LTE MAC Protocol Rel8 Sung Jun Park sungjparklge

LTE MAC Protocol (Rel-8) Sung. Jun Park (sungjpark@lge. com) Click to to edit Master subtitle style July 30, 2009 Copyright Notification . No part may be reproduced except as authorized by written permission. The copyright and the foregoing restriction extend to reproduction in all media. ⓒ 2009. LG 3 GPP RAN 2 team. All rights reserved. LG Electronics RAN 2 Team

MAC Layer App PDCP • HTTP, FTP, etc - IP • Header Compression and Security Click to to edit Master subtitle style RLC • Framing and ARQ MAC • Multiplexing and Scheduling PHY • Physical layer processing LG Electronics RAN 2 Team

UE side MAC structure PCCH BCCH CCCH DTCH Logical Channel Prioritization (UL only) Control (De-) Multiplexing Random Access Control HARQ PCH Copyright BCH DL-SCH All Rights Reserved UL-SCH RACH 3 / 35 LG Electronics RAN 2 Team

PCCH PCH BCCH CCCH BCH PBCH DCCH D Tr ed af ica fi te c d em st Sy Pa gi ng In fo Co C m at on m co n tro on nn o R l I ec RC nfo ti on D Co ed nt ica ro te l d Channel Mapping DTCH for Rel-9 MBMS MCCH MTCH DL-SCH PDCCH MCH PMCH Downlink Copyright All Rights Reserved CCCH RACH PRACH DCCH DTCH UL-SCH PUCCH PUSCH Uplink 4 / 35 LG Electronics RAN 2 Team

MAC Functions UL-SCH data transfer DL-SCH data transfer Random Access Procedure Copyright All Rights Reserved UL Timing Control Buffer Status Reporting Scheduling Request Discontinuous Reception 5 / 35 Measurement Gap Handling Logical Channel Prioritization LG Electronics RAN 2 Team

Data Transfer (1/6) Purposes Means HARQ PDCCHoriented (dynamic scheduling) DL: Asynchronous adaptive PDCCH-less (semipersistent scheduling) UL: Synchronous non-adaptive Receive / transmit data from / to e. NB Copyright All Rights Reserved 6 / 35 LG Electronics RAN 2 Team

Data Transfer (2/6) DL Resource Assignment Dynamic Scheduling -Time-Freq. Resource Information -Transport Block Format -HARQ Process ID n me DL Assignment Reception via t ign s As tion L D cep Re UE’s C-RNTI Temporary C-RNTI RA-RNTI SI-RNTI DL Co Assi g nfi gu nme rat ion nt Semi-persistent Scheduling DL Assignment Configuration Copyright All Rights Reserved 7 / 35 LG Electronics RAN 2 Team

Data Transfer (3/6) UL Resource Grant Dynamic Scheduling -Time-Freq. Resource Information -Transport Block Format UL Grant on PDCCH with t n a Gr tion L U cep Re UE’s C-RNTI UL Grant on MAC signaling in Random Access Response UL Co Gran nfi gu t rat Semi-persistent Scheduling ion UL Grant configuration Copyright All Rights Reserved 8 / 35 LG Electronics RAN 2 Team

Data Transfer (4/6) Dynamic Scheduling DL DATA (DL-SCH) DL ASSIGN(PDCCH ) UL GRANT(PDCCH) UL DATA (UL-SCH) Resource Request LG Electronics RAN 2 Team 9 / 35 All Rights Reserved Copyright 4 TTI difference Time Same TTI UL DL DATA (DL-SCH) DL Time

Data Transfer (5/6) Semi-Persistent Scheduling DL DATA (DL-SCH) DL Time UL DATA (UL-SCH) UL Time Copyright All Rights Reserved 10 / 35 LG Electronics RAN 2 Team

Data Transfer (6/6) Semi-Persistent Scheduling configuration – DL case e. NB UE Pre-configuration by RRC Msg. E. g. Resources information , Transport Block Format PDCCH for SPS Activation E. g. Interval, No. of SPS-processes DL-SCH for SPS SPS resource release PDCCH for SPS De-activation PDCCH for SPS Activation DL-SCH for SPS Copyright All Rights Reserved 11 / 35 LG Electronics RAN 2 Team

Special Handling on UL HARQ (1/3) Sticky Grant for Adaptive HARQ Re Tx UL Tx x e. T r. R fo PRACH resrc. Frequency Same Phy. Resources Copyright CK NA H CC PD CK NA UE Re Tx e. NB All Rights Reserved Same Phy. Resources 12 / 35 Time LG Electronics RAN 2 Team

Special Handling on UL HARQ (2/3) Fake ACK Re Tx x e. T r. R fo UE H CC PD K AC CK NA UL Tx e. NB Data in HARQ buffer is kept Frequency PRACH resrc. Phy. Resources Time Copyright All Rights Reserved 13 / 35 LG Electronics RAN 2 Team

Special Handling on UL HARQ (3/3) TTI Bundling e. NB UE PDCCH for UL Grant 2 * HARQ RTT DL-SCH Tx NACK DL-SCH Tx Copyright All Rights Reserved 3 consecutive Re. Tx without feedbacks 14 / 35 3 consecutive Re. Tx without feedbacks LG Electronics RAN 2 Team

Random Access Procedure (1/4) Purposes Obtain timesynchronization Request uplink resources Copyright All Rights Reserved Initiation By PDCCH order Categorization Contention based Use cases Initial Access Radio Link/HO Failure Handover By MAC sublayer itself Contention Free based 15 / 35 UL/DL data arrival LG Electronics RAN 2 Team

Random Access Procedure (2/4) Contention based RA Contention Free based RA UE UE e. NB Random Access Preamble allocation Random Access Response (T-CRNTI) Random Access Preamble Random Access Response Msg 3 (C-RNTI or CR ID) Non-CCCH SDU case Applicable at ØHandover ØDL arrival e. NB CCCH SDU case PDCCH with C-RNTI Contention Resolution ID on DL-SCH HARQ Feedback Promotion of Temporary C-RNTI ØT-C-RNTI is promoted to C-RNTI when CR is successful Special HARQ Handling ØWinner: ACK ØLoser: No feedback Copyright All Rights Reserved 16 / 35 LG Electronics RAN 2 Team

Random Access Procedure (3/4) RA Preamble Set selection • Selected by MAC (non-dedicated) • Signaled by PDCCH and RRC (dedicated) Total RA preamble set Non-dedicated RA preambles set Group. A e. g. 00 ~ xx Copyright Group. B e. g. xx ~ yy All Rights Reserved Dedicated RA preambles set RA Preamble Group selection • Depending on Msg 3 size and pathloss, e. g. • If Msg 3 size <= 56 bits and pathloss < 5 d. B Group. A • Otherwise Group. B e. g. yy ~ 63 17 / 35 LG Electronics RAN 2 Team

Random Access Procedure (4/4) RA Response reception • Selected PRACH resource and RA-RNTI are associated • One RA Response is intended for one or more UEs Configurable TTI window Selected PRACH resource PDCCH -Addressed by RA-RNTI PDSCH (RA Response) -Backoff Indicator -RA Preamble Id -TA command -UL grant -Temporary C-RNTI Time Copyright All Rights Reserved 18 / 35 LG Electronics RAN 2 Team

Buffer Status Report (1/2) Purposes Initiation By UL data arrival with higher priority Provide UE’s buffer status information to e. NB By periodic method (timer) By reliable method (timer) By padding Copyright All Rights Reserved 19 / 35 Formats Short BSR -1 byte * 1 LCG ID + 1 LCG info. Long BSR -3 bytes * No LCG ID + 4 LCGs info. LG Electronics RAN 2 Team

Buffer Status Report (2/2) 1 2 Start (Re)start Periodic Timer 3 Restart gr an t Re. Tx Timer Expire 4 Restart BS R U L BS R Triggering of BSR 5 Expire Buffer Trigger event Low Prio High Prio Time • 1. Data arrival in empty buffer • 2. Higher priority data arrival • 3. Padding exists • 4. Periodic timer expiry • 5. Re. Tx timer expiry (restart at new uplink grant) MAC PDU Padding Copyright All Rights Reserved 20 / 35 LG Electronics RAN 2 Team

Scheduling Request (1/3) Purposes Request UL resources for carrying BSR Copyright All Rights Reserved Initiation Means By PUCCH (D-SR) if configured By BSR when no UL resources are available By Random Access Procedure 21 / 35 LG Electronics RAN 2 Team

Scheduling Request (2/3) SR procedure (D-SR case) UE e. NB Triggered BSR D-SR transmission UL Grant BSR transmission UL Grant Actual data transmission Copyright All Rights Reserved 22 / 35 LG Electronics RAN 2 Team

Scheduling Request (3/3) D-SR failure UE e. NB Wrong power setting # of D-SR Tx =1 D-SR transmission # of D-SR Tx =2 D-SR transmission # of D-SR Tx =3 D-SR transmission Max. Tx reached • Release UL resource • Initiate RA procedure Random Access Preamble Copyright All Rights Reserved 23 / 35 LG Electronics RAN 2 Team

UL Timing Control (1/2) Purposes Maintain orthogonality between users Copyright All Rights Reserved Means States By Command & Timer -Timing Advance Command -Time Alignment Timer In sync Out of sync 24 / 35 LG Electronics RAN 2 Team

UL Timing Control (2/2) Reception of Time Alignment Command Start Time Alignment Timer Out of Sync. - Release any UL resources - Flush all HARQ buffers Copyright All Rights Reserved In Sync. Expiry of Time Alignment Timer 25 / 35 Reception of Time Alignment Command Restart Time Alignment Timer LG Electronics RAN 2 Team

Discontinuous Reception (DRX) (1/4) Purposes Means Types Save UE’s power consumption By various timers Short DRX Controlling UE’s PDCCH monitoring activities Copyright All Rights Reserved On duration T HARQ RTT T DRX Re. Tx T DRX Inactivity T DRX Short Cycle T Long DRX 26 / 35 LG Electronics RAN 2 Team

Discontinuous Reception (DRX) (2/4) Long DRX opportunity APP Time Loading Time Short DRX opportunity Reading Time Short DRX opportunity Time Copyright All Rights Reserved 27 / 35 LG Electronics RAN 2 Team

Discontinuous Reception (DRX) (3/4) Tx Re. Tx Short DRX opportunity Tx Re. Tx Tx Short DRX opportunity Long DRX opportunity Short DRX opportunity Time On Duration T HARQ RTT T DRX Re. Tx T Restart at DRX Inactivity T expiry DRX Inactivity T Short Cycle T Active Time (UE monitors PDCCH) = On Duration T + DRX Re. Tx T + DRX Inactivity T Copyright All Rights Reserved 28 / 35 LG Electronics RAN 2 Team

Discontinuous Reception (DRX) (4/4) DRX state transition Cont. Rx DRX Inactivity T expiry or DRX Command MAC CE DL/UL Assignment Short DRX Long DRX Short Cycle T expiry Copyright All Rights Reserved 29 / 35 LG Electronics RAN 2 Team

Measurement Gap (MG) (1/3) Purposes Impacted Areas UL/DL HARQ Measure different frequencies No Tx/RX during MG Random Access Copyright All Rights Reserved 30 / 35 LG Electronics RAN 2 Team

Measurement Gap (MG) (2/3) HARQ operation colliding with MG MG No PUCCH No PUSCH No PDCCH Copyright All Rights Reserved MG MG at reception of PHICH : treated as ACK 31 / 35 UL -S C Tx H UL -S CH Tx UL -S CH UE CK NA FB Tx e. NB MG MG at retransmission : treated as NACK LG Electronics RAN 2 Team

Measurement Gap (MG) (3/3) Random Access Procedure colliding with MG MG MG Ms g 3 MG RACH has priority over MG RACH and MG have equal priority All Rights Reserved MG MG at Msg 2/3 MG at Msg 1 Copyright MG K AC UE g 2 Ms Ms g 1 e. NB 32 / 35 LG Electronics RAN 2 Team

Logical Channel Prioritization (1/2) Purposes Allocate transmitting resources to logical channels Copyright All Rights Reserved Means Parameter Logical Channel Priority Token Bucket Prioritized Bit Rate 33 / 35 LG Electronics RAN 2 Team

Logical Channel Prioritization (2/2) LTE Prioritization (Relative Priority) UMTS TFC Selection (Absolute Priority) RB 1 (P 1) RB 2 (P 2) RB 1 (P 1) RB 3 (P 3) RB 2 (P 2) PBR 1 PBR 2 Starvation 1 Transmitting Resource Copyright All Rights Reserved 2 3 PBR 3 4 Transmitting Resource 34 / 35 LG Electronics RAN 2 Team

Thank You!! Authorized by LG Electronics 3 GPP RAN 2 Team Copyright All Rights Reserved 35 / 35 LG Electronics RAN 2 Team