1. 1 C00-20001204-014_LGE_CDSA Title : CDSA : A Fast and Robust PN Code Acquisition Scheme for Cellular DS/CDMA Application Abstract : This contribution discusses the key concepts, organization and operations of Correlation-Aided Distributed Sample Acquisition (CDSA) Based DS/CDMA Cellular System Source :B.K YiY.J Song B.H KimB.G Lee LGE Inc. LGE Inc. GCT SNU bkyi@lginfocomm.com yjsong@lginfocomm.combkyi@lginfocomm.comyjsong@lginfocomm.com Date : December 04, 2000 Recommendation : Discussion for 1xEV-DV Notice © 2000 LGE Incorporated. All rights reserved. The information contained in this contribution is provided for the sole purpose of promoting discussion within the 3GPP2 and its Organization Partners and is not binding on the contributor. The contributor reserves the right to add to, amend, or withdraw the statements contained herein. LGE Incorporated grants a free, irrevocable license to 3GPP2 and its Organization Partners to incorporate text or other copyrightable material contained in the contribution and any modifications thereof in the creation of 3GPP2 publications; to copyright and sell in Organizational Partner ’ s name any Organizational Partner ’ s standards publication even though it may include portions of the contribution; and at the Organization Partner ’ s sole discretion to permit others to reproduce in whole or in part such contributions or the resulting Organizational Partner ’ s standards publication.The contributor may hold one or more patents or copyrights that cover information contained in this contribution. A license will be made available to applicants under reasonable terms and conditions that are demonstrably free of any unfair discrimination. Nothing contained herein shall be construed as conferring by implication, estoppel, or otherwise any license or right under any patent, whether or not the use of information herein necessarily employs an invention of any existing or later issued patent, or copyright. The contributor reserves the right to use all material submitted in this contribution for his own purposes, including republication and distribution to others.

2. 2 C00-20001204-014_LGE_CDSA Outline I. Introduction Serial Search (SSA) Parallel Search (PSA) Rapid Acquisition by Sequential Estimation (RASE) Distributed Sample Acquisition (DSA) II. Correlation-Aided Distributed Sample Acquisition (CDSA) Based DS/CDMA Cellular System III. Application of CDSA to Inter-cell Asynchronous W-CDMA Cell Search VI. Concluding Remarks

3. 3 C00-20001204-014_LGE_CDSA I. Introduction  Issues on PN Code Acquisition u Acquisition Time Speed-up u Low Complexity (Hardware and Computation) u Robustness F Low-SNR (Cell-boundary, Shadowing) F Fading F Frequency Offset  PN Code Acquisition Techniques

4. 4 C00-20001204-014_LGE_CDSA  Correlation - based Search (SSA, PSA) Threshold Detector | | 2 N I ( ) Search Control Clock  d L-1 d L-2 d0d0 d1d1 d1d1 d2d2 d3d3 d4d4 d0d0 d2d2 d3d3 d4d4 d L-1 Transmitter SRG Receiver SRG sksk sksk bkbk b k +s k b k +s k +s k Scrambling Descrambling (continued) (User Channel) (Pilot Channel)

5. 5 C00-20001204-014_LGE_CDSA  Rapid Acquisition by Sequential Estimation: State Loading (AWGN, Moderate SNR, Coherent Acquisition) Transmitter SRGReceiver SRG Scrambling Descrambling d L-1 d L-2 d0d0 d1d1 d2d2 d3d3 d4d4 d L-1 d L-2 d0d0 d1d1 d2d2 d3d3 d4d4 sksk sksk b k +s k b k +s k +s k bkbk (continued) (User Channel) (Pilot Channel)

6. 6 C00-20001204-014_LGE_CDSA (continued)  Goal of the Work u Design of Noncoherent (or Differentially-coherent), Rapid, and Robust Acquisition / Cell-search Schemes with Minimal Complexity by employing Generalized State Loading Techniques

7. 7 C00-20001204-014_LGE_CDSA  Distributed Sample Acquisition (DSA) User Data State Correction Comparison State Sampling State Sampling d L-1 d0d0 d1d1 d2d2 d3d3 d0d0 d1d1 d2d2 d3d3 smsm smsm znzn znzn Main SRG (long) ScramblingDescrambling User Data Main Sequence Data Signal (User Channel) Main Sequence d S-1 d0d0 d1d1 Igniter SRG (short) State Signal (Pilot Channel) Transmitter Receiver cmcm Igniter Sequence (continued)

8. 8 C00-20001204-014_LGE_CDSA II. Correlation-Aided DSA Based DS/CDMA Cellular System u BS (Tx) and MS (Rx) have two kinds of SRG's F Igniter SRG with short period N I (=2 S ) F Main SRG with long period N M (=2 L ): targeted scrambling sequence u BS samples a main SRG state sample in every N I chip interval, spread it with a short igniter code of length N I, and then transmit it as a state signal (or the common pilot signal) of the BS. F Several samples may be transmitted concurrently to speed up the synchronization in a moderate SIR environment u After igniter code acquisition applying a conventional search method, MS’s detect the main SRG state samples sequentially. u State sample comparison-correction based main SRG Synchronization F L corrections and V verifications by a set of pertinent sampling-comparison- correction circuits synchronize the MS main SRG to the BS main SRG. u Asymptotically, 2 L / (2 S +L+V) times faster acquisition than Serial-search with minimal complexity increase (IS95/cdma2000: L=15) F (L=15, S=7): 256 times; (L=15, S=8): 128 times u State Symbol Correlation Process for Robust Acquisition in Worst-case Channel Environment

9. 9 C00-20001204-014_LGE_CDSA CDSA-based DS/CDMA System (BS) Data signal(1) Sampling Timing Data signal(2) DSA - Spreader Sample - Spreader Data signal(J) Q-main SRG I-main SRG Time-advanced Sampling NITcNITc {s m } aiai [1] {w m } [1] Igniter SRG-2 Igniter SRG-1 {c m } aiai [2] {w m } [2] aiai [J] {w m } [J] Spreading State signal (CPICH) PSK Symbol Mapping {z i } xixi fifi v 0

10. 10 C00-20001204-014_LGE_CDSA  Common Pilot Channel Modulation Example for CDSA u As I-channel PN state and Q-channel PN state have a one-to-one correspondence in cdma2000, the BS has only to broadcast I-main SRG state samples to the MS’s. u Each cell employ one of 16 Complex Igniter Codes (Group Codes) 16 igniter codes (group codes) of length 256 512 modulated common pilot codes of length 32768 (DBPSK encoding of state samples: f j ) 208 usec c o c 1 c 255 f o C i f 1 C i f 2 C i f 3 C i f 4 C i f 127 C i f j C i 26.67 ms 1 Sync Frame C i, i=0,1,…15

11. 11 C00-20001204-014_LGE_CDSA Global Timing Relations and Cell Group Plan  Neighboring cells shall employ different igniter codes F Trade-off relation between the number of igniter sequences in a cellular system and the amount of co-channel (co-igniter) cell interference: complexity and performance trade-off  Multiple main sequences and igniter sequences can be obtained by phase shifts in the inter-cell synchronous systems such as IS95 and cdma2000. F Ex: 512 main and 7 [or 16] igniter sequences can be derived from an extended m-sequence of length 32768 and 2 [or 4] Gold sequences of length 256 through the cyclic shifts by 64*n chips

12. 12 C00-20001204-014_LGE_CDSA u Timing relations among igniter/main sequences (Ex: 7 groups and 512 cells)

13. 13 C00-20001204-014_LGE_CDSA u Cell group (igniter code) plan (Ex: 7 groups and 48 cells) 6,6 1,1 0,0 2,2 0,42 5,19 3,3 5,12 6,13 0,35 0,7 1,8 1,36 6,20 6,12 0,14 1,15 5,5 4,18 3,17 2,16 4,4 5,26 6,27 0,21 1,22 2,23 3,24 5,33 6,34 4,11 3,10 1,43 4,32 0,28 1,29 4,25 2,9 2,30 3,31 2,37 3,38 4,39 5,40 6,41 2,44 3,45 4,46 5,47

14. 14 C00-20001204-014_LGE_CDSA State signal Despreading Data signal(u) Correction Timing Sampling Timing Sample - Despreader Sampling Correction Despreading DSA - Despreader NITcNITc iN I T c (i-1)N I T c dt NITcNITc 1 ( )* PSK Symbol Detection gigi {s m } {w m } [u] + Noise iN I T c (i-1)N I T c dt NITcNITc 1 Q-main SRG I-main SRG Igniter SRG-2 Igniter SRG-1 Comparison {c m } aiai [u] yiyi Store State Symbols for B Symbol Periods State Symbol Correlation Based Frame Boundary Search {z i } h 0 c0c0 {z i } CDSA-based DS/CDMA System (MS)

15. 15 C00-20001204-014_LGE_CDSA System Timing Diagram Igniter seq. Tx Main seq. DBPSK symbol State signal Rx Detected sample Main seq. Comparison Sampling result Correction sampling NINI N I -advanced D c (=1)

16. 16 C00-20001204-014_LGE_CDSA IS-95 I-Phase PN  (x) = 1 + x 5 + x 7 + x 8 + x 9 + x 13 + x 15 T= A  (x) t, h= [1 0 0 0] t, N I = 128 (a) DSA-Spreader (b) DSA-Despreader {z i } Sampling pulse v0v0 {s m } {b m } {b m + s m } Design Example

17. 17 C00-20001204-014_LGE_CDSA III. Mean Acquisition Time Performance F 512 Cells / System F 100 Hz Classical Rayleigh Fading F Igniter Seq. Period (Dwell Time), N I = 256 F Main Seq. Period N M = 32768 F False Acquisition Penalty Time = 1280N I (10 Frames) F False Alarm Prob. = 0.05 (Acq. Detection), 0.001 (Verification) F Verification Time = 10N I F Igniter Seq. Reuse Factor = 16 (4 Seq.’s, 4 Phase Offsets) F Symbol Sequence Length for State Symbol Correlation Process B = 128 Symbols F Conventional PSA : 4 Correlators Operate in Parallel : Comparable complexity

18. 18 C00-20001204-014_LGE_CDSA (continued)

19. 19 C00-20001204-014_LGE_CDSA IV.Concluding Remarks u CDSA scheme for rapid and robust acquisition of long-period PN sequences: F Igniter Sequence + Comparison-correction Process : DSA + State Symbol Correlation Process : CDSA u Revisit the goal of the work ! F Acquisition / Cell Search Time Reduction F Minimal Complexity F Robustness: Shadowing, fading, frequency offset, etc.