understanding-and-modeling-the-5g-nr-physical-layer (1).pdf
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understanding-and-modeling-the-5g-nr-physical-layer (1).pdf
understanding-and-modeling-the-5g-nr-physical-layer (1).pdf
- 1. 1 © 2015 The MathWorks, Inc. Understanding and Modeling the 5G NR Physical Layer Marc Barberis
- 2. 2 Objectives Understand some of 5G NR Physical Layer & Beyond See how 5G Toolbox can help you
- 3. 3 Smart City Smart Home/Building Gigabyte/sec data transfer Voice Self Driving Car Mission Critical Applications Industry Automation Work and Play in the Cloud 3D videos, UHD URLLC Ultrareliable and Low Latency eMBB Enhanced Mobile Broadband mMTC Massive Machine Type Comms
- 4. 4 URLLC Ultrareliable and Low Latency eMBB Enhanced Mobile Broadband mMTC Massive Machine Type Comms
- 5. 5 Let’s have a look at a few differences How different is 5G NR from 4G??
- 6. 6 5G vs LTE: Main Physical Layer Differences LTE 5G Use cases Mobile broadband access (MTC later) More use cases: eMBB, mMTC, URLLC Latency ~10 ms <1 ms Band Below 6 GHz Up to 60 GHz Bandwidth Up to 20 MHz Up to 100 MHz below 6 GHz Up to 400 MHz above 6 GHz Subcarrier spacing Fixed Variable Freq allocation UEs need to decode the whole BW Use of bandwidth parts “Always on” signals Used: Cell specific RS, PSS,SSS, PBCH Avoid always on signals, the only one is the SS block
- 7. 7 5G NR Waveform Analysis
- 8. 8 5G NR Waveform Analysis
- 9. 9 Not so fast… The fundamentals. Let’s step back a little
- 10. 10 Operating Frequencies Frequency Range Frequency Duplex Mode FR1 410 MHz - 7.125 GHz TDD and FDD FR2 24.25 - 52.6 GHz TDD ▪ Standard defines two frequency ranges
- 11. 11 Basic Principles: Similar to LTE ▪ Mostly same channels: data, control, broadcast, random access… ▪ Two operating modes: FDD and TDD (*) ▪ OFDM-based (**) but with different values for subcarrier spacing (**) Frequency Division Duplex, Time Division Duplex (*) Orthogonal Frequency Division Multiplexing
- 12. 12 OFDM Modulation and Subcarrier Spacing 1 0.8 1.2 15kHz 30kHz 45kHz . . . 30kHz 60kHz 90kHz Subcarrier spacing = 15kHz Subcarrier spacing = 30kHz IFFT When subcarrier spacing x 2, The OFDM symbol duration x Τ 1 2 Inverse Fast Fourier Transform
- 13. 13 Numerology and Subcarrier Spacing Slot configuration 0 Subcarrier spacing (kHz) 15 30 60 120 240 Symbol duration (no CP) (μs) 66.7 33.3 16.6 8.33 4.17 Nominal max BW (MHz) 49.5 99 198 396 397.4 Min scheduling interval (ms) 1 0.5 0.25 0.125 0.0625 • This flexibility is required to support different services (eMBB, mMTC, URLLC) and to meet short latency requirements
- 14. 14 Slot configuration 0 Subcarrier spacing (kHz) 15 30 60 120 240 Frequency range supported < 6GHz (data & sync) Everywhere (data) > 6GHz (data & sync) > 6GHz (sync) Symbol duration (no CP) (μs) 66.7 33.3 16.7 8.33 4.17 Symbol duration with CP (μs) 71.4 35.6 17.9 8.92 4.46 Min scheduling interval (ms) – 1 slot (14 symbols) 1 0.5 0.25 0.125 0.0625 Cell size : Large Delay spread: Long Cell size : Small Delay spread: short Large subcarrier: fight frequency-error and phase noise Numerology and Subcarrier Spacing
- 15. 15 Slots and OFDM Symbols (Normal CP) Subcarrier spacing (kHz) Symbols/slot Slots/subframe 15 14 1 30 14 2 60 14 4 120 14 8 240 14 16 15 kHz 30 kHz 60 kHz slot: 1 ms slot: 0.5 ms slot: 0.25 ms subframe
- 16. 16 Bandwidth Parts (BWP) ▪ BWPs address the following issues: – Devices may not be able to receive the full BW – Bandwidth adaptation: reduce energy consumption when only narrow bandwidth is required BWP 30 kHz SCS, normal CP BWP NRB Point A BWP RBOffset RBStart 15 kHz SCS Carrier, NRB ▪ Define a carrier as the addressable bandwidth ▪ Define a bandwidth part as the active part of the carrier
- 17. 17 Bandwidth Parts (BWP): Bandwidth Adaptation ▪ A UE can be configured with up to 4 bandwidth parts ▪ Only one bandwidth part is active at a time ▪ UE is not expected to receive data outside of active bandwidth part BWP1 active BWP2 active Carrier bandwidth (NDLRB) BWP3 active BWP1 active time
- 18. 18 Resource Elements and Resource Blocks Resource block: 12 subcarriers Resource element: smallest physical resource OFDM symbol Subcarrier (freq) OFDM symbols (time)
- 19. 19 Remember this picture?? 1 resource element
- 20. 20 Obervations? ▪ Repetitions ▪ DC offset? ▪ Not much transmission ➢ We may be looking at basic info broadcast by the base station
- 21. 21 How does a phone get onto the network?
- 22. 22 Synchronization Signal Block ▪ Primary Synchronization Sequence – One of 3 possible sequences – Provides timing estimate ▪ Secondary Synchronization Sequence – One of 336 possible sequences – Provides cell ID (one of 3*336 = 1008) ▪ Broadcast Channel and DMRS – Contains MIB = Master Information Block – Includes basic information to take next step: decode SIB1 (System Information Block)
- 23. 23 PBCH Content ▪ MIB contents (constant over 80 ms or 8 frames) ▪ Other PBCH content (not constant over 80 ms) Cell barred flag Are devices allowed in the cell? First PDSCH DM-RS position Time domain position of 1st DM-RS (type-A) SIB1 numerology SIB1 subcarrier spacing SIB1 configuration Search space, CORESET and PDCCH parameters CRB grid offset Freq domain offset between SS block and common resource grid SFN System frame number SS block index SS block time domain index (only present for FR2) Half frame bit Is the SS block in the 1st or 2nd half of the frame? SFN (4 LSB) 4 least significant bits of SFN CRC Cyclic redundancy check (24 bits)
- 24. 24 Synchronization Signal Burst ▪ Burst can be repeated several times SCS (kHz) Max number SS Blocks fc < 3 GHz 3 GHz ≤ fc ≤ 6 GHz 6 GHz < fc Case A 15 4 8 Case B 30 4 8 Case C 30 4 8 Case D 120 64 Case E 240 64 Why??
- 25. 25 Each SS Block is beamformed with a different pattern
- 26. 26 The receiver sees different beams with different signal strengths 0 1 2 3 4 5 6 7 Strongest beam • Transmitter can focus energy is narrower beams • Up to 64 possible beams for mmW: massive MIMO support
- 28. 28 Coming back to our picture…
- 29. 29 SS Block Functionality Summary & Demonstration ▪ Synchronization: – Symbol synchronization – Frame synchronization ▪ MIB decoding ▪ Beam search MATLAB Example
- 31. 31 Let’s look at another 5G waveform: Test Model MATLAB Example
- 34. 34 CORESETs (Control Resource Sets) ▪ Set of time/frequency resources where PDCCH can be transmitted ▪ Semi-statically configured by the network ▪ There can be many CORESETs in a carrier ▪ Can occur anywhere in the slot and in the frequency range of the carrier ▪ Max length of 3 symbols
- 35. 35 Main Difference with LTE Control Region ▪ Does not span the whole bandwidth ▪ Advantages – Supports limited bandwidth capabilities – Saves power
- 37. 37 Downlink Control in 5G NR
- 38. 38 DCI (Downlink Control Information) ▪ Carries control information used to schedule user data (PDSCH or PUSCH) ▪ Carried in the PDCCH (Physical Downlink Control Channel) ▪ Indicates: – Where is the data for a user? (time/frequency) – Modulation and coding scheme – HARQ related aspects (RV, process number, new data indicator) – Antenna ports and number of layers – … ▪ Users need to decode DCI before they can decode or transmit data Physical Downlink/Uplink Shared Channel
- 39. 39 DCI Processing Chain ▪ Main difference with LTE: use of polar coding ▪ CRC scrambled with RNTI DCI bits Codeword CRC Polar encoding Rate matching
- 40. 40 PDCCH Processing Chain (Physical Downlink Control Channel) ▪ Carries the DCI ▪ Modulated using QPSK DCI coding Scrambling Modulation Mapping to resource blocks DCI bits Resource grid QPSK
- 41. 41 DCI: PDSCH Scheduling Decode PDCCH Decode PDSCH Parse DCI • Where is the data for a user? (time/frequency) • What modulation and coding scheme? • HARQ related aspects (RV, process number, new data indicator) • Antenna ports and number of layers
- 42. 42 DCI: PUSCH Scheduling • Where is the data for a user? (time/frequency) • What modulation and coding scheme? • HARQ related aspects (RV, process number, new data indicator) • Antenna ports and number of layers • Precoding • CSI request
- 43. 43 Downlink Data in 5G NR
- 44. 44 Downlink Shared Channel (DL-SCH) ▪ Carries user data ▪ Can also carry the System Information Block (SIB) ▪ Main difference with LTE: use of LDPC coding ▪ Up to 8 layers = MIMO support ▪ Mapped to the PDSCH CRC Code block (CB) segmentation & CB-CRC LDPC Codeword (cw) Code blocks Code blocks Rate matching CB concatenation Tr block Code blocks More on that later
- 45. 45 Downlink Shared Channel (DL-SCH) Single Codeword CRC Code block (CB) segmentation & CB-CRC LDPC Codeword (cw) Code blocks Code blocks Rate matching CB concatenation Tr block Code blocks 5G Toolbox
- 46. 46 Physical Downlink Shared Channel (PDSCH) ▪ Highly configurable ▪ Parameters are configured by: – DCI (Downlink Control Information) – RRC (Radio Resource Control) DL-SCH Scrambling Modulation Layer mapping 1 or 2 cw 1 or 2 cw 1 or 2 cw 1 to 8 layers Multi-antenna precoding Resource mapping Tr block Resource grid DM-RS CSI-RS
- 47. 47 Physical Downlink Shared Channel (PDSCH) DL-SCH Scrambling Modulation Layer mapping 1 or 2 cw 1 or 2 cw 1 or 2 cw 1 to 8 layers Multi-antenna precoding Resource mapping Tr block Resource grid DM-RS CSI-RS Modulation scheme Modulation order QPSK 2 16QAM 4 64QAM 6 256QAM 8
- 48. 48 PDSCH Multi-antenna Precoding ▪ Achieves beamforming and spatial multiplexing ▪ Maps layers to antenna port ▪ Uses a precoding matrix WNantennas x Nlayers ▪ DM-RS has to go through the same precoding operation Precoding W layers Antenna ports DL-SCH Scrambling Modulation Layer mapping 1 or 2 cw 1 or 2 cw 1 or 2 cw 1 to 8 layers Multi-antenna precoding Resource mapping Tr block Resource grid DM-RS CSI-RS
- 49. 49 Physical Downlink Shared Channel (PDSCH) DL-SCH Scrambling Modulation Layer mapping 1 or 2 cw 1 or 2 cw 1 or 2 cw 1 to 8 layers Multi-antenna precoding Resource mapping Tr block Resource grid DM-RS CSI-RS 5G Toolbox
- 50. 50 PDSCH Mapping Types ▪ Two types of mapping PDSCH DM-RS other • First DM-RS in symbol 2 or 3 of the slot Mapping Type A • DM-RS in first symbol of the allocation • PUSCH partially mapped to slot Mapping Type B PDSCH allocation
- 51. 51 SIB1 and RACH
- 52. 52 Remember: PBCH Content ▪ MIB contents (constant over 80 ms or 8 frames) ▪ Other PBCH content (not constant over 80 ms) Cell barred flag Are devices allowed in the cell? First PDSCH DM-RS position Time domain position of 1st DM-RS (type-A) SIB1 numerology SIB1 subcarrier spacing SIB1 configuration Search space, CORESET and PDCCH parameters CRB grid offset Freq domain offset between SS block and common resource grid SFN System frame number SS block index SS block time domain index (only present for FR2) Half frame bit Is the SS block in the 1st or 2nd half of the frame? SFN (4 LSB) 4 least significant bits of SFN CRC Cyclic redundancy check (24 bits) MIB contains parameters required to decode System Information Block 1 (SIB1) SIB1 is the next piece of information the UE needs to connect to the network
- 53. 53 SIB1 Transmission ▪ SIB1 is transmitted on PDSCH with associated control (PDCCH) ▪ SIB1 is transmitted repeatedly with beamforming ▪ Once SIB1 is decoded, UE is ready to send a RACH (random access)
- 54. 54 Random Access Channel (RACH) ▪ Used to access the network – or send scheduling requests Decode MIB Decode SIB1
- 55. 55 Random Access Procedure RACH RACH access response: timing advance, temporary RNTI, scheduling grant. Uses RA-RNTI PDSCH Contention resolution: Device identity PUSCH Note: there could be 2 devices going through the exact same steps, but they have different identities RACH Contention resolution: device identity. DCI uses temporary RNTI PDSCH Device that recognized its device identity declares procedure successful and uses temporary RNTI as actual RNTI henceforth
- 56. 56 Final look at the waveform – and 5G Toolbox
- 58. 58 MATLAB 5G Toolbox Demodulation
- 59. 59 Challenges Test & validation Algorithm development Read specification and understand the theory … lets you focus on what matters
- 60. 60 5G Toolbox applications & use-cases Waveform generation and analysis ▪ New Radio (NR) subcarrier spacings and frame numerologies End-to-end link-level simulation ▪ Transmitter, channel model, and receiver ▪ Analyze bit error rate (BER), and throughput Golden reference design verification ▪ Customizable and editable algorithms as golden reference for implementation
- 61. 61 5G Toolbox has open customizable algorithms ▪ All functions are Open, editable, customizable MATLAB code ▪ C/C++ code generation: Supported with MATLAB Coder
- 62. 62 5G Toolbox: Content detail ▪ Waveform generation – Transport channels, physical channels and signals – Synchronization bursts ▪ Transmit and receive for DL and UL ▪ TDL and CDL channel models ▪ Reference designs as detailed examples – Link-level simulation & throughput measurements – Cell search procedures – Measurements (ACLR)
- 64. 64 End-to-end link-level simulation : NR PDSCH Throughput CP-OFDM demod Synchroniz. PDSCH DL-SCH CP-OFDM Channel model: CDL or TDL Channel estimation PDSCH decoding DL-SCH decoding HARQ Precoding Transmitter Receiver
- 65. 65 End-to-end link-level simulation : NR PUSCH Throughput
- 66. 66 Cell search and selection procedures ▪ Obtain cell ID and initial system information including Master Information Block (MIB) ▪ Perform the following steps: – Burst generation – Beam sweep – TDL propagation channel model and AWGN – Receiver synchronization and demodulation
- 67. 67 5G NR Downlink ACLR Measurement % Apply required oversampling resampled = resample(filtWaveform,aclr.OSR,1); % Calculate NR ACLR aclr = hACLRMeasurementNR(aclr,resampled);
- 68. 68 5G Toolbox Summary 5G NR waveform generation End-to-end link-level simulation & synchronization Full MATLAB source code 5G Toolbox lets you focus on what matters
- 69. 69 How to learn more ▪ Go to 5G Toolbox product page www.mathworks.com/products/5g ▪ Watch the 5G Toolbox video ▪ Watch the “5G Explained” Series: https://www.mathworks.com/videos/series/5g-explained.html
- 70. 70 Thank You!