IEEE 802.11 Regulatory SC DSRC Coexistence Tiger Team CCA issues for DSRC coexistence

1. IEEE 802.11 Regulatory SCDSRC Coexistence Tiger TeamCCA issues for DSRC coexistence Date: 2014-04-20 Authors: Jim Lansford, CSR Technology

2. Abstract Discussion about use of CCA in 802.11ac bandwidths for detection of DSRC signals. Jim Lansford, CSR Technology

3. Wide bandwidth channels desired to support high throughput requirements • At the same time, large number non-overlapping channels desired to support high QoS requirements • To avoid co-channel interference • Current UNII spectrum allows only • Six 80 MHz channels • Two 160 MHz channels • Additional unlicensed use of 5.35-5.47 GHz and 5.85-5.925 GHz would potentially allow a total of • Nine 80 MHz channels (Three new) • Four 160 MHz channels (Two new) Band Plan with Proposed New Spectrumin 5GHz (11ac) - NPRM 13-22/49 Possibly shared between DSRC and WLAN New channels Currently available channels 36 40 44 48 52 56 60 64 68 72 76 80 84 88 92 96 100 104 108 112 116 120 124 128 132 136 140 144 149 153 157 161 165 169 173 177 181 IEEE channel # DSRC 20 MHz 40 MHz 80 MHz 160 MHz UNII-1 UNII-2 NEW UNII-2 UNII-3 NEW 5250 MHz 5350 MHz 5470 MHz 5725 MHz 5825 MHz 5925 MHz Jim Lansford, CSR Technology

4. DSRC and U-NII-4 Devices in 5.9 GHz Band DSRC U-NII-4 U-NII-4 From 13/541r1 U-NII-4 U-NII-4 Jim Lansford, CSR Technology

5. Overview Proposed boundary of UNII4 DSRC Band 173 177 DSRC Channels • Two proposals so far: • #1: CCA-based detection and avoidance of DSRC in 10MHz BW • Based on document 13/994r0 • 10MHz CCA is not part of existing 802.11ac specifications • #2: Repacking of DSRC band with only 20MHz BW overlapping with 802.11ac, and CCA-based detection • Based on document 13/1449r2 • Requires changes to DSRC channelization X 161 165 169 173 177 181 80MHz 80MHz Wi-Fi Channels 160MHz Jim Lansford, CSR Technology

6. Proposal #1 Example • Assume 160MHz 802.11ac signal in U-NII-3 • Centered at channel 163 (5815MHz): BW from 5735-5895MHz • Overlaps DSRC channels 172/174/176/178 (all 10MHz BW) • 802.11ac does CCA in 20MHz BW today • So a 160MHz BW 802.11ac PHY would ordinarily do primary and secondary CCA (primary20/Ch157, secondary20/Ch161, secondary40/Ch149-153, secondary80/Ch165-177) • Consider the proposal: • Primary20/Ch157, Secondary10/Ch172(new), Secondary10/Ch178(new), other Secondary20 or Secondary40 in U-UNII-3 as appropriate • Other secondary assignments are possible – the most important thing is to add a Secondary10 CCA Jim Lansford, CSR Technology

7. 5 5 5 5 5 5 5 5 5 5 5 5 5 5 5 5 5 5 Frequency 8 8 8 8 8 8 8 8 8 8 8 8 9 9 9 9 9 9 4 4 5 5 6 6 7 7 8 8 9 9 0 0 1 1 2 2 ( MHz ) 0 5 0 5 0 5 0 5 0 5 0 5 0 5 0 5 0 5 DSRC DSRC DSRC DSRC DSRC DSRC DSRC [ 10 MHz ] [ 10 MHz ] [ 10 MHz ] [ 10 MHz ] DSRC Band [ 10 MHz ] [ 10 MHz ] [ 10 MHz ] Res . Service Service Service Service [ 10 MHz Channels ] Service Service Control Chan 172 Chan 180 Chan 182 Chan 184 Chan 174 Chan 176 Chan 178 Exp . U - NII - 4 Exp . U - NII - 4 Proposed Exp . U - NII - 4 Exp . U - NII - 4 [ 20 MHz ] [ 20 MHz ] U - NII - 4 Expansion [ 20 MHz ] [ 20 MHz ] Cente Chan 173 Center Chan 177 [ 20 MHz Channels ] Center Chan 169 Center Chan 181 Exp . U - NII - 4 Proposed Exp . U - NII - 4 [ 40 MHz ] U - NII - 4 Expansion [ 40 MHz ] Center Chan 167 [ 40 MHz Channels ] Center Chan 175 Proposed Exp . U - NII - 4 U - NII - 4 Expansion [ 80 MHz ] [ 80 MHz Channels ] Center Chan 171 Exp . UNII Proposed [ 160 MHz ] U - NII - 4 Expansion Center Chan 163 [ 160 MHz Channels ] 5 5 5 5 5 5 5 5 5 5 5 5 5 5 5 5 5 5 Frequency 8 8 8 8 8 8 8 8 8 8 8 8 9 9 9 9 9 9 4 4 5 5 6 6 7 7 8 8 9 9 0 0 1 1 2 2 ( MHz ) 0 5 0 5 0 5 0 5 0 5 0 5 0 5 0 5 0 5 CCA protection of DSRC Channels 172/178 using 802.11ac CCA Primary/Secondary (10MHz BW) Secondary10: Defers to all BSM traffic in Channel 172 Secondary40: 40MHz BW @ Ch. 151 & 163 Primary20: 20MHz BW @ Ch. 157 Secondary10: Defers to all CCH traffic in Channel 178 Possible CCA Protection? 5735 Jim Lansford, CSR Technology

8. How would this work? • No Changes to DSRC • Similar to 802.11a protection, but 10MHz CCA • Some changes to 802.11ac • BUT same Primary/Secondary CCA scheme as in 802.11ac today • Secondary20 replaced by 10MHz BW CCA when overlapping with ITS band: Secondary10 in Ch. 172, for example • Additional Secondary10 in Ch. 178…could add other secondary CCA • CCA for 10MHz BW exactly the same as 802.11a detection at ½ clock rate • 13/994r0 suggests a “NAV” during and for 10 seconds after the last PHY-CCA.indication(BUSY,(secondary10)) • Other details: CCA level, SIFS, slot times, etc. need to be worked out 802.11p PPDU Jim Lansford, CSR Technology

9. Summary • Existing 802.11ac Primary/Secondary CCA could be used with new 10MHz (½ clocked 802.11a) preambles • Handles very important use case: 160MHz channels that span across U-NII-3 into U-NII-4 • Does require addition of 10MHz CCA to 802.11ac • Adding two Secondary10 CCA would protect Channels 172 and 178 • Could possibly add other Secondary10 for Channels 174 and 176 • 80MHz and 40MHz channels could also add Secondary10 to use U-NII-4 or could stay in U-NII-3 • Only use Secondary10 when 802.11ac extended into DSRC band • No changes to DSRC Jim Lansford, CSR Technology