1. IEEE 802.15-10-0501-00-004g Submission Sangsung Choi & Cheolho Shin, ETRI Project: IEEE P802.15 Working Group for Wireless Personal Area Networks (WPANs) Submission Title: A proposal of Comment resolutions for Interleaver and Pad bits in OFDM Group. Date Submitted: July, 2010 Source: Sangsung Choi & Cheolho Shin Electronics and Telecommunications Research Institute(ETRI) Voice: +82 42 860 6722, +82 42 860 6831 Fax: +82 42 860 5218 E-maill: sschoi@etri.re.kr, chshin@etri.re.krsschoi@etri.re.krchshin@etri.re.kr Re: TG4g comment resolution Abstract: Working doc of OFDM Comment Resolutions Purpose: Comment Resolutions for CID #1041, #1409,#1411 and #1064 Notice:This document has been prepared to assist the IEEE P802.15. It is offered as a basis for discussion and is not binding on the contributing individual(s) or organization(s). The material in this document is subject to change in form and content after further study. The contributor(s) reserve(s) the right to add, amend or withdraw material contained herein. Release:The contributor acknowledges and accepts that this contribution becomes the property of IEEE and may be made publicly available by P802.15. Slide 1 July, 2010

2. Submission Sangsung Choi & Cheolho Shin, ETRI IEEE 802.15-10-0501-00-004g Comment resolutions for CID #1041, #1409 and #1411 Slide 2 Comments - CID #1041 : modify the Ncbps clearly - CID #1409 : Definition of Ncbps and Nbpsc are needed - CID #1411 : Definition of Ncbps and Nbpsc are needed Proposed Change - CID #1041 : for example, Ncbps = 96*{1,2} -> Ncbps = 96*Nbpsc - CID #1409 : Definition of Ncbps and Nbpsc are needed - CID #1411 : Provide the definitions Proposed Resolution - CID #1041 : proposed to modify accordingly. See also Document 15-10-0423-00-004g

3. Submission Sangsung Choi & Cheolho Shin, ETRI IEEE 802.15-10-0501-00-004g Comment resolutions for CID #1041, #1409 and #1411 Slide 3 Nrow = 12; OFDM Option 1: Ncbps = 96 *Nbpsc OFDM Option 2: Ncbps = 48 *Nbpsc OFDM Option 3: Ncbps = 24 *Nbpsc OFDM Option 4: Ncbps = 12 *Nbpsc OFDM Option 5: Ncbps = 6 *Nbpsc

4. Submission Sangsung Choi & Cheolho Shin, ETRI IEEE 802.15-10-0501-00-004g Comment resolutions for CID #1041, #1409 and #1411 Slide 4 For example, in MCS 0 of OFDM Option 1 - Nbpsc = 1 (BPSK), Ncbps = 96 * 1 = 96 - Interleaving size = 96 For example, in MCS 0 of OFDM Option 2 - Nbpsc = 1 (BPSK), Ncbps = 48 * 1 = 48 - Interleaving size = 48 For example, in MCS 1 of OFDM Option 3 - Nbpsc = 1 (BPSK), Ncbps = 24 * 1 = 24 - Interleaving size = 24 For example, in MCS 2 of OFDM Option 4 - Nbpsc = 2 (QPSK), Ncbps = 12 * 2 = 24 - Interleaving size = 24 For example, in MCS 6 of OFDM Option 5 - Nbpsc = 2 (QPSK), Ncbps = 6 * 2 = 12 - Interleaving size = 12

5. Submission Sangsung Choi & Cheolho Shin, ETRI IEEE 802.15-10-0501-00-004g Comment resolutions for CID #1064 Slide 5 Comments - CID #1064 : OPFM symbol number for the PHY header of Option 1 and Option 2 should be modified considering the interleaver size Proposed Change - CID #1064 : 4 OFDM symbols for the PHY header of Option 1 and 8 OFDM symbols for the PHY header of Option 2 Proposed Resolution - CID #1064 : Proposed resolution in document 15-10-0423-00-004g.

6. Submission Sangsung Choi & Cheolho Shin, ETRI IEEE 802.15-10-0501-00-004g PHY Header fields for OFDM Slide 6 PHY Header fields are 36 bits including HCS and tail bits

7. Submission Sangsung Choi & Cheolho Shin, ETRI IEEE 802.15-10-0501-00-004g Construction of Symbol number and Pad bits Slide 7 The Symbol number and Pad bits can be constructed by the formulas (16), (17) and (18) in page 67 of draft standard. According to these formulas, the PHY header occupies 3 OFDM symbols for OFDM 1 and 6 OFDM symbols for Options 2,3,4 and 5. However, these formulas should be corrected considering the Interleaving size and FDS repetition because the Interleaving cant be completed in several data rate modes using FDS if we use these formulas.

8. Submission Sangsung Choi & Cheolho Shin, ETRI IEEE 802.15-10-0501-00-004g Slide 8 - According to Formula (16), (17), and (18) Nsym=Ceiling((8xLENGTH+6)/NDBPS) Nsym = ceiling(8x3.75+6)/12)=3 NDATA=Nsym x NDBPS MDATA=3 x 12 =36 Npad=NDATA-(8XLENGTH+6), Npad = 36-(8 X 3.75+6) = 0 For Example of Option 1

9. Submission Sangsung Choi & Cheolho Shin, ETRI IEEE 802.15-10-0501-00-004g Slide 9 For Example of Option 1(Continued) - According to the formula in page 67 of draft standard, The bit number of PHY header fields is 36, and then it increases 72 bits after Convolutional encoder.

10. Submission Sangsung Choi & Cheolho Shin, ETRI IEEE 802.15-10-0501-00-004g Slide 10 For Example of Option 1(Continued) - In this case, the interleaving size is 96. - Thus, the interleaving of 96 can't be completed using 72 bits of PHY header fields as shown below figure.

11. Submission Sangsung Choi & Cheolho Shin, ETRI IEEE 802.15-10-0501-00-004g Slide 11 - According to Formula (16), (17), and (18) Nsym=Ceiling((8xLENGTH+6)/NDBPS) Nsym = ceiling(8x3.75+6)/6)=6 NDATA=Nsym x NDBPS MDATA=6 x 6 =36 Npad=NDATA-(8XLENGTH+6), Npad = 36-(8 X 3.75+6) = 0 For Example of Option 2

12. Submission Sangsung Choi & Cheolho Shin, ETRI IEEE 802.15-10-0501-00-004g Slide 12 For Example of Option 2(Continued) - According to the formulas in page 67 of draft standard, The bit number of PHY header fields is 36, and then it increases 72 bits after Convolutional encoder.

13. Submission Sangsung Choi & Cheolho Shin, ETRI IEEE 802.15-10-0501-00-004g Slide 13 For Example of Option 2(Continued) - In this case, the interleaving size is 48. - Thus, the interleaving of 48 can't be completed using 72 bits of PHY header fields as shown below figure.

14. Submission Sangsung Choi & Cheolho Shin, ETRI IEEE 802.15-10-0501-00-004g PSDU fields for OFDM Slide 14 The maximum PSDU are 2047bytes For convenience of explanation, PSDU Length of 3 bytes is assumed. Although the formulas in page 67 of draft standard generate the Symbol number and Pad bits in PHY Header fields correctly, the Interleaving still cant be completed in several data rate modes Using FDS of Option3 and 4.

15. Submission Sangsung Choi & Cheolho Shin, ETRI IEEE 802.15-10-0501-00-004g Slide 15 - If the PSDU Length of 3bytes is assumed in 50Kbps mode of Option 3 and 4, the number of Symbol and Pads bits can be calculated by the formula (16), (17), and (18) in page 67 of draft standard. Nsym = Ceiling((8xLENGTH+6)/NDBPS) Nsym = ceiling(8x3+6)/6)=5 NDATA = Nsym x NDBPS MDATA=5 x 6 =30 Npad = NDATA-(8XLENGTH+6), Npad = 30-(8 X 3+6) = 0 For Example of Option 3 & 4

16. Submission Sangsung Choi & Cheolho Shin, ETRI IEEE 802.15-10-0501-00-004g Slide 16 - PHY Payload of 30 bits including PSDU and tail bits increase (3*8 + 6)*2 = 60 bits after Convolutional encoder. For Example of Option 3 & 4(Continued)

17. Submission Sangsung Choi & Cheolho Shin, ETRI IEEE 802.15-10-0501-00-004g Slide 17 - In this case, the interleaving size is 24. - Thus, the interleaving of 24 can't be completed using 60 bits as shown below figure. For Example of Option 3 & 4(Continued)

18. Submission Sangsung Choi & Cheolho Shin, ETRI IEEE 802.15-10-0501-00-004g Propose new formulas for Construction of Symbol number and Pad bits Slide 18 We propose new formulas for PAD bits and the number of symbols considering the Interleaving size and FDS repetition. - refer the document #15-10-0423 NCBPS = Ncbps NDBPS = NCBPS * R NPAD = NDBPS * ceiling ((8*LENGTH + 6)/NDBPS) - (8*LENGTH + 6) NSYM = Ns F * ceiling ((8*LENGTH + 6)/NDBPS) -R: Coding rate -Ns F : Spreading Factor of FDS -Ncbps: Coded Bits per OFDM symbol at interleaver -NCBPS : Coded Bits per Ns F OFDM symbols at IFFT -NDBPS : DATA Bits per Ns F OFDM symbols at IFFT

19. Submission Sangsung Choi & Cheolho Shin, ETRI IEEE 802.15-10-0501-00-004g Symbol Number and Pad bits in PHY Header fields by the new proposed formulas Slide 19 Construction of Symbol number and Pad bits of PHY Header using the new proposed formulas

20. Submission Sangsung Choi & Cheolho Shin, ETRI IEEE 802.15-10-0501-00-004g Slide 20 For Example of Option 1 - According to the new proposed formulas, The bit number of PHY header fields including pad bits is 48, and then it increases 96 bits after Convolutional encoder.

21. Submission Sangsung Choi & Cheolho Shin, ETRI IEEE 802.15-10-0501-00-004g Slide 21 For Example of Option 1(Continued) - In this case, the interleaving size is 96. - Thus, the interleaving of 96 can be completed using 96 bits of PHY header fields as shown below figure.

22. Submission Sangsung Choi & Cheolho Shin, ETRI IEEE 802.15-10-0501-00-004g Slide 22 For Example of Option 2 - According to the new proposed formulas, The bit number of PHY header fields including pad bits is 48, and then it increases 96 bits after Convolutional encoder.

23. Submission Sangsung Choi & Cheolho Shin, ETRI IEEE 802.15-10-0501-00-004g Slide 23 For Example of Option 2(Continued) - In this case, the interleaving size is 48. - Thus, the interleaving of 48 can be completed using 96 bits of PHY header fields as shown below figure.

24. Submission Sangsung Choi & Cheolho Shin, ETRI IEEE 802.15-10-0501-00-004g PSDU fields for OFDM Slide 24 The maximum PSDU are 2047bytes For convenience of explanation, PSDU Length of 3 bytes is assumed.

25. Submission Sangsung Choi & Cheolho Shin, ETRI IEEE 802.15-10-0501-00-004g Slide 25 - If the PSDU Length of 3bytes is assumed in 50Kbps mode of Option 3 and 4, the number of Symbol and Pads bits can be calculated by the new proposed formulas. NCBPS = 24 NDBPS = 24 * ½ = 12 NPAD = 12 * ceiling ((8*3 + 6)/12) - (8*3 + 6) = 6 NSYM = 2 * ceiling ((8*3 + 6)/12) = 6 For Example of Option 3 & 4

26. Submission Sangsung Choi & Cheolho Shin, ETRI IEEE 802.15-10-0501-00-004g Slide 26 - PHY Payload of 36 bits including PSDU, tail bits and Pad bits increase (3*8 + 6 +6)*2 = 72 bits after Convolutional encoder. For Example of Option 3 & 4(Continued)

27. Submission Sangsung Choi & Cheolho Shin, ETRI IEEE 802.15-10-0501-00-004g Slide 27 - In this case, the interleaving size is 24. - Thus, the interleaving of 24 can be completed using 72 bits as shown below figure. For Example of Option 3 & 4(Continued)

28. Submission Sangsung Choi & Cheolho Shin, ETRI IEEE 802.15-10-0501-00-004g Conclusion Slide 28 July, 2010 The generation formulas for the number of symbol and PAD bits in page 67 of draft standard can not consider the Interleaver size and FDS repetition. - In several data rate modes using FDS, Interleaving cant be completed. Then, we propose new generation formulas for PAD bits and the number of symbol considering the Interleaver size and FDS repetition. - The proposed formulas can be good solution for all data rate modes of all Options.