![59
Power Control Bit Puncturing
z 19.2 ksps: 384 symbols / 20ms frame
z Each 20ms frame is divided into 16 power control
group (1.25 ms each)
z 24 modulation symbols in each power control group
Long Code Decimated
Data Decimator
19.2 ksps
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16
0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23
4 symbols = 16 combinations
20ms
1.25ms
If [20,21,22,23]=[1,1,0,1],then puncture bit 11,12](https://image.slidesharecdn.com/r1ikyxwtwmrchdopwgcg-cdma2000-fundamentals-220829171205-f3f42bcd/85/cdma2000_Fundamentals-pdf-59-320.jpg)
![103
Access Probe
Access Channel Message
40 - 880 bits
Padding
as reqd
Frame Body
88 bits
T
8
Frame Body
88 bits
T
8
……
Access Channel Message Capsule
Access
Chan Frame
96 b/20ms
Access
Chan Frame
96 b/20ms
Access
Chan Frame
96 b/20ms
Access
Chan Frame
96 b/20ms
Access
Chan Frame
96 b/20ms
Access
Chan Frame
96 b/20ms
Access Probe (or Access Channel Slot)
( 4 + PAM_SZ + MAX_CAP_SZ) x 20ms [ Max value = 26 frames ]
Preamble
(1 + PAM_SZ) x 20ms
[ max = 16 frames ]
Access Channel Message Capsule
(3 + MAX_CAP_SZ) x 20 ms
[ Max = 10 frames ]
Preamble
96 bits “0”s
Preamble
96 bits “0”s
PAM_SZ = No. of preamble frames
MAX_CAP_SZ = No. of message capsule frames](https://image.slidesharecdn.com/r1ikyxwtwmrchdopwgcg-cdma2000-fundamentals-220829171205-f3f42bcd/85/cdma2000_Fundamentals-pdf-103-320.jpg)
cdma2000_Fundamentals.pdf
- 2. 2 Agenda • CDMA introduction • CDMA makes use of Diversity • Power control • CDMA Forward Link • CDMA Reverse Link • CDMA call processing • CDMA Measurement
- 3. 3 Cellular Access Methods Power Time Frequency FDMA Power Time Frequency Power Time Frequency TDMA CDMA
- 4. 4 User #3 Frequency Domain User #2 User #1 Synch Paging Pilot 1.2288 MHz freq Code Domain 0 1 2 3 4 5 6 7 8 9 32 40 63 User 1 User 3 User 2 Walsh Code Pilot Paging Synch Code Domain Power (cdma2000/IS-95) The CDMA Concept
- 5. 5 CDMA is Also Full Duplex US Cellular Channel 384 Amplitude Frequency AMPS CDMA Frequency Amplitude Reverse Link Reverse Link Forward Link Forward Link 45 MHz 45 MHz 836.52 MHz 836.52 MHz 881.52 MHz 881.52 MHz
- 6. 6 Code Division Multiple Access What is CDMA ? • Spread spectrum technique • Multiple users share the same frequency in one cell • Same frequency in all the cells • Operates under presence of interference • Takes advantage of multipath • Capacity is soft
- 7. 7 Cellular Frequency Reuse Patterns 3 6 CDMA Reuse FDMA Reuse 1 1 1 1 1 1 1 1 1 6 2 2 1 4 5 7
- 8. 8 The CDMA Concept Baseband Data Encoding & Interleaving Walsh Code Spreading Walsh Code Correlator Baseband Data Decode & De- Interleaving 0 0 fc fc fc fc fc fc 10 Khz BW 1.23 Mhz BW 10 Khz BW 1.23 Mhz BW 1.23 Mhz BW 1.23 Mhz BW Spurious Signals -113 dBm/1.23 Mhz CDMA Transmitter CDMA Receiver 9.6 kbps 19.2 kbps 1228.8 kbps 9.6 kbps 19.2 kbps 1228.8 kbps Background Noise External Interference Other Cell Interference Other User Noise Interference Sources
- 9. 9 z Multiple user data can be spread by using combinations of this PN code Direct Sequence Spread Spectrum • Baseband data multiplied by a Pseudo Random Noise (PN) Code, which is a sequence of chips valued -1 & +1 or 0 & 1 • PN code is a noise-like code with certain properties (ex: orthogonal)
- 10. 10 Direct Sequence Spread Spectrum • Direct sequence spread spectrum signal is generated by multiplying narrowband user data with a well-defined wideband pseudo-random sequence. • Recovering the narrowband user data is achieved by multiplying the received signal by an identical, accurately timed pseudo- random sequence. Direct Sequence Spread Spectrum Power Spectral Density Freq Direct sequence spread signal Narrowband user data
- 11. 11 Direct Sequence Spread Spectrum Source Information Bits I-Q Modulator Carrier Code Generator Bit Stream Transmit DSSS Signal Block diagram of a Direct Sequence Spread Spectrum Transmitter Bits to I-Q
- 12. 12 Direct Sequence Spread Spectrum Received DSSS signal Code Synchronization Code Generator Demodulator Carrier Data Block diagram of a Direct Sequence Spread Spectrum Receiver
- 13. 13 What is Correlation ? • Is a Measure of How Well a Given Signal Matches a Desired Code • The Desired Code is Compared to the Given Signal at Various Test times Received Signal Time Correlation = 1 Correlation = 0 Correlation = 0 Correlation = 0
- 14. 14 Auto-Correlation • Is a Comparison of a Signal Against Itself • Good Pseudo-Random Patterns Have: ¾ Strong Correlation at Zero Time Offset ¾ Weak Correlation at Other Time Offsets Pseudo-Random Sequence Auto-Correlation Versus Time Offset 1 0 1 30 0 5 10 15 20 25 0 10 20 5 15 25 30 0 Chip Offset
- 15. 15 Analog Analog CDMA Paradigm Shift ¾ Multiple Users on One Frequency 9 9 Analog/TDMA Try to Prevent Multiple Users Analog/TDMA Try to Prevent Multiple Users Interface Interface ¾ Channel is Defined by Code 9 9 Analog Systems Defined Channels by Analog Systems Defined Channels by Frequency Frequency ¾ Traditional FDMA/TDMA are capacity- limited 9 9 Given N timeslots per frame and K Given N timeslots per frame and K frequency channels, maximum number of frequency channels, maximum number of users is KN; users is KN; 9 9 To increase the number of users in the To increase the number of users in the system, frequency reuse is used system, frequency reuse is used ¾ Capacity Limit is Soft 9 9 Allows Degrading Voice Quality to Allows Degrading Voice Quality to Temporarily Increase Capacity Temporarily Increase Capacity 9 9 Reduce Surrounding Cell Capacity to Reduce Surrounding Cell Capacity to Increase a Cell Increase a Cell’ ’s Capacity s Capacity CDMA
- 16. 16 CDMA Capacity Gains Processing Processing Gain Gain AMPS = 1.5 MHz / 30 kHz = 50 Channels Capacity = 50 Channels / 7 ( 1/7 Frequency Reuse ) AMPS = 7 Calls ( Using 1.5 MHz BW ) CDMA = 42 Calls ( Using 1.5 MHz BW ) (1,230,000) (1) (1) CDMA = ____________ X _____ X _____ X (0.67) (9,600) (5.01) (.40) Capacity = _____________ X _____ X ____ X (Fr) (Data Rate) (S/N) (Vaf) (Chan BW) (1) (1)
- 17. 17 CDMA makes use of Diversity • Spatial Diversity ¾ Making Use of Differences in Position • Frequency Diversity ¾ Making Use of Differences in Frequency • Time Diversity ¾ Making Use of Differences in Time
- 18. 18 CDMA Spatial Diversity • Diversity Reception: ¾ Multiple Antennas at Base Station 9 9Each Antenna is Affected by Each Antenna is Affected by Multipath Multipath Differently Due to Their Differently Due to Their Different Location Different Location 9 9Allows Selection of the Signal Least Affected by Allows Selection of the Signal Least Affected by Multipath Multipath Fading Fading • If Diversity Antennas are Good, Why Not Use Base Stations as a Diversity Network? ¾ Soft Handoff
- 19. 19 Spatial Diversity During Soft Handoff MTSO Base Station 1 Land Link Vocoder / Selector Base Station 2
- 20. 20 CDMA Frequency Diversity • Combats Fading, Caused by Multipath • Fading Acts like Notch Filter to a Wide Spectrum Signal • May Notch only Part of Signal 1.23 MHz BW Amplitude Frequency
- 21. 21 CDMA Time Diversity • Rake Receiver to Find and Demodulate Multipath Signals • Data is Interleaved ¾Spreads Adjacent Data in time to Improve Error Correction Efficiency • Convolutional Encoding ¾Adds Error Correction and Detection • Viterbi Decoding ¾Most Likely Path Decoder for Convolutionaly Encoded Data
- 22. 22 Why Interleaving Works 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 1 5 9 13 3 7 11 15 4 8 12 16 1 2 3 4 9 10 11 12 13 14 15 16 5 6 7 8 Original Data Frame Interleaved Data Frame Errors/Time TX 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 Errors/Time 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 RX Errors/Time TX 1 5 9 13 2 6 10 14 3 7 11 15 4 8 12 16 Errors/Time RX 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 2 6 10 14
- 24. 24 Rake Receiver Design T0 T1 T4 T3 T2 W0 W1 W2 W3 W4 Antenna Output Delay Taps Tap Weights +
- 25. 25 Synchronization • All Direct Sequence, Spread Spectrum Systems Should be Accurately Synchronized for Efficient searching • Finding the Desired Code Becomes Difficult without Synchronization
- 26. 26 Power Control Near-end Far-end Problem - 60dBm - 30dBm A B At the BS receiver, SNR for A reception = 30 dB, certified SNR for B reception = -30 dB, not certified
- 27. 27 z Acceptable SNR is at least 7 dB z For B, the signal needs 37 dB gain to meet the condition z What if we increase the processing gain from 21 dB to 37 dB? Pgain = 10 log ( W / R ) R is fixed at 9600 bps, W can be increased Is there another way to improve S/N? In this case, W = 48 MHz not practical Power Control
- 28. 28 z In this case, B is the Signal and A is the Noise z Both A and B are transmitting at constant power z Since A is near, it can be asked to transmit at low power z Since B is far, it can increase the power This is Power Control ! This is Power Control ! z Base Station will change power levels based on the Path loss. z Base Station will also command Mobile to increase or decrease power levels. Power Control
- 29. 29 • Maximum System Capacity is Achieved if: 9 All Mobiles are Power Controlled to the Minimum Power for Acceptable Signal Quality 9 As a Result, all Mobiles are Received at About Equal Power at the Base Station Independent of Their Location • Two Types of Control • Open Loop Power Control • Closed Loop Power Control • Open & Closed Loop Power Control are Always Both Active Always Both Active Reverse Link Power Control
- 30. 30 Open Loop Power Control • Assumes Loss is Similar on Forward and Reverse Paths • Receive Power + Transmit Power = -73(-76dB for PCS Band ¾ All Powers in dBm • Example: ¾ For a Received Power of -85 dBm Transmit Power = ( Transmit Power = (- -73) 73) - - ( (- - 85) 85) Transmit Power = +12 Transmit Power = +12 dBm dBm • Provides an Estimate of Reverse TX Power for Given Propagation Conditions
- 31. 31 • Directed by Base Station • Updated Every 1.25 msec • Commands Mobile to Change TX Power in +/- 1 dB Step Size • Fine Tunes Open Loop Power Estimate • Power Control Bits are “Punctured” over the Encoded Voice Data • Puncture Period is Two 19.2 kbps Symbol Periods = 104.2 usec Closed Loop Power Control
- 32. 32 CDMA Variable Rate Speech Coder • DSP Analyzes 20 Millisecond Blocks of Speech for Activity • Selects Encoding Rate Based on Activity: aHigh Activity Full Data Rate Encoding (9600 bps) aSome Activity Half Data Rate Encoding (4800 bps) aLow Activity Quarter Data Rate Encoding (2400 bps) aNo Activity 1/8 Data Rate Encoding (1200 bps) • How Does This Improve Capacity? ¾ Mobile Transmits in Bursts of 1.25 ms • System Capacity Increases by 1/Voice Activity Factor
- 33. 33 Mobile Power Bursting • Each Frame is Divided into 16 Power Control Groups • Each Power Control Group Contains 1536 Chips (represents 12 encoded voice bits) • Average Power is Lowered 3 dB for Each Lower Data Rate CDMA Frame = 20 ms Full Rate Half Rate Quarter Rate Eighth Rate
- 34. 34 The CDMA2000 evolution path is flexible and future-proof • Voice • Data up to 14.4 kbps • Voice • Data up to 115 kbps • 2x increases in voice capacity • Up to 307 kbps* packet data on a single (1.25 MHz) carrier • First 3G system for any technology worldwide • Optimized, very high-speed data (Phase 1) • Up to 2.4 Mbps* packet data on a single (1.25 MHz) carrier • Integrated voice and data (Phase 2); up to 4.8 Mbps *downlink From CDG
- 35. 35 CDMA Protocol Stacks IS -95 Rev 0 Original System-never actually deployed ARIB T53 Japan CDMA System Cellular Protocol IS -95 Rev A Backwards compatible with IS-95. First Deployed Protocol TBS- 74 Cellular Protocol that adds 14400 Channel Support J-STD-008 Not Backwards Compatible, PCS only Protocol EIA/TIA-95 Rev B Combines TSB-74 & J-STD-008 for a Universal Protocol EIA/TIA/IS-2000 Rev 0 First release of IS-2000 standard(add QPCH) EIA/TIA/IS-2000 Rev A Add BCH,CCCH,CACH…new channel EIA/TIA/IS-2000 Rev B Add new functionality and support EIA/TIA/IS-2000 Rev C(1x EV-DV) Segment channel between Voice and Data EIA/TIA/IS-856(1x EV-DO) Optimized for packet data.
- 36. 36 The architecture for CDMA2000 IS634 PSDN MSC HLR/AUC HLR/AUC Laptops with Cell Phones Cell Phones Smartphones and PDAs BSC AAA AAA Server Server PSTN Internet IWF IP Router Core Elements Core Elements From CDG
- 37. 37 cdma2000 Key Standards • EIA/TIA/IS-2000 rev. 0 Interoperability Standard for cdma2000 Spread Spectrum Systems ¾Defines channel coding, call processing procedures, protocol and other mobile / base procedures and RF requirements to ensure interoperability of equipment from multiple vendors ¾Defines how entire system works together in extreme detail ¾Revision 0 was first release of standard. ¾Revision A adds enhanced channels for paging, call set-up and call control. ¾Revision B enhanced from the cdma2000 Release A specifications
- 38. 38 TIA/EIA-95-B IS-2000 IS-2000-A F-Pilot F-Pilot F-Pilot F-Sync F-Sync F-Sync F-PCH F-PCH F-BCCH F-CCCH F-QPCH optional F-QPCH optional F-CACH F-CPCCH Forward Channels F-Traffic F-FCH F-SCH F-DCCH optional F-FCH F-SCH F-DCCH optional N/A R-Pilot R-Pilot R-ACH R-ACH R-EACH or R-CCCH Reverse Channels R-Traffic R-FCH R-SCH R-DCCH optional R-FCH R-SCH R-DCCH optional cdma2000 Standards Overview - IS-2000 Release 0 versus Revision A
- 39. 39 Benefits of cdma2000 • Improved Performance and Capacity: ¾ About 2X Voice Capacity of TIA/EIA-95-B ¾ Handles a Wide Range of Data Rates: 9 9Voice and Low Speed Data while Driving Voice and Low Speed Data while Driving 9 9Up to 384 kbps Packet or Circuit Data while Moving Up to 384 kbps Packet or Circuit Data while Moving 9 9Up to 2 Mbps Data Rates for Fixed Installations Up to 2 Mbps Data Rates for Fixed Installations • Meets All IMT-2000 Requirements • Easy Upgrade for Service Providers Who Currently Operate TIA/EIA-95 Systems
- 40. 40 cdm a 2000 Performance Enhancements • Reverse Link Pilot for Each Mobile • True QPSK Modulation • Continuous Reverse Link Waveform • Improved Convolutional Encoding for 14.4 kbps Voice Channels • Fast Forward & Reverse Link Power Control • Supports Auxiliary Pilots for Beam Forming • Forward Link Transmit Diversity - OTD, STS, Multi-Antenna
- 41. 41 Reuse of TIA/EIA-95-B • cdma2000 is Fully Backwards Compatible with TIA/EIA-95-B • Reused Aspects of TIA/EIA-95-B: 9 9 TIA/EIA TIA/EIA- -95 95- -B Air Interface (RC1, RC2) B Air Interface (RC1, RC2) 9 9 IS IS- -127 EVRC 8 kbps 127 EVRC 8 kbps Vocoder Vocoder and IS and IS- -733 13 kbps 733 13 kbps Vocoder Vocoder 9 9 All Existing Service Options All Existing Service Options 9 9 IS IS- -637 SMS & IS 637 SMS & IS- -683 Over the Air Activation 683 Over the Air Activation 9 9 IS IS- -98 and IS 98 and IS- -97 Minimum Performance Standards 97 Minimum Performance Standards 9 9 Common Broadcast Channels (Pilot, Sync ,Paging) Common Broadcast Channels (Pilot, Sync ,Paging) • Allows cdma2000 to be Deployed Sooner
- 42. 42 Terms and Definitions • Chip 9 9Is the period of a data bit at the final spreading rate Is the period of a data bit at the final spreading rate • SR - Spreading Rate 9 9Defines the final spreading rate in terms of 1.2288 Mcps(SR1). Defines the final spreading rate in terms of 1.2288 Mcps(SR1). So a 3.6864 So a 3.6864 Mcps Mcps system is called a SR3 system. system is called a SR3 system. • RC - Radio Configuration 9 9Defines the physical channel configuration based upon a base Defines the physical channel configuration based upon a base channel data rate. channel data rate. 9 9RCs RCs contain rates derived from their base rate. For example, contain rates derived from their base rate. For example, RC3 is based on 9.6 kbps and includes 1.5, 2.7, 4.8, 9.6, 19.2, RC3 is based on 9.6 kbps and includes 1.5, 2.7, 4.8, 9.6, 19.2, 38.4, 76.8, 153.6, and 307.200 kbps. 38.4, 76.8, 153.6, and 307.200 kbps. 9 9RCs RCs are coupled to specific Spreading Rates are coupled to specific Spreading Rates
- 43. 43 IS-2000 SR1 (aka 1xRTT) • Is an Improved TIA/EIA-95-B Narrowband System • Occupies the Same 1.23 MHz Bandwidth as TIA/EIA-95-B ¾ Forward Link: 9 9Adds Fast Power Control Adds Fast Power Control 9 9Quick Paging Channel to Improve Standby Time Quick Paging Channel to Improve Standby Time 9 9Uses QPSK Modulation Rather than Dual BPSK to: Uses QPSK Modulation Rather than Dual BPSK to: – Use 3/8 Rate Convolutional Encoder instead of 3/4 for 14.4 Service (improves error correction) – 128 Walsh Codes to Handle More Soft Handoffs for 9.6 service ¾ Reverse Link: 9 9Uses Pilot Aided BPSK to Allow Coherent Demodulation Uses Pilot Aided BPSK to Allow Coherent Demodulation 9 9Uses 1/4 Rate Uses 1/4 Rate Convolutional Convolutional Encoder Instead of 1/2 or 1/3 Encoder Instead of 1/2 or 1/3 9 9Uses HPSK Spreading Uses HPSK Spreading • Doubles System Voice Capacity
- 44. 44 SR1 Forward Radio Configurations • Radio Configuration 1 - Required 9 9Backwards compatible mode with TIA/EIA Backwards compatible mode with TIA/EIA- -95 95- -B B 9 9Based on 9,600 bps Traffic(RS1) Based on 9,600 bps Traffic(RS1) • Radio Configuration 2 9 9Backwards compatible mode with TIA/EIA Backwards compatible mode with TIA/EIA- -95 95- -B B 9 9Based on 14,400 bps Traffic(RS2) Based on 14,400 bps Traffic(RS2) • Radio Configurations 3, 4, and 5 9 9All use new cdma2000 coding for improved capacity All use new cdma2000 coding for improved capacity 9 9RC3 is based on 9,600 bps and goes up to 153,600 bps RC3 is based on 9,600 bps and goes up to 153,600 bps 9 9RC4 is based on 9,600 bps and goes up to 307,200 bps RC4 is based on 9,600 bps and goes up to 307,200 bps 9 9RC5 is based on 14,400 bps and goes up to 230,400 bps RC5 is based on 14,400 bps and goes up to 230,400 bps
- 45. 45 SR1 Forward Channels • F-Pilot (Using TIA/EIA-95-B Coding) • F-Sync (Using TIA/EIA-95-B Coding) • Up to 7 F-Paging (Using TIA/EIA-95-B Coding) • IS-2000 Rev.0 ¾ 0 to 3 F-QPCH (Quick Paging Channel) • IS-2000 Rev.A/B ¾ 0 or 8 F-BCH (Broadcast Channel) ¾ 0 to 4 F-CPCCH (Common Power Control Channel) ¾ 0 to 7 F-CACH (Common Assignment Channel) ¾ 0 to 7 F-CCCH (Common Control Channels) • Many F-Traffic Channels, Each Consisting of: 9 9 0 or 1 F 0 or 1 F- -DCCH (Dedicated Control Channels) DCCH (Dedicated Control Channels) 9 9 1 F 1 F- -FCH (Fundamental Channel) FCH (Fundamental Channel) 9 9 0 to 7 F 0 to 7 F- -SCCH (Supplemental Code Channels for RC1 & RC2) SCCH (Supplemental Code Channels for RC1 & RC2) 9 9 0 to 2 F 0 to 2 F- -SCH (Supplemental Channel for RC3, 4, 5) SCH (Supplemental Channel for RC3, 4, 5)
- 46. 46 Base Station Variable Rate Vocoder • Base Stations Do Not Pulse TX Channels • How Does the Base Station Handle Variable Rate Vocoding? ¾Repeats Data Bits When Transmitting at Reduced Rates ¾Repeating Data Adds 3 dB Coding Gain ¾Lowers the TX Power 3dB for Each Lower Rate
- 47. 47 Walsh Code Generator Forward Link Traffic Channel Physical Layer (RC1,RC2) 1/2 Rate 3/4 Rate P.C. Mux Vocoded Speech Data 20 msec blocks Convolutional Encoder Interleaver Long Code Scrambling Power Control Puncturing 800 bps Walsh Coder 9.6 kbps 14.4 kbps 19.2 kbps 19.2 kbps Long Code 19.2 kbps 19.2 kbps 19.2 kbps 19.2 kbps 1.2288 Mbps 1.2288 Mbps 1.2288 Mbps 1.2288 Mbps Short Code Scrambler 800 bps FIR FIR I Q I Short Code Q Short Code
- 48. 48 Forward FCH Physical Layer RC3 (9.6 kbps) Optional Can be Carried by F-DCCH 8.6 kbps 1228.8 kbps Long Code Decimator Interleaver 38.4 ksps 1/4 Rate Conv. Encoder 38.4 ksps 9.6 kbps Long Code Generator 38.4 kbps Power Control Puncture Walsh 64 Generator 1228.8 kcps 1228.8 kcps 1228.8 kbps 1228.8kbps Q I S -P 800 bps PC User Long Code Mask Q I PC Dec 1228.8 kcps Q Short Code I Q 1228.8 kcps Complex Scrambling Q I FIR FIR I Short Code Orthogonal Spreading 1228.8 kcps 1228.8 kcps + + + - 38.4 ksps 19.2 ksps 19.2 ksps P.C. Bits Decimate by Walsh Length/2 Gain Gain Puncture Timing Full Rate Data Bits Add CRC and Tail Bits 800 bps
- 49. 49 CDMA Vocoders • Vocoders Convert Voice to/from Analog Using Data Compression • There are Three CDMA Vocoders: ¾ IS-96A Variable Rate (8 kbps maximum) ¾ CDG Variable Rate (13 kbps maximum) ¾ EVRC Variable Rate (improved 8 kbps) • Each has Different Voice Quality: • IS-96A - moderate quality • EVRC - near toll quality • CDG - toll quality
- 50. 50 15 24 bits in a ms frame 39 79 171 266 124 54 20 1200 bps Frame 8 Mixed Mode Bit Information Bits 1-bit Reserved 8 8 8 8 12 12 8 10 8 6 8 8 8 Mixed Mode Bit Mixed Mode Bit Mixed Mode Bit Information Bits Information Bits Information Bits 2400 bps Frame 9600 bps Frame 4800 bps Frame 192 bits in a ms frame 96 bits in a ms frame 48 bits in a ms frame 1800 bps Frame 3600 bps Frame 7200 bps Frame 14400 bps Frame 288 bits in a ms frame 144 bits in a ms frame 72 bits in a ms frame 36 bits in a ms frame 1-bit Reserved 1-bit Reserved 1-bit Reserved Mixed Mode Bit Mixed Mode Bit Mixed Mode Bit Mixed Mode Bit Encoder Tail Bits CRC CRC Encoder Tail Bits Encoder Tail Bits Encoder Tail Bits Information Bits Information Bits Information Bits Information Bits Encoder Tail Bits Encoder Tail Bits Encoder Tail Bits Encoder Tail Bits CRC CRC CRC CRC CDMA Frame Formats
- 51. 51 Forward Error Protection • Uses Half-Rate Convolutional Encoder • Outputs Two Bits of Encoded Data for Every Input Bit Data Out 9600 bps Data Out 9600 bps D D D D D D D D + + Data In 9600 bps z z z z z z z
- 52. 52 14.4 Traffic Channel Forward Link Modifications • Replaces 8 kbps Vocoder with a 13 kbps Vocoder(both Variable Rate) • Effects: ¾ Provides Toll Quality Speech ¾ Uses a 3/4 Rate Encoder ¾ Reduces Processing Gain 1.76 dB ¾ Results in Reduced Capacity or Smaller Cell Sizes 3/4 rate Vocoded Speech Data Convolutional Encoder 20 msec blocks 14.4 kbps 19.2 kbps
- 53. 53 • 384 symbols are sequentially written in an input array • Interleaved symbols are then read from the output array 19.2 ksps 9.6 ksps 4.8 ksps 2.4 ksps Symbol Repetition 19.2 ksps 384 Symbols 20 ms Block Interleaver Input Array / output Array 16 x 24 Array Interleaved Output 16 24 Interleaver • Process of permuting a sequence of symbols to achieve time diversity • CDMA uses block interleaving with 20 ms blocks
- 54. 54 CDMA System Time • How Does CDMA Achieve Synchronization for Efficient searching? ¾ Use GPS Satellite System • Base Stations Use GPS Time via Satellite Receivers as a Common Time Reference • GPS Clock Drives the Long Code Generator 1 12 2 3 4 5 6 7 8 9 10 11
- 55. 55 Modulo-2 Addition Long Code Output Long Code Generator 1 User Assigned Long Code Mask 42 bits 2 4 3 42 41 5 Long Code Generation
- 56. 56 Long Code Generation Modulo-2 Addition Long Code Output 3 4 1 2 User Assigned Long Code Mask 42 bits 41 42 5 Long Code Generator (Driven by System Time) 1100011000 Permuted ESN 41 32 31 0 Long Code Mask
- 57. 57 Long Code Scrambling • User’s Long Code Mask is Applied to the Long Code • Masked Long Code is Decimated Down to 19.2 kbps • Decimated Long Code is XOR’ed with Voice Data Bits • Scrambles the Data to Provide Voice Security Encoded Voice Data Long Code Generator Long Code Decimator XOR 1.2288 Mbps 19.2 kbps 19.2 kbps 19.2 kbps
- 58. 58 19.2 kbps Closed Loop Power Control Puncturing • Long Code is Decimated Down to 800 bps • Decimated Long Code Controls the Puncture Location • Power Control Bits Replace Voice Data • Voice Data is Recovered by the Mobile’s Viterbi Decoder Long Code Scrambled Voice Data Long Code Decimated Data Closed Loop Power Control Bits P. C. Mux Long Code Decimator 800 bps 800 bps 19.2 kbps 19.2 kbps
- 59. 59 Power Control Bit Puncturing z 19.2 ksps: 384 symbols / 20ms frame z Each 20ms frame is divided into 16 power control group (1.25 ms each) z 24 modulation symbols in each power control group Long Code Decimated Data Decimator 19.2 ksps 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 4 symbols = 16 combinations 20ms 1.25ms If [20,21,22,23]=[1,1,0,1],then puncture bit 11,12
- 60. 60 Payload Data Bits 1228.8 kbps Long Code Decimator Interleaver 1/2 Rate Convolutional Encoder 307.2 ksps Channel Coder Add CRC and Tail Bits 153.6 kbps Long Code Generator User Long Code Mask Decimate by Walsh Length/2 307.2 ksps 307.2 ksps 307.2 ksps Gain Walsh 8 Generator 1228.8 kcps 1228.8 kcps 1228.8 kbps 1228.8kbps Q I S -P Q I 1228.8 kcps Q Short Code I Q 1228.8 kcps Complex Scrambling FIR FIR I Short Code Orthogonal Spreading 1228.8 kcps 1228.8 kcps + + + - 153.6 ksps 153.6 ksps 152.4 kbps SR1, RC4 (152.4 kbps) F-SCH
- 61. 61 Walsh Codes W= 0 0 0 1 W= 0 0 0 0 0 0 1 0 1 0 0 1 1 0 1 1 0 W= 1 2 4 = n n n n n W W W W W 2
- 62. 62 2 Match - 2 don’t = 0 Checking for Orthogonality W = 4 0 0 0 0 0 1 0 1 0 0 1 1 0 1 1 0 0 0 0 0 0 0 1 1 Y Y N N Cross Correlation = N agreements - N disagreements Ntotal_number_of_digits
- 63. 63 SF=16 SF=2 SF=4 SF=8 1 1 1 1 1 1 1 1 1 1 1 1 -1 -1 -1 -1 1 1 -1 -1 1 1 1 1 1 1 1 -1 1 -1 1 -1 1 -1 -1 1 1 1 -1 1 -1 1 -1 1 -1 1 -1 1 -1 -1 1 -1 1 1 -1 -1 1 1 -1 -1 1 1 -1 -1 1 -1 1 1 -1 1 1 -1 -1 -1 -1 1 1 1 1 -1 -1 1 1 -1 -1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 -1 -1 -1 -1 -1 -1 -1 -1 1 1 1 1 -1 -1 -1 -1 1 1 1 1 -1 -1 -1 -1 1 1 1 1 -1 -1 -1 -1 -1 -1 -1 -1 1 1 1 1 1 1 -1 -1 1 1 -1 -1 1 1 -1 -1 1 1 -1 -1 1 1 -1 -1 1 1 -1 -1 -1 -1 1 1 -1 -1 1 1 1 1 -1 -1 -1 -1 1 1 1 1 -1 -1 -1 -1 1 1 1 1 -1 -1 -1 -1 1 1 -1 -1 1 1 1 1 -1 -1 1 -1 1 -1 1 -1 1 -1 1 -1 1 -1 1 -1 1 -1 1 -1 1 -1 1 -1 1 -1 -1 1 -1 1 -1 1 -1 1 1 -1 1 -1 -1 1 -1 1 1 -1 1 -1 -1 1 -1 1 1 -1 1 -1 -1 1 -1 1 -1 1 -1 1 1 -1 1 -1 1 -1 -1 1 1 -1 -1 1 1 -1 -1 1 1 -1 -1 1 1 -1 -1 1 1 -1 -1 1 -1 1 1 -1 -1 1 1 -1 1 -1 -1 1 -1 1 1 -1 1 -1 -1 1 -1 1 1 -1 1 -1 -1 1 -1 1 1 -1 -1 1 1 -1 1 -1 -1 1 Effects of Using Variable Length Walsh Codes for Spreading • Using Shorter Walsh Codes Precludes Using all Longer Codes Derived from the Original • Shorter Codes on a Branch map into Longer Codes
- 64. 64 Walsh Code Spreading Encoded Voice Data Walsh Code Generator 19.2 kbps 1.2288 Mbps 1.2288 Mbps What is the Spreading Rate Increase ?
- 65. 65 Why Spread Again with the Short Sequence • Provides a Cover to Hide the 64 Walsh Codes • Each Base Station is Assigned a Time Offset in its Short Sequences • Time Offsets Allow Mobiles to Distinguish Between Adjacent Cells • Also Allows Reuse of All Walsh Codes in Each Cell Walsh Coded Data at 1.2288 Mbps 1.2288 Mbps 1.2288 Mbps I Channel Short Sequence Code Generator Q Channel Short Sequence Code Generator To I/Q Modulator
- 66. 66 Multi-Layer Code Assignment Walsh Code layer (spreading code) Full code set per cell W64,1 W64,2 W64,0 Cells A/Sector A W64,1 W64,2 W64,0 Cells B/Sector B PN 0 PN 1 Convolutional Encoder Long code Walsh Code Short Code CDMA as an Onion CDMA as an Onion
- 67. 67 Short Code (PN) Generation z PN sequence codes are generated using 15-bit shift registers z PN sequence pattern repeats every 26.666 ms z 75 PN sequences repetition occur every 2 seconds z On every even second clock, MS will get PN sequence initial state Jan 6, 1980 00:00:00 1, 0, 0, 0.............. 0 R1,R2,R3,R4..........R15 ( initial state of 15 registers ) PN Code Combinations: 215 = 32768 Clock Rate = 1.2288 Mcps Return of Initial State = 26.666 ms 32768 3 2 7 6 8 1 2 74 75 32768 2 sec 26.666ms
- 68. 68 PN Offsets • Each BS scrambles PN sequence with data by some time offset • Time offsets are in intervals of 64 clock chips (52.08 us) from even second clock • 512 unique offsets are created (32768/64 = 512) • Each BS is allotted an offset for PN sequence scrambling PN 0 PN 120 PN 237 PN 511 PN 489
- 69. 69 Short Code Correlation • Short Codes are Designed to Have: ¾ Strong Auto-Correlation at Zero Time Offset ¾ Weak Auto-Correlation at Other Offsets ¾ Good Auto-Correlation in Very Poor Signal-to-Noise Ratio Environments • Allows Fast Acquisition in Real World Environment Auto-Correlation Versus Time Offset With 17 dB Noise Added 0 10 20 5 15 25 30 Chip Offset
- 70. 70 Convert to I/Q & PN Spreading FIR LP Filter & D/A Conversion I Data Q Data 1228.8 kbps Walsh Code 0 Pilot Channel All 0’s Convert to I/Q & PN Spreading FIR LP Filter & D/A Conversion I Data Q Data 1228.8 kbps Walsh Code 32 Sync Channel 4.8 kbps Convert to I/Q & PN Spreading FIR LP Filter & D/A Conversion I Data Q Data 1228.8 kbps Walsh Codes 1 to 7 Paging Channels 1 up to 7 Channels 19.2 kbps Convert to I/Q & PN Spreading FIR LP Filter & D/A Conversion I Data Q Data 1228.8 kbps Walsh Codes 8-31,33-63 Traffic Channels 1 up to 55 Channels 19.2 kbps I Q Forward Link Channel Format Σ Σ
- 71. 71 Walsh Coding Example W2 = 0 0 - User A 0 1 - User B -1 -2 +1 +2 -1 +1 Channel A Walsh Encoded Voice Data +1 -1 Channel A Voice Data For a 1 Input Use Code 11 +1 -1 For a 0 Input Use Code 00 User A User B For a 0 Input Use Code 01 For a 1 Input Use Code 10 Channel B Voice Data Channel B Walsh Encoded Voice Data Sum of A & B Walsh Encoded Data Streams 0 0 1 1 0 0 1 1 0 0 0 0 +1 -1 +1 -1 0 1 1 0 -1 +1 1 0 0 1 0 1 1 0 + 0 +1 1 0 0 1 +1 0 1 0 0 1
- 72. 72 Walsh Decoding Example Correlation Coefficient f i (t) r f j (t) dt z i j = 1 T +1 0 1 0 0 1 +1 -1 +2 -2 Original User B Voice Data User A & B Walsh Data Multiply Summed Data with Desired Walsh Code +1 0 1 0 0 1 +1 -1 +2 -2 Original User A Voice Data User A & B Walsh Data Multiply Summed Data with Desired Walsh Code +1 -1 +2 -2 X +1 -1 1 1 +1 -1 +2 -2 ∫ -1 +1 -1 +2 -2 +1 -1 1 0 1 +1 -1 +2 -2 = = = = + ∫ 0 T ∫
- 73. 73 What if Walsh Codes are Not Time Aligned ? Channel B Walsh Encoded Voice Data -1 +1 1 0 0 1 0 1 1 0 -1 +1 Channel A Walsh Encoded Voice Data 0 0 1 1 0 0 0 0 -1 -2 +1 Sum of A & B Walsh Encoded Data Streams Original Data Was 0 (-1), We Have Interference Now! Multiply Summed Data with Desired Walsh Code +1 -1 +2 -2 +1 -1 1 1 +1 -1 +2 -2 -0.75 Original Time Delayed + X = = ∫
- 74. 74 Pilot Channel Physical Layer Walsh Modulator 1.2288 Mbps 1.2288 Mbps 1.228 8 Mbps 1.228 8 Mbps Short Code Scrambler FIR FIR I Q Walsh Code Generator Q Short Code I Short Code All 0 Inputs 19.2 kbps Walsh Code 0 • Uses Walsh Code 0: ¾ All 64 bits are 0 • All Data into Walsh Modulator is 0 • Output of Walsh Modulator is therefore all 0’s • Pilot Channel is just the Short Codes
- 75. 75 1/2 Rate 2x Convolutional Encoder Interleaver Walsh 32 Coder 1.2 kbps 2.4 kbps 4.8 kbps 1.2288 Mbps 1.2288 Mbps 1.2288 Mbps 1.2288 Mbps Short Code Scrambler FIR FIR I Q Sync Channel Physical Layer Sync Channel Message Data Symbol Repetition 4.8 kbps Walsh Code Generator Q Short Code I Short Code
- 76. 76 Paging Channel Physical Layer Paging Channel Long Code 1/2 Rate Convolutional Encoder Interleaver 4.8 kbps 9.6 kbps 19.2 kbps Paging Channel Message Data 2x Symbol Repetition 19.2 kbps Walsh 1 to 7 Coder 1.2288 Mbps 1.2288 Mbps 1.2288 Mbps 1.2288 Mbps Short Code Scrambler I Q Walsh Code Generator QShort Code Long Code Scrambling 19.2 kbps 19.2 kbps FIR I Short Code FIR
- 77. 77 SR1 Reverse Radio Configurations • Radio Configuration 1 - Required 9 9 Backwards compatible mode with TIA/EIA Backwards compatible mode with TIA/EIA- -95 95- -B B 9 9 Based on 9,600 bps Traffic Based on 9,600 bps Traffic • Radio Configuration 2 9 9 Backwards compatible mode with TIA/EIA Backwards compatible mode with TIA/EIA- -95 95- -B B 9 9 Based on 14,400 bps Traffic Based on 14,400 bps Traffic • Radio Configurations 3 and 4 9 9 All use new IS All use new IS- -2000 coding for improved capacity 2000 coding for improved capacity 9 9 RC3 is based on 9,600 bps and goes up to 307,200 bps RC3 is based on 9,600 bps and goes up to 307,200 bps 9 9 RC4 is based on 14,400 bps and goes up to 230,400 bps RC4 is based on 14,400 bps and goes up to 230,400 bps
- 78. 78 SR1 Reverse Channels • Each Mobile Transmits Several Channels: ¾ ¾ 1 R 1 R- -Pilot Pilot (Reverse Pilot) 9 9 Includes Power Control Sub Includes Power Control Sub- -Channel Channel ¾ ¾ 1 R 1 R- -ACH or R ACH or R- -EACH EACH (Access or Enhanced Access Channel) 9 9 Used to Initiate Calls Used to Initiate Calls ¾ ¾ 0 or 1 R 0 or 1 R- -CCCH CCCH (Common Control Channel) 9 9 Used to Initiate Calls in the Reservation Access Mode Used to Initiate Calls in the Reservation Access Mode ¾ ¾ 0 or 1 R 0 or 1 R- -DCCH DCCH (Dedicated Control Channel) 9 9 Provides Signaling while a Traffic Channel is Active Provides Signaling while a Traffic Channel is Active ¾ ¾ 0 or 1 R 0 or 1 R- -FCH FCH (Reverse Fundamental Channel) 9 9 Primary Channel, usually Voice Primary Channel, usually Voice ¾ ¾ 0 to 2 R 0 to 2 R- -SCHs SCHs (Reverse Supplemental Channels) 9 9 Carries High Speed Data Carries High Speed Data
- 79. 79 R-FCH Coding for SR1(RC1,RC2) 1/2 Rate Vocoded Speech Data 20 msec blocks Convolutional Encoder Interleaver 9.6 kbps 14.4 kbps 28.8 kbps 28.8 kbps 28.8 kbps 1.2288 Mbps 1.2288 Mbps Short Code Scrambler I Q 1/3 Rate Long Code 64-ary Modulator 1 of 64 Walsh Codes Walsh Code 2 Walsh Code 63 Walsh Code 62 Walsh Code 61 Walsh Code 1 Walsh Code 0 Long Code Modulator 307.2 kbps 1.2288 Mbps 1.2288 Mbps Q Short Code FIR I Short Code FIR t/ 2 1/2 Chip Delay
- 80. 80 Reverse Error Protection • Uses Third-Rate Convolutional Encoder • Outputs Three Bits for Every Input Bit Data Out 9600 bps D D D D D D D D + + Data Out 9600 bps + Data In 9600 kbps Data Out 9600 bps z z z z z z z z z z z
- 81. 81 14.4 Traffic Channel Reverse Link Modifications • Replaces 8 kbps Vocoder with a 13 kbps Vocoder (both Variable Rate) • Effects: ¾ Provides Toll Quality Speech ¾ Uses a 1/2 Rate Encoder ¾ Reduces Processing Gain 1.76 dB ¾ Results in Reduced Capacity or Smaller Cell Sizes 1/2 Rate Vocoded Speech Data 20 msec blocks Convolutional Encoder 14.4 kbps 28.8 kbps
- 82. 82 64-ary Modulation • Every 6 Encoded Voice Data Bits Points to one of the 64 Walsh Codes • Spreads Data from 28.8 kbps to 307.2 kbps ¾ (28.8 kbps * 64 bits) / 6 bits = 307.2 kbps) • Is Not the Channelization for the Reverse Link 307.2 kbps 28.8 kbps > Walsh Code 2 Walsh Code 1 Walsh Code 0 Walsh Code 63 Walsh Code 62 Walsh Code 61
- 83. 83 Why Aren’t Walsh Codes Used for Reverse Channelization ? • All Walsh Codes Arrive Together in Time to All Mobiles From the Base Station • However, Transmissions from Mobiles DO NOT Arrive at the Same Time at the Base Station
- 84. 84 Reverse Channel Long Code Spreading • Long Code Spreading Provides Unique Mobile Channelization • Mobiles are Uncorrelated but not Orthogonal with Each Other Long Code Generator Walsh Modulated Voice Data XOR 307.2 kbps 1.2288 kbps 1.2288 kbps
- 85. 85 Data Burst Randomizer 0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 576 code symbols (28.8ksps) 96 modulation symbols (576 / 6) 20 ms = 1.25 ms =36 code symbols 6 modulation symbols 12 13 14 15 b0 b1 b2 b3 b4 b5 b6 b7 b8 b9 b10 b11 b12 b13 Long Code Bits used for spreading PCG14 Previous Frame Algorithm At 4800 bps rate, Transmission should occur on the PCG's numbered: b0, 2 + b1, 4 + b2, 6 + b3, 8 + b4,10 + b5, 12 + b6, 14 + b7 0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 (Example) (50% Gated-On, 50% Gated-Off)
- 86. 86 Data Burst Randomizer Algorithm At 2400 bps rate , Transmission should occur on the PCG's numbered: b0 if b8 = 0, or 2 + b1 if b8 = 1 (i.e. 1 out of PCG 0...3) 4 + b2 if b9 = 0, or 6 + b3 if b9 = 1 (i.e. 1 out of PCG 4...7) 8 + b4 if b10 = 0, or 10 + b5 if b10 = 1 (i.e. 1 out of PCG 8...11) 12+b6 if b11 = 0, or 14 + b7 if b11 = 1 (i.e. 1 out of PCG 12..15) (Example) ( 25% Gated-On, 25% Gated-Off ) 0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 At 1200 bps rate , Transmission should occur on the PCG's numbered: b0 if (b8 = 0 and b12=0), or 2 + b1 if (b8 = 1 and b12=1) or 4 + b2 if (b9 = 0 and b12=0), or 6 + b3 if (b9 = 1 and b12=1) (i.e. 1 out of PCG 0...7) 8 + b4 if (b10 = 0 and b13=0), or 10 + b5 if (b10 = 1 and b13=1) or 12 + b6 if (b11 = 0 and b13=0), or 14 + b7 if (b11 = 1 and b13=1) (i.e. 1 out of PCG 8..15) (Example) (12.5% Gated-On, 12.5% Gated-Off) 0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15
- 87. 87 Gated-On and Gated-Off Power 7 us 7 us 20 dB or to the noise floor (-60dBm) 3 dB 1.247 ms Mean output of the ensemble average Ensemble average: Average of power control groups, all with the same output power
- 88. 88 Reverse Channel Short Sequence Spreading • Same PN Short Codes Are Used by Mobiles • Short Sequence spreading Aids Base Station Signal Acquisition • Extra 1/2 Chip Delay is Inserted into Q Path to Produce OQPSK Modulation to Simplify Power Amplifier Design 1.2288 Mbps Short Code Scrambler I Q 1.2288 Mbps I Short Code FIR I Short Code FIR t/ 2 1/2 Chip Delay 1.2288 Mbps
- 89. 89 OQPSK Modulation • QPSK Makes one Symbol Change Every Period • OQPSK Makes two Symbol Changes Every Period if Q Data Changes • Example Symbol Pattern is: - 00,10,01,11 I Q n n n n 00 01 10 11 I Q n n n n 00 01 10 11
- 90. 90 CDMA Modulation Formats Filtered Offset QPSK Filtered QPSK I I Q Q Mobile Station TX Base Station Pilot Channel TX
- 91. 91 MUX Pilot Data Power Control Bits To I Channel Summer One Power Control Group Pilot Pilot Pilot PC Bits 312.5 us 312.5 us 312.5 us 312.5 us 1.25 ms Reverse Pilot/Power Control Multiplexing (RC3,4) • There are 16 Power Control Groups per 20 ms Frame • Each Power Control Group is Split into 4 Sub-Groups • 1 Power Control Bit is Sent per Power Control Group • Pilot and Power Control are Multiplexed Together
- 92. 92 R-FCH Data Bits 8.6 kbps Walsh Code Generator 1 Frame 1/4 Rate Convolutional Encoder 38.4 ksps Channel Coder Add CRC and Tail Bits 9.6 kbps Interleaver 1,1, 1, 1,-1, -1, -1, -1, 1,1, 1, 1,-1, -1, -1, -1 R-FCH Coding for a 20 ms Frame Orthogonal Spreading Spread Factor = 16 2 Reps Symbol Repeat 38.4 ksps 76.8 ksps 1228.8 kcps SR1, RC3 R-FCH Coding(RC3,RC4) • R-FCH Carries Voice Information • Uses a 20 ms Frames Length • Using ¼ rate convolutional coding
- 93. 93 1,1,1,1,1,1,1,1,-1,-1,-1,-1,-1,-1,-1,-1 I Channel Short Code Generator User Long Code Mask Complex Scrambling Q I + + + - R-DCCH R-Pilot + Power Control R-SCH 1 or R-EACH or R-CCCH R-FCH Walsh 16 Generator 1,1, 1, 1 -1,-1, -1, -1, 1, 1, 1, 1, -1, -1, -1, -1 Walsh 2/4/8 Generator 1,-1 or 1 -1 1,-1, or 1,1,-1,-1,1,1,-1,-1 Walsh 16 Generator 1228.8 kcps R-SCH 2 Walsh 4/8 Generator 1, 1, -1, -1 or 1, 1, -1, -1, -1, -1, 1, 1 Walsh 2 Generator 1,-1 Gain Scale Gain Scale Gain Scale Gain Scale Deci by 2 1228.8 kcps 1228.8 kcps 1228.8 kcps 1228.8 kcps 1228.8 kcps 1228.8 kcps 1228.8 kcps 1228.8 kcps Q Channel Short Code Generator 1228.8 kcps 1-Chip Delay Long Code Generator 1,1,1,1,-1,-1,-1,-1 for R-EACH or R-CCCH SR1 Reverse Channel Spreading(RC3,RC4)
- 94. 94 Channelization Summary Function 9.6 kbps Convolutional Encoder 14.4 kbps Convolutional Encoder Walsh Coding Long Code Spreading Short Code Spreading Forward Link (Base to Mobile) 1/2 Rate (9600 in 19200 out) 3/4 Rate (14400 in 19200 out) Channelization Voice Privacy Base Station Identification Reverse Link (Mobile to Base) 1/3 Rate (9600 in 28800 out) 1/2 Rate (14400 in 28800 out) 64-ary Modulation Channelization Aid Base Station Searching
- 95. 95 CDMA Multiplex Sublayer Layer 1 Physical Layer Channel Data - 9600 bps or 14400 bps Multiplex Sublayer Traffic Channel Layer 2 Link Layer Paging & Access Channels Layer 2 Primary Traffic Layer 2 Signaling Layer 3 Call Processing & Control
- 96. 96 Station Class Mark (SCM) Extended SCM Indicator 7 Band Class 0 0XXXXXXX Band Class 1 1XXXXXXX Dual Mode 6 CDMA Only X0 XXXXXX Dual Mode X1XXXXXX Slotted Class 5 Non-Slotted XX0XXXXX Slotted XX1XXXXX IS- 54 Power Class 4 Always 0 XXX0XXXX 25 MHz Bandwidth 3 Always 1 XXXX1XXX Transmission 2 Continous XXXXX0XX Discontinous XXXXX1XX Power Class for Band Class "0" Analog Operation ( For CDMA only "00") 1- 0 Class I XXXXXX00 Class II XXXXXX01 Class III XXXXXX10 Reserved XXXXXX11 Function Bit(s) Setting
- 97. 97 Ten Minutes in the Life of a CDMA Mobile Phone • Turn-on ¾ System Access • Travel ¾ Idle State Hand-Off • Initiate Call • System Access • Continue Travel ¾ Initiate Soft Handoff ¾ Terminate Soft Handoff • End Call
- 98. 98 CDMA Turn On Process • Find All Receivable Pilot Signals ¾ Choose Strongest One • Establish Frequency and PN Time Reference (Base Station I.D.) • Demodulate Sync Channel • Establish System Time • Determine Paging Channel Long Code Mask
- 99. 99 Sync Channel Message • Contains the Following Data: ¾ Base Station Protocol Revision ¾ Min Protocol Revision Supported ¾ SID, NID of Cellular System ¾ Pilot PN Offset of Base Station ¾ Long Code State ¾ System Time ¾ Leap Seconds From Start of System Time ¾ Local Time Offset from System Time ¾ Daylight Savings Time Flag ¾ Paging Channel Data Rate ¾ Channel Number SYNC
- 100. 100 Read the Paging Channel • Demodulate the Paging Channel: ¾ Use Long Code Mask Derived from the Pilot PN Offset Given in Sync Channel Message • Decode Messages • Register, if Required by Base Station • Monitor Paging Channel Paging
- 101. 101 CDMA Idle State Handoff • No Call In Progress • Mobile Listens to New Cell • Move Registration Location if Entering a New Zone
- 102. 102 Access Procedures • Controlled by BS by broadcasting Access Parameters Message on the paging channel • Access attempt is the process of sending one message and receiving (or failing to receive) an ACK for that message = groups of access probe sequence • Access probe sequence = groups of access probes • Access probe = each transmission in an access attempt
- 103. 103 Access Probe Access Channel Message 40 - 880 bits Padding as reqd Frame Body 88 bits T 8 Frame Body 88 bits T 8 …… Access Channel Message Capsule Access Chan Frame 96 b/20ms Access Chan Frame 96 b/20ms Access Chan Frame 96 b/20ms Access Chan Frame 96 b/20ms Access Chan Frame 96 b/20ms Access Chan Frame 96 b/20ms Access Probe (or Access Channel Slot) ( 4 + PAM_SZ + MAX_CAP_SZ) x 20ms [ Max value = 26 frames ] Preamble (1 + PAM_SZ) x 20ms [ max = 16 frames ] Access Channel Message Capsule (3 + MAX_CAP_SZ) x 20 ms [ Max = 10 frames ] Preamble 96 bits “0”s Preamble 96 bits “0”s PAM_SZ = No. of preamble frames MAX_CAP_SZ = No. of message capsule frames
- 104. 104 Access Probe Sequence Access Probe Sequence Access Probe 1 Access Probe 2 Access Probe 3 Access Probe n TA TA TA RT RT RT Preamble + Access Message Capsule Max = 26 frames RN RN RN RN IP P1 P2 P3 IP = Open Loop Power + NOM_PWR + INIT_PWR where Open Loop Power = -( Received Power ) - 73
- 105. 105 Access Attempt RS : Backoff delay, which is random value between 0 to BKOFF slots Process for Response Messages Process for Response Messages message ready for transmission Access Probe Sequence Access Probe Sequence Access Probe Sequence Access Probe Sequence Access Attempt MAX_RSP_SEQ RS RS RS
- 106. 106 Access Attempt PD: (Persistence Delay) resulted from a pseudo-random test by MS; the first access probe of the sequence begins in the slot only if the test passes within that slot The test result depends on the ESN, reason for attempt (call origination, register, etc.) and the access overload class of the MS, and a PSSIST value broadcasted by BS for that access class. If the PSSIST is all “1”s for some access class, the test for that access class will always fail Process for Request Messages Process for Request Messages message ready for transmission Access Probe Sequence Access Probe Sequence Access Probe Sequence Access Probe Sequence Access Attempt MAX_REQ_SEQ RS PD RS PD RS PD PD
- 107. 107 Access Channel Messages Registration Message - for registration as well as Global Challeng Authentication Process Order Message -for transmission of order messages (e.g., BS challenge order, SSD update confirmation, MS acknowledgement order, etc.) Data Burst Message -to get a trigger from the user to send a message to BS (information message like SMS) Origination Message-MS information Page Response message Authentication Challenge Response Message Status Response Message - response to BS status request order which may include MS terminal information, station class mark, service option supported, multiplex option support, IMSI, ESN, etc.
- 108. 108 CDMA Call Initiation • Dial Numbers, Then Press Send • Mobile Transmits on a Special Channel Called the Access Channel • The Access Probe Uses a Long Code Mask Based On: bAccess & Paging Channel Numbers bBase Station ID bPilot PN Offset
- 109. 109 CDMA Call Completion • Base Answers Access Probe using the Channel Assignment Message • Mobile Goes to A Traffic Channel Based on the Channel Assignment Message Information • Base Station Begins to Transmit and Receive Traffic Channel
- 110. 110 CDMA Soft Handoff Initiation • Mobile Finds Second Pilot of Sufficient Power (exceeds T_add Threshold) • Mobile Sends Pilot Strength Message to First Base Station • Base Station Notifies MTSO • MTSO Requests New Walsh Assignment from Second Base Station • If Available, New Walsh Channel Info is Relayed to First Base Station
- 111. 111 Hard, Soft, and Softer Handoffs • Hard Handoff ¾ “Break before make.” • Soft Handoff ¾ “Make before break.” ¾ MS communicates with more than one BS at a time. ¾ Improves reception on cell boundaries. ¾ MS will receive different power control from the two BSs. • Softer Handoff ¾ MS communicates with more than one sector of a cell. ¾ MS will receive identical power control from both sectors. f1 f2 Hard Handoff f1 f1 Soft Handoff f1 Softer Handoff
- 112. 112 Pilot Ec/I0 T_ADD BS1 BS2 Pilot Ec/I0 T_DROP BS1 BS2 cdma2000 CONCEPT: Soft Handoff • Terms: ¾ Active Set: MS is in soft handoff. ¾ Candidate Set: MS identifies as strong. • Parameters: ¾ T_ADD ¾ T_COMP ¾ T_DROP ¾ T_TDROP Pilot Ec/I0 0.5xT_COMP BS1 BS2
- 113. 113 CDMA Soft Handoff Completion • First Base Station Orders Soft Handoff with new Walsh Assignment • MTSO Sends Land Link to Second Base Station • Mobile Receives Power from Two Base Stations • MTSO Chooses Better Quality Frame Every 20 Milliseconds MTSO BaseStation1 LandLink Vocoder/ Selector BaseStation2
- 114. 114 Ending CDMA Soft Handoff • First BS Pilot Power Goes Low at Mobile Station (drops below T_drop) • Mobile Sends Pilot Strength Message • First Base Station Stops Transmitting and Frees up Channel • Traffic Channel Continues on Base Station Two
- 115. 115 CDMA End of Call • Mobile or Land Initiated • Mobile and Base Stop Transmission • Land Connection Broken
- 116. 116 cdma2000 Standards Overview - TIA/EIA-98- D/E • I.e.3GPP2 C.S0011-A/B: ¾ “Recommended Minimum Performance Standards for cdma2000 Spread Spectrum Mobile Stations.” • Important test sections: ¾ 2 Standard Radiated Emissions Measurement Procedure ¾ 3 CDMA Receiver Minimum Standards ¾ 4 CDMA Transmitter Minimum Standards • Covers both SR1 and SR3 ¾ No Minimum Standards specified for SR3. ¾ This presentation only covers SR1 testing.
- 117. 117 CDMA Service Options ¾ Service Options Are: 9 91 1- - Voice Using 9600 bps IS Voice Using 9600 bps IS- -96 96- -A A Vocoder Vocoder 9 92 2- - Rate Set 1 Rate Set 1 Loopback Loopback (9600 bps) (9600 bps) 9 93 3- - Voice Using 9600 bps (EVRC) Voice Using 9600 bps (EVRC) 9 94 4- - Asynchronous Data Service (circuit switched) Asynchronous Data Service (circuit switched) 9 95 5- - Group 3 Fax Group 3 Fax 9 96 6- - Short Message Service (9600 bps) Short Message Service (9600 bps) 9 97 7- - Internet Standard PPP Packet Data Internet Standard PPP Packet Data 9 98 8- - CDPD Over PPP Packet Data CDPD Over PPP Packet Data 9 99 9- - Rate Set 2 Rate Set 2 Loopback Loopback (14400 bps) (14400 bps) 9 914 14- -Short Message Service (14400 bps) Short Message Service (14400 bps) 9 932,768 32,768- - Voice Using 14400 bps (CDG) Voice Using 14400 bps (CDG)
- 118. 118 Section 3 - Receiver Test Receiver Test 3.1 Frequency Coverage Requirements 3.4.1 Demod of Fwd Traffic Channel with AWGN 3.4.2 Demod of Fwd Traffic Channel with Multipath Fading 3.5.1 Receiver Sensitivity and Dynamic Range 3.5.2 Single Tone Desensitization 3.5.3 Intermodulation Spurious Response Attenuation 3.5.4 Adjacent Channel Selectivity 3.5.5 Receiver Blocking Characteristics 3.7.1 Supervision Paging Channel
- 119. 119 Section 4 - Transmitter Test Transmitter Test 4.1 Frequency Accuracy 4.2 Handoff 4.3 Modulation Requirements 4.4 RF Output Power Requirements 4.4.1 4.4.1 Range of Open Loop Output Power Range of Open Loop Output Power 4.4.2 Time Response of Open Loop Power Control 4.4.2 Time Response of Open Loop Power Control 4.4.3 Access Probe Output Power 4.4.3 Access Probe Output Power 4.4.4 Range of Closed Loop Power Control 4.4.4 Range of Closed Loop Power Control 4.4.5 Maximum RF Output Power 4.4.5 Maximum RF Output Power 4.4.6 Minimum Controlled Output Power 4.4.6 Minimum Controlled Output Power 4.4.7 Standby Output Power and Gated Output Power 4.4.7 Standby Output Power and Gated Output Power 4.4.8 Power Up Function Output Power 4.4.8 Power Up Function Output Power 4.4.9 Code Channel to Reverse Pilot Channel Output Power Accurac 4.4.9 Code Channel to Reverse Pilot Channel Output Power Accuracy y 4.4.10 Reverse Pilot Channel Transmit Phase Discontinuity 4.4.10 Reverse Pilot Channel Transmit Phase Discontinuity 4.4.11 Reverse Traffic Channel Output Power During Changes in Da 4.4.11 Reverse Traffic Channel Output Power During Changes in Data ta Rate Rate
- 120. 120 CDMA Conclusions • New Access Method ¾Code Based • Designed for Use in Interfering Environment • Uses Multipath to Improve Reception in Fading Conditions • cdma2000 is Backwards Compatible with TIA/EIA-95-B • Provides 2x Capacity Improvement Over TIA/EIA-95-B 9 9 Improved Coding Improved Coding 9 9 Improved Modulation Improved Modulation 9 9 Coherent Reverse Link Demodulation (Mobile Pilot) Coherent Reverse Link Demodulation (Mobile Pilot) 9 9 Fast Forward Link Power Control Fast Forward Link Power Control • Has Options for Green Field and Overlay Operation: 9 9 Direct Spread for Green Field Spectrum Applications Direct Spread for Green Field Spectrum Applications • Supports High Speed Data for New Applications