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:M-ary Code Shift Keying/Binary PPM (MCSK/BPPM) Based Impulse Radio Date Submitted: January 2005 Source: [Dong In Kim (1), Serhat Erküçük (1), Kyung Sup Kwak (2)] Company: [(1) Simon Fraser University, (2)UWB-ITRC, Inha University] Address: [(1) School of Engineering Science, 8888 University Drive, Burnaby, BC V5A 1S6, Canada (2) 253 Yonghyun-Dong, Nam-Gu, #401, Venture Bldg. Incheon, 402-751 Korea] Voice: [+1 (604) 291-3248], Fax: [(1) +1 (604) 291-4951 (2) +82-32-876-7349] E-Mail: [(1) dikim@sfu.ca (2) kskwak@inha.ac.kr] Abstract: [Proposed modulation format increases the ranging and location capability of time hopping impulse radios] Purpose: [Proposal for the IEEE802.15.4a standard] 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.

2. Proposal for IEEE 802.15.4 Alternate PHY M-ary Code Shift Keying/Binary PPM (MCSK/BPPM) Based Impulse Radio SFU, Canada & UWB-ITRC, Inha UniversityRepublic of Korea

3. Motivation • MCSK/BPPM increases the location/ranging capability of existing Time Hopping (TH) Impulse Radios (IRs) • H/W complexity is not increased • Same signal space with respect to TH-BPPM • “MCSK” can be applied to other TH-IRs; eg. MCSK/BPSK

4. Contents • TG4a Requirements • MCSK/BPPM • PHY TX Structure • TH Code Assignment • Transceiver Architecture • Information Rate • Location Accuracy • Conclusion

5. TG4a Requirements *MCSK/BPPM: M-ary Code Shift Keying/Binary Pulse Position Modulation **TH-BPPM: Time Hopping Binary Pulse Position Modulation

6. t t 0 0 only for multiple access c3 for multiple access and data modulation MCSK/BPPM MCSK: M-ary Code Shift Keying BPPM: Binary Pulse Position Modulation TX TH PPM – user #1 1 1 0 1 TH-BPPM 1 user specific TH code MCSK/BPPM – user #1 … 110 101 TH-BPPM choose a code M=4 M user specific TH codes 1 TH code Bit time Frame time

7. MCSK BPPM PHY TX Structure (1/2) TX • TH codes are periodic with Np • each pulse should be repeated Nstimes • - Np/Ns=k is an integer M user specific TH codes Example: C2 5 8 7 3 1 4 2 6 t 0 Bit time Frame time

8. PHY TX Structure (2/2) TX • TH codes are periodic with Np • each pulse should be repeated Nstimes • - Np/Ns=k is an integer M user specific TH codes Information rate vs. BER performance for fixed Ns and varying Np and M Scenario Time domain illustration Info. rate BER performance 2 bits (MCSK) 1 bit (BPPM) Np/Ns same M increasing 3 bits (MCSK) 1 bit (BPPM) M same 3 bits (MCSK) 1 bit (BPPM) 1 bit (BPPM) Np/Ns increasing Frame time Bit time

9. 46 20 55 c3 c3 c2 c2 c0 c0 c1 c1 user #2 user #1 TH Code Assignment (1/2) TX ? Each user has M user specific TH codes sample-long sequence NO! Generation of TH codes – “Case 1: random assignment” For Tf = 100ns, Tc = 1ns: 100 slots for multiple access 0 m-sequence:

10. user #2 user #1 n: number of overlaps TH Code Assignment (2/2) TX Generation of TH codes – “Case 2: no overlapping” . . . user #2 user #k user #1 no collisions allowed within user codes

11. Fixed signal space • Increased information rate General Modulation Format TX • Extra information • Random selection of TH codesImproved spectrum

12. Receiver Structure - MLSE RX M M template signals 2M Np/Ns hardware structure computation complexity correlator

13. can be adjusted to achieve higher information rate at lower transmit power and still maintain better BER performance at the same time Information Rate (1/3) A TH-BPPM Ns = 2, M=1 Info. rate Rs R 2 0 A’ MCSK/BPPM “Constant Energy/Bit” Constraint Ns = 2, Np=2, M=2 2R 2 0 A MCSK/BPPM “Constant Power” Constraint Ns = 2, Np=2, M=2 2R 2 0 A’ R MCSK/BPPM (same info. rate) “Constant Power” Constraint Ns = 2, Np=2, M=2 2 0

14. Information Rate (2/3) MCSK/BPPM “Constant Power” Constraint for Ns = 1, M=8 A BER performance (wrt TH-BPPM) Scalable info. rates 0 A’=2A 4R  R - increased SNR - reduced collusions - no processing gain - not much improvement 0 A 0 - increased SNR - reduced collusions - processing gain - improved BER - TX power can be lowered - info rate can be increased 2.5R  R A’=1.58A 0 A 0 2R  R A’=1.41A 0

15. Information Rate (3/3) • “Constant Power” Constraint • Improved performance at the same information rate for M=8

16. Location Accuracy MCSK/BPPM “Constant Power” Constraint Procedure Result Comment R0 (information rate); BER0(performance) TX0 (power) Initial conditions for TH-BPPM Step 0 Step 1 Increase M Step 2 BER2may or may not be less than BER0 Increase Np/Ns BER3may or may not be less than BER0 Step 3 Increase T’f Increased frame time with longer observation period, higher information rate, better BER performance and lower transmit power Step 4 Increase A’ Accurate Ranging/Location

17. Simultaneously! IEEE 802.15.4a PHY Conclusion • MCSK/BPPM provides:  increased information rate  lower transmit power  better BER performance  improved spectral characteristics • MCSK/BPPM is capable of:  information rate scalability  location/ranging accuracy

18. Back-up Slides

19. MCSK/BPPM “Constant Power” Constraint

20. MCSK/BPPM “Constant Energy/Bit” Constraint

21. Effects of TH Code Design on the Performance MCSK/BPPM “Constant Power” Constraint

22. TH Code Spectrum of: • TH-BPPM, Np=10 • ideal MCSK/BPPM, Np  • realistic MCSK/BPPM Fig. a. TH-BPPM Fig. b. ideal MCSK/BPPM Fig. c. realistic MCSK/BPPM