potential loss in spectrum efficiency in single BSS scenarios
Roberto Aiello, Stefan MangoldSlide 10
doc.: IEEE 802.11-10/0533-02-0wng
Submission
uplink: stations to AP
downlink: from AP to stations
DATA
(1)stations and AP transmit and
receive at the same time
(2)no UL / DL
frame collision
ACK
freqtime
DATA
RTS DATA ACK
DATA ACK
DATA ACK
full-duplex with dual radio(CCA on single channel, separate rx and
tx)• advantages:
– spectrum efficient, leverages all FDM characteristics known from cellular environments
• disadvantages:– complexity, power consumption
Roberto Aiello, Stefan MangoldSlide 11
doc.: IEEE 802.11-10/0533-02-0wng
Submission
uplink: stations to AP
DATA
downlink: from AP to stations
ACK
IDATA
DATA
DATA
ACK L
(1)frame collision
(2)AP indicates collision
(3)stations suspend
gain
freqtime
uplink collision detectionwith feedback channel
• advantages:– protocol efficiency, potential improvement for cross-layer
performance with TCP
• disadvantage:– complexity
Roberto Aiello, Stefan MangoldSlide 12
doc.: IEEE 802.11-10/0533-02-0wng
Submission
5 10 15 20 25 300
10
20
30
40
# stations
thro
ug
hp
ut
(Mb
ps
)
at 54 Mbpsat 24 Mbpsat 6 Mbps
5 10 15 20 25 300
10
20
30
40
# stations
thro
ug
hp
ut
(Mb
ps
)
at 54 Mbpsat 24 Mbpsat 6 Mbps
performance analysis of uplink collision detection
• modified analytics [ref: BIANCHI, G. (2000)]– actual results depend on TXOP duration (frame body length)
versus duration of collision detection
802.11 with ACK 802.11 FDM with collision detection
Roberto Aiello, Stefan MangoldSlide 13
doc.: IEEE 802.11-10/0533-02-0wng
Submission
802.11 FDM advantages
• more TVWS channels available for 802.11
• 802.11 could be deployed in paired spectrum– WiMAX, LTE, including 700 MHz
• allows to reserve capacity to the access point
• uplink collision detection instead of collision avoidance
• 802.11 with FDM can be backward compatible
Roberto Aiello, Stefan MangoldSlide 14
doc.: IEEE 802.11-10/0533-02-0wng
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802.11 FDM disadvantages
• modifying 802.11 towards FDM would require– single transmitter for half duplex: dual channel CCA & NAV
– coordinated dual-radio for full duplex: dual channel CCA & NAV
– modified NAV rules, other
• careful evaluation is needed in the areas of– complexity: similar to dual radio?
– power consumption: state-of-art sleep modes sufficient?
– backward compatibility: coexistence and interoperability feasible at what cost?
Roberto Aiello, Stefan MangoldSlide 15
doc.: IEEE 802.11-10/0533-02-0wng
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conclusion and outlook
• FDM is a step towards carrier-grade 802.11– enables use of other spectrum
• outlook– verify and evaluate open questions about complexity,
performance, backward compatibility
Roberto Aiello, Stefan MangoldSlide 16
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Submission
references
MANGOLD, S. AND AIELLO, R. (2010a) Towards carrier-grade 802.11 at Disney theme parks. IEEE 802.11 working document, March 2010. 11-10-0287-03.
BIANCHI, G. (2000) Performance Analysis of the IEEE 802.11 Distributed Coordination Function. IEEE Journal of Selected Areas in Communications, 18 (3), 535-547.
CEPT (2009) Technical considerations regarding harmonization options for the digital dividend in the European Union – Frequency (channeling) arrangements for the 790-862 MHz band” . Final Report 31 by ECC within CEPT. Oct. 2009.