doc.: IEEE 802.15-09-0114-00-004g-Trends-in-SUN-capacity <month year> Apr. 2013 Project: IEEE P802.15 Working Group for Wireless Personal Area Networks(WPANs) Submission Title: Comment on OFDM LTF sequence Date Submitted: Apr. 2013 Source: Jaehwan Kim, Byounghak Kim, Cheolho Shin, Mi-Kyung Oh, Sangsung Choi (ETRI) and Soo-Young Chang (SYCA) Contact: kimj@etri.re.kr Voice: +82 42 860 5338, E-Mail: kimj@etri.re.kr Re: LB88 Comment Abstract: Purpose: 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 ETRI Emmanuel Monnerie, Landis+Gyr
Current LTF Sequence LTF sequence LTF sequence design Apr. 2013 Current LTF Sequence LTF sequence LTF sequence design Need for OFDM symbol boundary detection and channel estimation, etc Tone# Value -64 -48 1 -32 -16 16 32 48 -63 -1 -47 -31 -15 17 33 49 -62 -46 -30 -14 2 18 34 50 -61 -45 -29 -13 3 19 35 51 -60 -44 -28 -12 4 20 36 52 -59 -43 -27 -11 5 21 37 53 -58 -42 -26 -10 6 22 38 54 -57 -41 -25 -9 7 23 39 55 -56 -40 -24 -8 8 24 40 56 -55 -39 -23 -7 9 25 41 57 -54 -38 -22 -6 10 26 42 58 -53 -37 -21 -5 11 27 43 59 -52 -36 -20 -4 12 28 44 60 -51 -35 -19 -3 13 29 45 61 -50 -34 -18 -2 14 30 46 62 -49 -33 -17 15 31 47 63 ETRI
OFDM Symbol Boundary Detection Apr. 2013 OFDM Symbol Boundary Detection Current SHR To help symbol boundary detection, cross correlation of received signal and LTF should be performed in time domain Problem 32 tap and 64 tap LTF cross correlation need about 3 dB and 0 dB SNR, respectively for symbol boundary detection Cross correlation with more than 64 tap, desired data is passed at symbol boundary detection point Latency and hardware complexity are increased ETRI
Proposed LTF Sequence Proposed LTF sequence Apr. 2013 ETRI Tone# Value -64 -48 1 -32 -1 -16 16 32 48 -63 -47 -31 -15 17 33 49 -62 -46 -30 -14 2 18 34 50 -61 -45 -29 -13 3 19 35 51 -60 -44 -28 -12 4 20 36 52 -59 -43 -27 -11 5 21 37 53 -58 -42 -26 -10 6 22 38 54 -57 -41 -25 -9 7 23 39 55 -56 -40 -24 -8 8 24 40 56 -55 -39 -23 -7 9 25 41 57 -54 -38 -22 -6 10 26 42 58 -53 -37 -21 -5 11 27 43 59 -52 -36 -20 -4 12 28 44 60 -51 -35 -19 -3 13 29 45 61 -50 -34 -18 -2 14 30 46 62 -49 -33 -17 15 31 47 63 ETRI
Proposed LTF Sequence Property of the proposed LTF sequence Apr. 2013 Proposed LTF Sequence Property of the proposed LTF sequence IFFT result of the first 32 tap is similar to negative s in STF ETRI
Benefits of the Proposed LTF Sequence Apr. 2013 Benefits of the Proposed LTF Sequence OFDM symbol boundary detection probability Cross correlation for current LTF and Autocorrelation for the proposed LTF Current LTF needs about 3 dB SNR for symbol boundary detection If we use new LTF, -1 dB SNR is needed to detect symbol boundary ETRI
Apr. 2013 Conclusion Current LTF sequence is not proper to perform time domain correlation for OFDM symbol boundary detection Proposed LTF can increase the symbol boundary detection probability Change the current LTF sequence to the proposed LTF sequence ETRI