802.11 WNG Presentation: 6-9GHz extensions to 802.11, Part 2

1. 802.11 WNG Presentation: 6-9GHz extensions to 802.11, Part 2 Date: 2012-01-17 Authors:

2. Abstract This document presents the possibility of using existing shared spectrum allocation in 6-10.5GHz as an extension frequency band for an 802.11ac PHY with a 500MHz bandwidth. It is a follow up to document 11/743r0 (and 11/385r1)

3. Background • The US FCC announced spectrum availability of 3-10.5GHz 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 • 802.15.3a – withdrew PAR in January 2006 • 802.15.4a – Approved in March 2007, but minimal market deployment • Spectrum is underutilized and globally available

4. Wider BW: Shannon Capacity (SISO) • 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 Courtesy Prof. Jeff Reed, Va Tech)

5. Worldwide Regulations US Feb-02 • 3GHz of contiguous bandwidth from 6-9GHz is available • Japan & Korea don’t allow operation from 6-7.15/7.25GHz • 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 EU Dec-06 2010 w/DAA 2010 w/DAA 2010 w/DAA See Note Japan Sep-2006 2010 w/DAA 2010 w/DAA Korea Sep-2006 2010 w/DAA 2010 w/DAA 2010 w/DAA Canada March-2009 2010 w/DAA China Jan-09 3.168 GHz 4.752 6.336 7.392 7.920 8.976 9.504 10.560

6. Why a frequency extension for 802.11ac? • Gives needed capacity for high rate communications • Wireless docking/monitors using 802.11ac 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 802.11ac/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. 7 5 6 3 2 4 4 1 5 1 7 6 7 5 6 2 3 4 2 3 1 6-10 GHz offers excellent spatial capacity 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. 1 3 3 2 1 1 3 3 2 2 2 2 1 1 4 1 3 1 3 3 3 3 4 2 2 2 2 1 1 2 3 4 3 3 4 1 1 2 3 4 1 2 2 3 4 4 1 2 3 4 1 2 1 3 4 1 2 3 Three channels are not adequate for cubicles 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 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. Other Comments • Existing 802.11ac/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 • Much work has been done on propagation models • http://grouper.ieee.org/groups/802/15/pub/2002/Nov02/02368r4P802-15_SG3a-Channel-Modeling-Subcommittee-Report.ZIP )

12. Example link budget • Based on 802.15.3a model with 528MHz BW

13. 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 802.11ac • 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