Transcript 80211s

March 2005
doc.: IEEE 802.11-05/0267r0
Proposal for Higher Spatial Reuse
Date: 2005-03-16
Authors:
Name
Company Address
Jack Winters
Motia
Phone
103 Old Wagon Road
Middletown, NJ 07748
email
(732) 208-5568 [email protected]
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Submission
Slide 1
Jack Winters
March 2005
doc.: IEEE 802.11-05/0267r0
Issues
• IEEE802.11s will be based on AP’s using existing
standards (IEEE802.11a/b/g)
• When IEEE802.11s becomes a standard (in 2 years?)
the dominant AP’s will most likely use 802.11n and/or
other smart antenna techniques
– Many AP vendors already have products with MIMO
– A primary application of IEEE802.11s is residential
systems which may include multimedia distribution, a
main area of application of 802.11n
Submission
Slide 2
Jack Winters
March 2005
doc.: IEEE 802.11-05/0267r0
Issues (cont.)
• IEEE802.11s may not work well with 802.11n AP’s or
AP’s with smart antennas:
– Addition of smart antenna AP’s into mesh networks
designed without smart antenna considerations can
actually degrade performance (Even though the link
performance is higher, the network performance can be
worse).
Submission
Slide 3
Jack Winters
March 2005
doc.: IEEE 802.11-05/0267r0
Issues (cont.)
• The ability to have higher spatial reuse greatly
increases the capacity of a mesh network:
– Smart antennas can suppress co-channel interference
(up to M-1 co-channel interferers with M antennas),
allowing for spatial reuse in the adjacent cell
– Spatial multiplexing (as proposed for IEEE802.11n)
with MIMO permits multiple channels in the same
frequency band
Submission
Slide 4
Jack Winters
March 2005
doc.: IEEE 802.11-05/0267r0
Issues (cont.)
• The ability to have spatial reuse greatly increases the
capacity of a mesh network (cont.):
– These techniques can increase the link capacity by a
factor of M or more (2, 4, or even 8 times capacity of
networks without smart antennas – with 2 or 4 antennas
at the AP)
– These gains can dwarf the variation of performance of
various routing techniques/protocols, but these gains
can be lost if IEEE802.11s techniques do not
accommodate smart antenna capabilities
Submission
Slide 5
Jack Winters
March 2005
doc.: IEEE 802.11-05/0267r0
Concerns
• The functional requirements state that "out of scope" are:
– Specification of BSS measurements (e.g., 802.11k AP-STA
measurements)
• TGs may use relevant measurements defined in TGk or other
groups that are relevant for a WLAN Mesh, but the group does not
intend to modify BSS-specific measurements
– MAC extension to support the use of dynamic directional antenna.
• Likely requires high complexity, e.g. TDMA scheduling
to know when a neighbor’s antenna is pointed at a node.
– Algorithms to steer directional antennas.
Submission
Slide 6
Jack Winters
March 2005
doc.: IEEE 802.11-05/0267r0
Concerns (Cont.)
• Specification of BSS measurements (e.g., 802.11k AP-STA
measurements):
– IEEE802.11k (draft) is currently not “antenna aware”
– We are working to modify IEEE802.11k to add this feature, not
just for mesh networks, as this feature is essential for effective use
of smart antennas in any network/system
– Smart antennas can be used in current (standard-based) systems.
• Algorithms to steer directional antennas:
– This does not (and should not) be an issue for consideration of
smart antennas in IEEE802.11s (and we aren’t proposing this)
Submission
Slide 7
Jack Winters
March 2005
doc.: IEEE 802.11-05/0267r0
Smart Antenna Types
Adaptive Array
Directional Antenna
SIGNAL
BEAMFORMER
SIGNAL
BEAM
SELECT
SIGNAL
OUTPUT
INTERFERENCE
INTERFERENCE
Submission
Slide 8
BEAMFORMER
WEIGHTS
Jack Winters
March 2005
doc.: IEEE 802.11-05/0267r0
Concerns (Cont.)
• Concern: “MAC extension to support the use of dynamic
directional antenna - Likely requires high complexity”:
– Consideration of smart antennas can be done without significant
increase in complexity (particularly, the consideration of adaptive
antenna arrays, rather than dynamic directional antennas – adaptive
arrays are the main type of smart antenna to be considered for
products by AP vendors)
– Since interference suppression/spatial reuse can increase capacity
so substantially, consideration of these capabilities can permit an
IEEE802.11s standard to use less complex routing
algorithms/protocols, yet have performance higher than more
complex techniques that don’t consider higher frequency reuse
with smart antenna capabilities
Submission
Slide 9
Jack Winters
March 2005
doc.: IEEE 802.11-05/0267r0
Implementation
• Capabilities that need to be included in a proposal:
– Modify frequency assignment techniques to include
reusing a frequency (up to M-1 times) if AP’s have M
antennas
– Modify the inclusion of multiple radio capability to
include multiple radios in the same channel
Submission
Slide 10
Jack Winters
March 2005
doc.: IEEE 802.11-05/0267r0
Summary
• Smart antenna techniques need to be considered in
IEEE802.11s
• Smart antenna capabilities can be included in
IEEE802.11s without increasing the complexity of the
standard
Submission
Slide 11
Jack Winters