doc.: IEEE 802.11-10/0533-02-0wng
carrier-grade 802.11
operating in paired spectrum
Date: 2010-05-18
Authors:
Name
Affiliations
Roberto Aiello
Disney Research
Stefan Mangold
Disney Research
Submission
Address
Phone email
Disney Research,
Glendale CA, USA
Disney Research,
Zurich, CH
Slide 1
[email protected]
[email protected]
Roberto Aiello, Stefan Mangold
doc.: IEEE 802.11-10/0533-02-0wng
introduction
• 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
Submission
Slide 2
Roberto Aiello, Stefan Mangold
doc.: IEEE 802.11-10/0533-02-0wng
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
Submission
Slide 3
Roberto Aiello, Stefan Mangold
doc.: IEEE 802.11-10/0533-02-0wng
a modification of 802.11 was
discussed 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
–
–
–
–
Submission
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
Slide 4
Roberto Aiello, Stefan Mangold
doc.: IEEE 802.11-10/0533-02-0wng
carrier-grade 802.11 deployment
area
outdoor coverage in theme park
unwanted
antennas
Submission
indicator for
quality per user
Slide 5
This is jemula802.
large number of
devices
in hotspot
Roberto
Aiello, Stefan
Mangold
doc.: IEEE 802.11-10/0533-02-0wng
frequency division multiplex
Base Stations
(fixed TVWD)
time
...
...
ACK
ACK
“downlink“
uplink
“backhaul“
ACK
mesh
“uplink“
backhaul
ACK
downlink
“direct / mesh“
ACK
ACK
mesh
backhaul
...
...
Stations
(portable TVWDs)
mesh spectrum usage
Submission
Slide 6
Roberto Aiello, Stefan Mangold
doc.: IEEE 802.11-10/0533-02-0wng
802.11 FDM in TVWS - regulation
• FCC regulation separates fixed and portable channels
– example: TV channel 14: downlink only, no uplink
rules for
portable (uplink)
rules for fixed
(downlink)
example
Submission
Slide 7
Roberto Aiello, Stefan Mangold
doc.: IEEE 802.11-10/0533-02-0wng
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
TV channel 9 could be
used for fixed (downlink)
Submission
TV channel 28 could be used for
portable (uplink)
Slide 8
Roberto Aiello, Stefan Mangold
doc.: IEEE 802.11-10/0533-02-0wng
802.11 in LTE paired spectrum
• preferred harmonized frequency arrangement for the
band 790-862 MHz [ref: CEPT (2009)]
• other LTE bands:
– 1.8 GHz, 2 GHz, 2.6 GHz mainly paired spectrum
– “technology neutral“ regulation: there is no reason for regulators to
mandate a standard  802.11 might as well be deployed
Submission
Slide 9
Roberto Aiello, Stefan Mangold
doc.: IEEE 802.11-10/0533-02-0wng
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
downlink:
from AP to stations
uplink:
stations to AP
freq
Submission
DATA
(2)
AP cannot transmit in DL while
receiving frames from station
(1)
stations defer in UL
ACK
while receiving from AP
DATA
ACK
DATA
RTS
(3)
UL and DL frames
may collide
time
Slide 10
Roberto Aiello, Stefan Mangold
doc.: IEEE 802.11-10/0533-02-0wng
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
downlink:
from AP to stations
uplink:
stations to AP
freq
Submission
DATA
DATA
time
ACK
DATA
ACK
DATA
ACK
DATA
ACK
RTS
(1)
stations and AP transmit and
receive at the same time
(2)
no UL / DL
frame collision
Slide 11
Roberto Aiello, Stefan Mangold
doc.: IEEE 802.11-10/0533-02-0wng
uplink collision detection
with feedback channel
• advantages:
– protocol efficiency, potential improvement for cross-layer
performance with TCP
• disadvantage:
(2)
AP indicates collision
– complexity
downlink:
from AP to stations
DATA
uplink:
stations to AP
freq
Submission
ACK
time
I
DATA
ACK
L DATA
(1)
frame collision
DATA
gain
(3)
stations suspend
Slide 12
Roberto Aiello, Stefan Mangold
doc.: IEEE 802.11-10/0533-02-0wng
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
at 54 Mbps
at 24 Mbps
at 6 Mbps
40
throughput (Mbps)
throughput (Mbps)
40
30
20
10
0
5
10
15
20
25
# stations
Submission
30
20
10
0
30
at 54 Mbps
at 24 Mbps
at 6 Mbps
5
10
15
20
25
# stations
Slide 13
Roberto Aiello, Stefan Mangold
30
doc.: IEEE 802.11-10/0533-02-0wng
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
Submission
Slide 14
Roberto Aiello, Stefan Mangold
doc.: IEEE 802.11-10/0533-02-0wng
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?
Submission
Slide 15
Roberto Aiello, Stefan Mangold
doc.: IEEE 802.11-10/0533-02-0wng
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
Submission
Slide 16
Roberto Aiello, Stefan Mangold
doc.: IEEE 802.11-10/0533-02-0wng
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.
Submission
Slide 17
Roberto Aiello, Stefan Mangold
doc.: IEEE 802.11-10/0533-02-0wng
thank you for your attention!
www.disneyresearch.com
Submission
Slide 18
Roberto Aiello, Stefan Mangold