IEEE 802.11bd Midamble Design and Spectrum Considerations
Discussing the design of midambles in IEEE 802.11bd PDDUs to avoid spectral limitations in output power by randomizing midambles and addressing spectrum requirements related to regulatory PSD limits. Recommendations are provided for randomization practices to mitigate concentration of PSD in narrow bands, ensuring compliance with regulatory standards.
Download Presentation
Please find below an Image/Link to download the presentation.
The content on the website is provided AS IS for your information and personal use only. It may not be sold, licensed, or shared on other websites without obtaining consent from the author. If you encounter any issues during the download, it is possible that the publisher has removed the file from their server.
You are allowed to download the files provided on this website for personal or commercial use, subject to the condition that they are used lawfully. All files are the property of their respective owners.
The content on the website is provided AS IS for your information and personal use only. It may not be sold, licensed, or shared on other websites without obtaining consent from the author.
E N D
Presentation Transcript
March 2020 doc.: IEEE 802.11-20/0476r0 Remark on PPDUs with midambles Date: 2020-03-14 Authors: Name Miguel L pez Affiliations Ericsson Address Phone email Miguel.m.lopez@ericsson.co m Leif Wilhelmsson Ericsson Submission Slide 1 Miguel L pez, Ericsson
March 2020 doc.: IEEE 802.11-20/0476r0 Abstract This contribution discusses the design of the midambles in 11bd PDDUs Specifically, to avoid discrete components in the spectrum which may limit the maximum output power, it is suggested to randomize the midambles Submission Slide 2 Miguel L pez, Ericsson
March 2020 doc.: IEEE 802.11-20/0476r0 Recap - Midambles in 802.11bd TGbd has agreed [1]: 1. That the 11bd PPDU design shall support midambles with periodicity 4, 8 2. That a midamble comprises a Long Training Field (LTF) 3. To support up to two spatial streams Submission Slide 3 Miguel L pez, Ericsson
March 2020 doc.: IEEE 802.11-20/0476r0 Repeated deterministic signal components In general, randomization or scrambling of repeated deterministic signal components is a good practice in wireless communications Reoccurring deterministic signals are often randomized in 802.11 OFDM PHYs: Pilots are randomized The LTFs in MIMO PPDUs are randomized by means of the P matrix. For example the 6x6 VHT P matrix is not a DFT matrix but a modification in order to eliminate the row consisting of ones only. Padding bits are scrambled HE midambles seem to be the exception Repetition of deterministic signal components leads to spectral lines repetition of midambles leads to spectral lines Slide 4 Submission Miguel L pez, Ericsson
March 2020 doc.: IEEE 802.11-20/0476r0 Spectrum Requirements The spectrum requirements for 802.11bd devices are uncertain at the time of writing this contribution, due to upcoming decisions by the FCC [2] The FCC and other regulatory bodies typically impose limits on the PSD, in terms of the maximum power in a given band, requiring that the power spectral density conducted to the antenna shall not exceed X dBm / Y Hz For example in Section 15.247 of [3], X = 8 (dBm) and Y = 3000 (Hz) The smaller the resolution bandwidth (i.e. the term Y in the previous bullet), the more expensive and time consuming become the tests This fact is recognized by regulators Spectral lines may make it more difficult to fulfill PSD limits Submission Slide 5 Miguel L pez, Ericsson
March 2020 doc.: IEEE 802.11-20/0476r0 Randomization of the midambles in 802.11bd It is suggested to randomize the midambles Without randomization there can be a non-negligible concentration of the PSD in narrow bands 1. Example: 10 MHz PPDU with 2 SS and midamble periodicity = 4: power in 3 kHz band increases up to 5.5 dB with respect to PPDU without midambles 2. Example: 10 MHz PPDU with 1 SS and midamble periodicity = 4 : power in 3 kHz band increases up to 3.0 dB with respect to PPDU without midambles 3. Example: 10 MHz PPDU with 2 SS and midamble periodicity = 4: power in 100 kHz band increases up to 0.8 dB with respect to PPDU without midambles Submission Slide 6 Miguel L pez, Ericsson
March 2020 doc.: IEEE 802.11-20/0476r0 Summary It is desirable to enable the testing of PSD limits with wide resolution bandwidths OFDM signal designs without spectral lines make a compelling case to argue in favour of spectrum tests with wide resolution bandwidths It is suggested to randomize the midambles in order to suppress spectral lines It is good engineering practice In view of the possibility of new regulations for DSRC Submission Slide 7 Miguel L pez, Ericsson
March 2020 doc.: IEEE 802.11-20/0476r0 Straw poll Do you agree to include the following text into the 11bd spec draft? The midambles shall be randomized Note: The randomization method is TBD Y: N: A: Submission Slide 8 Miguel L pez, Ericsson
March 2020 doc.: IEEE 802.11-20/0476r0 References [1] https://mentor.ieee.org/802.11/dcn/19/11-19-0497-06-00bd-802-11bd- specification-framework-document.docx [2] In the Matter of: Use of the 5.850-5.925 GHz Band, ET Docket No. 19- 138, NOTICE OF PROPOSED RULEMAKING , Released: December 17, 2019, FCC 19-129 [3] FEDERAL COMMUNICATIONS COMMISSION, 47 CFR Part 15 Submission Slide 9 Miguel L pez, Ericsson
