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![OAI Project Team
Agenda item
⢠LTE Overview [Gina]
- [18:00] â [18:10]
⢠Channel in LTE [Ali] [Nikita]
- [18:10] â [18:25]
⢠Random Access Procedure [Gina]
- [18:25] â [19:00]
⢠Scheduling [Ali] [Nikita]
- [19:00] â [21:00]
2](https://image.slidesharecdn.com/ltetrainingcourse-190123155714/85/LTE-Training-Course-2-320.jpg)
![OAI Project Team
How to Generate 64 PRACH Preamble Sequences
1. Generate a Zaddoff Chu sequence (849 samples) using rootSequenceIndex (let's call this sequence as
'base sequence')
2. Generate 64 different sequency by doing cyclic shift of the base sequence. The cyclic shift interval is
determined by Ncs and the Ncs is determined by zeroCorrelationZoneConfig and Highspeedflag.
Ex..
Let's suppose SIB2 broadcast the parameters as follows.
a) rootSequenceindex = 22 ď From a, the base Zaddoff-Chu sequence with u = 1
b) Highspeedflag = false
c) zeroCorrelationZoneConfig = 5 ď From b and c, the Nzc (Cyclicshift interval) = 26
45
64 different PRACH sequence as follows.
PRACH Sequence[0] = base sequence
PRACH Sequence[1] = do cyclic shift to base sequence by 1 * 26 samples
PRACH Sequence[2] = do cyclic shift to base sequence by 2 * 26 samples
....
PRACH Sequence[31] = do cyclic shift to base sequence by 31 * 26 samples
PRACH Sequence[32] = do cyclic shift to base sequence +1
PRACH Sequence[33] = do cyclic shift to base sequence +1 by 1 * 26 samples
PRACH Sequence[34] = do cyclic shift to base sequence +1 by 2 * 26 samples
âŚâŚ
PRACH Sequence[63] = do cyclic shift to base sequence+1 by 31 * 26 samples](https://image.slidesharecdn.com/ltetrainingcourse-190123155714/85/LTE-Training-Course-45-320.jpg)
More Related Content
LTE Training Course
- 1. OAI Project Team Speaker:Gina, Ali, Nikita Date: 2017/12/13 LTE Training course
- 2. OAI Project Team Agendaitem ⢠LTE Overview [Gina] - [18:00] â [18:10] ⢠Channel in LTE [Ali] [Nikita] - [18:10] â [18:25] ⢠Random Access Procedure [Gina] - [18:25] â [19:00] ⢠Scheduling [Ali] [Nikita] - [19:00] â [21:00] 2
- 3. OAI Project Team â˘LTE Overview What is LTE Introduction for each layer LTE Generic Frame Structure ⢠Channel in LTE LTE MAC Layer MAC Architecture Why channel is important LTE channel mapping ⢠Cell Search Procedure PSS/SSS ⢠System information MIB/SIB ⢠Random Access Procedure Message sequence chart Preamble PRACH information Various trigger events under the random access process 3 Outline
- 4. OAI Project Team â˘Uplink Scheduling Protocol Layer Architecture - RLC - PDCP - RRC BSR (Buffer Status Report) HARQ - HARQ vs ARQ - Application of HARQ - Process for Uplink ⢠Downlink scheduling Downlink transmission - Downlink transmission procedure - Downlink control information - Channel state information - Downlink MAC control element Hybrid automatic repeat request - Hybrid automatic repeat request - Incremental redundancy - HARQ process - New data indicator - Downlink HARQ - Downlink HARQ process Channel quality - Modulation coding scheme, Modulation - Channel quality indicator Discontinuous Reception ⢠Overview porting OAI UE Tutorial 4 Outline
- 5. OAI Project Team â˘LTE Overview What is LTE Introduction for each layer LTE Generic Frame Structure ⢠Channel in LTE LTE MAC Layer MAC Architecture Why channel is important LTE channel mapping ⢠Cell Search Procedure PSS/SSS ⢠System information MIB/SIB ⢠Random Access Procedure Message sequence chart Preamble PRACH information Various trigger events under the random access process 5 LTE Overview
- 6. OAI Project Team Whatis LTE (Long Term Evolution) ? ⢠LTE is a wireless data communication technology standard ⢠LTE Enhances Data Transmission Capabilities and Data Transmission Speed of Wireless Networks with New Technology and Modulation 6
- 7. OAI Project Team Whatis LTE (Long Term Evolution) ? 7 Characteristic High data rate Low network latency Save electricity Support FDD/TDD Support MBSFN *MBSFN : Multicast / Broadcast Single- frequency Network *FDD : Frequency Division Duplex *TDD : Time Division Duplex
- 8. OAI Project Team Introductionfor each layer 8
- 9. OAI Project Team Introductionfor each layer 9 ⢠Function: connect the radio resource of control plane and user plane. ⢠Ex. Configuration for PDCP, RLC and MAC layers
- 10. OAI Project Team Introductionfor each layer 10 ⢠Main function: â Data transmit in Control and User plane â PDCP serial number maintenance â data encryption / decryption â Make sure that the order of packets from upper layer is correct and not repeat in reconstruction. â Header compression and decompression (only apply to DRB â data integrity protection (only apply to SRB *DRB: dedicated radio resource *SRB: signaling radio resource
- 11. OAI Project Team Introductionfor each layer 11 ⢠Main function: â Make sure that the packet order â Remove duplicate packets and retransmission â Packet cutting and reorganization â Automatic Repeat Request (ARQ) â TM/AM/UM mode handling *SDU: Service Data Unit *PDU: Protocol Data Unit *TM: Transparent Mode *AM: Acknowledged Mode *UM: Unacknowledged Mode
- 12. OAI Project Team Introductionfor each layer 12 ⢠Main function: â Managing HARQ â Scheduling information reporting (DCI generation) â Multiplexing â Logical channel prioritization â RA management and radio resource allocation to different radio bearer â Mapping between logical channels and transport channels *DCI : Downlink Control Information
- 13. OAI Project Team Introductionfor each layer 13 ⢠Main function: â Transport channel error detection â Forward Error Correction (FEC) â Decode â Synchronization â Provide CQI to MAC layer â Data transmit â HARQ Ack â Schedule request (SR) *CQI: Channel Quality Indicator *HARQ: Hybrid Automatic Repeat Request
- 14. OAI Project Team LTEGeneric Frame Structure 14 =10 subframes =2 slots =TTI (Transmission Time Interval) Vs. ⢠6 ODFM symbols (short cyclic prefix) =6 or 7 ODFM symbols ⢠7 ODFM symbols (short cyclic prefix) * CP : cyclic prefixExtended CP Normal CP
- 15. OAI Project Team â˘LTE Overview What is LTE Introduction for each layer LTE Generic Frame Structure ⢠Channel in LTE LTE MAC Layer MAC Architecture Why channel is important LTE channel mapping ⢠Cell Search Procedure PSS/SSS ⢠System information MIB/SIB ⢠Random Access Procedure Message sequence chart Preamble PRACH information Various trigger events under the random access process 15 Channel in LTE
- 16. OAI Project Team LTEMAC Layer ⢠MAC is a radio network protocol which resides both in the UE and in the E-UTRAN. ⢠MAC protocol is available for both User plane and also for the control plane. User Plane Control Plane UE Protocol Stack eNB Protocol Stack NAS RRC PDCP RLC MAC PHY RRC PDCP RLC MAC PHY UE Protocol Stack RRC PDCP RLC MAC PHY NAS RRC PDCP RLC MAC PHY eNB Protocol Stack EPC P-GW S-GW MME NAS IP Address Packet Filtering Mobility Anchoring Inter -net
- 17. OAI Project Team MACArchitecture E-UTRA defines two MAC entities ⢠one in the UE and one in the E-UTRAN. The MAC layer is composed of ⢠a HARQ entity, ⢠a multiplexing/de-multiplexing entity, ⢠a logical channel prioritization entity, ⢠and a control entity.
- 18. OAI Project Team WhyChannel is needed in LTE ⢠In order that data can be transported across the LTE radio interface ⢠Variety type of data will be transported across the radio access network ⢠In the LTE Protocol Structure, different channel provide interface to the higher layers
- 19. OAI Project Team MappingChannel 19 http://www.artizanetworks.com/resources/tutorials/lay_2_log.htmlCC Uplink Mapping Channel Downlink Mapping Channel ⢠Physical channels: These are transmission channels that carry user data and control messages. ⢠Transport channels: The physical layer transport channels offer information transfer to Medium Access Control (MAC) and higher layers. ⢠Logical channels: Provide services for the Medium Access Control (MAC) layer within the LTE protocol structure.
- 20. OAI Project Team â˘LTE Overview What is LTE Introduction for each layer LTE Generic Frame Structure ⢠Channel in LTE LTE MAC Layer MAC Architecture Why channel is important LTE channel mapping ⢠Cell Search Procedure PSS/SSS ⢠System information MIB/SIB ⢠Random Access Procedure Message sequence chart Preamble PRACH information Various trigger events under the random access process 20 Cell Search Procedure
- 21. OAI Project Team UEconnect to network after booting 21 Cell selection Random Access
- 22. OAI Project Team Cellsearch procedure ⢠Mainly related to PSS / SSS and UE through PSS / SSS can get useful information. ⢠Main purpose: ⢠Scenario: 22 *PSS: Primary Synchronization Signal *SSS: Secondary Synchronization Signal *PCI: Physical-layer cell identity Get synchronization Get system frame timing Determine the PCI UE ⢠Handover ⢠Cell re-selection UE
- 23. OAI Project Team PSS/ SSS time domain location ⢠In order to support community search, LTE defines two downlink sync signals - PSS: Primary Synchronization Signal - SSS: Secondary Synchronization Signal 23 1 slot 1 symbols = 1/7 slot
- 24. OAI Project Team PSS â˘PSS structure ⢠Zadoff-chu sequence The sequence corresponding to the PSS of a certain cell is determined by the PCI of this cell .(đđźđˇ đđđđ %3) 24 5 subcarriers is for protecting the frequency band
- 25. OAI Project Team Howthe UE decodes the SSS ⢠After knowing PSS, UE will know the possible location of SSS ⢠The exact location of SSS is also related to the length of the Cyclic Prefix 25 Structure of PSS / SSS frame and slot in time domain in FDD mode
- 26. OAI Project Team Theinformation obtained at each stage 26 Check the reference signal Decode PBCH Check PSS Check SSS ⢠đđźđˇ 2 ⢠5 ms timing ⢠đđźđˇ 1 ⢠10 ms timing ⢠TDD/FDD ⢠Time-frequency position ⢠The length of Cyclic Prefix Initial synchronization ⢠Check PBCH timing ⢠Get the system message Identify neighborhood cells ⢠RSRP/RSRQ ⢠Indicate to RRC *RSRP: Reference Signal Receiving Power *RSRQ: Reference Signal Receiving Quality Check PSS Check SSS
- 27. OAI Project Team â˘LTE Overview What is LTE Introduction for each layer LTE Generic Frame Structure ⢠Channel in LTE LTE MAC Layer MAC Architecture Why channel is important LTE channel mapping ⢠Cell Search Procedure PSS/SSS ⢠System information MIB/SIB ⢠Random Access Procedure Message sequence chart Preamble PRACH information Various trigger events under the random access process 27 System information
- 28. OAI Project Team Systeminformation ⢠MIBďź - Downlink system bandwidth, PHICH configuration, System Frame Number (SFN) - Transmission channel: PBCH -> BCH - Period: 40 ms 28 SI : System information frame subframe
- 29. OAI Project Team Systeminformation ⢠SIB1ďź - Parameters are used to determine whether a cell is suitable for cell selection or not. - Time-domain scheduling information of other SIBs - Transmission channel: PDSCH -> DL-SCH - Period: 80 ms ⢠Scheduling information for other SIBs - According to schedulingInfolist specified SI messages, base station will tell UE which sibs are in each SI message, and also how the SI messages will be transmitted. 29 frame subframe
- 30. OAI Project Team â˘LTE Overview What is LTE Introduction for each layer LTE Generic Frame Structure ⢠Channel in LTE LTE MAC Layer MAC Architecture Why channel is important LTE channel mapping ⢠Cell Search Procedure PSS/SSS ⢠System information MIB/SIB ⢠Random Access Procedure Message sequence chart Preamble PRACH information Various trigger events under the random access process 30 Random Access Procedure
- 31. OAI Project Team RandomAccess Procedure ⢠Main purpose - Get uplink synchronization - Assign UE a unique identifier C-RNTI 31 RNTI : Radio Network Tempory Identity C-RNTI RA-RNTI SI-RNTI P-RNTI Temp C-RNTI value 003Dď˝FFF3 0001ď˝003C FFFF FFFE 003Dď˝FFF3 function PDSCH transmission for dynamic scheduling For Random Access Response For identify the transmission of SIB messages For identify the transmission of paging messages For Msg3 transmission, conflict resolution
- 32. OAI Project Team RandomAccess Procedure ⢠Steps of Random access procedure 32 MSG 1 MSG 2 MSG 3 MSG 4
- 33. OAI Project Team WhenRACH Process occurs 33 Contention based RA procedure Contention free RA procedure situation ⢠Initial access from RRC_IDLE ⢠RRC Connection Re-establishment procedure ⢠Handover ⢠DL data arrival during RRC_CONNECTED requiring random access procedure ⢠UL data arrival during RRC_CONNECTED requiring random access procedure ⢠Handover ⢠DL data arrival during RRC_CONNECTED requiring random access procedure ⢠For positioning purpose during RRC_CONNECTED requiring random access procedure difference ⢠Preamble is assigned by UE ⢠Preamble is assigned by eNodeB ⢠In RRC Connected status, not in RRC idle status
- 34. OAI Project Team Contentionbased 34 ⢠Choose preamble index - Contention based: The preamble index is randomly selected by the UE 1. Select group (A or B) 2. the UE randomly selects a preamble from the group and sets the PRACH Mask Index to 0 - Contention free: The preamble index is specified by eNodeB ⢠The eNodeB assigns a dedicated preamble index to the UE and specifies a PRACH Mask Index ⢠Select the PRACH resource for sending preamble ⢠Determine the corresponding RA-RNTI ⢠Determine the target received power (PREAMBLE_RECEIVED_TARGET_POWER) How to select ⢠there is a preamble group B ⢠MSG3 is larger than messageSizeGroupA ⢠pathloss is less than PCMAX, c - preambleInitialReceivedTargetPower - deltaPreambleMsg3 - messagePowerOffsetGroupB MSG1 : UE send preamble
- 35. OAI Project Team Contentionbased ⢠eNodeB sends "Random Access Response" to UE on DL-SCH addressed to RA-RNTI calculated from the timeslot in which preamble was sent. ⢠RA response window ⢠RAR MAC PDU 35 ⢠MAC RAR Used to specify the amount of time required for UE uplink synchronization Inform the UE of the next uplink data transmission resources for MSG3 For the initial identity authentication of the UE, if the RA succeeds, this temporary identity authentication will be converted to a formal identity identification. MSG2 : eNodeB sends Random Access Response
- 36. OAI Project Team â˘Only MSG3 and MSG4 are required for contention-based random access ⢠Using UL-SCH, UE sends "RRC connection request message" to eNodeB ⢠MSG3 contains UE identify and the reason for launching RA ⢠UE is identified by temporary C-RNTI (TC-RNTI) ⢠Contention resolution timer â Check RA is finished or not and the connection with layer2 is done or not ⢠With HARQ 36 UE identity (TMSI or Random Value ) ⢠TMSI is used if UE has previously connected to the same network. ⢠Random value is used if UE is connecting for the very first time to network. Why we need contention resolution?? Contention based MSG3 : UE send MSG3
- 37. OAI Project Team â˘After eNB receive MSG3, MAC layer informs the RRC layer ⢠If the RRC recognizes the UE and allows the connection, the MSG4 is sent to the UE ⢠UE and eNB start to build up control plane and user planeâs signal channel ⢠Uplink power control, counter setting, HARQ parameters, CQI ,uplink schedule relative module(like scheduling request). 37 In RRC_CONNECTED state, UE has C-RNTI Not in RRC_CONNECTED state Contention based MSG4 : eNodeB sends contention resolution Vs.
- 38. OAI Project Team Preamble â˘How to select preamble (0-63)? 1. Select group (A or B) Random Access Preambles group B exists the potential message size is greater than messageSizeGroupA the pathloss is less than PCMAX â preambleInitialReceivedTargetPower â deltaPreambleMsg3 â messagePowerOffsetGroupB ď choose group B ď else choose group A 2. Randomly select a Random Access Preamble within the selected group. 3. Set PRACH Mask Index to 0. 38
- 39. OAI Project Team PreambleFormat 39 *Frame structure type 2 and special subframe configurations with UpPTS lengths and only. Longer T_SEQ : Help decoding PRACH under noised condition because it provide correlation window to detect PRACH. Why Multiple Preamble Format ? Ans. Depending on the environment, the required conditions will be differentLonger T_CPďź Have better tolerance in fading environment and reduce ISI
- 40. OAI Project Team PRACHinformation ⢠PRACH Parameters and it's Physical Meaning - prach-ConfigIndex - prach-FreqOffset - rootSequenceIndex - zeroCorrelationZoneConfig and Highspeedflag 40 sib2 radioResourceConfigCommon rach-ConfigCommon ⌠... prach-Config rootSequenceIndex: 22 prach-ConfigInfo prach-ConfigIndex: 3 ..0. .... highSpeedFlag: False zeroCorrelationZoneConfig: 5 prach-FreqOffset: 4 ...
- 41. OAI Project Team prach-ConfigIndex â˘This parameter determines what type of preamble format should be used and at which system frame and subframe UE can transmit PRACH Preamble. 41 Which "PRACH Configuration Idex" to use, the network is most likely to detect RACH from UE? why? ⢠PRACH Parameters and it's Physical Meaning - prach-ConfigIndex - prach-FreqOffset - rootSequenceIndex - zeroCorrelationZoneConfig and Highspeedflag
- 42. OAI Project Team prach-FreqOffset â˘prach-FreqOffset is the parameter that determines the location of PRACH preamble in frequency domain. This location in frequency domain is calculated in the unit of PRB index and calculated by following equation. As you see, the equation gets different depending on Preamble Format. 42 ⢠PRACH Parameters and it's Physical Meaning - prach-ConfigIndex - prach-FreqOffset - rootSequenceIndex - zeroCorrelationZoneConfig and Highspeedflag
- 43. OAI Project Team rootSequenceIndex â˘There are 838 root Zadoff-Chu sequences available for preambles. ⢠The length of each root sequence is 839. ⢠This rootSequenceIndex is a logical value. 43 Ex.. prach-Config rootSequenceIndex: 22 prach-ConfigInfo prach-ConfigIndex: 3 ..0. .... highSpeedFlag: False zeroCorrelationZoneConfig: 5 prach-FreqOffset: 4 ⢠PRACH Parameters and it's Physical Meaning - prach-ConfigIndex - prach-FreqOffset - rootSequenceIndex - zeroCorrelationZoneConfig and Highspeedflag
- 44. OAI Project Team zeroCorrelationZoneConfigand Highspeedflag ⢠zeroCorrelationZoneConfig and Highspeedflg information elements is to specify the cyclic shift intervals to generate 64 PRACH Sequence from a single base sequence. - Unrestricted Set (HighSpeedFlack = False) - Restricted Set (HighSpeedFlack = True) 44 Ex.. prach-Config rootSequenceIndex: 22 prach-ConfigInfo prach-ConfigIndex: 3 ..0. .... highSpeedFlag: False zeroCorrelationZoneConfig: 5 prach-FreqOffset: 4 ⢠PRACH Parameters and it's Physical Meaning - prach-ConfigIndex - prach-FreqOffset - rootSequenceIndex - zeroCorrelationZoneConfig and Highspeedflag
- 45. OAI Project Team Howto Generate 64 PRACH Preamble Sequences 1. Generate a Zaddoff Chu sequence (849 samples) using rootSequenceIndex (let's call this sequence as 'base sequence') 2. Generate 64 different sequency by doing cyclic shift of the base sequence. The cyclic shift interval is determined by Ncs and the Ncs is determined by zeroCorrelationZoneConfig and Highspeedflag. Ex.. Let's suppose SIB2 broadcast the parameters as follows. a) rootSequenceindex = 22 ď From a, the base Zaddoff-Chu sequence with u = 1 b) Highspeedflag = false c) zeroCorrelationZoneConfig = 5 ď From b and c, the Nzc (Cyclicshift interval) = 26 45 64 different PRACH sequence as follows. PRACH Sequence[0] = base sequence PRACH Sequence[1] = do cyclic shift to base sequence by 1 * 26 samples PRACH Sequence[2] = do cyclic shift to base sequence by 2 * 26 samples .... PRACH Sequence[31] = do cyclic shift to base sequence by 31 * 26 samples PRACH Sequence[32] = do cyclic shift to base sequence +1 PRACH Sequence[33] = do cyclic shift to base sequence +1 by 1 * 26 samples PRACH Sequence[34] = do cyclic shift to base sequence +1 by 2 * 26 samples âŚâŚ PRACH Sequence[63] = do cyclic shift to base sequence+1 by 31 * 26 samples
- 46. OAI Project Team Varioustrigger events under the random access process ⢠Three ways to trigger the random access procedure 1. PDCCH order trigger 2. MAC sublayer trigger 3. The upper trigger 46
- 47. OAI Project Team 1.PDCCH order trigger ⢠DL Data arrival when Out-of-Sync ⢠UE positioning. (through a special DCI format 1A) 47
- 48. OAI Project Team 1.PDCCH order trigger 48 Contention based Contention free
- 49. OAI Project Team 2.MAC sublayer trigger ⢠UE has uplink data to send, but there is no valid PUCCH resource available for sending SR in any TTI ⢠What situation may the UE have no SR resources? - When the UE loses uplink synchronization, it also releases SR resources. ⢠The function of the random access based on contention may replace the function of the SR to apply for the uplink resource. 49 *SR: scheduling request *TTI : Transmission Time Interval
- 50. OAI Project Team 3.The upper trigger ⢠The upper layer triggered random access process includes - Initial access - RRC connection re-establishment - handover 50
- 51. OAI Project Team 3.The upper trigger 51 Initial access RRC Re-establishment
- 52. OAI Project Team 3.The upper trigger 52 Handover - Contention based Handover - Contention free
- 53. OAI Project Team â˘Uplink Scheduling Protocol Layer Architecture - RLC - PDCP - RRC BSR (Buffer Status Report) HARQ - HARQ vs ARQ - Application of HARQ - Process for Uplink ⢠Downlink scheduling Downlink transmission - Downlink transmission procedure - Downlink control information - Channel state information - Downlink MAC control element Hybrid automatic repeat request - Hybrid automatic repeat request - Incremental redundancy - HARQ process - New data indicator - Downlink HARQ - Downlink HARQ process Channel quality - Modulation coding scheme, Modulation - Channel quality indicator Discontinuous Reception ⢠Overview porting OAI UE Tutorial 53 Uplink Scheduling - Protocol Layer Architecture
- 54. OAI Project Team RLCFunction ⢠Transfer of Upper Layer PDUs - Signaling Radio Bearer (SRB) from RRC - Radio Bearer (RB) from PDCP ⢠Error Correction through ARQ ⢠Concatenation, Segmentation and Reassembly of SDUs ⢠Re-segmentation of RLC PDUs ⢠In-Sequence delivery of Upper Layer PDUs ⢠Duplicate Detection ⢠Protocol Error Detection and Recovery
- 55. OAI Project Team RLCModes for Uplink Logical Channel ⢠RLC has several modes, that is Transparent Mode (TM), Unaknowledged Mode (UM), Aknowledged Mode (AM)
- 56. OAI Project Team DifferenceRLC Between LTE and HSPA LTE RLC HSPA RLC RLC located in eNB RLC located in RNC Flexible RLC PDU sizes to match underlying PHY layer capacity RLC PDU sizes are semi-statically configured by RRC layer (except for R7 and beyond) Re-segmentation of RLC PDUs during retransmission to match PHY layer capacity Re-segmentation for retransmissions not allowed No ciphering at RLC layer (performed at PDCP layer) Ciphering supported for UM and AM modes Transparent mode for common signaling channels only Sometimes, even the traffic channels as well as signaling should use transparent mode
- 57. OAI Project Team PDCPFunction ⢠Transfer of Data (C-Plane and U-Plane) between RLC and Higher U-Plane interface ⢠Maintenance of PDCP SN(Sequence Number) ⢠Transfer of SN Status (for use Upon Handover) ⢠ROHC (Robust Header Compression) ⢠In-Sequence delivery of Upper Layer PDUs at re-establishment of lower layer ⢠Elimination of duplicate of lower layer SDUs at re-establishment of lower layer for RLC AM ⢠Ciphering and Deciphering of C-Plane and U-Plane data ⢠Integrity Protection and Integrity verification of C-Plane Data ⢠Timer based Discard ⢠Duplicate Discard ⢠For split and LWA bearers, routing and reordering.
- 58. OAI Project Team PDCPin the LTE Protocol Stack
- 59. OAI Project Team LTEPDCP Layer View
- 60. OAI Project Team RRCFunction ⢠Broadcast of System Information related to the non-access stratum (NAS); ⢠Broadcast of System Information related to the access stratum (AS); ⢠Paging; ⢠Establishment, maintenance and release of an RRC connection between the UE and E-UTRAN ⢠Security functions including key management; ⢠Establishment, configuration, maintenance and release of point to point Radio Bearers; ⢠Mobility functions ⢠QoS management functions; ⢠UE measurement reporting and control of the reporting; ⢠NAS direct message transfer to/from NAS from/to UE.
- 61. OAI Project Team RRCState The System Information required by an UE depends on the RRC state of the UE. ⢠RRC Idle ⢠RRC Connected
- 62. OAI Project Team RRC_Idle â˘This state indicates that there is not signaling radio bearer is established i.e. no RRC connection is established. RRC_IDLE state can further characterized as follows - Transfer of broadcast/multicast data to UE. - A UE specific DRX may be configured by upper layers. - UE controlled mobility. - The UE: ⢠Monitors control channels associated with the shared data channel to determine if data is scheduled for it. ⢠Performing neighboring cell measurements and measurement reporting. ⢠Acquires system information
- 63. OAI Project Team RRC_Connected â˘This state indicates that there is signaling radio bearer established i.e. RRC connection is established. RRC_CONNECTED state can be further characterized as follows - Transfer of unicast data to/from an UE, transfer of broadcast/multicast data to UE. - At the lower layers, the UE may configure with a UE specific DRX/DTX - Network Control Mobility, i.e. handover and cell change order with network assistance (NACC) to GEREN. - The UE: ⢠Monitors control channels associated with the shared data channel to determine if data is scheduled for it ⢠Provides channel quality and feedback information Performing neighboring cell measurements and measurement reporting. ⢠Acquires system information.
- 64. OAI Project Team â˘Uplink Scheduling Protocol Layer Architecture - RLC - PDCP - RRC BSR (Buffer Status Report) HARQ - HARQ vs ARQ - Application of HARQ - Process for Uplink ⢠Downlink scheduling Downlink transmission - Downlink transmission procedure - Downlink control information - Channel state information - Downlink MAC control element Hybrid automatic repeat request - Hybrid automatic repeat request - Incremental redundancy - HARQ process - New data indicator - Downlink HARQ - Downlink HARQ process Channel quality - Modulation coding scheme, Modulation - Channel quality indicator Discontinuous Reception ⢠Overview porting OAI UE Tutorial 64 Uplink Scheduling - BSR
- 65. OAI Project Team UplinkScheduling 65 ⢠Uplink Data Transmission Scheduling - Persistent Scheduling : UE can send UL data every time - Non-Persistent Scheduling : UE will always ask NW to send UL Grant (DCI 0) eNB UE PUCCH Scheduling Request PDSCH DCI format 0 PUSCH Uplink Data PHICH Send ACK/NACK eNB UE PDCCH DCI format 1, DCI format 0 PCFICH CFI value PUCCH UCI (Carrying ACK/NACK) PUSCH Uplink Data PHICH Send ACK/NACK Persistent Non Persistent
- 66. OAI Project Team BufferStatus Report BSR is a kind of MAC Control Element, which carrying an information on how much data in UE buffer from UE to Network ⢠Allocate UL resources only when a particular UE has something to transmit. ⢠Avoid allocating resources when UE has nothing to transmit to save network resources.
- 67. OAI Project Team Classificationof BSR ⢠Data Structure - Short BSR - Long BSR ⢠BSR Timing - Regular BSR - Periodic BSR - Padding BSR 67 Scheduling Request Buffer Status Report This mechanism avoid wasting resource allocation 1. eNB have no idea amount of UL Grant needed 2. If grant allocation is no sufficient, UE need to retransmit
- 68. OAI Project Team BufferSize according to Data Structure ⢠Buffer Size bit field size is always 6 which means it can represent only 0~63 68
- 69. OAI Project Team RegularBSR ⢠BSR will be sent by UE if : - UE has some data to transmit in RLC or PDCP entity for a certain LCG. - New Data Arrives in UL Buffer and no already existing data - New Data has a higher priority than those which wait in UL Buffer - RetxBSR-Timer expires and the UE has data available for transmission ⢠If there are UL Resources for new Transmission, transmitted on the allocation resource ⢠If no UL resources, triggers scheduling request 69
- 70. OAI Project Team PeriodicBSR ⢠Timer Controlled periodic reporting ⢠Trigerred if periodicBSR-Timer expires ⢠Tranmitted on UL resources allocated for new Tranmission 70
- 71. OAI Project Team PaddingBSR ⢠Transmitted, instead of padding, on UL resources allocated for new transmission if there are enough padding bits ⢠Number of padding bits after UL grant is allocated is equal to or larger than the size of the Buffer Status Report MAC CE and its subheader. 71
- 72. OAI Project Team Whenis Long or Short BSR sent? 72 if( the number of LCG with allocated data > 1) --> Long BSR else --> Short BSR if( the number of padding bit >= the size of the Short BSR plus its subheader && the number of padding bit <= the size of the Long BSR plus its subheader) { if( the number of LCG with allocated data > 1) --> Truncated BSR else --> Short BSR } else { --> Long BSR } Periodic & Regular BSR Padding BSR
- 73. OAI Project Team â˘Uplink Scheduling Protocol Layer Architecture - RLC - PDCP - RRC BSR (Buffer Status Report) HARQ - HARQ vs ARQ - Application of HARQ - Process for Uplink ⢠Downlink scheduling Downlink transmission - Downlink transmission procedure - Downlink control information - Channel state information - Downlink MAC control element Hybrid automatic repeat request - Hybrid automatic repeat request - Incremental redundancy - HARQ process - New data indicator - Downlink HARQ - Downlink HARQ process Channel quality - Modulation coding scheme, Modulation - Channel quality indicator Discontinuous Reception ⢠Overview porting OAI UE Tutorial 73 Uplink Scheduling - HARQ
- 74. OAI Project Team HARQVs ARQ ARQ HARQ
- 75. OAI Project Team Applicationof HARQ
- 76. OAI Project Team ULHARQ ⢠Synchronous protocol - Retransmission occurs at a pre-defined time after the initial transmission - The process number can be implicitly derived ⢠Non-adaptive protocol, âtypicallyâ ⢠Retransmission must occur at the same frequency resources and with the same transmission format as the initial transmission ⢠Adaptive retransmission are sometimes needed ⢠to avoid fragmenting the uplink frequency resource ⢠to avoid collisions with random-access resources
- 77. OAI Project Team HARQProcess for Uplink ⢠it have to use the specific process in a specific subframe called Synchronous ⢠There are two mode of operations : Adaptive and Non-Adaptive HARQ Adaptive HARQ Non Adaptive HARQ
- 78. OAI Project Team HARQProcedure Example ⢠Non-adaptive and adaptive HARQ procedure example in UL
- 79. OAI Project Team HARQTiming ⢠Timing relation betweenw downlink data in subframe n and uplink HARQ acknowledgement in subframe n+4 for FDD is as in the figure below ⢠Upon reception of HARQ acknowledgement, eNB can, if needed, retransmit the downlink data in subframe n+8 - 8 HARQ processes are used - HARQ round-trip time is 8ms
- 80. OAI Project Team â˘Uplink Scheduling Protocol Layer Architecture - RLC - PDCP - RRC BSR (Buffer Status Report) HARQ - HARQ vs ARQ - Application of HARQ - Process for Uplink ⢠Downlink scheduling Downlink transmission - Downlink transmission procedure - Downlink control information - Channel state information - Downlink MAC control element Hybrid automatic repeat request - Hybrid automatic repeat request - Incremental redundancy - HARQ process - New data indicator - Downlink HARQ - Downlink HARQ process Channel quality - Modulation coding scheme, Modulation - Channel quality indicator Discontinuous Reception ⢠Overview porting OAI UE Tutorial 80 Downlink Scheduling - Downlink transmission
- 81. OAI Project Team Downlinktransmission procedure 81 UE eNB CSI PUCCH DCI1 PDCCH(without DCI0) Downlink Data:initial PDSCH ACK/NACK PUCCH (If no Grant(no DCI0)) Downlink Data:new data or retransmission PDSCH ACK/NACK PUCCH http://msc-generator.sourceforge.net v6.1 UE eNB CSI PUSCH DCI1 PDCCH(with DCI0) Downlink Data:initial PDSCH ACK/NACK PUSCH (If Grant(DCI0)) Downlink Data:new data or retransmission PDSCH ACK/NACK PUSCH http://msc-generator.sourceforge.net v6.0
- 82. OAI Project Team DCI(Downlink control information) ⢠DCI carries those detailed information - Which resource block carries data - Which demodulation scheme use to decode data - Resource allocation - Power control command - CSI report request - CQI report request ⢠Downlink control information: - Format 1, 1A, 1B, 1C, 1D, 2, 2A, 2B, 2C 82 without DCI, UE canât decoding the data from eNB
- 83. OAI Project Team CSI(Channel State Information) ⢠CSI: UE report channel status information to eNB ⢠CSI is a kind of collective name of several different type of indicators - Channel Quality Indicator(CQI) - precoding matrix indicator (PMI) - precoding type indicator (PTI) - rank indication (RI) 83 UE eNB UE get CSI Report CQI to eNB eNB consider channel quality Transmit MCS by DCI
- 84. OAI Project Team DownlinkMAC control element ⢠MAC control element: special MAC structure carrying the control information. - This special MAC structure is implemented as a special bit string in LCID field of MAC Header. 84 Values of LCID for DL-SCH MAC PDU MAC sub-header R: Reserved bit E: Extension field LCID: Logical Channel ID field
- 85. OAI Project Team â˘Uplink Scheduling Protocol Layer Architecture - RLC - PDCP - RRC BSR (Buffer Status Report) HARQ - HARQ vs ARQ - Application of HARQ - Process for Uplink ⢠Downlink scheduling Downlink transmission - Downlink transmission procedure - Downlink control information - Channel state information - Downlink MAC control element Hybrid automatic repeat request - Hybrid automatic repeat request - Incremental redundancy - HARQ process - New data indicator - Downlink HARQ - Downlink HARQ process Channel quality - Modulation coding scheme, Modulation - Channel quality indicator Discontinuous Reception ⢠Overview porting OAI UE Tutorial 85 Downlink Scheduling - HARQ
- 86. OAI Project Team HARQ(hybrid automatic repeat request) ⢠HARQ = FEC(forward error correction) + ARQ(automatic repeat request) ⢠HARQ in MAC layer: retransmission loss or wrong data more qrickly. ⢠Classification: - Time domain: synchronous and asynchronous - Frequency domain: adaptive and non-adaptive 86 HARQ Downlink Uplink Time domain asynchronous synchronous Frequency domain adaptive adaptive and non-adaptive
- 87. OAI Project Team Incrementalredundancy ⢠HARQ with soft combining: - Chase combining and incremental redundancy ⢠Use âincremental redundancyâ in LTE. 87 RV RV: Redundancy Version Value: 0 ~ 3
- 88. OAI Project Team HARQprocess ⢠HARQ use âstop-and-wait protocolâ to send data. ⢠In LTE, we use âMultiple parallelâ stop-and-wait process. 88 Multiple parallel HARQ process HARQ entity 8 HARQ process
- 89. OAI Project Team NDI(newdata indicator) ⢠NDI : parameter of HARQ - Same NDI ď the same HARQ process ď stored in HARQ buffer to soft combining (retransmission) - Different NDI ď different HARQ process ď clear the HARQ buffer (new transmit) 89 0 1 0 0 0 1 0 0 0 1 0 0 0 NDI toggled
- 90. OAI Project Team DownlinkHARQ ⢠Downlink HARQ asynchronous: - Retransmission can happen at anytime. (ie. HARQ process can be used in any order.) - It is the reason why we need DCI which contain HARQ process number. (The eNB will clearly tell the UE about the current HARQ process. ) ⢠Downlink HARQ adaptive: - It means that eNB can change retransmission PRB and MCS. (ie. eNB need to reschedule downlink retransmission.) 90
- 91. OAI Project Team DownlinkHARQ process 91 UE Base_Station DCI1(Downlink Assignment) PDCCH(with/without DCI0) New Downlink Data PDCCH ACK/NACK PUCCH(No grant,no DCI0) ACK/NACK PUSCH(grant,with DCI0) If NACK DCI1(Downlink Assignment) PDCCH(with/without DCI0) Retransmit Downlink Data PDSCH(with/without DCI0) http://msc-generator.sourceforge.net v6.1 4 sub-frame delay At least 4 sub-frame delay
- 92. OAI Project Team DownlinkHARQ process ⢠PDCCH : for DCI ⢠PDSCH : for data 92
- 93. OAI Project Team â˘Uplink Scheduling Protocol Layer Architecture - RLC - PDCP - RRC BSR (Buffer Status Report) HARQ - HARQ vs ARQ - Application of HARQ - Process for Uplink ⢠Downlink scheduling Downlink transmission - Downlink transmission procedure - Downlink control information - Channel state information - Downlink MAC control element Hybrid automatic repeat request - Hybrid automatic repeat request - Incremental redundancy - HARQ process - New data indicator - Downlink HARQ - Downlink HARQ process Channel quality - Modulation coding scheme, Modulation - Channel quality indicator Discontinuous Reception ⢠Overview porting OAI UE Tutorial 93 Downlink Scheduling - Channel quality
- 94. OAI Project Team Modulation â˘Modulation: Located in the MAC of the eNB side, whose function is to make good use of the radio resources of the uplink and downlink channels. - The two schedulers on the uplink and the downlink respectively control the operation of the schedule. - Allocate resources and codes on the physical layer to the uplink and downlink transmission channels respectively. ⢠There are three modulation modes in LTE. - QPSK - 16QAM - 64QAM 94
- 95. OAI Project Team MCS(Modulation coding scheme) ⢠Modulation Coding Scheme is related to Modulation Order. - Modulation order is defined as a Parameter called Qm. ⢠Code rate: How many percentages of real data are in a transmission. - Ex. 5/6: data ď 5 checksum ď 1 - Channel signal is well ď 64QAM - Channel signal is bad ď QPSK 95 Qm Modulation Method 2 QPSK 4 16QAM 6 64QAM
- 96. OAI Project Team CQI(Channel quality indicator) ⢠CQI is the information that UE sends to the network via PUCCH (periodic CQI) or PUSCH (aperiodic, period CQI) - Current communication channel quality - UE wants to get the data with transport block size ⢠The CQI value ranges from 0 ~ 30 - 30 indicates the best channel quality - 0,1 indicates the poorest channel quality 96
- 97. OAI Project Team CQI(Channel quality indicator) ⢠UE reports low CQI ď cause waste of radio resources 97 UE Base Station Too big transport block Failed to decode it Report low CQI Retransmission Response NACK
- 98. OAI Project Team CQI(Channel quality indicator) ⢠Base station gets âhighâ CQI value from UE ď transmit the data with âlargerâ transport block size ⢠Base station gets âlowâ CQI value from UE ď transmit the data with âsmallerâ transport block size 98
- 99. OAI Project Team â˘Uplink Scheduling Protocol Layer Architecture - RLC - PDCP - RRC BSR (Buffer Status Report) HARQ - HARQ vs ARQ - Application of HARQ - Process for Uplink ⢠Downlink scheduling Downlink transmission - Downlink transmission procedure - Downlink control information - Channel state information - Downlink MAC control element Hybrid automatic repeat request - Hybrid automatic repeat request - Incremental redundancy - HARQ process - New data indicator - Downlink HARQ - Downlink HARQ process Channel quality - Modulation coding scheme, Modulation - Channel quality indicator Discontinuous Reception ⢠Overview porting OAI UE Tutorial 99 Downlink Scheduling - Discontinuous Reception
- 100. OAI Project Team DRX(Discontinuous Reception) ⢠DRX: Itâs kind of mechanism, which can improve the battery life by sleeping for a while there is no data transmission. ⢠While UE in RRC_CONNECTED state, it will deploy a âDRX cycleâ. - DRX cycle = On Duration + Opportunity for DRX - UE receive PDCCH on Duration, otherwise UE will go to sleep 100
- 101. OAI Project Team DRX(Discontinuous Reception) ⢠Case 1: Only Long DRX Cycle is configured and No PDCCH is received during the cycle ⢠Case 2: Only Long DRX Cycle is configured and a PDCCH is received during a cycle 101
- 102. OAI Project Team DRX(Discontinuous Reception) ⢠Case 3: Only Long DRX Cycle is configured and a PDCCH and DRX Command MAC CE are received during a cycle 102
- 103.
- 104. OAI Project Team Reference â˘Sharetechnote â˘ ćˇąĺ Ľç解LTE-A ⢠Spec 36.212 for DCI format ⢠Spec 36.213 for Downlink transmission procedure ⢠Spec 36.321 for MAC control element 104
Editor's Notes
- #7 ćĺ常常說LTEĺ°ąćŻ4Gĺ śĺŻŚä¸Śä¸ćŻé樣ç LTEćŻ4Gçĺ躍ďźćĺäżç¨ą3.9G 4Gćĺ稹ĺŽçşLTE-Advance
- #8Â Characteristic Peak download speeds up to 300 Mbit / s, peak upload speeds up to 75 Mbit / s. (high data rate) Low network latency (small IP packets can have less than 5ms delay under optimal conditions) Save electricity(Download using OFDMA, Upload using SC-FDMA) Support Multicast / Broadcast Single-frequency Network (MBSFN) Supports Frequency Division Duplex (FDD) and Time Division Duplex (TDD) communications
- #10 RRC: RRCéŁçˇćľç¨ćé¨ĺ°ąç RRCéŁçˇççć ĺŻĺçşé罎ĺéŁçľĺ Šç¨Žçć ďźĺ¨ä˝żç¨č ć˛ćčłććč¨ćŻĺłéçéćąćďźRRCéŁçˇćčćźé罎çć ďźć¤ćĺşĺ°ĺ°ä¸ćé 罎çĄçˇčłćşçľŚä˝żç¨č ďźčçśä˝żç¨č ćčłćĺłčź¸éćąćďźäžżć觸çźRRCéŁçˇçć§ĺśčĄçşďźĺ芌ĺ°éŁçˇçć č˝ĺ ĽéŁçľçć ďźé˛ĺ ĽéŁçľçć äšĺžďźä˝żç¨č äžżć袍é 罎çĄçˇčłćşčç˛ĺžčłćĺłčź¸çč˝ĺă  ĺ¨éŁçľçć ä¸ďźRRCéŁçˇćçśčˇçĺ §ĺŽšćŻéćźä¸ĺ使ç¨č ć袍é 罎ĺ°ççĄçˇčłćşäťĽĺ使ç¨č 芲ĺŚä˝éç¨éäşçĄçˇčłćşďźĺ¨éäşçĄçˇčłćşä¸ďźč˝ĺ¤ ç¨äžĺłčź¸čłćçćŻçĄçˇéťćżčź(Radio Bearer, RB)ďźĺ¨ĺťşçŤRRCéŁçˇçéç¨ä¸ć袍坺罎ĺ¤ć˘RBďźéäşRBäžç¨éĺĺŻč˘Ťĺć俥䝤çĄçˇéťćżčź(Signaling Radio Bearer, SRB)ĺčłćçĄçˇéťćżčź(Data Radio Bearer, DRB)ďźSRBç¨äťĽĺłčź¸RRCĺ幤çć§ĺśč¨ćŻďźDRBĺç¨äžĺłčź¸ä˝żç¨č ç眲衯ĺ°ĺ ďźçąćźä˝żç¨č ćłé˛ĺ ĽéŁçľçć çççąĺ°ąćŻčłćĺłčź¸ďźĺ ć¤RRCéŁçˇçć§çŽĄéç¨ä¸ďźéčŚçäžżćŻĺ°ĺć˘RBçĺťşçŤĺ使ç¨ďźäťĽä¸ĺ°ĺ°ąRRCéŁçˇçĺé掾ć§çŽĄćľç¨ĺäťç´šă
- #11 ĺ ĺŤ ä˝żç¨č é˘(User Plane)čć§ĺśé˘(Control Plane)čłćĺłé PDCPĺşčçśčˇ čłćĺ č§ŁĺŻ ç˘şäżä¸ĺą¤čłćĺ°ĺ ćźéĺťşćçé ĺşćŁç˘şĺä¸éč¤ ć¨é ĺŁç¸Ž/解ĺŁç¸Žĺč˝(ĺŞéŠç¨ćźDRB čłćĺŽć´ć§äżčˇ(ĺ éŠç¨ćźSRB Control plane: Transmit the command from RRC Implement the related configuration from RRC User plane: Receive the IP data from upper layer Package IP data into a packet and transmit to RLC
- #12 TM:çşç´ćĽçŠżé樥ĺźďźčłćä¸é ĺ¨RLC幤é˛čĄéć°ĺ°čŁç塼ä˝ďźSDUĺłçşPDUăThe information does not need to be re-packaged in RLC layer AMăUM塎ĺĽ: ćŻĺŚćŻć´ARQĺč˝é˛čĄĺĺ Whether to support the ARQ function to distinguish ćżčŞć¨Ąĺźé ćŻć´ARQĺč˝ďźčéćżčŞć¨Ąĺźĺä¸ćŻć´ARQĺč˝ MACĺż é ĺ¨ćĽćśçŤŻĺ°ćźPDUćĽćśççľćé˛čĄĺĺ ąďźĺĺ ąçľćçşćĽćśćĺ(ACK)ććĽćśĺ¤ąć(NACK)ďźçśçľćçşNACKćďźRLCçĺłéçŤŻĺż é é˛čĄéĺł
- #13 MAC丝čŚĺč˝ćŻĺ°ä¸ĺçĄçˇćżčźé˛čĄRA玥çăçĄéčłćşĺé ďźĺ ćŹMCS(modulation and coding scheme)ăRB(resource block)čCCE(channel control elemaent)çé¸ćăĺ¤ĺˇĽäťĽĺHARQćŠĺśçă MAC entityééćąşĺŽćŻĺçĄçˇćżčźçć¸ć總é䝼ĺć示RLC幤ććäžçĺ°ĺ 大ĺ°ďźäžä˝żćŻĺçĄçˇćżčźé˝č˝ĺä¸ĺŽĺŞĺ ç´ć˘äťśä¸é˛čĄĺłčź¸ďźĺ çşčłćşé˝ćŻĺ ąäşŤçďźć䝼ĺ¨čć ŽĺŞĺ ç´çĺćďźĺ°çĄçˇčłćşçćçć§ĺĺ Źĺšłć§é˝ĺ°MACç富çžćĺşäşć´éŤçčŚćąă The main function of the MAC is to perform RA management and radio resource allocation for different radio bearers Including MCS, RB, CCE, multiplexing, HARQ.
- #14 FEC:ćŻĺ˘ĺ ć°ćŽé莯ĺŻäżĄĺşŚçćšćł
- #15 â˘One frame =10 ms. â˘One Frame = 10 subframes. â˘One subframe = 1.0 ms (=TTI) â˘One subframe = 2 slots. â˘One slot = 0.5 ms. â˘One Slot = either 6 or 7 ODFM symbols, depending on whether the normal or extended cyclic prefix is employed. âOne slot = 3 symbols when 7.5KHz subchannel is used. â˘Each 1ms Transmission Time Interval (TTI) consists of two slots (Tslot). CPçĺŞçźşéťé常簥ĺŽă ĺŞ:ćśé¤äşISI Eliminate ISI (inter symbol interference) çźş:ć¸ĺ°äşĺŻäťĽĺ¨ç¸ĺćéééĺ §ĺłčź¸ç珌čć¸é Reduce the number of symbols that can be transmitted in the same time interval â˘Normal CP: with a duration of 4.7 microseconds. â˘Extended CP: with a duration of 16.67 microseconds.
- #18Â In order to specify the advanced explanation just study through this link https://en.wikipedia.org/wiki/Radio_access_network
- #20Â Logical channel PCCH (Paging control channel) Paging, does not use HARQ procedure (no retransmission mechanism). PCCH is mapped only to PCH. BCCH (Broadcast control channel) MIB, SIB BCCH for MIB is mapped to BCH and BCCH for SIB is mapped to DL-SCH CCCH (Common control channel) Signaling message DCCH (Dedicated control channel) Signaling message, DCCH is mapped to DL-SCH DTCH (Dedicated traffic channel) User data, DTCH is mapped to DL-SCH MTCH (Multicast traffic channel) MBMS MCCH (Multicast control channel) MBMS Transport channel PCH (Paging channel) P-RNTI use to paging and system information BCH (Broadcast channel) DL-SCH (Downlink shared channel) MCH (Multicast channel)
- #22 When you switch on smartphone for the very first time, it will start searching for the network. There are many frequencies from different operators available in the air to which UE can connect. Therefore, UE needs to synchronize to each frequency and check whether this is frequency from the right operator to which it wants to connect to. UE does this by going through very initial synchronization process. Once synchronized UE reads the master information block and System information blocks to check whether this is the right PLMN. Letâs assume that it finds that PLMN value to be correct and so UE will proceed with reading System information block 1 and System information block 2. The next step is known as Random Access Procedure in which the network for the first time knows that some UE is trying to get access. çść¨çŹŹä¸ćŹĄćéćşč˝ććŠćďźĺŽĺ°éĺ§ć索眲羥ă UEĺŻäťĽéŁćĽĺ°ç犺ä¸ćä¸ĺéçĺĺŻç¨ç訹ĺ¤é ťçă ĺ ć¤ďźUEéčŚčćŻĺé ťçĺćĽďźä¸ŚćŞ˘ćĽéćŻĺŚćŻäžčŞćŁç˘şçéçĺçé ťçďźĺŽćłčŚéŁćĽĺ°ĺŞĺé ťçă UEééé˛čĄé常ĺĺ§çĺćĽéç¨äžĺĺ°éä¸éťă ä¸ćŚĺćĽUEčŽĺ丝俥ćŻĺĄĺ糝羹俥ćŻĺĄďźäťĽćŞ˘ćĽéćŻĺŚćŻćŁç˘şçPLMNă ĺč¨ĺŽçźçžPLMNĺźćŻćŁç˘şçďźĺ ć¤UEĺ°çšźçşéąčŽçłťçľąäżĄćŻĺĄ1ĺ糝羹俥ćŻĺĄ2ă ä¸ä¸ćĽç¨ąçşé¨ćŠč¨Şĺéç¨ďźĺ śä¸çś˛çľĄéŚćŹĄçĽéćäşUEćŁĺ¨ĺ芌訪ĺ Start searching for the network. UE check the frequency from the right operator to which it wants to connect to. Check whether this is the right PLMN after receive MIB and SIB UE will proceed with reading System information block 1 and System information block 2. The next step is known as Random Access Procedure
- #23Â Scenario / Main purpose: Get frequency and symbol synchronization from cell. Get the system frame timing (the starting position of frame) Determine the PCI (physical-layer cell identity) In order to support mobility, UE will keep searching its neighbor community, synchronize and estimate the reception quality of the community signal. Handover(UE in RRC_CONTECTED status) cell re-selection(UE in RRC_IDLE status)
- #24 寚äşFDDčč¨ďźPSSĺ¨ĺ帧0ĺ5ç珏ä¸ä¸Şslotçćĺä¸ä¸Şsymbolä¸ĺéďźSSSä¸PSSĺ¨ĺä¸ĺ帧ĺä¸slotĺéďźä˝SSSä˝äşĺć°çŹŹäşä¸Şsymbolä¸ďźćŻPSSćĺä¸ä¸Şsymbol
- #25 PSS uses a length of 63 Zadoff-Chu sequence Plus 5 additional subcarriers reserved for the guard band by the border, PSS has 3 values, corresponding to three different Zadoff-Chu sequences, each corresponding to a N PSSć3个ĺĺźďźĺŻšĺşä¸ç§ä¸ĺçZadoff-ChuĺşĺďźćŻç§ĺşĺ寚ĺşä¸ä¸ŞNid(2)ă ć个ĺ°ĺşçPSS寚ĺşçĺşĺçąčŻĽĺ°ĺşçPCIĺłĺŽďźĺłÂ % 3ă äť36.211ç6.11.1.1ĺŻäťĽçĺşďźä¸ĺç寚ĺşä¸ĺçRoot index uďźčżčĺłĺŽäşä¸ĺZadoff-Chuĺşĺďźč§ĺž3ďźă UE为äşćĽćśPSSďźäźä˝żç¨36.211ä¸Table 6.11.1.1-1ćĺŽçRoot index ućĽĺ°čŻč§Łç PSSďźç´ĺ°ĺ śä¸ć个Root index ućĺ解ĺşPSS为ć˘ă čżć ˇďźUEĺ°ąçĽéäşčŻĽĺ°ĺşçăĺçąäşPSSĺ¨ćśĺä¸çä˝ç˝ŽćŻĺşĺŽçďźč§ĺž1ďźďźĺ ć¤UEĺĺŻäťĽĺžĺ°čŻĽĺ°ĺşç5 ms timing ďźä¸ä¸Şçłťçťĺ¸§ĺ ć两个PSSďźä¸čżä¸¤ä¸ŞPSSçç¸ĺçďźĺ ć¤UEä¸çĽé解ĺşçPSSćŻçŹŹä¸ä¸ŞčżćŻçŹŹäşä¸Şďźć䝼ĺŞč˝ĺžĺ°5 ms timingďźă
- #26 Extended CPĺŻäťĽć´ĺĽ˝çćĺśĺ¤ĺžĺťśé˛é ćç珌čé嚲ćžăčźé ťé嚲ćžďźä˝ćŻĺŽä¸ĺćéĺŞč˝ĺł6ĺOFDMďźĺNormal CPç¸ćŻäťŁĺšćŻć´ä˝ç糝羹厚éďźĺ¨LTE FDDä¸éťčŞä˝żç¨Normal CPă UEĺ¨ćŁćľĺ°SSSäšĺďźčżä¸çĽé诼ĺ°ĺşćŻĺˇĽä˝ĺ¨FDDčżćŻTDD樥ĺźä¸ ĺ śćŹĄďźSSSç祎ĺä˝ç˝ŽčżĺCPďźCyclic PrefixďźçéżĺşŚćĺ łă ĺ¨ć¤éśćŽľďźUEčżä¸çĽéĺ°ĺşçCPé 罎ďźNormal CPčżćŻExtended CPďźďźĺ ć¤äźĺ¨čżä¸¤ä¸ŞĺŻč˝çä˝ç˝Žĺťç˛ćŁSSSăďźéčżćŁćľSSSďźUEçĽéĺ°ĺşçCPé 罎
- #27 ĺŚććŻĺĺ§ĺćĽďźć¤ćśUEčżć˛Ąć銝çćčżćĽĺ°ä¸ä¸ŞLTEĺ°ĺşďźďźĺ¨ćŁćľĺŽĺćĽäżĄĺˇäšĺďźUEäźč§Łç PBCHďźäťĽčˇĺćéčŚççłťçťäżĄćŻă ĺŚććŻčŻĺŤéťĺą ĺ°ĺşďźUEĺšśä¸éčŚč§Łç PBCHďźčĺŞéčŚĺşäşćć°ćŁćľĺ°çĺ°ĺşĺč俥ĺˇćĽćľéä¸čĄäżĄĺˇč´¨éć°´ĺšłďźäťĽĺłĺŽćŻčżčĄĺ°ĺşééďźUEĺ¤äşRRC_IDLEćďźčżćŻhandoverďźUEĺ¤äşRRC_CONNECTEDćăć¤ćśUEäźéčżRSRPĺ°čżäşćľéçťćä¸ćĽçťćĺĄĺ°ĺşďźĺłĺŽćŻĺŚčżčĄhandoverďź RSRP Reference Signal Receiving Power The key parameter representing the strength of the wireless signal in the LTE network is the average of the signal power received on all REs carrying the reference signal within a symbol. -140 ~ -43dBm RSSI Received Signal Strength Indicator It refers to the total power of the received mobile phones, including the desired signal, interference and noise floor. -100 ~ -20dBm RSRQ Reference Signal Receiving Quality RSRQ=10log(N)+(RSPR-RSSI) Represents the LTE reference signal reception quality, this measure is mainly based on the signal quality of different LTE candidate community to sort. This measurement is used as input for handover and community reselection decisions -20 ~ -3dB SINR Signal to Interference plus Noise Ratio It refers to the ratio of the intensity of the useful signal received with the intensity of the received interference signal, which can be understood as the signal-to-noise ratio -10 ~ 40dB
- #29 ĺ: Located on the BCH time domain First 4 OFDM symbols in the 2nd slot of subframe 0 (ĺ帧0ç珏2个slotçĺ4个OFDM symbol
- #30 Not all SIBs must exist. For example, for the operator's base station, SIB9 is not needed, and if a cell does not provide MBMS, SIB13 is not needed. MIBĺSIB1ĺ¨ćĺä¸çä˝ç˝Žĺĺ¨ććŻĺşĺŽçďźčSIćśćŻĺ¨ćĺä¸çä˝ç˝Žĺĺ¨ććŻçąSIB1ćĺŽçă eNodeB ĺŞćééSystemInformationBlockType1ĺ訴UEćĺŞäşSIďźćŻĺSIĺ ĺŤäşĺŞäşSIBďźéäşSIćĺ¨ĺŞĺSIçŞĺŁçźé䝼ĺSIçŞĺŁçćĺä˝ç˝ŽĺéˇĺşŚďźä˝ä¸ćĺ訴UEĺ¨SIçŞĺŁçĺŞäşĺĺščŞżĺşŚäşčŠ˛SIă çśUEéčŚćĺSIBćďźĺŽĺ°ąćĺ¨čŠ˛SIBĺ°ćçSIćśćŻĺ°ćçSIçŞĺŁçćŻĺĺĺšďźĺžSIçŞĺŁç辡ĺ§ĺĺšéĺ§ďźĺ ąćçşsi-WindowLengthĺĺĺšďźä˝ä¸ĺ ĺŤéŁäşä¸č˝čŞżĺşŚSIçĺĺšďźďźä˝żç¨SI-RNTIĺťĺ芌解碟ďźç´ĺ°ćĺćĽćśĺ°SIćśćŻçşć˘ă
- #32 ééć芲čŚç¨ĺžŽäťç´šä¸ä¸RNTIďźRNTIçvalueĺž0-65535 çąćźćĺĺ¨ä¸ćŽľbandwidth裥ćĺ¤ĺPRBďźćĺčŚčçąä¸ĺçRNTIčŽUEçŽĺşäťčŠ˛ĺžĺŞĺPRBéĺ§ĺłé/ćĽćśčłćă ĺ°ćźä¸ĺçŽçć§çUEććä¸ĺçRNTIďźĺ ć¤UEĺŻäťĽčçąéĺčłč¨ĺťĺĺžäťĺćłčŚçč¨ćŻă Function: Identity of the UE Each UE may correspond to multiple RNTIs simultaneously. With different RNTIs, UE calculates which PRB from which to start transmitting / receiving data RNTI : Inside the signal information between the UE and the UTRAN, it is used as an identifier of the UE (ĺ¨UE ĺUTRAN äšéç俥č俥ćŻĺ §é¨ä˝çşUE çć¨č) RNTIĺłçĄçˇçś˛çľĄč¨ćć¨čďźĺ¨LTEä¸ćç §ĺč˝çä¸ĺďźĺĺäşĺ¤ç¨ŽRNTIďźćŻĺUEĺŻäťĽĺćĺ°ćĺ¤ĺRNTIă ééç¨RNTIĺ°PDCCHć§ĺśćśćŻĺ ćžçćšĺźďźĺŻŚçžçłťçľąĺťŁćăçšĺŽçç¨ćśčŞżĺşŚçĺč˝ă Functions such as system broadcast and specific user scheduling are implemented by using the RNTI to scramble the PDCCH control message. C-RNTI : ç¨ćźĺć 調庌çPDSCHĺłčź¸ PDSCH transmission for dynamic scheduling RA-RNTI : ç¨ćźé¨ćŠćĽĺ ĽéżćďźRARďźRA-RNTI: Used for Random Access Response (RAR) SI-RNTI : ç¨ćźć¨čSIBćśćŻçĺłčź¸ Used to identify the transmission of SIB messages P-RNTI : ç¨ćźć¨čĺ°ĺźćśćŻçĺłčź¸ Used to identify the transmission of paging messages
- #33Â UE also needs to give its own identity to the network so that network can address it in next step. Typical 'Contention Free' RACH Procedure is as follows : Â
- #34 i) Initial access from RRC_IDLE ii) RRC Connection Re-establishment procedure iii) Handover (Contention Based or Non Contetion Based) iv) DL data arrival during RRC_CONNECTED requiring random access procedure     E.g. when UL synchronisation status is ânon-synchronisedâ v) UL data arrival during RRC_CONNECTED requiring random access procedure     E.g. when UL synchronisation status is "non-synchronised" or there are no PUCCH resources for SR available. vi) For positioning purpose during RRC_CONNECTED requiring random access procedure;     E.g. when timing advance is needed for UE positioning
- #36 UEéčżRARć希çRA-RNTIĺpreamble indexćĽçĄŽĺŽćŻĺŚćĺćĽćśĺ°čŞĺˇąćłčŚçRARďźçśĺĺčżčĄĺçťĺ¤ç UEĺéäşpreambleäšĺďźĺ°ĺ¨RARćśé´çŞďźRA Response windowďźĺ çĺŹPDCCHďźäťĽćĽćśĺŻšĺşRA-RNTIçRARă ĺŚćĺ¨ć¤RARćśé´çŞĺ 沥ććĽćśĺ°eNodeBĺĺ¤çRARďźĺ莤为ć¤ćŹĄéćşćĽĺ Ľčżç¨ĺ¤ąč´Ľă RARćśé´çŞčľˇĺ§äşĺépreambleçĺ帧ďźĺŚćpreambleĺ¨ćśĺä¸čˇ¨ĺ¤ä¸Şĺ帧ďźĺ䝼ćĺä¸ä¸Şĺ帧莥çŽďźÂ + 3个ĺ帧ďźĺšśćçťra-ResponseWindowSize个ĺ帧ă č¨ćC-RNTIďźFor Msg3 transmission, conflict resolution ĺ°ćźUEçĺĺ§čşŤäť˝čŞčďźĺŚćRAćĺďźĺĺ°čŠ˛č¨ć躍䝽čŞčč˝ćçşćŁĺźç躍䝽ć¨čă For the initial identity authentication of the UE, if the RA successfully succeeds, this temporary identity authentication will be converted to a formal identity identification. ĺŽććĺĺźďźInform the transmission time of uplink data between UE and eNB. ä¸čĄććŹčłćşďźInform the UE of the next uplink data transmission resources
- #37 ĺşćźé獜ççé¨ćŠćĽĺ Ľďź preamblećŻćĺUEĺ°ç¨çďźć䝼ä¸ĺĺ¨čĄçŞďźĺĺ çşčŠ˛UE塲çśććĺ¨ćĽĺ Ľç¤žĺĺ §çĺŻä¸ć¨čŞC-RNTIďźć䝼äšä¸éčŚeNodeB羌ĺŽĺé C-RNTIă UE identity (TMSI or Random Value ) TMSI is used if UE has previously connected to the same network. With TMSI value, UE is identified in the core network Random value is used if UE is connecting for the very first time to network. çąćźeNBĺ¨ĺ¤ĺUEé¸ĺ°ĺä¸ĺpreambleçć ćłä¸ďźčŚçĺ°Msg3ćč˝ĺŻčŚş(ĺĺTC-RNTIä¸ĺUE_id)ďźĺ ć¤UEĺŚćć˛ćśĺ°Msg4ďźĺžćĺŻč˝ĺ°ąćŻç˘°ćäşďźč¨ä¸ĺtimerćä¸ćčŽĺĽšä¸ç´ç
- #38 eNodeBĺ¨ćĽéŠ3ä¸ćĺćĽćśĺ°ĺ śćśćŻč˘ŤćĺćĽćśĺ°çUEççç¨č§ŁćąşćśćŻă芲ćśćŻćŻéĺ°TMSIĺźćé¨ćŠć¸ďźäžčŞĺé˘çćĽéŠďźçĺ°ĺďźä˝ćŻĺ ĺŤĺ°č˘Ťç¨ćźé˛ä¸ćĽé俥çć°C RNTI In RRC_CONNECTED state UE has C-RNTI In step 3, Msg3 will bring this C-RNTI to the eNodeB through the C-RNTI MAC control element In step 4, The eNodeB uses this C-RNTI to scramble the PDCCH. The UE receives the PDCCH scrambled with this C-RNTI and knows that the access is successful. Not in RRC_CONNECTED state In step 3, Msg3 will bring the unique flag to eNodeB In step 4, The eNodeB sends back the information of step 3 to the UE through the UE Contention Resolution Identity MAC Control Element
- #40Â format is composed of cyclic prefiex with the sequence
- #41 ĺžéäşč¨ćŻ ćĺĺŻäťĽçĽépreamble sequencećŻäťéşź éäşčłč¨ćĺĺŻäťĽĺžSib2 prach-ConfigçĽéäťçĺź
- #42 âPRACHé 罎索ĺźâçĺć¸ç˛žç˘şĺ°éĄŻç¤şUEä˝ććçśçźéRââACH EX. ĺŚćPRACHé 罎索ĺźćŻ10ďźĺŚäťĽä¸ç¤şäžć示ďźĺ使ç¨ĺĺ°ç˘źć źĺź0 使ç¨ĺŞĺâPRACH Configuration Idexâďźçś˛çľĄć厚ć檢渏äžčŞUEçRACHďźçşäťéşźďź çćĄćŻ14ďźĺ çşUEĺŻäťĽĺ¨äťťä˝SFNĺĺšĺ §çäťťä˝ćéçźéRACHă
- #43 prach-FreqOffsetćŻç˘şĺŽPRACHĺĺ°ç˘źĺ¨é ťĺä¸çä˝ç˝Žçĺć¸ăé ťĺä¸çéĺä˝ç˝ŽäťĽPRMćć¸çşĺŽä˝é˛čĄč¨çŽä¸Śéé䝼ä¸ćšç¨é˛čĄĺĺşă f_RAćŻä¸ä¸Şé˘çä˝ç˝Žçłťć°ďźç¨äşčŽĄçŽPRACHĺ ç¨çRB辡ĺ§ä˝ç˝Žn_RA_PRB PRACHĺşĺŽĺ 6个RBďźĺ ć¤LTEćŻćç希厽ä¸č˝ĺ°äş6个RB ďźEach random access preamble occupies a bandwidth corresponding to 6 consecutive resource blocks for bothframe structures.ďźă
- #48 1ďźeNodeBčŚçźéä¸čĄć¸ććďźçźçžä¸ĺ¤ąäşUEçä¸čĄĺćĽďźĺŽć埡ĺśUEéć°çźčľˇé¨ćŠćĽĺ Ľéç¨äťĽç˛ĺćŁç˘şçćé調ć´éďź When the eNodeB needs to send downlink data, finding that the UE's uplink synchronization is lost, it will force the UE to re-initiate the random access process to obtain the correct time adjustment value. 2ďźUEĺŽä˝ăéćeNodeBćééçšćŽçDCI format 1A ĺ訴UEéčŚéć°çźčľˇé¨ćŠćĽĺ Ľďźä¸Śĺ訴UEć芲使ç¨çPreamble IndexĺPRACH Mask Indexă In this case, the eNodeB will inform the UE that it needs to restart random access through a special DCI format 1A, and notify the UE of the Preamble Index and the PRACH Mask Index that should be used.
- #50 TTI(Transmission Time Interval)ďźčłćźäťéşźćŻTTIďźćŻćĺşĺ°ĺ°çľŚç¨ćśĺŽćčłćşçĺŽä˝ćéďźéĺĺ°ąćŻĺŤSchduelingăLTEćŻ1msă ć¤ćä¸čĄć¸ćĺłčź¸çćľç¨čŽçşďź       1ďźUE çźépreambleďź Â Â Â Â Â Â 2ďźeNodeBĺĺ¤RARďźRARć帜äşUL grant俥ćŻďź       3ďźUEéĺ§çźéä¸čĄć¸ćă äťéşźć ćłUEĺŻč˝ćć˛ćSRčłćşĺ˘ďź çśUEä¸ĺ¤ąäşä¸čĄĺćĽďźĺŽäšćéćžSRčłćş çśUEć˛ć袍ĺé SRčłćşćďźĺşćźçŤśççrandom accessĺŻäťĽćżäťŁSRçĺč˝ç¨ćźçłčŤä¸čĄčłćş ĺ çş out of syncďźĺŚććdownlinkčŚĺłďźeNBĺż é 丝ĺĺťşçŤRAéŁçľďźć䝼DCI 1AĺŻäťĽĺ訴UEćéşźéĺ§ĺłpreambleă
- #57Â TTA LTE/MIMO Standards/Technology Training
- #66Â In Persistent scheduling, UE can send data to eNB any time since eNB is sending grant all the time, non-persistent scheduling UE needs the grant from the network to send the data. The detailed procedure is described in the figure below.
- #67Â UE inform to Network that it will transmit a data and asking about the grant. "I have something to transmit, would you give me a Grant to send this data ?" Then Network would allocate the bare minimum amount of UL Grant (Resources for PUSCH) if the resource is available Network would allocate the bare minimum amount of UL Grant (Resources for PUSCH) if the resource is available. Scheduler assigns initial resources without detailed knowledge of buffer content
- #82 This is flow chart of downlink transmission procedure First, UE will ĺ Šĺźľĺç塎ç°ĺ¨ćźćć˛ć DCI 0 ďźć˛ćDCI 0ç芹ćç¨PUCCHĺĺłACK/NACK ćDCI 0 ç¨PUSCHĺĺłACK/NACK CSI : Channel State Information : UEä¸ĺ ąçľŚeNodeBçééçć čłč¨ PUSCH ćŻuplink channel
- #83 Downlink transmission ç¨ DCI 1 I will introduce CSI report request and CQI report request in following slides
- #84 CSI: UE report channel status information to eNB ä¸ĺ ąeNBééĺ質 there are many different types of CSIs and depending on which CSI is reported, UE should use different PUCCH Format ć訹ĺ¤ä¸ĺéĄĺçCSIďźä¸Śä¸ĺćąşćźĺŞĺCSIč˘Ťĺ ąĺďźUEć芲使ç¨ä¸ĺçPUCCHć źĺź CSI is a kind of collective name of several different type of indicators嚞税ä¸ĺéĄĺçćć¨çä¸ç¨ŽééŤĺ稹 UEéé渏éćĽćśĺ°çä¸čĄĺč俥čďźç¤žĺçšĺŽçĺč俥čćCSI-RSďźäžç˛ĺCSIčłč¨ ď ä¸ĺ ąçľŚeNodeB ď eNdoeBĺ¨ä¸čĄčŞżĺşŚććĺ°ééĺ質čć Žĺ¨ĺ § eNodeB丌ä¸ä¸ĺŽéľĺžŞUEä¸ĺ ąçä¸čĄééçć ĺ ąĺäžé˛čĄä¸čĄĺłčź¸ăç¸ĺçďźUEä¸ĺ ąçĺŞćŻĺťşč°eNodeB使ç¨çĺłčź¸éć¸ďźĺą¤ć¸ďźĺé 硨碟çŠéŁďźäťĽĺeNodeBä¸ćčŠ˛čś éçćéŤčŞżčŁ˝ĺ硨碟ćšćĄďźMCSďźăeNodeBĺŻäťĽä˝żç¨CSIĺ ąĺçĺťşč°ďźäšĺŻäťĽéć°é¸ćčŞĺˇąçĺłčź¸ĺć¸ďźeNodeBćééDCIĺ°çśĺĺłčź¸çćŁä˝żç¨çMCSă幤ć¸ĺé 硨碟çŠéŁçčłč¨ĺ訴UEă CSIä¸ĺ ąĺŻäťĽćŻéąćć§çďźperiodicďźďźäšĺŻäťĽćŻééąćć§çďźaperiodicďź The more important one is CQI
- #85 MAC control element : MAC layerĺ §é¨çćşé MAC PDU consisting of MAC header, MAC control elements, MAC SDUs and padding R: Reserved bit, set to "0". E: The Extension field is a flag indicating if more fields are present in the MAC header or not. Logical Channel ID field: identifies corresponding MAC SDU or the type of the corresponding MAC control element or padding F: The Format field indicates the size of the Length field L: The Length field indicates the length of the corresponding MAC SDU in bytes SDU čˇä¸ĺą¤ćżç MAC SDUćŻčˇRLCćżç
- #87 Downlink: éĺćĽHARQďźasynchronous HARQďźćĺłčéĺłĺŻäťĽçźçĺ¨äťťä¸ćĺťďźäšćĺłčč˝äťĽäťťćé ĺşä˝żç¨HARQ process čŞć調ć´HARQďźadaptive HARQďźćĺłčĺŻäťĽćščŽéĺłć使ç¨çPRBčłćşäťĽĺMCS Uplink: ĺćĽHARQďźsynchronous HARQďźćĺłčéĺłĺŞč˝ĺ¨ĺä¸ćŹĄĺłčź¸äšĺžçĺşĺŽćĺťçźéďźäšćĺłčĺ¨ćĺçšĺŽçĺĺšďźĺŞč˝ä˝żç¨ćĺçšĺŽçHARQ processă čŞć調ć´HARQďźadaptive HARQďźćĺłčĺŻäťĽćščŽéĺłć使ç¨çPRBčłćşäťĽĺMCSăéčŞć調ć´HARQďźnon-adaptive HARQďźćĺłčéĺłĺż é čĺä¸ćŹĄĺłčź¸ďźć°ĺłćĺä¸ćŹĄéĺłďźä˝żç¨ç¸ĺçPRBčłćşĺMCSă
- #88 HARQ with soft combining:ć šćéĺłçćŻçščłč¨čĺĺ§ĺłčź¸ćŻĺŚç¸ĺ ćĽćśĺ°çéŻčޤčłćĺ ćäżĺĺ¨ä¸ĺHARQ bufferä¸ďźä¸ŚčĺžçşćĽćśĺ°çéĺłčłćĺ é˛čĄĺ佾ďźĺžčĺžĺ°ä¸ĺćŻĺŽç¨č§Łç˘źć´ĺŻé çčłćĺ ďźâčťĺ佾âçéç¨ďźăçśĺžĺ°ĺ佾ĺžçčłćĺ é˛čĄč§Łç˘źďźĺŚćéćŻĺ¤ąćďźĺéč¤âčŤćąéĺłďźĺé˛čĄčťĺ佾âçéç¨ TBSďźTransport Block Sizeç縎寍ăéĺłçTBSé常ćŻä¸čŽçďźä¸ŚčĺĺłçTBSäżćä¸č´ďźĺŚĺçĄćłé˛čĄčťĺ佾čç Chase combining(ä¸éĺłçćŻçščłč¨čĺĺ§ĺłčź¸ç¸ĺ) and incremental redundancy(éĺłçćŻçščłč¨ä¸éčŚčĺĺ§ĺłčź¸ç¸ĺ) çąćźéĺłĺŻč˝ć帜äşä¸ĺ ĺŤĺ¨ĺ揥ĺłčź¸ä¸çéĄĺ¤ĺä˝ćŻçšďźparity bitďźďźć䝼éĺłç碟çćéä˝ăćŻćŹĄéĺłĺŻäťĽĺ ĺŤčĺĺ§ĺłčź¸ć¸çŽä¸ĺçcoded bitďźä¸ä¸ĺéĺłç調製ćšĺźäšĺŻäťĽä¸ĺ
- #89 HARQ use âstop-and-wait protocolâ to send data čŚçĺ°ćĽćśçŤŻćśĺ°čłćĺĺłACKććĺéä¸ä¸ĺčłć çźé獯çźéä¸ĺTBĺžďźĺ°ąĺä¸äžçĺž ç˘şčŞčłč¨ăćĽćśçŤŻć使ç¨1ćŻçšçčłč¨ĺ°čŠ˛TBé˛čĄčŻĺŽďźACKďźćĺŚĺŽďźNACKďźçç˘şčŞ ä˝ćŻćŻćŹĄĺłčź¸ĺžçźé獯尹ĺä¸äžçĺž ç˘şčŞďźćĺ°č´čź¸ééĺžä˝ LTE使ç¨ĺ¤ĺ丌čĄçstop-and-wait processďźçśä¸ĺHARQ processĺ¨çĺž ç˘şčŞčłč¨ćďźçźé獯ĺŻäťĽä˝żç¨ĺŚä¸ĺHARQ processäžçšźçşçźéčłćďźä˝ä˝żç¨ĺ¤ĺ丌čĄçstop-and-wait processĺŻč˝ĺ°č´ćĽćśçŤŻçMAC幤éĺžRLC幤çčłććŻäşĺşç HARQ entity is composed of HARQ process, and every UE has one HARQ entity. HARQ processĺ ąĺçľćäşä¸ĺHARQ 富éŤďźHARQ entityďźćŻĺUEé˝ćä¸ĺHARQĺŻŚéŤ ĺ¨çŠşĺč¤ç¨ä¸ďźä¸ĺTTIćĺšłčĄĺłčź¸2ĺTBďźćŻĺTBćĺčŞç¨çŤçHARQ確čŞčłč¨ďźä¸Śä˝żç¨ä¸ĺçHARQ processäžčçăć¤ć1ĺHARQ富éŤĺ ĺŤ2ĺHARQ processéĺă Every HARQ process processing a TB(transport block) in one TTI. Every HARQ process receiver has independent HARQ buffer. The HARQ entity directs HARQ information and associated TBs received on the DL-SCH to the corresponding HARQ processes. HARQ富éŤĺ°ĺ¨DL-SCHä¸ćĽćśĺ°çHARQ俥ćŻĺç¸éčŻçTBćĺźĺ°ĺ°ćçHARQéç¨
- #90 ćŻĺHARQ processćäżĺä¸ĺNDIĺźďźčŠ˛ĺźä˝żç¨1ćŻçšäžć示袍調庌çčłććŻć°ĺłéćŻéĺłăĺŚćĺä¸HARQ processçNDIĺźčäšĺç¸ćŻçźçäşčŽĺďźNDI toggledďźďźĺ襨示çśĺĺłčź¸ćŻä¸ĺć°çTBçĺĺłďźĺŚĺďźNDI not toggledďźčĄ¨ç¤şçśĺĺłčź¸ćŻĺä¸ĺTBçéĺł
- #91 Downlink HARQ éĺćĽďźéŠćć§ éĺćĽ: éĺłĺŻäťĽçźçĺ¨äťťä˝ćé
- #96Â MCS is abbreviation of Modulation coding scheme Code rate: How many percentages of real data are in a transmission. Ex. 5/6: data ď 5 checksum ď 1 Percentage of checksum rise ď Error rate decline (less data transmission) Signal well use 64QAM, signal bad use QPSK Modulation Coding Scheme is related to Modulation Order.(QPSK Modulation Order = 2, 16QAM Modulation Order = 4, 64QAM Modulation Order = 6)
- #97 CQI䝣襨俥é質éć示珌 CQI stands for Channel Quality Indicator CQI it is an indicator carrying the information on how good/bad the communication channel quality is. the CQI value ranges from 0 ~ 30. 30 indicates the best channel quality and 0,1 indicates the poorest channel quality. Depending which value UE reports, network transmit data with different transport block size.
- #98 ĺłä˝żUEĺ ąĺä˝CQIďźçś˛çľĄäšćçźé大çĺłčź¸ĺĄ UEĺžĺŻč˝çĄćłĺ°ĺ śé˛čĄč§Łç˘ź What would happen if UE send inaccurate CQI ?ĺŚćUEçźéä¸ĺ確çCQIćçźçäťéşźďź Depending which value UE reports, network transmit data with different transport block size.ć šćUEĺ ąĺçĺźďźçś˛çľĄĺłčź¸ĺ ˇćä¸ĺĺłčź¸ĺĄĺ¤§ĺ°çć¸ć If network gets high CQI value from UE, it transmit the data with larger transport block size.ĺŚć眲羥ĺžUEç˛ĺžéŤCQIĺźďźĺĺłčź¸ĺ ˇćčźĺ¤§ĺłčź¸ĺĄĺ¤§ĺ°çć¸ć What if network sends a large transport block even though UE reports low CQI, it is highly probable that UE failed to decode it (cause CRC error on UE side) and UE send NACK to network and the network have to retransmit it which in turn cause waste of radio resources.ĺłä˝żUEĺ ąĺä˝CQIďźĺŚć眲羥çźé大çĺłčź¸ĺĄďźĺŚćUEä¸č˝ĺ°ĺ śé˛čĄč§Łç˘źďźUEĺžĺŻč˝ćçźéNACK羌眲羥ďźä¸Śä¸çś˛çľĄĺż é éĺłďźĺ°č´çĄçˇčłćşç澪貝ďźĺ°č´UEĺ´çCRCéŻčŞ¤ďź How UE estimate CQI ? UEĺŚä˝äź°č¨CQIďź signal-to-noise ratio (SNR) č¨éćŻ(SNR) signal-to-interference plus noise ratio (SINR) 俥ččäšžćžĺ ĺŞč˛ćŻďźSINRďź signal-to-noise plus distortion ratio (SNDR) 俥ĺŞćŻĺ 夹çćŻďźSNDRďź
- #99 What would happen if UE send inaccurate CQI ?ĺŚćUEçźéä¸ĺ確çCQIćçźçäťéşźďź Depending which value UE reports, network transmit data with different transport block size.ć šćUEĺ ąĺçĺźďźçś˛çľĄĺłčź¸ĺ ˇćä¸ĺĺłčź¸ĺĄĺ¤§ĺ°çć¸ć If network gets high CQI value from UE, it transmit the data with larger transport block size.ĺŚć眲羥ĺžUEç˛ĺžéŤCQIĺźďźĺĺłčź¸ĺ ˇćčźĺ¤§ĺłčź¸ĺĄĺ¤§ĺ°çć¸ć What if network sends a large transport block even though UE reports low CQI, it is highly probable that UE failed to decode it (cause CRC error on UE side) and UE send NACK to network and the network have to retransmit it which in turn cause waste of radio resources.ĺłä˝żUEĺ ąĺä˝CQIďźĺŚć眲羥çźé大çĺłčź¸ĺĄďźĺŚćUEä¸č˝ĺ°ĺ śé˛čĄč§Łç˘źďźUEĺžĺŻč˝ćçźéNACK羌眲羥ďźä¸Śä¸çś˛çľĄĺż é éĺłďźĺ°č´çĄçˇčłćşç澪貝ďźĺ°č´UEĺ´çCRCéŻčŞ¤ďź In LTE, 15 different CQI values randing from 1 to 15 (4 bits) and mapping between CQI and modulcation scheme, transport block size is defined as follows UEĺĺ ąçžĺ¨çŽĺćĺĺ°EnodeBč¨čççćłăEnodeBćśĺ°CQIäšĺžćé¸ćĺ°UEć弽çĺłčź¸ćšĺźďźĺć示UEé˛čĄModulaton Code Scheme(MSC)çčŽć´ďźĺťéŠćçŽĺééççćłďźéćčźä˝çéŻčޤçĺć´éŤçćçďźć䝼CQIĺĺ ąĺ°ąčŽĺžĺžéčŚă䝼ä¸ćŻCQIčˇmodulationçĺ°ćéäżăĺŻäťĽççĺ°čśéŤçCQIĺ°ąćĺ°ćĺ°čśĺĽ˝çmodulationčˇcode rateă
- #101 Even while there is no traffic between the network and UE, UE has to keep listening to Network. At least it should be ready to decode PDCCH. It means UE has to be "ON" all the time even when there is no traffic. But being ON all the time would drain the battery.  it should be ready to decode PDCCH http://www.sharetechnote.com/html/Handbook_LTE_DRX.html
- #102 Case 1: Only Long DRX Cycle is configured and No PDCCH is received during the cycle.ĺ é 罎éˇDRXéąćďźä¸Śä¸ĺ¨ĺ¨ćĺ §ć˛ććĽćśĺ°PDCCH Case 2: Only Long DRX Cycle is configured and a PDCCH is received during a cycle (You will notice the real 'ON time' May get extended depending on DRX Inactivity Timer and when the PDCCH is recieved as shown in thick Blue line).ĺ¨ä¸ĺéąćĺ §ďźĺŞé 罎éˇDRXéąć丌ćĽćśä¸ĺPDCCHďźçćŁçâéĺćéâĺŻč˝ćĺťśéˇďźĺ ˇéŤĺćąşćźDRXä¸ć´ťĺč¨ćĺ¨ďźäťĽĺçśćĽćśĺ°çPDCCHĺŚç˛čçˇć示ďźă drx-InactivityTimerćĺŽäşçśUEćĺ解碟ä¸ĺć示ĺĺłçULćDL使ç¨č čłćçPDCCHĺžďźćçşčćźĺĺć çéŁçşPDCCHĺĺšć¸ă drx-RetransmissionTimerćĺŽäşĺžUEćĺž ćśĺ°DLéĺłçĺĺšďźHARQ RTTäšĺžďźéĺ§ďźéŁçşçŁč˝çâPDCCHĺĺšć¸â
- #103 Case 3:  Only Long DRX Cycle is configured and a PDCCH and DRX Command MAC CE are received during a cycle (You will notice the real 'ON time' MAY get shorter depending on exactly when DRX Command MAC CE is received as shown in thick Blue line). ĺ¨ä¸ĺéąćĺ §ĺŞé 罎éˇDRXéąćďźćĽćśPDCCHĺDRXĺ˝äť¤MAC CEďźćĽćśDRXĺ˝äť¤MAC CEćç富éâéĺćéâĺŻč˝ć縎çďźĺŚç˛čçˇć示ďźă