5/038 13 - EN/LZU 108 5306 Rev A WCDMA Air Interface Part 5: 1 of 34 WCDMA Air Interface Training...

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Transcript of 5/038 13 - EN/LZU 108 5306 Rev A WCDMA Air Interface Part 5: 1 of 34 WCDMA Air Interface Training...

  • Slide 1
  • 5/038 13 - EN/LZU 108 5306 Rev A WCDMA Air Interface Part 5: 1 of 34 WCDMA Air Interface Training Part 5 WCDMA Acquisition, Synchronization, and Handover
  • Slide 2
  • 5/038 13 - EN/LZU 108 5306 Rev A WCDMA Air Interface Part 5: 2 of 34 WCDMA Physical Layer Procedures Physical Layer Timing and procedures BS Downlink timing Fast Synchronization Codes Synchronization Code 1 (PSC) Synchronization Code 2 (SSC i ) Downlink Scrambling Codes Used by UE to distinguish desired Base Station 8192 possible codes, 64 Scrambling Code Groups Slot Synchronization Frame Synchronization System Timing Synchronization Soft Handover Random Access protocol Packet Access protocol Inter-Frequency Handover
  • Slide 3
  • 5/038 13 - EN/LZU 108 5306 Rev A WCDMA Air Interface Part 5: 3 of 34 Downlink Transmission Timing Secondary SCH Primary SCH S-CCPCH,k 10 ms Frame P-CCPCH, (SFN modulo 2 = 0) P-CCPCH, (SFN modulo 2 = 1) CPICH (Common Pilot Channel) AICH access slots #0#1#2#3#14#13#12#11#10#9#8#7#6#5#4 Any PDSCH PICH DPCH,n Common Pilot Channel Primary CCPCH (Broadcast Data) Secondary CCPCH (Paging, Signaling) Paging Indication Channel SCH (PSC+SSC) P-CCPCH S-CCPCH PICH AICH PDSCH DPCH S-CCPCH,k = N x 256 chips DPCH,n = N x 256 chips PICH = 7680 chips (3 slots) 3GPP TS 25.211 7.0 k:th S-CCPCH PICH for n:th S-CCPCH n:th DPCCH/DCDPH Downlink Shared Channel Dedicated Physical Control/Data Channel
  • Slide 4
  • 5/038 13 - EN/LZU 108 5306 Rev A WCDMA Air Interface Part 5: 4 of 34 Downlink Scrambling Codes Used to distinguish Base Station transmissions on Downlink Each Cell is assigned one and only one Primary Scrambling Code The Cell always uses the assigned Primary Scrambling Code for the Primary and Secondary CCPCHs Secondary Scrambling Codes may be used over part of a cell, or for other data channels Primary SC 0 Secondary Scrambling Codes (15) Secondary Scrambling Codes (15) Secondary Scrambling Codes (15) Secondary Scrambling Codes (15) Code Group #1Code Group #64 8192 Downlink Scrambling Codes Each code is 38,400 chips of a 2 18 - 1 (262,143 chip) Gold Sequence 3GPP TS 25.213 5.2.2 Primary SC 7 Primary SC 504 Primary SC 511
  • Slide 5
  • 5/038 13 - EN/LZU 108 5306 Rev A WCDMA Air Interface Part 5: 5 of 34 Downlink Scrambling Codes Downlink Scrambling Code Generation 10 mSec Gold Code formed by Modulo-2 Addition of 38,400 chips from two m-sequences Initial Conditions: x(0) =1; X(1)... X(17) = 0 y(0)... Y(17) = 1 3GPP TS 25.213 5.2.2 Primary Scrambling code i (where i = 0,...,511) is generated by offsetting the X sequence by (16*i) clock cycles from the Y sequence
  • Slide 6
  • 5/038 13 - EN/LZU 108 5306 Rev A WCDMA Air Interface Part 5: 6 of 34 Synchronization Codes Synchronization Codes (PSC, SSC) Broadcast by BS First 256 chips of every SCH time slot Allows UE to achieve fast synchronization in an asynchronous system Primary Synchronization Code (PSC) Fixed 256-chip sequence with base period of 16 chips Provides fast positive indication of a WCDMA system Allows fast asynchronous slot synchronization Secondary Synchronization Codes (SSC) A set of 16 codes, each 256 bits long Codes are arranged into one of 64 unique permutations Specific arrangement of SSC codes provide UE with frame timing, BS code group P-CCPCH (PSC + SSC + BCH ) 2304 Chips 256 Chips 3GPP TS 25.213 5.2.3 Broadcast Data (18 bits) SSC i PSC
  • Slide 7
  • 5/038 13 - EN/LZU 108 5306 Rev A WCDMA Air Interface Part 5: 7 of 34 Primary Synchronization Code Primary Synchronization Code (PSC) let a = PSC (1...256) = 123456789101112131415 1 Frame = 15 slots = 10 mSec Note: PSC is transmitted Clear (Without scrambling) 3GPP TS 25.213 5.2.3 Broadcast Data (18 bits) SSC i 2304 Chips 256 Chips SCHBCH PSC
  • Slide 8
  • 5/038 13 - EN/LZU 108 5306 Rev A WCDMA Air Interface Part 5: 8 of 34 Secondary Synchronization Code Group 16 Fixed 256-bit Codes; Codes arranged into one of 64 patterns Note: The SSC patterns positively identify one and only one of the 64 Scrambling Code Groups. This is possible because no cyclic shift of any SSC is equivalent to any cyclic shift of any other SSC. 3GPP TS 25.213 5.2.3 123456789101112131415 1 Frame = 15 slots = 10 mSec SSC i SSC 1 SSC 15
  • Slide 9
  • 5/038 13 - EN/LZU 108 5306 Rev A WCDMA Air Interface Part 5: 9 of 34 Slot Synchronization Slot Synchronization using Primary Synchronization Code BCH Data PSC [1] BCH Data PSC [2] BCH Data PSC [3] BCH Data PSC [4] BCH Data PSC [15] Matched Filter (Matched to PSC) 10 mSec Frame (15 slots x 666.666 uSec) Matched Filter Output time P-CCPCH (PSC) 3GPP TS 25.214 Annex C
  • Slide 10
  • 5/038 13 - EN/LZU 108 5306 Rev A WCDMA Air Interface Part 5: 10 of 34 Frame Synchronization, SCG ID Frame Synchronization using Secondary Synchronization Code BCH Data SSC [1] BCH Data SSC [2] BCH Data SSC [3] BCH Data SSC [4] BCH Data SSC [15] Matched Filter Matched to SSC code group pattern 10 mSec Frame (15 slots x 666.666 uSec) Matched Filter Output time SSC [2] SSC [3] SSC [4] SSC [1] SSC [6] SSC [7] SSC [8] SSC [5] SSC [10] SSC [11] SSC [12] SSC [9] SSC [14] SSC [15] SSC [13] SSC Code Group Pattern provides Frame Synchronization Positive ID of Scrambling Code Group Remember, no cyclic shift of any SSC is equal to any other SSC 3GPP TS 25.214 Annex C
  • Slide 11
  • 5/038 13 - EN/LZU 108 5306 Rev A WCDMA Air Interface Part 5: 11 of 34 Random Access Random Access Attempt and AICH Indication Pre- amble AICH RACH No Ind. Acq. Ind. RACH message part (UE Identification) UE BS 3GPP TS 25.211 7.3 4096 chips (1.066 msec)
  • Slide 12
  • 5/038 13 - EN/LZU 108 5306 Rev A WCDMA Air Interface Part 5: 12 of 34 Random Access Procedure Prior to initiating a Random Access attempt, the UE receives: - The preamble spreading code for this cell - The available random access signatures - The available spreading factors for the message part - The message length (10 ms or 20 ms) - Initial preamble transmit power - Power ramping factor - The AICH transmission timing parameter - The power offset DP p-m between preamble and the message part. - Transport Format parameters 3GPP TS 25.214 6.1
  • Slide 13
  • 5/038 13 - EN/LZU 108 5306 Rev A WCDMA Air Interface Part 5: 13 of 34 Random Access Preamble Signatures Preamble codes are 16-long Orthogonal Walsh Codes. Preamble = [ P 0, P 1, P 15 ] repeated 256 times (4096 chips total). Preamble codes help the BS distinguish between UE making simultaneous Random Access Attempts. 3GPP TS 25.213 4.3.3.3
  • Slide 14
  • 5/038 13 - EN/LZU 108 5306 Rev A WCDMA Air Interface Part 5: 14 of 34 Random Access Scrambling Codes Random Access Preamble Scrambling Codes Preamble Scrambling Code is a 4096-chip segment of a 2 25 -long Gold Code The UE targets one BS by using the BSs indicated preamble scrambling code All UE accessing this cell shall use Random Access Preamble Spreading Code n2 All UE accessing this cell shall use Random Access Preamble Spreading Code n1 3GPP TS 25.213 4.3.3
  • Slide 15
  • 5/038 13 - EN/LZU 108 5306 Rev A WCDMA Air Interface Part 5: 15 of 34 Acquisition Indication Channel Acquisition Indication Channel (AICH) Transmits Acquisition Indicators in response to UE Access Attempts AIs are derived from the UEs Access Preamble Signature Identifies the UE which is the target of the AICH response 1024 chips AS #0AS #1AS #iAS #14 a1a1 a2a2 a0a0 a 31 a 30 AI part 20 ms AS #14AS #0 (Transmission Off) 3GPP TS 25.211 5.3.3.6
  • Slide 16
  • 5/038 13 - EN/LZU 108 5306 Rev A WCDMA Air Interface Part 5: 16 of 34 Random Access Message Sent only after positive AICH indication 3GPP TS 25.211 5.2.2 Random Access Message (10, 20, 40, or 80 bits per slot) RACH Data Slot (0.666 mSec) Pilot (8 bits) RACH Message Slot (0.666 mSec) 123456789101112131415 1 Frame = 15 slots = 10 mSec I Q TFCI (2 bits)
  • Slide 17
  • 5/038 13 - EN/LZU 108 5306 Rev A WCDMA Air Interface Part 5: 17 of 34 Random Access Offset Timing Random Access Procedure Available RACH time slots determined by upper layers, sent over BCH UE selects slot based on pseudo-random algorithm #0#1#2#3#4#5#6#7#8#9#10#11#12#13#14 5120 chips radio frame: 10 ms Access slot #0 Random Access Transmission Access slot #1 Access slot #7 Access slot #14 Random Access Transmission Access slot #8 P P P Message = Random Access Transmission 3GPP TS 25.211 5.2.2.1.1
  • Slide 18
  • 5/038 13 - EN/LZU 108 5306 Rev A WCDMA Air Interface Part 5: 18 of 34 Acquisition and Synchronization Physical Layer Procedures 1) UE Acquisition and Synchronization Initiate Cell Synchronization P-CCPCH ( PSC + SSC + BCH) UE Monitors Primary SCH code, detects peak in matched filter output Slot Synchronization Determined ------> UE Monitors Secondary SCH code, detects SCG and frame start time offset Frame Synchronization and Code Group Determined ------> UE Determines Scrambling Code by correlating all possible codes in group Scrambling Code Determined ------> UE Monitors and decodes BCH data BCH data, Super-frame synchronization determined ------> Cell Synchronization Complete UE adjusts transmit timing to match timing of BS + 1.5 Chips
  • Slide 19
  • 5/038 13 - EN/LZU 108 5306 Rev A WCDMA Air Interface Part 5: 19 of 34 Random Access Physical Layer Procedures 2) UE Requests System Access and Registration Cell Synchronization Complete P-CCPCH (PSC + SSC + BCH ) UE Reads Random Access parameters from BS; Calculates Random Access probe power Initiate Random Access Attempt; Respond to Authentication challenge When system Registratio