CCA schemes for the 120MHz spectrum in China November 2010 November 2010 CCA schemes for the 120MHz spectrum in China Authors: Date: 2010-11-06

November 2010 November 2010 Background The channelization in Chinese spectrum has been considered in the proposed specification framework for TGac. A 120MHz spectrum for channelization is recommended in China to improve the throughput.

5GHz Spectrum in China The 5GHz spectrum for legacy device November 2010 November 2010 5GHz Spectrum in China The 5GHz spectrum for legacy device from 5735MHz to 5835MHz 20MHz×5, 40MHz×2 very few legacy devices work on 5GHz spectrum in China Total available 5GHz spectrum for 11ac from 5725MHz to 5850MHz 20MHz×6, 40MHz×3, … , provide additional 20MHz and 40MHz channels

Enhanced mode and compatible mode November 2010 November 2010 Enhanced mode and compatible mode Two modes are defined to deal with above two spectrums. Enhanced mode 5727.5MHz ~ 5847.5MHz High Throughput compatible mode 5735MHz ~ 5835MHz Compatible with legacy device The ac devices selectively work on these two modes while the legacy devices only work on compatible mode

One Scenario of two-modes OBSS November 2010 One Scenario of two-modes OBSS Assume BSS2 works on enhanced mode channels BSS3 works on compatible mode channels BSS2 and BSS3 are non-overlapped in position BSS1 is overlapped with BSS2 and BSS3 The transmission of BSS1 may affect BSS2 and BSS3, so the CCA should help BSS1 detect the channel state and avoid the collision with BSS2 and BSS3

TBD2(<-62+10log10(TBD1/20)) dBm November 2010 CCA Requirement The CCA should detect any signal on the target channel, no matter the signal belongs to enhanced mode transmission, compatible mode transmission or other systems. The CCA sensitivity should be same as current sensitivity requirement in the proposed specification framework for TGac. For valid 802.11 signals: TBD2(<-62+10log10(TBD1/20)) dBm For any signal -62+10log10(TBD1/20) dBm

CCA on Two Modes channel November 2010 November 2010 CCA on Two Modes channel According to the CCA requirement, the CCA should be not only on the target channel but also on the channels which are overlapped with the target channel. It implies that the CCA should be on two modes channel. If CCA is on one mode channel ONLY It’s HARD to achieve the CCA sensitivity requirement, especially for the valid 802.11 signals on the channel of other mode which is overlapped with the target detecting channel.

CCA on Two Modes channel November 2010 CCA on Two Modes channel If CCA is on one mode channel ONLY CCA on blue channel of compatible mode or the red channel of enhanced mode only receive fragmentary (12.5MHz or 7.5MHz bandwidth) signal It is difficulty to achieve the CCA requirement with the fragmentary signal

CCA on Two Modes channel November 2010 CCA on Two Modes channel Possible CCA mechanism for the approach 1 in [1] Channel state is based on the CCA result of the two modes channels The channel state of each channel is the OR-operation result The OR-operation should perform with the CCA results of itself and two overlapped channels in another mode e.g. the red and green channels in slice 8 Channel State of Red Channel = CCA result: 0: Idle 1: Busy (CCA of Red Channel) OR (CCA of Green Channel 149 ) OR (CCA of Green Channel 153 )

CCA on Two Modes channel November 2010 CCA on Two Modes channel Possible CCA mechanism for the approach 2 in [1] A 120MHz channel CCA is required CCA on compatible mode channels provides the channel state of compatible mode channels The 120MHz channel state is the OR-operation result of CCA results of all compatible mode channels and120MHz channel BUSY : If any channel of compatible mode or 120MHz channel is busy; IDLE : Only when all the CCA results of compatible mode and120MHz channel are idle; CCA result: 0: Idle 1: Busy

November 2010 Conclusion The CCA of Chinese two modes devices should perform on both enhanced and compatible mode channels. The CCA of Chinese two modes devices should satisfy the CCA requirement in slice 6.

References [1] “11-10-1242-00-00ac-120mhz-channelization-solution.ppt” November 2010 References [1] “11-10-1242-00-00ac-120mhz-channelization-solution.ppt” [2] “11-10-1259-00-00ac-channelization-for-china-s-spectrum.ppt” [3] “11-09-0992-15-00ac-proposed-specification-framework-for-tgac.doc”