Doc.: IEEE 802.11-14/0880r1 Submission July 2014 James Wang et. al., MediaTekSlide 1 Increased...

doc.: IEEE 802.11-14/0880r1

Submission

July 2014

James Wang et. al., MediaTekSlide 1

Increased Network Throughput with Channel Width Related CCA and Rules

Date: 2014-07-14

Name Affiliations Address Phone email

James Wang

MediaTek

2860 Junction Ave., San Jose, CA 95134

USA

+1-408-526-1899-88109

[email protected]

Jianhan Liu [email protected]

Thomas Pare [email protected]

James Yee [email protected]

Chingwa Yu [email protected]

Alvin Hsu [email protected]

Authors:

doc.: IEEE 802.11-14/0880r1

Submission

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)

July 2014

2 James Wang et. al., MediaTek

doc.: IEEE 802.11-14/0880r1

Submission

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

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3

• 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

doc.: IEEE 802.11-14/0880r1

Submission

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 22-27 is met

July 2014


doc.: IEEE 802.11-14/0880r1

Submission

11ac EDCA TXOP and Channel Access

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

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• 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


doc.: IEEE 802.11-14/0880r1

Submission

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

Jan 2014

Slide 6

AP2

20M radius AP1

20MHz PPDU

STA1

80 or 160MHz PPDU

STA2

6 dB

160 MHz

Transmit Spectral Density

80 MHz

9 dB 20

MHz40

MHz


doc.: IEEE 802.11-14/0880r1

Submission

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

July 2014


AP1Intended channel width=80M

STA1STA2

20M @-82dBm 20M @-76dBm

80M @-76dBm

STA3

• 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)

doc.: IEEE 802.11-14/0880r1

Submission

80 MHz

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

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Transmit Spectral Density

80 MHz

Reduce the transmit power of 20M and 40M PPDUs such that it has the same power spectral density as 80MHz PPDU used

20MHz

40MHz

40MHz

20MHz


AP1Intended channel

width=80M

40M PPDU(reduced power)

20M PPDU(reduced power)

20M PPDU

• 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)

80MHz

80M PPDU

doc.: IEEE 802.11-14/0880r1

Submission

Primary CCA Levels for Different TX Channel Widths

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doc.: IEEE 802.11-14/0880r1

Submission

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 9.19.2.3 (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:

a) Transmit a 160 MHz or 80+80 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

b) 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

c) 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

d) Transmit a 20 MHz mask PPDU at a power spectral density ≤ PD80M on the primary 20 MHz channele) Restart the channel access attempt by invoking the backoff procedure as specified in 9.19.2 (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

July 2014


doc.: IEEE 802.11-14/0880r1

Submission

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)

23/04/11


160MHz

doc.: IEEE 802.11-14/0880r1

Submission

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

July 2014


doc.: IEEE 802.11-14/0880r1

Submission

References

1. Ron Porat, Broadcom, 11-14-0082-00 Improved Spatial Reuse Feasibility - Part I

2. Jinjing Jiang, Marvell, 11-14-0372-00 System level simulations on increased spatial reuse

3. Graham Smith, DSP Group, 11-14-1290-01 Dynamic Sensitivity Control for HEW

4. Graham Smith, DSP Group, 11-14,0294-02 Dynamic Sensitivity Control Channel Selection and Legacy Sharing

5. Imad Jamil, Orange, 11-14-0523-00-00ax Mac Simulation Results for DSC and TPC

6. Graham Smith, DSP Group, 11-14-0328-02 Dense Apartment Complex Throughput Calculations

7. Graham Smith, DSP Group, 11-14-0045-02 E-Education Analysis

8. Graham Smith, DSP Group, 11-14-0058-01 Pico Cell Use Case Analysis

9. Graham Smith, DSP Group, 11-13-1489-05 Airport Capacity Analysis

10. Graham Smith, DSP Group, 11-13-1487-02 Apartment Capacity - DSC and Channel Selection

July 2014

Slide 13 James Wang et al, Mediatek

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