1 / 8

Fair Sub-Channels Access

This proposal explores the issue of fair channel access rules for 20MHz operation in 11bd, considering the coexistence of 11p/11bd devices and the importance of legacy services carried on both 10MHz sub-channels. A concept for a single-radio decoder capable of decoding L-SIG length field in both sub-channels is proposed, enabling fair 20MHz channel access without the need for multiple receivers.

sievert
Download Presentation

Fair Sub-Channels Access

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. Authors: Fair Sub-Channels Access Date: 2019-09-16 Yossi Shaul, Autotalks

  2. Background • It was agreed to support 20MHZ operation for 11bd • 11bd main advantage is co-channel coexistence with 11p • Open issue: channel access rules for 20MHZ channel assuming both 11p/11bd devices Yossi Shaul, Autotalks

  3. Motivation • Both 10MHz sub-channels may carry equally important legacy services • Existing WiFi operation decodes NAV in a single sub-channel • By default, one (which one? arbitrary?) sub-channel has better protection than the other • Fair 20MHz channel access is achieved by decoding L-SIG length field in both sub-channels, without preferring one sub-channel over the other • Implementation would require two receivers, which is undesired due to cost and complexity • Without NAV / L-SIG length field, legacy sub-channel would have less transmission opportunities and higher hidden node collision probability • A concept of lightly-modified single-radio decoder capable of decoding L-SIG length field in both sub-channels is proposed Yossi Shaul, Autotalks

  4. 20MHz 11bd PPDU • From SFD: “In20MHz bandwidth, L-STF, L-LTF, and L-SIG for 10MHz PPDU are duplicated asshown in the figure below.” 10MHz L-SIG L-STF L-LTF 10MHz L-STF L-LTF L-SIG 11bd PPDU Yossi Shaul, Autotalks

  5. Block Diagram of 20MHz Receiver with single NAV decoding Synchronization Primary ch. subcarriers Equalization NAV state machine RF A/D Symbol -> Data processing FFT Cyclic shift removal • Sample packet reception flow • Baseline receiver performs preamble detection and NAV calculation on the primary channel • Remaining of 20MHz PPDU is decoded at entire band • Decoding of 10MHz PPDU is unnecessary if received packet belongs to a different service, as when 20MHz transmission doesn’t fallback to 10MHz Yossi Shaul, Autotalks

  6. Block Diagram of 20MHz Receiver with dual L-SIG packet length decoding Synchronization Lower 10MHz Upper + lower subcarriers Synchronization Upper 10MHz Upper ch. subcarriers Equalization Packet length RF A/D Symbol -> Data processing FFT Lower ch. subcarriers Cyclic shift removal L-SIG buffer • Sample packet reception flow • Preamble is searched in both upper and lower sub-channels • Packet length is extracted from L-SIG using the sub-channels that contained the preamble (sum of both sub-channels can be used when found in both) • Receiver continues to monitor the other sub-channel after receiving L-SIG (10MHz packet isn’t decoded) • Buffer stores L-SIG samples if sub-channel preamble was received while L-SIG of other sub-channel is decoded Yossi Shaul, Autotalks

  7. Packet Flow Example Scan +CCA L+U Scan +CCA U Scan State 10MHz header 20MHz reception Scan 10MHz header Scan +CCA L 10MHz header Scan +CCA L+U Scan +CCA U Scan 10MHz header Scan +CCA L Processed sub-channel Lower Upper Lower Upper Upper + lower All (upper and lower) Received packets Header Header Body Header Body 20MHz Body Header Header Header Body Successful reception L-SIG packet length decoded L-SIG decoded (given dynamic range) L-SIG buffer enables decoding of both sub-channels Yossi Shaul, Autotalks

  8. September 2019 Straw Poll • Do you agree to add the following text into Section 3 of SFD? • 802.11bd 20MHz shall be capable to decode both 10MHz sub-channels L-SIG and to extract legacy length field • Y: • N: • A: Yossi Shaul, Autotalks

More Related