1. Increased Network Throughput with Channel Width Related CCA and Rules
May 2013
doc.: IEEE /xxxxr0
July 2014
Increased Network Throughput with Channel Width Related CCA and Rules
Date:
Authors:
James Wang et. al., MediaTek
James Wang (MediaTek)

2. Background and Objectives
July 2014
Background and Objectives
Raising CCA levels has been shown to increase spatial re-use which leads to significant increase in the network throughput in dense deployment scenarios (ref. 1-10).
However, raising CCA levels leads to high collisions
This contribution investigates method to alleviate the above issues when raising the CCA levels, thereby increasing the network throughpu
This presentation focuses on inter-BSS traffic. (Method of distinguishing inter-BSS traffic and inter-BSS traffic is not included)
James Wang et. al., MediaTek

3. High Channel Width Transmission
July 2014
High Channel Width Transmission
Higher channel width transmission is more bandwidth/power efficient
Reduced guard tones (higher number of subcarriers)
Lower rate codes are more powerful
Higher channel width transmission causes less interference in dense deployment environment
TX spectral density is lower
Same power, different data rates
James Wang et. al., MediaTek

4. 11ac EDCA TXOP and Channel Access
July 2014
11ac EDCA TXOP and Channel Access
11ac obtains an EDCA TXOP is based solely on activity of the primary channel (busy or idle conditions)
The primary channel is BUSY, if one of the conditions listed in Table is met
James Wang et. al., MediaTek

5. 11ac EDCA TXOP and Channel Access
July 2014
11ac EDCA TXOP and Channel Access
Transmit channel width determination is based on the secondary channel CCA during an interval (PIFS) immediately preceding the start of TXOP.
Secondary channel CCA levels
2nd Channel
CCA Level
Any signal within the secondary 20 MHz channel
≥-62 dBm
Any signal within the secondary 40 MHz channel
≥-59 dBm
Any signal within the secondary 80 MHz
≥-56 dBm
80 MHz non-HT duplicate or VHT PPDU
≥-69 dBm
40 MHz non-HT duplicate, HT_MF, HT_GF or VHT PPDU
≥-72 dBm
20 MHz NON_HT, HT_MF, HT_GF or VHT PPDU
≥-72dBm
James Wang et. al., MediaTek

6. Channel Width Considerations
Month Year
doc.: IEEE yy/xxxxr0
Jan 2014
Channel Width Considerations
Signal propagation range is determined by the TX spectral density (power/Hz) and the channel propagation loss
Same transmit power, wider TX channel widths  lower TX spectral density  shorter range
The baseline (primary channel) CCA levels are based on equal spectral density for all RX channel widths
CCA_Level/channel width (in unit of 20MHz) = -82 dBm for 20, 40, 80, 160 MHz
However, the TX spectral density is not the same for all TX channel widths
TX_PWR/20M > TX_PWR/40M > TX_PWR/80M > TX_PWR/160M
Narrower TX ch. width transmission interferes (defers) a wider ch. width transmission
The likelihood of the wider ch. width transmission is reduced
STA2
Transmit Spectral Density
STA1 20
MHz
6 dB
9 dB
AP2 40
MHz
20MHz PPDU
80 MHz
160 MHz
AP1
20M radius
80 or 160MHz PPDU
James Wang et. al., MediaTek
John Doe, Some Company

7. July 2014
Proposed Enhanced Channel Access for Wider TX Channel Width Transmission -1
Based the CCA Level on the intended TX channel width(s)
Wider intended TX channel width, higher CCA levels
As shown, if AP1 intends to transmit a 80MHz PPDU, it can ignore the 20MHz PPDU by STA1 at -82 dBm. The CCA level for 20MHz PPDU can be raised by 6 dB (from -82 dBm to -76 dBm).
This illustration is only for inter-BSS transmission (STA1, STA2, STA3 are OBSS)
STA1
STA2
STA3
AP1
Intended channel width=80M
James Wang et. al., MediaTek

8. Intended channel width=80M
July 2014
Proposed Enhanced Channel Access for Wider TX Channel Width Transmission - 2
If AP gain channel access for wider channel width transmission with higher CCA level, it should transmit the signal at the same power spectral density as the intended TX channel width
As shown AP1 reduces TX power of 20M, 40MHz PPDUs such that it has the same spectral density as 80MHz PPDU (intended TX BW=80MHz)
20M PPDU
Reduce the transmit power of 20M and 40M PPDUs such that it has the same power spectral density as 80MHz PPDU used
20M PPDU
(reduced power)
Transmit Spectral Density
40M PPDU
(reduced power) 20
MHz
80M PPDU 40
MHz
AP1
Intended channel width=80M
80 MHz
80 MHz 20
MHz 40
MHz 80
MHz
James Wang et. al., MediaTek

9. Primary CCA Levels for Different TX Channel Widths
July 2014
Primary CCA Levels for Different TX Channel Widths
Proposed that CCA busy level shall be based on the transmit channel width instead of receive channel width
For intended 20 MHz transmission channel width,
CCA for primary 20MHz: -82 dBm
Max tx spectral density = tx power/20MHz
For intended 40 MHz transmission channel width,
CCA for primary 20MHz: dBm
CCA for 40MHz: -79 dBm
Max tx spectral density=tx power/40MHz
For intended 80MHz transmission channel width,
CCA for primary 20MHz: dBm
CCA for primary 40MHz: dBm
CCA for 80MHz: -76dBm
Max tx spectral density = tx power/80MHz
For intended 160MHz (80MHz+80MHz) transmission channel width,
CCA for primary 20MHz: dBm
CCA for primary 40MHz: dBm
CCA for primary 80MHz: -7973dBm
CCA for 160MHz: -73dBm
Max tx spectral density = tx power/160MHz
Note 1: We only recommend adjusting relative CCA levels based on TX channel widths. We are open to proposals adjusting absolute CCA levels.
Note 2: For multiple intended TX channel widths, transmitter can run multiple EDCA queues.
James Wang et. al., MediaTek

10. Example EDCA Channel Access Transmission Rules
July 2014
Example EDCA Channel Access Transmission Rules
In the example, the intended transmit channel width is 80MHz. It is assumed that the device has a transmit power spectral density for the 80MHz transmission is PD80M(=TX Power/80MHz) and the corresponding CCA level (Slide 7) for 80MHz transmit channel width.
Proposed Modified EDCA Channel Access in a VHT BSS for intended Transmit channel width of 80MHz:
If a STA is permitted to begin a TXOP (as defined in (Obtaining an EDCA TXOP)) and the STA has at least one MSDU pending for transmission for the AC of the permitted TXOP, the STA shall perform exactly one of the following steps:
Transmit a 160 MHz or MHz mask PPDU if the secondary channel, the secondary 40 MHz channel and the secondary 80 MHz channel were idle during an interval of PIFS immediately preceding the start of the TXOP
Transmit an 80 MHz mask PPDU at a power spectral density = PD80M on the primary 80 MHz channel if both the secondary channel and the secondary 40 MHz channel were idle during an interval of PIFS immediately preceding the start of the TXOP
Transmit a 40 MHz mask PPDU at a power spectral density ≤ PD80M on the primary 40 MHz channel if the secondary channel was idle during an interval of PIFS immediately preceding the start of the TXOP
Transmit a 20 MHz mask PPDU at a power spectral density ≤ PD80M on the primary 20 MHz channel
Restart the channel access attempt by invoking the backoff procedure as specified in (HCF contention-based channel access (EDCA)) as though the medium is busy on the primary channel as indicated by either physical or virtual CS and the backoff timer has a value of 0
James Wang et. al., MediaTek

11. Transmission based on 80MHz Intended TX Channel Width
May 2013
doc.: IEEE /xxxxr0
2017/4/6
Transmission based on 80MHz Intended TX Channel Width
Illustration of a device run EDCA transmission based on 80MHz intended TX channel width CCA levels (6 dB above current CCA level for 20MHz)
160MHz
James Wang et. al., MediaTek
James Wang (MediaTek)

12. Conclusions and Future Works
July 2014
Conclusions and Future Works
Current CCA levels and transmission rules
lower likelihood of high channel width transmission (deferred inappropriately due to out-of-range narrower channel width transmission)
Significant network throughput increase can be accomplished in a dense deployment scenarios due to
Higher CCA levels (based on the intended transmission channel width) increase the likelihood of wide channel width transmission
Wider channel width transmission is more bandwidth/power efficiency due to more powerful low rate code and less guard tones
Simulation results will be provided in Part 2 of this contribution
James Wang et. al., MediaTek

13. July 2014
References
Ron Porat, Broadcom, Improved Spatial Reuse Feasibility - Part I
Jinjing Jiang, Marvell, System level simulations on increased spatial reuse
Graham Smith, DSP Group, Dynamic Sensitivity Control for HEW
Graham Smith, DSP Group, 11-14, Dynamic Sensitivity Control Channel Selection and Legacy Sharing
Imad Jamil, Orange, ax Mac Simulation Results for DSC and TPC
Graham Smith, DSP Group, Dense Apartment Complex Throughput Calculations
Graham Smith, DSP Group, E-Education Analysis
Graham Smith, DSP Group, Pico Cell Use Case Analysis
Graham Smith, DSP Group, Airport Capacity Analysis
Graham Smith, DSP Group, Apartment Capacity - DSC and Channel Selection
James Wang et al, Mediatek