1. 802.11 WNG Presentation: 6-9GHz extensions to 802.11, Part 2
July 2007
Nov 2009
January 2012
WNG Presentation: 6-9GHz extensions to , Part 2
Date:
Authors:
Peter Ecclesine (Cisco Systems)

2. Nov 2009
January 2012
Abstract
This document presents the possibility of using existing shared spectrum allocation in GHz as an extension frequency band for an ac PHY with a 500MHz bandwidth. It is a follow up to document 11/743r0 (and 11/385r1)

3. January 2012
Background
The US FCC announced spectrum availability of GHz for ultrawideband in February, 2002
“Spectral underlay” – operates without any spectrum etiquette or spectrum sensing
PSD limit: -41.3dBm/MHz ≈ -14dBm in a 500MHz BW
500MHz (or 20% fractional bandwidth) minimum
Most other countries have now finalized regulations
UK, EU, Korea, China, Canada, Japan
Operation from 5-6GHz generally not allowed
Many restrictions in 3-5GHz, including spectrum sensing (DAA)
Some countries have expressed an interest in allowing higher Tx power
Some IEEE efforts have addressed this spectrum
a – withdrew PAR in January 2006
a – Approved in March 2007, but minimal market deployment
Spectrum is underutilized and globally available

4. Wider BW: Shannon Capacity (SISO)
January 2012
Wider BW: Shannon Capacity (SISO)
Courtesy Prof. Jeff Reed, Va Tech)
Wide bandwidths can have high capacity at low SNR
Small cells increase spatial capacity
Can achieve MIMO speeds of narrowband with SISO simplicity
Using MIMO can achieve even higher capacity

5. Worldwide Regulations
Nov 2009
January 2012
Worldwide Regulations US
Feb-02 EU
Dec-06
2010
w/DAA
2010
w/DAA
See
Note
2010
w/DAA
Japan
Sep-2006
2010
w/DAA
2010
w/DAA
Korea
Sep-2006
2010
w/DAA
2010
w/DAA
2010
w/DAA
Canada
March-2009
China
Jan-09
2010
w/DAA
3.168 GHz
4.752
6.336
7.392
7.920
8.976
9.504
10.560
3GHz of contiguous bandwidth from 6-9GHz is available
Japan & Korea don’t allow operation from /7.25GHz
EU has a detection requirement in 8.5-9GHz similar to 5.4GHz
Minimum bandwidth is 450 or 500MHz
Five or more channels available globally
Peter Ecclesine (Cisco Systems)

6. Why a frequency extension for 802.11ac?
January 2012
Why a frequency extension for ac?
Gives needed capacity for high rate communications
Wireless docking/monitors using ac will tax existing 5GHz spectrum allocation
Some countries highly restrict 5GHz spectrum (China)
High density environments (cubicle farms) will have serious spatial capacity problems…interference, frequency reuse, etc.
Could leverage existing ac/ad MAC and PHY extensions
MU-MIMO, STBC, and other extensions will greatly enhance link budget…more than doubling range of SISO
Relatively “low hanging fruit” for existing 5GHz radios
Band starts at 6GHz – just above 5GHz ISM band
Extension of 5GHz bands – minimal antenna and RF impact
High bandwidth allows precision ranging/location
For applications that need relatively short range (<10 meters) and very high spatial capacity, this spectrum could be ideal

7. 6-10 GHz offers excellent spatial capacity
January 2012
6-10 GHz offers excellent spatial capacity 5 7 4 1 6 3 2
Same channel is reused ~11 meters away…>20dB of extra path loss
Capacity is maximized by assuming hexagonal pattern
Same channel can be reused in device 11 meters away with negligible interference (>14dB signal-to-interference ratio) – perfect for cube farms
Closed loop power control will improve this capacity
≈22 meters

8. Three channels are not adequate for cubicles
Jan 2012
Three channels are not adequate for cubicles 1 2 3 3 4 2 1 1 2 3 4
Another view of four channel reuse in a cubicle layout
Three channel reuse can’t work with rectangular cubicles
Four channels CAN work
In theory, three channels can be made to work, BUT…
In a cube farm, 4 channels are required, since the cubicles are joined at the corners…and the cluster may not always be in the same location in the cube (4 color map problem)

9. 6-10GHz gives superb capacity for cube farms
Jan 2012
6-10GHz gives superb capacity for cube farms
2.5 m
At 320Mb/s, radius of coverage is ~3 meters (7.5GHz, SISO, CM2)
In a cubicle, each user could have a dedicated channel
No beamforming assumed
Negligible interference between users
Specific results will depend on Eb/No, frequency, etc.
Small cells yield highest spatial capacity in users per square meter
6-10GHz has a coverage area just larger than an average cubicle
With 7 channels available, channel reuse can be optimized for maximum capacity with minimum interference

10. January 2012
Other Comments
Existing ac/ad PHY + MAC provides most of the hooks
450/500MHz minimum bandwidth will require new MCS combinations
Effectiveness of beamforming is TBD
MIMO/MU-MIMO could be very useful
Can use simpler OFDM modulation (e.g. 16-QAM)
Shannon capacity of 500MHz channel is very high at low SNR
At least five 500MHz channels are available in 6-9GHz
Allows k=4 frequency reuse for high user density
Studies may be required to see how well MU-MIMO will operate
Other regulatory domains may permit <500MHz BW
Power consumption will be attractive
SISO: Estimate <400mW for 1Gbps in 40nm
2x2 MIMO: Estimate <500mW for 1Gbps in 40nm

11. Background Work on Channel Models
January 2012
Background Work on Channel Models
Much work has been done on propagation models )
Target Channel Characteristics
RMS delay
Notes
CM1
5.28nsec
LOS(0~4m)
CM2
8.03nsec
NLOS(0~4m)
CM3
14.28nsec
NLOS(4~10m)
CM4
25nsec
25nsec RMS delay spread to represent an extreme multi-path channel

12. Example link budget Based on 802.15.3a model with 528MHz BW
January 2012
Example link budget
Parameter
Value
Information Data Rate
106.7 Mb/s
200 Mb/s
480 Mb/s
Average TX Power
-10.3 dBm
Total Path Loss
64.2 dB 10 meters)
56.2 dB 4 meters)
50.2 dB 2 meters)
Average RX Power
-74.5 dBm
-66.5 dBm
-60.5 dBm
Noise Power Per Bit
-93.7 dBm
-91.0 dBm
-87.2 dBm
CMOS RX Noise Figure
6.6 dB
Total Noise Power
-87.1 dBm
-84.4 dBm
-80.6 dBm
Required Eb/N0
3.8 dB
4.4 dB
4.7 dB
Implementation Loss
2.5 dB
Link Margin
6.3 dB
11.0 dB
12.9 dB
RX Sensitivity Level
-80.8 dBm
-77.5 dBm
-73.4 dB
Based on a model with 528MHz BW

13. January 2012
Summary
Additional spectrum will be needed for wireless docking and sync
6-10 GHz offers a minimum of 5 channels, each of which can have 1Gbps or more in a cubicle usage model
Spectrum regulations are in place worldwide
Design of a 6-10 GHz RF is a relatively easy extension to existing ac
Band begins just above 5.7GHz ISM band
Antennas exist that cover 5-10 GHz, allowing “11ac+”
Can use SISO or “easy” MIMO (2x2, 16-QAM)
Most capacity improvement comes from B term in Shannon
Some new MCS will need to be added to 11ac
Much work has already been done on channel models, regulations, link budgets