xohhactsexhmcmxr0vgn-nr-frame-structure-and-air-interface-resources-221122182052-a390f86c.pptx

Air interface

1. NR Frame Structure and Air Interface Resources 2018-05-20 5G Training Course

2. Contents 1 Numerology 2 Time-Domain Resources 3 Frequency-Domain Resources 4 Space-Domain Resources

3. Numerology (system parameter): refers to subcarrier spacing (SCS) in New Radio (NR) and related parameters, such as the symbol length and cyclic prefix (CP ) length. Overview of NR Air Interface Resources (Time-, Frequency-, and Space-domain Resources ) Numerology Time-domain resources Frequency-domain resources Space-domain resources Symbol length SCS CP Slot 1 slot = 14 symbols Subframe Frame REG CCE RB RBG Bandwidth part ( BWP) Carrier 1 subframe = 1 ms 1 frame = 10 ms 1 RB = 12 subcarriers Antenna port QCL Basic scheduling unit 1 RBG = 2 to 16 RBs 1 BWP = Multiple RBs/RBGs One or more BWPs can be configured in one carrier. 1 REG = 1 PRB 1 CCE = 6 REGs Data channel/control channel scheduling unit Existed in LTE Unchanged in NR Existed in LTE Modified in NR Added in NR The SCS determines the symbol length and slot length. Codeword Layer NR uses orthogonal frequency division multiple access (OFDMA ), same as LTE does. The main description dimensions of air interface resources are similar between LTE and NR except that BWP is added to NR in the frequency domain.

4. SCS–Background and Protocol-provided Definition Numerologies defined in 3GPP Release 15 (TS 38.211) with SCS identified by the parameter µ . Available SCS for data channels and synchronization channels in 3GPP Release 15 Parameter µ SCS CP 15 kHz Normal 1 30 kHz Normal 2 60 kHz Normal, extended 3 120 kHz Normal 4 240 kHz Normal Based on LTE SCS of 15 kHz, a series of numerologies ( mainly different SCS values) are supported to adapt to different requirements and channel characteristics. Parameter µ SCS Supported for Data (PDSCH, PUSCH etc ) Supported for Sync (PSS, SSS, PBCH) 15 kHz Yes Yes 1 30 kHz Yes Yes 2 60 kHz Yes No 3 120 kHz Yes Yes 4 240 kHz No Yes * (LTE supports only 15 kHz SCS.) Background Service types supported by NR: eMBB , URLLC, mMTC , etc. Frequency bands supported by NR: C-band, mmWave , etc. Moving speed supported by NR: up to 500 km/h Requirements for SCS vary with service types, frequency bands, and moving speeds . URLLC service ( short latency): large SCS Low frequency band (wide coverage ): small SCS High frequency band (large bandwidth, phase noise): large SCS Ultra high speed mobility: large SCS NR SCS design principle NR supports a series of SCS values.

5. Coexistence of different SCS values and FDM The eMBB and URLLC data channels use different SCS values and coexist through FDM. The PBCH and PDSCH/PUSCH use different SCS values and coexist through FDM. SCS : Application Scenarios and Suggestions Impact of SCS on coverage, latency, mobility, and phase noise Coverage : The smaller the SCS, the longer the symbol length/CP, and the better the coverage. Mobility: The larger the SCS, the smaller the impact of Doppler shift, and the better the performance. Latency : The larger the SCS, the shorter the symbol length/latency. Phase noise: The larger the SCS, the smaller the impact of phase noise, and the better the performance . SCS application suggestions for different frequency bands ( eMBB service data channel ): SCS (kHz ) 15 30 60 120 240 3.5 GHz 28 GHz Coverage Mobility Latency Coverage Mobility Latency good bad good bad good bad good bad good bad good bad good bad Phase Noise It is recommended that the SCS be 30 kHz for C-band and 120 kHz for 28 GHz. Different SCS values and coexistence through FDM are supported.

6. SCS Configuration for Physical Channels and Signals Channel SCS Defined in 3GPP Release 15 Configuration Scheme Initial access SS/PBCH Sub-6 GHz: 15/30 kHz Above-6 GHz: 120/240 kHz RAN4 defines the default SCS for each frequency band (see Table 5.4.3.3-1 in 3GPP TS 38.104). RMSI, Msg2/4 (PDSCH) Sub-6 GHz: 15/30 kHz Above-6 GHz: 60/120 kHz MIB Msg1 ( PRACH), Msg3 (PUSCH) Long PRACH: SCS = {1.25 5} kHz Short PRACH: SCS = {15, 30, 60, 120} kHz, where: s ub-6 GHz: 15/30 kHz, above-6 GHz: 60/120 kHz RMSI RRC connected mode PDSCH/PDCCH/CSI-RS Sub-1 GHz: 15/30 kHz 1 GHz to 6 G Hz: 15/30/60 kHz Above-6 GHz: 60/120 kHz RRC signaling PUSCH/PUCCH/SRS Sub-1 GHz: 15/30 kHz 1 G Hz to 6 G Hz: 15/30/60 kHz Above-6 GHz: 60/120 kHz RRC signaling The protocol-defined SCS is used by the synchronization and broadcast channels involved in initial access. The SCS for other channels is configured in the MIB, RMSI, and RRC signaling. gNodeB UE SS/PBCH SCS: protocol-defined default value PRACH SCS: configured in RMSI RMSI (SIB1) SCS: configured in MIB Msg2 (random access response) SCS: same as RMSI Msg3 (transmitted over PUSCH ) SCS: configured in RMSI Msg4 (transmitted over PDSCH) SCS: same as RMSI DL: PDSCH/PDCCH/CSI-RS SCS: configured in RRC signaling UL: PUSCH/PUCCH/SRS SCS: configured in RRC signaling

7. Contents 2 Time-Domain Resources: CP, Symbol, Slot, Frame Structure 1 Numerology 3 Frequency-Domain Resources 4 Space-Domain Resources

8. Time-domain Resources : Radio Frame , Subframe , S lot , Symbol Radio frame Subframe Subframe Subframe ... S lot S lot S lot ... Inherited from LTE and has a fixed value of 1 ms Symbol Symbol Symbol ... Symbol Inherited from LTE and has a fixed value of 10 ms Basic unit for modulation Minimum unit for data scheduling Sampling point ... Sampling point Sampling point Basic time unit at the physical layer In the time domain, slot is a basic scheduling unit for data channels. The concepts of radio frames and subframes are the same as those in LTE.

9. Symbol Length–Determined by SCS Symbol = CP + Data SCS vs CP length/ symbol length/ slot length Length of OFDM symbols in data: T_data = 1/SCS CP length: T_cp = 144/2048 x T_data Symbol length ( data+CP ): T_symbol = T_data +T_cp Slot length: T_slot = 1 / 2^(µ) Parameter/Numer o logy (µ) 1 2 3 4 SCS ( kH z): SCS = 15 x 2^(µ) 15 30 60 120 240 OFDM Symbol Duration (µs): T_data = 1/SCS 66.67 33.33 16.67 8.33 4.17 CP Duration (µs): T_cp = 144/2048 x T_data 4.69 2.34 1.17 0.59 0.29 OFDM Symbol I ncluding CP (µs): T_symbol = T_data + T_cp 71.35 35.68 17.84 8.92 4.46 Slot Length (ms ): T_slot = 1/2 ^(µ) 1 0.5 0.25 0.125 0.0625 CP data … T_slot = 1 ms (14 symbols) SCS = 15 kHz … T_slot = 0.5 ms (14 symbols) SCS = 30 kHz … T_slot = 0.125 ms (14 symbols) SCS = 120 kHz T_symbol T_symbol T_symbol A symbol consists of a CP and data. The length of the data is the reciprocal of SCS . The larger the SCS, the smaller the symbol length and the slot length.

10. CP: Background and Principles Multipath latency extension The width extension of the received signal pulse caused by multipath is the difference between the maximum transmission latency and the minimum transmission latency. The latency extension varies with the environment, terrain, and clutter, and does not have an absolute mapping relationship with the cell radius. Impact Inter-Symbol Interference (ISI) is generated, which severely affects the transmission quality of digital signals. Inter-Channel Interference (ICI ) is generated. The orthogonality of the subcarriers in the OFDM system is damaged, which affects the demodulation on the receive side . Solution: CP for reduced ISI and ICI Guard intervals reduce ISI. A guard interval is inserted between OFDM symbols, where the length ( Tg ) of the guard interval is generally greater than the maximum latency extension over the radio channel. CP is inserted in the guard interval to reduce ICI. Replicating a sampling point following each OFDM symbol to the front of the OFDM symbol. This ensures that the number of waveform periods included in a latency copy of the OFDM symbol is an integer in an FFT period, which guarantees subcarrier orthogonality . CPs between OFDM symbols resolve ISI and ICI caused by multipath propagation.

11. CP length for different SCS values : Key factors that determine the CP length Multipath latency extension : The larger the multipath latency extension , the longer the CP. OFDM symbol length : Given the same OFDM symbol length , a longer CP indicates a larger system overhead. NR CP design principle Same overhead as that in LTE Aligned symbols between different SCS values and the reference numerology (15 kHz ) CP: Protocol-defined Parameter µ SCS (kHz) CP (µs) 15 NCP: 5.2 µs for l = 0 or 7; 4.69 µs for others 1 30 NCP: 2.86 µs for l = 0 or 14; 2.34 µs for others 2 60 NCP: 1.69 µs for l = 0 or 28; 1.17 µs for others Extended CP (ECP): 4.17 µs 3 120 NCP: 1.11 µs for l = 0 or 56; 0.59 µs for others 4 240 NCP: 0.81 µs for l = 0 or 112; 0.29 µs for others 1 2 3 1 1 1 If normal CP (NCP ) is used, the CP of the first symbol present every 0.5 ms is longer than that of other symbols . The CP length in NR is designed in line with the same principles as LTE. Overheads are the same between NR and LTE . Aligned symbols are ensured between different SCS values and the SCS of 15 kHz.

12. Frame structure architecture: Example: SCS = 30 kHz/120 kHz Frame Structure: Architecture SCS (kHz) Slot Configuration (NCP) Number of Symbols/Slot   Number of Slots/ Subframe Number of Slots /Frame 15 14 1 10 30 14 2 20 60 14 4 40 120 14 8 80 240 14 16 160 480 14 32 320 Frame length: 10 ms SFN range: 0 to 1023 Subframe length: 1 ms Subframe index per system frame: 0 to 9 Slot length: 14 symbols Slot Configuration (ECP) 60 12 4 40 1 frame = 10 ms = 10 subframes = 20 slots 1 subframe = 1 ms = 2 slots 1 slot = 0.5 ms = 14 symbols SCS = 30 kHz SCS = 120 kHz 1 frame = 10 ms = 10 subframes = 80 slots 1 subframe = 1 ms = 8 slots 1 slot = 0.125 ms = 14 symbols The lengths of a radio frame and a subframe in NR are consistent with those in LTE. The number of slots in each subframe is determined by the subcarrier width.

13. X Slot Format and Type Slot structure (section 4.3.2 of 3GPP TS 38.211) Downlink, denoted as D, for downlink transmission Flexible, denoted as X, for uplink or downlink transmission, GP, or reserved . Uplink, denoted as U, for uplink transmission Main slot types Case 1: DL-only slot Case 2 : UL-only slot Case 3 : flexible-only slot Case 4 : mixed slot (at least one downlink slot and/or one uplink slot) D U D X X U D X U D X U D X U D X U Case 1 : DL-only slot Case 2 : UL-only slot Case 3 : flexible-only slot Compared with LTE, NR has the following slot format features : Flexibility: symbol-level uplink/downlink adaptation in NR and subframe -level in LTE Diversity: More slots are supported in the NR system to cope with more scenarios and service types. Examples of application scenarios of different slots : Case 4-1 Case 4-2 Case 4-3 Case 4-4 Case 4-5 Slot Type Application Scenario Example Case 1 DL-heavy transmission Case 2 UL-heavy transmission Case 3 1. Forward compatibility: Resources are reserved for future services. 2. Adaptive adjustment of uplink and downlink resources: such as dynamic TDD Case 4-1 1. Forward compatibility: Resources are reserved for future services. 2. Flexible data transmission start and end locations: such as unlicensed frequency bands and dynamic TDD Case 4-2 Case 4-3 Downlink self-contained transmission Case 4-4 Uplink self-contained transmission Case 4-5 Mini-slot (seven symbols) for URLLC services The number of uplink and downlink symbols in a slot can be flexibly configured. In Release 15, a mini-slot contains 2 , 4, or 7 symbols for data scheduling in a short latency or a high frequency band scenario.

14. The self-contained slot or subframe type is not defined in 3GPP specifications. The self-contained slots or subframes discussed in the industry and literature are featured as follows : One slot or subframe contains uplink part, downlink part, and GP. Downlink self-contained slot or subframe : includes downlink data and corresponding HARQ feedback. Uplink self-contained slot or subframe : includes uplink scheduling information and uplink data . Self-contained Slots/ Subframes D U UL control or SRS D U DL control ACK/NACK UL grant Self-contained slot/ subframe design objectives Faster downlink HARQ feedback and uplink data scheduling: reduced RTT Shorter SRS transmission period: to cope with fast channel changes for improved MIMO performance Problems in application The small GP limits cell coverage. High requirements on UE hardware processing: Release 15 defines two types of UE processing capabilities. The baseline capability is 10 to 13 symbols if the SCS is 30 kHz and self-contained transmission is not supported. Frequent uplink/downlink switching increases the GP overhead . In the downlink, only the retransmission latency can be reduced. E2E latency depends on many factors, including the core network and air interface. The latency on the air interface side is also limited by the uplink/downlink frame configuration, and the processing latency on the gNodeB and UE . D U Downlink data processing time: Part of the GP needs to be reserved for demodulating downlink data and generating ACK/NACK feedback. Air interface round-trip latency Self-contained subframes reduce the RTT latency on the RAN side but limits cell coverage. Therefore, high requirements are posed on hardware processing capabilities of UEs.

15. Mini-slot: fewer than 14 symbols in the time domain Basic scheduling units are classified into the following types: Slot-based: The basic scheduling unit is slot, and the time-domain length is 14 symbols. Non-slot - based : The basic scheduling unit is mini-slot. In Release 15, the time - domain length is 2, 4, or 7 symbols . Mini-slot: S upport for the L ength of 2, 4, or 7 S ymbols in Release 15 Application s cenario Short- latency scenario: reduces the scheduling waiting latency and transmission latency . Unlicensed frequency band: Data can be transmitted immediately after listen before talk (LBT). mmWave scenario: TDM is applied for different UEs in a slot . 1. URLLC for low latency 2. eMBB in unlicensed band 3. mmWave Release 15 supports mini-slots with the length of 2, 4, or 7 symbols, which can be applied in short latency and mmWave scenarios. PDCCH PDSCH (mini-slot) PDSCH (mini-slot) Slot - based Non-slot - based PDSCH

16. UL/DL Slot/Frame Configuration Configuration: in line with section 11.1 of 3GPP TS 38.213 Layer 1: semi-static configuration through cell-specific RRC signaling SIB1: UL-DL-configuration-common and UL-DL-configuration-common-Set2 Period: { 0.5,0.625,1,1.25,2,2.5,5,10 } ms , SCS dependent Layer 2: semi-static configuration through UE-specific RRC signaling Higher layer signaling: UL-DL-configuration-dedicated Period: { 0.5,0.625,1,1.25,2,2.5,5,10 } ms, SCS dependent Layer 3: dynamic configuration through UE-group SFI DCI format 2_0 Period: { 1,2,4,5,8,10,20 } slots, SCS dependent Layer 4: dynamic configuration through UE-specific DCI DCI format 0, 1 Main characteristics: hierarchical configuration or separate configuration of each layer Different from LTE, the NR system supports UE-specific configuration, which delivers high flexibility. Support for symbol-level dynamic TDD D D D X D X D X D U D X X D X D X D X X D X D X D D D U D D D U D D D D D D X D D D U D D D U D D D D D D D D U D D D U D 1. Cell-specific RRC configuration 2. UE-specific RRC configuration 3. SFI 4 . DCI Hierarchical configuration Separate layer configuration D D D D D D D D U D D D U D Cell-specific RRC configuration/SFI D Frame configuration supports hierarchical configuration through RRC signaling and DCI to deliver symbol-level dynamic TDD and high flexibility . If X slots/symbols are configured at the upper layer , D or U slots/symbols are also configured at the lower layer.

17. Single-period configuration: DDDSU Dual-period configuration: DDDSU DDSUU UL/DL Slot/Frame Configuration: Cell-specific Semi-static Configuration X: DL/UL assignment periodicity x1: full DL slots y1: full UL slots x2: DL symbols y2: UL symbols Cell-specific RRC signaling parameters Parameter: SIB1 UL-DL-configuration-common: {X, x1, x2, y1, y2} UL-DL-configuration-common-Set2 : {Y, x3, x4, y3, y4} X/Y: assignment period { 0.5, 0.625, 1, 1.25, 2, 2.5, 5, 10} ms 0.625 ms is used only when the SCS is 120 kHz. 1.25 ms is used when the SCS is 60 kHz or larger. 2.5 ms is used when the SCS is 30 kHz or larger. A single period or two periods can be configured. x1/x3: number of downlink-only slots {0,1 ,…, number of slots in the assignment period } y1/y3: number of uplink-only slots {0,1 ,…, number of slots in the assignment period } x2/x4: number of downlink symbols following downlink-only slots {0,1,…,13} y2/y4: number of uplink symbols followed by uplink-only slots {0,1,…,13 } D D D D D U D D D D U D D D X: DL/UL assignment periodicity x1 y1 x2 y2 D D D D D U D D D D U D D U Y: DL/UL assignment periodicity x3 y3 x4 y4 Cell-specific semi-persistent configuration supports limited configuration period options, and flexible static configuration of DL/UL resources are realized through RRC signaling.

18. UL/DL Slot Configuration: Dynamic Configuration Through SFI Slot Format Indicator (SFI) is transmitted over the group-common PDCCH. SFI is identified by indexes in the following tables ( reference: Table 4.3.2-3 in 3GPP TS 38.211 ). The slot type can be notified to the UE through SFI over the PDCCH to dynamically set the slot/frame configuration.

19. Features of the f our c onfiguration s chemes Typical configuration schemes for commercial use: Unified static network-wide frame configuration with th e configuration period within the protocol-specified range : configured in cell-specific RRC signaling. Unified static network-wide frame configuration with th e configuration period outside the protocol-specified range : configured in cell-specific and UE-specific RRC signaling. SFI - and DCI -indicated configuration s can be added. Dynamic TDD: Cell-specific RRC+SFI/DCI configuration s or direct SFI/DCI configuration s Comparison Among and Application of Different Frame Configuration S cheme s Configuration Scheme Feature and Resource Configuration Priority Cell-specific RRC signaling Features: Cell-specific+static , or semi-persistent resource configuration Resource configuration priority: Highest. C ell-specific - signaling- indicate d D or U cannot be modified through other configurations . UE-specific RRC signaling Features: UE-specific+static , or semi-persistent resource configuration Resource configuration priority: High. The X configurations indicated in cell-specific signaling can be further configured. UE-specific -signaling- indicate d D or U cannot be modified through SFI/DCI. SFI Features: UE- or UE group-specific+periodic (1–20 slots) dynamic configuration Resource configuration priority: L o w . The X configurations indicated in cell-specific or UE-specific signaling can be further configured. DCI Features: UE-specific+slot-specific dynamic configuration Resource configuration priority: Very l ow . The X configurations indicated in the cell-specific signaling /UE-specific signaling /SFI can be further configured. Different configuration schemes are used to adapt to scenarios and requirements. The cell-specific RRC signaling configuration scheme deliver s unified static network-wide frame configuration.

20. Contents 2 Time-Domain Resources 1 Numerology 3 Frequency-Domain Resources: RB, RBG, REG, CCE, BWP 4 Space-Domain Resources

21. Basic Concepts of Frequency-Domain Resources Resource Grid Resource Block Resource Element Resource Grid ( RG ) Physical-layer resource group, which is defined separately for the uplink and downlink ( RGs are defined for each n umerology). Frequency domain: available RB resources within the transmission bandwidth Time domain: 1 subframe Resource Block ( RB ) Basic scheduling unit for data channel resource allocation in the frequency domain Frequency domain: 12 consecutive subcarriers Resource Element ( RE ) Minimum granularity of physical-layer resources Frequency domain: 1 subcarrier Time domain: 1 OFDM symbol   In NR, an RB corresponds to 12 subcarriers (same as LTE) in the frequency domain. The frequency-domain width is related to SCS and is calculated using 2 µ x 180 kHz.

22. Basic scheduling unit for control channel s : CCE RE Group (REG): basic unit for control channel resource allocation Frequency domain: 1 REG = 1 PRB (12 subcarriers) Time domain: 1 OFDM symbol Control Channel Element (CCE): basic scheduling unit for control channel resource allocation Frequency domain: 1 CCE = 6 REGs = 6 PRBs CCE aggregation level: 1, 2, 4, 8, 16 PRB/RBG and CCE: Frequency-domain Basic Scheduling Units Basic scheduling unit for data channel s : PRB/RBG Physical RB (PRB): Indicates the physical resource block in the BWP. Frequency domain: 12 subcarriers Resource Block Group (RBG): a set of physical resource blocks Frequency domain: The size depends on the number of RBs in the BWP. BWP S ize (RBs) RBG S ize Config 1 Config 2 1–36 2 4 37–72 4 8 73–144 8 16 145–275 16 16 In the frequency domain, t he PRB or an RBG is a basic scheduling unit for data channel s, and th e CCE is a basic scheduling unit for control channel s . RB0 RB1 RB2 RB3 RB4 RB5 RB6 RB7 RB8 RB9 RB10 RB11 RB12 … RBG0 RBG1 RBG2 … RB RBG 4 RBs REG DMRS DMRS DMRS CCE PRB

23. Channel Bandwidth and Transmission Bandwidth Channel bandwidth Channel bandwidth supported by the FR1 frequency band (450 MHz to 6000 MHz): 5 MHz (minimum), 100 MHz (maximum) Channel bandwidth supported by the FR2 frequency band (24 GHz to 52 GHz): 50 MHz (minimum), 400 MHz (maximum). Maximum transmission bandwidth (maximum number of available RBs) Determined by the channel bandwidth and data channel SCS. Defined on the gNodeB side and UE side separately. For details about the protocol-configuration of the UE side, see the figure on the right. Guard bandwidth With F-OFDM, the guard bandwidth decreases to about 2% in NR ( corresponding to 30 kHz SCS , 100 MHz channel bandwidth ). Compared with the guard bandwidth (10%) in LTE , NR uses F-OFDM to reduce the guard bandwidth to about 2%. Active RBs Guard band

24. Maximum Number of Available RBs and Spectrum Utilization Spectrum utilization = Maximum transmission bandwidth/Channel bandwidth Maximum transmission bandwidth on the gNodeB side: See Table 5.3.2-1 and 5.3.2-2 in 3GPP TS 38.104. Maximum transmission bandwidth on the UE side: See 3GPP TS 38.101-1 and TS 38.101-2 . SCS [kHz] 5 MHz 10 MHz 15 MHz 30 MHz 20 MHz 25 MHz 40 MHz 50 MHz 60 MHz 70 MHz 80 MHz 90 MHz 100 MHz N RB and Spectrum Utilization ( FR1:400 MHz to 6000 MHz) 15 25 52 79 [160] 106 133 216 270 N/A N/A N/A N/A N/A 90% 93.6% 94.8% [ 96% ] 95.4% 95.8% 97.2% 97.2% \ \ \ \ \ 30 11 24 38 [78] 51 65 106 133 162 [189] 217 [245] 273 79.2% 86.4% 91.2% 91.8% 93.6% 95.4% 95.8% 97.2% 97.7% 98.3% 60 N/A 11 18 [38] 24 31 51 65 79 [93] 107 [121] 135 79.2% 86.4% 86.4% 893% 91.8% 93.6% 94.8% 93.6% 97.2% SCS [kHz] 50 MHz 100 MHz 200 MHz 400 MHz N RB and Spectrum Utilization ( FR2: 24 GHz to 52 GHz) 60 66 132 264 N/A 95% 95% 95% \ 120 32 66 132 264 92.2% 95% 95% 95% Spectrum utilization is related to the channel bandwidth. The higher the bandwidth, the higher the spectral efficiency.

25. RB Location Index and Indication BWP is introduced to the NR system, which causes differences in the RB location index and indication from LTE. Related concepts ( section 4.4 of 3GPP TS 38.211) RG: In the frequency domain, an RG includes all available RBs within the transmission bandwidth. BWP: new concept introduced in the NR system. It refers to some RBs in the transmission bandwidth and is configured by the gNodeB . Point A: basic reference point of the RG Defined for the uplink, downlink, PCell , SCell , and SUL separately Point A = Reference Location + Offset For details about the reference location and offset for different reference points, see the figure on the right. Common RB ( CRB ): index in the RG The center of # subcarrier of CRB#0 is aligned with that of Point A . Physical RB ( PRB): index in the BWP Index: 0 to Relationship between PRB and CRB: is the number of CRBs between the BWP start position and CRB#0 . Point A Reference Location Offset PCell DL (TDD/FDD) SSB start location UEs perform blind detection to obtain this information. UEs are informed of this information through the RMSI. Parameter: PRB-index-DL-common PCell UL (TDD) Same as Point A for the PCell downlink UEs are informed of this information through the RMSI. Parameter: PRB-index- U L-common PCell UL (FDD) Frequency-domain location of the ARFCN UEs are informed of this information through the RMSI (SIB1). UEs are informed of this information through the RMSI. Parameter: PRB-index- U L-common SCell DL/UL Frequency-domain location of the ARFCN UEs are informed of this information through the SCell configuration message. UEs are informed of this information through RRC signaling. Parameter: PRB-index-DL-Dedicated PRB-index- U L-Dedicated SUL Frequency-domain location of the ARFCN UEs are informed of this information through the SCell configuration message. UEs are informed of this information through RRC signaling. Parameter: PRB-index- SU L-common 1 2 3 … 1 2 3 … BWP Offset Reference Location Point A CRB Index in RG PRB Index in BWP RG Freq. Point A is the basic reference point in the RG. CRB is the RB index in the RG, and PRB is the RB index in the BWP.

26. Definition and characteristics The Bandwidth Part ( BWP) is introduced in NR. It is a set of contiguous bandwidth resources configured by the gNodeB for UEs to achieve flexible transmission bandwidth configuration on the gNodeB side and UE side. Each BWP corresponds to a specific numerology . BWP is specific to UEs (BWP configurations vary with UEs). UEs do not need to know the transmission bandwidth on the gNodeB side but only needs to support the configured BWP bandwidth. Application scenarios Scenario#1: UEs with a small bandwidth access a large-bandwidth network. Scenario#2: UEs switch between small and large BWPs to save battery power. Scenario#3: The numerology is unique for each BWP and service-specific. BWP Definition and Application Scenarios BWP BWP Bandwidth Carrier B andwidth # 1 BWP 2 # 2 BWP 1 N umerology 1 BWP 1 Carrier B andwidth # 3 N umerology 2 BWP 2 Carrier B andwidth BWP is a set of contiguous bandwidth resources configured by the gNodeB for UEs. The application scenario examples are as follows: UEs supporting small bandwidths, power saving, and support for FDM on services of different numerologies.

27. BWP Types BWP types Initial BWP: configured in the initial access phase. Signals and channels are transmitted in the initial BWP during initial access. Dedicated BWP: configured for UEs in RRC_CONNECTED mode. A maximum of four dedicated BWPs can be configured for a UE. Active BWP: one of the dedicated BWPs activated by a UE in RRC_CONNECTED mode. According to Release 15, a UE in RRC_CONNECTED mode can have only one active BWP at a given time. Default BWP: It is one of the dedicated BWPs and is indicated by RRC signaling. A fter the BWP inactivity timer expires, the UE in RRC_CONNECTED mode switches to the default BWP. Carrier Bandwidth Initial BWP Carrier Bandwidth UE1 Active BWP Random Access Procedure RRC Connected Procedure Carrier Bandwidth default D efault UE1 Dedicated BWPs UE1 UE2 D efault UE2 Dedicated BWPs UE2 Active BWP UE2 Active BWP UE1 Active BWP UE2 BWP inactivity timer PDCCH indicating downlink assignment UE2 switches to the default BWP. Active Active Switch

28. Initial BWP Configuration Initial DL BWP definition and configuration Function: The PDSCH used to transmit RMSI, Msg2, and Msg 4 must be transmitted in the initial active DL BWP. Definition of the initial DL BWP: frequency-domain location and bandwidth of RMSI CORESET (control channel resource set) and a numerology corresponding to the RMSI The frequency-domain location and bandwidth of the RMSI CORESET are indicated in the PBCH (MIB). The default bandwidth is { 24,48,96 } RBs. Procedure for UEs to determine the initial BWP F requency T ime SSB CORESET PDSCH Frequency offset Initial DL BWP The frequency offset in PRB level which is between RMSI CORESET and SS/PBCH block is defined as the frequency difference from the lowest PRB of RMSI to the lowest PRB of SS/PBCH block. Initial UL BWP definition and configuration Function: The PUSCH used to transmit Msg3, PUCCH used to transmit Msg4 HARQ feedback, and PRACH resources during initial access must be transmitted in the initial active UL BWP. The initial DL BWP and initial UL BWP are separately configured. Numerology: same as that of Msg3 (configured in RMSI). Frequency-domain location: FDD ( paired spectrum ), SUL: configured in RMSI TDD ( unpaired spectrum ) : same as the center frequency band of the initial DL BWP Bandwidth Configured in RMSI and no default bandwidth option is available . UEs search for the SSB to obtain the frequency-domain location of the SSB. UEs demodulate the PBCH to obtain the frequency offset and bandwidth information of the RMSI CORESET and determine the initial DL BWP . UEs receive the RMSI to obtain the frequency-domain location, bandwidth, and numerology information of the initial UL BWP .

29. Dedicated BWP Configuration Dedicated BWP configuration Sent to UEs through RRC signaling FDD (paired spectrum): Up to four downlink dedicated BWPs and four uplink dedicated BWPs can be configured. TDD (unpaired spectrum): A total of four uplink/downlink BWP pairs can be configured. SUL : 4 uplink dedicated BWPs The smallest unit is one PRB. The dedicated BWP is equal to or smaller than the maximum bandwidth supported by a UE . Each dedicated BWP can be configured with the following attributes through RRC signaling: Numerology (SCS, CP type) Bandwidth (a group of contiguous PRBs) Frequency location ( start location) UEs can activate only one dedicated BWP at a given time as the active BWP . UE Dedicated PRB Location Dedicated BWP locations of all UEs in a cell are based on the same common reference point (Point A). UEs determine the start location of the dedicated BWP based on the offset relative to Point A. Based on the dedicated BWP bandwidth, UEs obtain the end location of the dedicated BWP. UEs obtain the frequency-domain location and size of the dedicated BWP. Cell Carrier Bandwidth UE1 Active BWP UE2 Active BWP Point A UE1 Offset UE2 Offset Offset: UEs can obtain the offset for each dedicated BWP from RRC signaling. After a UE accesses the network, the dedicated BWP is configured through RRC signaling. A maximum of four dedicated BWPs can be configured.

30. BWP Adaptation BWP Adaptation UEs in RRC_CONNECTED mode switch between dedicated BWPs (only one dedicated BWP can be activated at a given time). BWP Adaptation is completed through switchovers and involves the following: DCI FDD : downlink : downlink DCI, uplink: uplink DCI TDD: If the uplink or downlink DCI includes a switchover indication, BWP switchovers are performed in the uplink and downlink . Timer mechanism If the BWP inactivity timer expires, UEs switch to the d efault BWP ( one of the dedicated BWPs ). Timer granularity: 1 ms for sub-6 GHz , 0.5 ms for mmWave BWP Adaptation application scenarios The BWP bandwidth changes: e.g . switching to the power saving state. BWP location movement in the frequency domain: e.g . to increase scheduling flexibility. The BWP n umerology changes: e.g . to allow different services. RF conversion time (defined in RAN4, sub-6 GHz) UE BWP inactivity timer PDCCH indicating downlink assignment T he UE switches to the default BWP. Relationship Between BWP1 and BWP2 Intra-Band Inter-Band Same Center Frequency Different Center Frequency Time ≤ 20µs 50–200 µs ≤ 900 µs In RRC connected mode, switching between BWPs is realized through DCI or timer mechanisms.

31. Contents 2 Time-Domain Resources 1 Numerology 3 Frequency-Domain Resources 4 Space-Domain Resources: Layer , Antenna Port, QCL

32. Codewords and Antenna Ports Basic concepts Codeword Upper-layer service data on which channel coding applies. Codewords uniquely identify data flow. By transmitting different data, MIMO implements spatial multiplexing . The number of codewords depends on the rank of the channel matrix. Layer The number of codewords is different from the number of transmit antennas. Therefore, codewords need to be mapped to transmit antenna. Antenna port Logical ports used for transmission. Antenna ports do not have a one-to-one relationship with physical antennas. They can be mapped to one or more physical antennas. Antennas ports are defined based on reference signals . Number of codewords ≤ Number of layers ≤ Number of antenna ports Protocol-defined number of codewords 1 to 4 layers: 1 codeword 5 to 8 layers: 2 codewords Protocol-defined number of layers DL: up to eight layers for a single user and four layers for multiple users UL: up to four layers for a single user or multiple users Protocol-defined number of antenna ports Channel/Signal Maximum Number of Ports Antenna Port# UL PUSCH with DMRS 8 or 12 {0,1,2,…,7} DMRS type 1 {0,1,2,…,11} DMRS type 2 PUCCH 1 {2000} PRACH 1 {4000} SRS 4 {1000,1001, 1002,1003} DL PDSCH with DMRS 8 or 12 {1000, 1001,…,1007} DMRS type 1 {1000, 1001,…,1011} DMRS type 2 PDCCH 1 {2000} CSI-RS 32 {3000,3001,3002,…,3031} SSB 1 {4000} Scrambling Scrambling Modulation mapper Modulation mapper Layer mapper Antenna Port mapper RE mapper RE mapper OFDM signal generation OFDM signal generation Codewords Layers Antenna ports In NR, a maximum of two codewords are supported. The maximum number of DMRS antenna ports is increased to 12.