Efficient Midamble Design for IEEE 802.11-17/0998r1 - July 2017 Document
Explore the considerations and updates for midamble design in IEEE 802.11-17/0998r1 document for improved receiver processing time and packet extension support in 11ax. Understand the implications of setting the Doppler bit to 1 and the efficient insertion of midambles in the HE PPDU. Discover the challenges in decoding data OFDM symbols and determining TPE from a received HE PPDU. Optimize midamble design for better performance in wireless communication systems.
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July 2017 doc.: IEEE 802.11-17/0998r1 NSYMand TPEat RX side for Midamble design Date: 2017-07-10 Authors: Name Affiliation Address Phone Email Yujin Noh yujin.noh at newracom.com 9008 Research Dr. Irvine, CA 92618 Newracom Minho Cheong minho.cheong at newracom.com Submission Slide 1 Yujin Noh, Newracom
July 2017 doc.: IEEE 802.11-17/0998r1 Background For 11ax, Mid-amble design has been introduced by setting Doppler bit to 1 at the last meeting [1][2]. Considering SP results, it seems not to have big resistance on Doppler procedure based on Mid-ambles. To secure the receiver processing time, 11ax decided to support the packet extension. The receiver computes NSYMand TPEusing Equation (28-110) and (28- 111) in D1.3, respectively Two equations need to be updated for Mid-amble design Submission Slide 2 Yujin Noh, Newracom
July 2017 doc.: IEEE 802.11-17/0998r1 Considerations (1/2) E.g.) NSYM= 30, M =10 NMA= 3 Preamble DATA_1 DATA_2 DATA_k Midamble Midamble Midamble PE 10 data symbols 10 data symbols 10 data symbols Depending on NSYM and M to derive NMA, the last Midamble of the HE PPDU can be inserted just before the PE field that consists of arbitrary values. Number of data OFDM symbols Midamble inserted every M data OFDM symbols N = = / N T N M T HE-STF may not be needed MA SYM ( ) + T MA HE LTF HE LTF HE STF Depending on the implementation of channel estimation, this Midable deign allows unnecessary cost and complexity to increase. Submission Slide 3 Yujin Noh, Newracom
July 2017 doc.: IEEE 802.11-17/0998r1 Considerations (2/2) When Doppler bit sets to 1, how to identify the number of NSYMfor decoding data OFDM symbols and duration of packet extension, TPE, from a received HE PPDU? NMA is a function of NSYMand vise versa. Each equation includes floor function. It might be tricky to obtain the NSYM directly with Equation 1) and Equation 2) below. = / N N M Equation 1) MA SYM + + L_LENGTH 3 m = 4 / N T N T T b Equation 2) PE Disambigui ty SYM PA MA MA SYM 3 =T TPA where HE PREAMBLE Submission Slide 4 Yujin Noh, Newracom
July 2017 doc.: IEEE 802.11-17/0998r1 Efficient Midamble design E.g.) NSYM= 30, M =10 NMA= 2 Preamble PE DATA_1 DATA_2 DATA_k Midamble Midamble 10 data symbols 10 data symbols 10 data symbols Slightly modified equation below prevents Midamble from being inserted unnecessarily in HE PPDU. ( ) = 1 / N N M MA SYM ( ) = + T N T T MA HE LTF HE LTF HE STF Submission Slide 5 Yujin Noh, Newracom
July 2017 doc.: IEEE 802.11-17/0998r1 How to get NSYMand TPE Option 1 leave it implementation-dependent with Equation 1 and Equation 2. It is unavoidable burden to derive each value, NMA, NSYM and TPE because it is not intuitive. Given the Equation (28-110) computing NSYMwhen Doppler bit sets to 0, it is natural to provide NSYMas well when Doppler bit sets to 1. Option 2 with closed-form equation Provide the equation for NMA for the receiver to use. With NMA, the receiver derives NSYMand TPE. Submission Slide 6 Yujin Noh, Newracom
July 2017 doc.: IEEE 802.11-17/0998r1 Equation for NMA at the RX (1/2) When Doppler bit sets to 1, + + ( ) L_LENGTH 3 m + 4 1 T SYM T b PE Disambigui ty PA 3 = N MA + T M SYM T MA or Exactly the same values + + ( ) L_LENGTH 3 m + + 4 1 T SYM T b M PE Disambigui ty PA 3 = N MA + T M SYM T MA How to get NMA is shown in Appendix. Submission Slide 7 Yujin Noh, Newracom
July 2017 doc.: IEEE 802.11-17/0998r1 Equation for NMA at the RX (2/2) Once NMA is obtained, the receiver computes NSYMand TPE below + + L_LENGTH 3 m = 4 / N T N T T b PE Disambigui ty SYM PA MA MA SYM 3 Only updated part + + L_LENGTH 3 m 4 T N T N T PA MA MA SYM SYM 3 = 4 T Only updated part PE 4 Submission Slide 8 Yujin Noh, Newracom
July 2017 doc.: IEEE 802.11-17/0998r1 Comparison 1/2 Updated After verifying two different equations from 17/0998 and 17/0994, each value is exactly the same. NMAat the TX side, NMA ,NSYM and TPE at the RX side N ( ) = = 1 / N N M 1 SYM N MA SYM MA M MA + + 3 LENGTH m No conditional statement and additional variable required = mod 4 , Residue T HE PREAMBLE T PE Disambiguity SYM b T T MA 3 0 Doppler = 0 0, Doppler = 0 + + ty SYM + + + + ( ) L_LENGTH 3 m + 4 1 T SYM T b 3 LENGTH m = PE Disambigui ty PA N = 3 4 / 1, Doppler = 1 and 0 N HE PREAMBLE T PE Disambigui b T T Residue T SYM T MA MA MA 3 + T M SYM T Doppler = 1 MA 3 LENGTH m 4 / 1, Otherwise HE PREAMBLE T PE Disambiguity SYM b T T MA 3 + + + + L_LENGTH 3 m _ 3 L LENGTH m = = 4 / N T N T T b 4 / N HE PREAMBLE T N N HE LTF T SYM T PE Disambiguity b HE LTF PE Disambigui ty SYM PA MA MA SYM SYM MA 3 3 + + L_LENGTH 3 m + + _ 3 L LENGTH m 4 T N T N T 4 HE PREAMBLE T N SYM T N N HE LTF T PA MA MA SYM SYM 3 HE LTF SYM MA 3 = 4 T = 4 T PE PE 4 4 Submission Slide 9 Yujin Noh, Newracom
July 2017 doc.: IEEE 802.11-17/0998r1 Comparison 2/2 Updated + + 3 LENGTH m = mod 4 , Residue T HE PREAMBLE T PE Disambiguity SYM b T T MA 3 0, Doppler = 0 + + ty SYM + + 3 LENGTH m = 4 / 1, Doppler = 1 and 0 N HE PREAMBLE T PE Disambigui b T T Residue T SYM T MA MA 3 3 LENGTH m 4 / 1, Otherwise HE PREAMBLE T PE Disambiguity SYM b T T MA 3 Depending on a value by TResidue, NMAis finally determined to get NSYM and TPE at the RX side. In order to get the proper NMA, precise TResidue is very important. Mod operation with rational numbers may not provide precise Tresidue because of simulator s internal operation such as floating point error (e.g. the fourth decimal position or something.) When implemented, this conditional statement may require additional memory to calculate and store the precise Tresidue Submission Slide 10 Yujin Noh, Newracom
July 2017 doc.: IEEE 802.11-17/0998r1 Summary This document has provided the required equations in the 11ax spec when Doppler bit sets to 1. In order to support simple and efficient implementation in Doppler effect driven environment, explicit/closed form equations NMA, NSYMand TPE at the RX side need to be taken into account. Submission Slide 11 Yujin Noh, Newracom
July 2017 doc.: IEEE 802.11-17/0998r1 Strawpoll #1 Do you agree to adopt the equation of NMA at the TX side when the Doppler bit sets to 1 for the next version of D1.3? If SP is agreed, the text proposal will be prepared. ( ) = 1 / N N M MA SYM ( ) = + T N T T MA HE LTF HE LTF HE STF Y/N/A Submission Slide 12 Yujin Noh, Newracom
July 2017 doc.: IEEE 802.11-17/0998r1 Strawpoll #2 Do you agree to adopt the equation of NMA at the RX side when the Doppler bit sets to 1 for the next version of D1.3? If SP is agreed, the text proposal will be prepared. + + ( ) L_LENGTH 3 m + 4 1 T SYM T b PE Disambigui ty PA 3 = N MA + T M SYM T MA Y/N/A Submission Slide 13 Yujin Noh, Newracom
July 2017 doc.: IEEE 802.11-17/0998r1 Strawpoll #3 Do you agree to adopt the equation of NSYMand TPE at the RX side when the Doppler bit sets to 1 for the next version of D1.3? If SP is agreed, the text proposal will be prepared. + + L_LENGTH 3 m = 4 / N T N T T b PE Disambigui ty SYM PA MA MA SYM 3 + + L_LENGTH 3 m 4 T N T N T PA MA MA SYM SYM 3 = 4 T PE 4 Submission Y/N/A Slide 14 Yujin Noh, Newracom
July 2017 doc.: IEEE 802.11-17/0998r1 Reference [1] 11-17/0734r1 802.11AX Midamble Design for Doppler [2] 11-17/0773r2 Thoughts on Doppler Design in 802.11ax Submission Slide 15 Yujin Noh, Newracom
July 2017 doc.: IEEE 802.11-17/0998r1 APPENDIX Submission Slide 16 Yujin Noh, Newracom
July 2017 doc.: IEEE 802.11-17/0998r1 Step 1) by Equation 1 on slide 4 1 N n = 0 SYM N where MA 0 1 n M M 0 Step 2) from Equation 2 on slide 4 + + L_LENGTH 3 m = + + where 4 / T N T T N b PE Disambigui ty PA MA MA SYM SYM 3 0 1 Step 3) by Step 1) and Step 2) 3 + + ( ) L_LENGTH 3 m = + + 4 T N T T N b PE Disambigui ty PA MA MA SYM SYM + + ( ) L_LENGTH 3 m = + + + + 4 1 T N T T M N n b 0 PE Disambigui ty PA MA MA SYM MA 3 + + ( ) L_LENGTH 3 m + + + 4 1 T SYM T n b 0 PE Disambigui ty PA 3 Equation 3) = N MA + T M SYM T MA Submission Slide 17 Yujin Noh, Newracom
July 2017 doc.: IEEE 802.11-17/0998r1 Step 4) find minimum value and maximum value of Equation 3) to find the boundary , 1 Given 0 0 1 n M 0 Assuming = 0= , 0 0 n + + ( ) L_LENGTH 3 m + 4 1 T SYM T b PE Disambigui ty PA 3 = N Upper , MA + T M SYM T MA = = Assuming , 1 1 n M 0 + + ( ) L_LENGTH 3 m + + 4 1 T SYM T b M PE Disambigui ty PA 3 = N , MA Lower + T M SYM T MA + + ( ) L_LENGTH 3 m + + ( ) L_LENGTH 3 m + 4 1 T SYM T b + + 4 1 T SYM T b M PE Disambigui ty PA 3 PE Disambigui ty PA 3 N MA + + T M SYM T T M SYM T MA MA Submission Slide 18 Yujin Noh, Newracom
July 2017 doc.: IEEE 802.11-17/0998r1 Step 5) check ( ) to see the range of NMA MA Upper MA N N , , Lower M M SYM T = N N 1 Upper , , MA MA Lower + ( ) T SYM T = + where T N T T MA MA HE LTF HE LTF HE STF ( ) 1 Given , since NMAis supposed to be a positive integer, NMAshould be the only one positive integer between NMA,Upper and NMA,Lower. NMA = floor(NMA,Upper) = ceil(NMA,Lower ) 0 - N N , , MA Upper MA Lower + + ( ) L_LENGTH 3 m + 4 1 T SYM T b PE Disambigui ty PA 3 = N MA + T M SYM T MA + + ( ) L_LENGTH 3 m + + 4 1 T SYM T b M PE Disambigui ty PA 3 = + T M SYM T MA Submission Slide 19 Yujin Noh, Newracom
