Project: IEEE P802.15 Working Group for Wireless Personal Area Networks (WPANs)

1. Project: IEEE P802.15 Working Group for Wireless Personal Area Networks (WPANs) Submission Title: [Advanced interleaving for high data rate 60 GHz communications] Date Submitted: [March 2007] Source: [P. Pagani,I. Siaud, A.M. Ulmer-Moll, W. Li] Company [France Telecom Research and Development Division] Address [4 rue du Clos Courtel, BP 91226, F-35512 Cesson Sévigné, France] Voice:[], FAX: [], E-Mail:[] Re: [] Abstract: [] Purpose: [Contribution to IEEE 802.15.3c Task Group] 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. France Telecom

2. Advanced Interleaving for High Data Rate 60 GHz Communications P. Pagani, I. Siaud, A. M. Ulmer-Moll, W. Li France Telecom Research and Development Division France Telecom

3. Outline • An interleaving proposal for the future 802.15.3c PHY • Binary and data symbol interleaving for single-carrier and multi-carrier systems • Algorithm description • Simulation scenarios • BER performance and comparison to other interleaving schemes • Further interleaving implementations France Telecom

4. Motivation • After the channel encoding, it is necessary to scramble (interleave) the coded bits in order to increase the system robustness. • This feature is particularly important when considering high data rates systems, as the coding rate is necessarily high. • This interleaving operation may be split into two phases : • A bit interleaving is applied on a FEC block. • A frequency interleaving is applied on the data symbols before they are mapped on the sub-carriers. • This document presents a rationale for the use of well designed interleaving and the gain this brings to the system. France Telecom

5. NFFT IFFT sub-carrier Modulation sub-carrier Interleaving In(k) Guard sub-carrier Binary interleaving Data scrambingl FEC coding Multipath channel Pilot insertion X Tcp Insertion S/P + X X AWGN X Information binary Source Tx block diagram France Telecom

6. X(k) j+s k 0 j L(k) L(k) L(j) L(0) L(j+s) X'(k) j 0 j+s Binary interleaving • Rationale : if data symbols are corrupted, a set of 2, 4, or 6 contiguous bits is corrupted • Purpose : to spread the bits of a data symbol onto several data symbols • Block interleaving : a unique mathematical algorithm L(k) to generate block interleaving with a size K France Telecom

7. x'0 x'1 x'2x'3 … x'p-1 x'p…. x'2p-1 x'pmx'1+pmx'2+pm x'3+pm ..x'p(m+1)-1 S=1 S=1 S=p Block interleaving proposal Main properties [1, 2]  • Controlled interleaving spreading DI(s) • between samples separated with (s-1) samples • s is chosen to increase the interleaving spreading along typical system parameter criteria that improve BER performance • algebraic calculation ofDI(s) and L(s) • DI(s) is maximized using several criteria (adjacent sub-carriers , spreading in a sub-carrier, others) France Telecom

8. Stream # 1 P/S P/S X(k) interleaving Stream#2 Interleaving interleaving X'(k) interleaving ……… X'(k)=X(L(k)) interleaving Virtual stream#p Block interleaving proposal Main properties [1, 2]  • Conservation of a sample interleaving pattern • the interleaver is equivalent to a multi-stream interleaver which preserves data multiplexing France Telecom

9. k I I I I Block interleaving proposal Overall structure [1, 2] • Empirical research on structures oriented on scalabity • An iterative structure of the algorithm generates different permuation rules in a scalable way • This structure preserves  and  technical requirements France Telecom

10. 18000 16000 14000 12000 10000 L(k) 8000 6000 4000 2000 0 0 5 10 15 20 25 30 35 40 k Interleaving pattern selection • Maximize interleaving spreading  {p, q, j} interleaving parameters • Between adjacent bits within a data symbol (s < n) • Between adjacent data symbols (s = n) n encoded bits per data symbol Example, K = 17664 6 OFDM symb. (16QAM) p = 16, q = 2, j = 3 ΔI(1) = 8161 ΔI(2) = 1342 ΔI(3) = 6819 ΔI(4) = 2684 France Telecom

11. Simulation results France Telecom

12. Simulation parameters (1) • System parameters • OFDM modulation over a 528 MHz band (carrier frequency : 60 GHz) • Channel model • CEPD model [1] based on experimental measurements in the residential NLOS environment [3] • Moderate NLOS channel: σRMS = 6.9 ns • Selective NLOS channel: σRMS = 12.4 ns France Telecom

13. 6 32 736x4 23x4 1st stage 2nd stage Simulation parameters (2) • Assessed interleaving schemes • ECMA type : a 2 stage matrix interleaver derived from ECMA standard [4] without multiband processing • Random interleaver • FTRD interleaver proposal {p,q,j}= (16,2,3) France Telecom

14. Simulation results France Telecom

15. Possible options • Frequency interleaving • At the sub-carrier level (after symbol mapping) • Channel mitigation : avoids frequency fades • Dynamic interleaving • Use different permutation laws cyclically • Benefits from channel diversity • Lowers inter-piconet interference TG3c CM1.3 channel Permutation rule #1 Permuation rule #2 Permutation rule #1 Permuation rule #2 time N OFDM symbols France Telecom

16. Conclusions • The interleaving process is worth to be studied since an optimized interleaver can help to spare some dBs at low cost. • The approach illustrated above will be continued and confirmed by : • using TG3c channel models • applying the proposed scheme to a complete TG3c system • Additional gain could be obtained by considering • Frequency (sub-carrier) interleaving • Dynamic use of several interleaving rules [1, 2] France Telecom

17. References • [1] Siaud.I, Ulmer-Moll A.M, "A Novel Adaptive sub-carrier Interleaving : application to millimeter-wave WPAN OFDM Systems (IST MAGNET project)", IEEE portable 2007 conf, 25-29 March 2007, Orlando (USA). • [2] Siaud.I, Ulmer-Moll, "Advanced Interleaving algorithms for OFDM based millimeter wave WPAN transmissions", SCEE Seminar, 8 February 2007, France. • [3] Pagani, P., Malhouroux, N., Siaud, I. & Guillet, V., "Characterization and modeling of the 60 GHz indoor channel in the office and residential environments", IEEE 802.15 Working Group for WPANs, no. IEEE 802.15-06/027r3, Jan. 2006. • [4] Standard ECMA-368, "High Rate Ultra Wideband PHY and MAC Standard", 1st Edition - December 2005, http://www.ecma-international.org/ • [5] N.Cassiau, I. Siaud, A.M. Ulmer-Moll, T. Hulzinker, K. Schoo , "Coexistence Aspects of the MAGNETPAN-optimized Air Interface Targeting High Data Rates", WWRF#17, Heidelberg, November 2006. France Telecom

18. Thank you !Questions ? pascal.pagani@orange-ftgroup.com isabelle.siaud@orange-ftgroup.com wei3.li@orange-ftgroup.com France Telecom

19. Backup slides France Telecom

20. Binary interleaving proposal X(k) DI(s=1)= 8161 DI(s=1)= 8161 X'(k) X(k) DI(s=2)= 1342 DI(s=2)= 1342 X'(k) France Telecom

21. Moderate NLOS Selective NLOS Channel model used in the simulations • CEPD model [1] based on experimental measurements in the residential NLOS environment [3] France Telecom