lte in-depth (sf)
TRANSCRIPT
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Network Architecture
QPSK Quadrature Phase Shift KeyingRRC Radio Resource Control
S1AP S1 Application Protocol
SGW Serving Gateway
SRB Signalling Radio BearerUSIm Universal Subscriber Identity Module
UTRAN Universal Terrestrial Radio Access Netwo
X2AP X2 Application Protocol
ARQ Automatic Repeat Request AS Access Stratum
C-RNTI Cell Radio Network Temporary Identity
DRB Data Radio Bearer
eNB Evolved NodeBEPC Evolved Packet Core
EPS Evolved Packet System
E-RAB E-UTRAN Radio Access Bearer
MME Mobility Management EntityNAS Non Access Stratum
OFDM Orthogonal Frequency Division Multiplexi ng
PCRF Policy and Charging Rules Function
PDCP Packet Data Convergence ProtocolPGW Packet Data Network Gateway
QAM Quadrature Amplitude Modulation
QoS Quality of Service
36.300 23.401
eNB
eNB
PCRF
PGW
HSS
SGW
MME
IMS/Internet/…
• Security: Authentication and key agreement
• Registration: Attach, Tracking Area Update
Provides QoS policiesand charging rules
SGi
S11(GTP)
S1-MME
(S1AP)
S1-U
(GTP)
X2-C(X2AP)
S5
(GTP)
S6a
(Diameter)
Uu
(RRC)
Uu
Subscription profiles
Security parameters
• Bearer mgmt: Default and dedicated bearers
RRC Connection
Signalling RB (SRB)
S1 Connection
NAS Signalling Connection
X2-U(GTP)
+ + = EPS BearerData RB (DRB) S1 Tunnel S5 Tunnel
• Radio Resource Control• Channel aware scheduling
5 UE categories
DL: 10-300 Mb/s
UL: 5-75 Mb/s
GxQoS aware
routingRx
UE identities
USIM id: IMSI
Radio id: C-RNTI
EPC id: GUTI
• Shared data channels
• 1ms Transmission Time Interval• Multi-layer Re-Tx (ARQ and HARQ)• Adaptive modulation (QPSK/xQAM)
• OFDM and MIMO (2 or 4 antennas)
• System Bw: 1.4, ..., 5, …, 20 MHz
LTE Radio Techniques
NAS securit
y
AS security
E-UTRAN + EPC
Control Plane
interface
User Plane
interface
(PDCP)
E-UTRAN RAB (E-RAB)
E-UTRAN Evolved UTRANGTP GPRS Tunnelling Protocol
GUTI Globally Unique Temporary Identity
HARQ Hybrid Automatic Repeat Request
HSS Home Subscriber ServerIMS IP Multimedia Subsystem
LTE Long Term Evolution
MIMO Multiple Input Multiple Output
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NAS ProtocolsEMM and ESM
PDN Packet Data Netwo
QoS Quality of Service
SHT Security Header TyTA Tracking Area
TAU Tracking Area Upd
IMEI International Mobile Equipment Id.
MME Mobility Management Entity
NAS Non Access StratumPCRF Policy and Charging Rules Function
PD Protocol Discriminat or
NAS
RRC
PDCP
RLC
MAC
PHY
RRC
PDCP
RLC
MAC
PHY
S1AP
SCTP
IP
L1/L2
S1AP
SCTP
IP
L1/L2
NAS
UE
eNB
MME
Uu S1-MME
Registration in EPS,
IP-addr alloc.
Request IMSI (or IMEI)
Mutual authentication
and key agreement
Activate security context
(ciphering and integrity)
Idle to Conn transition
Request secure NAS conn.
EMM Procedures
UE power off orNW initiated
Registration Proc:
Security Proc:
Attach
Identification
Authentication
Security Mode Ctrl
Tracking Area Update
Service Request
Detach
Connection Mgmt:
MME
Normal (new TA)
or periodic (T3412)
NAS Signalling Conn.
Triggered by:
- UL data/signalling or
- Paging
EMM EPS Mobility Management
eNB Evolved NodeB
EPS Evolved Packet SystemESM EPS Session Management
HSS Home Subscriber Server
Dedicated EPS Bearer CTX Act.
Default EPS Bearer CTX Act.
Bearer Resource Allocation Req
PDN Connectivity Req
ESM Procedures
MMENAS Signalling Conn.
Default EPS bearer:- Static QoS (from HSS)
- One per PDN Connection
Dedicated EPS bearer:
- Dynamic QoS (from PCRF)
- One or more /PDN Connection
Sec. Header Type
EPS Bearer ID
Protocol
Discriminator
Procedure Transaction ID
Message Type
Other Infirmation Elements
(mand/opt/cond)
Only for
ESM messages
5678 1234
EMM or ESM
Links Request with Response
Protected
or not
Plain NAS Message
SHT PD=EMM
Message
Authentication
Code (4 oct)
Sequence Number
Plain NASMessage
Protected Message
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MME
PDNSGW
PGW
SGSN
HSS
May be optimised by:
• UE & location-specific TA lists
• Alignment of TAs and RAs
• Idle Mode Signalling Reduction (ISR
• UE-specific list
• based on mobility history
• refreshed each TAU
1TIN = GUTI
Initial Attach
Old GUTI
1 Bearer/session
CreationTA 2
2 TA change
no TAU needed
TIN = GUTI
TA 1
3 RAT Change
• RAU is needed
• PTMSI & RAI derived
from GUTI
”old” PTMSI, RAI
1
old PTMSI & RAI
ISR = activated
3
UE Context
Retrieval
UE MM and PDN
Contexts
HSS maintains
double registration
K ASME CK, IK
PDN CTX
PDP CTX
3
Bearer modification
possible QoS change
SGSN address,
ISR = activated
3
new PTMSI, RAI
ISR = activatedRA 1RA 2
While ISR Active4
• UE can move between
RA1/TA1/TA2 with no update
• Independent periodic TA/RA timers
• UE stores PTMSI/RAI and GUTI
TIN = RAT-related TMSI
23.401, 24.3015 RAU ISR Deactivation
Signalled to UE in RAU Accept
TIN = PTMSI
No LTE Coverage
ISR meaningless
ISR Deactivation Triggers
• No LTE coverage
• RAU to pre-R8 SGSN
• Failed periodic registration
• Bearer act/mod after ISR act.
Idle Mode Mobility
RAT Radio Access TechnologyRAU Routing Area Update
SGW Serving Gateway
TA Tracking AreaTAU Tracking Area Update
TIN Temporary Id used in Next Update
TMSI Temporary Mobile Subscriber Ident
ASME Access Security Management EntityCK Ciphering Key
GUTI Globally Unique Temporary Id.
HSS Home Subscriber ServerIK Integrity Key
ISR Idle Mode Signalling Reduction
MM Mobility Management
MME Mobility Management EntityPDP Packet Data Protocol
PDN Packet Data Network
PGW Packet Data Network GatewayPTMSI Packet TMSI
RA Routing Area
RAI Routing Area Identity
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SGSN
E-UTRAN PDN
MME
ePDG/
AAA
eNB
GERAN
UTRAN
Non-3GPP
IP-access
BSC/
RNC
SGW
PGW
e.g. WLAN, WiMAX
Fixed access etc
• Access authentication
• QoS authorization
• Generates charging data
S2a/S2b (PMIP)
If Gn-SGSN:
PGW assumes
GGSN roleIf Gn-SGSN:
EPS QoS mapped to
UMTS QoS profile
If Gn-SGSN:
MME assumes
SGSN role
Always:
Convert K ASME
CK, IK
Non-optimised Mobility
IETF mobility solutions used:
- MIPv4 or DSMIPv6
- MIP tunnel UE PGW/ePDG
Handover/Cell Change• Standard 3GPP signalling
• EPS adapts to target system
(Security, QoS, containers)
UE Mobility Capability
R8 Feature Group Indicators:
• PS HO to UTRAN/GERAN?
• Meas event B1 and/or B2?
RAN Features:
• PS HO support?
• DTM support?
• QoS support?
RAN Container:
UE RAC and
RB description
RAN Container:
Radio interface
HO Command msg
Optimised Mobility
Tunneling of non-3GPP msgs
- UE pre-registration- Handover execution
CDMA2000
HRPD S101 (GTPv2)
Trusted
Connected Mode Mobility
PDN Packet Data Network
PMIP Proxy Mobile IPRAC Radio Access Capability
RAN Radio Access Network
RB Radio Bearer
RNC Radio Network ControllerSGSN Serving GPRS Support No
GGSN Gateway GPRS Support Node
GTP GPRS Tunnelling ProtocolHRPD High Rate Packet Data
IETF Internet Engineering Task Force
IK Integrity Key
K ASME ASME KeyMIPv4 Mobile IPv4
AAA Authentication, Authorization, Accounting
ASME Access Security Management EntityBSC Base Station Controller
CK Ciphering Key
DSMIPv6 Dual Stack Mobile IPv6
DTM Dual Transfer ModeePDG Evolved Packet Data Gateway
If S4-SGSN:
EPS QoS mapped to
UMTS QoS profile
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CS Fallback
GERAN/
UTRANMSC/
VLR
BSC/
RNCPSTN/ISDN
SGsAP
SCTP/IP
L1/L2
E-UTRANPDN
(IMS)SGW
MME
PGW
GMSC
Voice Domain Selection (UE):
- Terminal capabilities
- User preference/setting
- Network policy/indication
- Registration status (IMS/CS)
- Ongoing call/session
• Registration (Attach & LAU)
• Paging and Service Request
• SM transfer (no fallback)
SGs
23.272, 29.118
Simultaneous PS Session:
- Handed over and continued
- Suspended during CS call
- Disconnected (GBR service)
SGSN
HSS
CS or IMS
call?CS call7
SM-SC
SM
4
PS Handover
involving SGSN
and SGW
3Paging with
CN domain = CS
Paging
(if ISR active)3
1Combined Attach or
TA/LA Update
CS Call setup6
5 Paging Respose MT call: MSISDN2( IMSI LAI MME)
Mapping from TA
to (default) LA
CS Fallback
• No IMS voice support in UE/NW
(or CS voice preferred in UE)
• Requires TA, LA alignment
• Combined registration needed
(PS session)
PDN Packet Data Network
SCTP Stream Control Transmission PrSGsAP SGs Application Protocol
SM Short Message
SM-SC Short Message Service CenterTA Tracking Area
CSFB Circuit Switched Fallback
DTM Dual Transfer ModeGBR Guaranteed Bit Rate
HO Handover
IMS IP Multimedia SubsystemISR Idle Mode Signalling Reduction
LA Location Area
LAI Location Area IdentityLAU Location Area Update
MGCF Media Gateway Control Function
MSISDN Mobile Station ISDN NumberMT Mobile Terminating
SMS over
SGs or IP?
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NAS
RRC
PDCP
RLC
MAC
PHY
RRC
PDCP
RLC
MAC
PHY
S1AP
SCTP
IP
L1/L2
S1AP
SCTP
IP
L1/L2
NAS
UE
eNB
MME
Uu S1-MME
36.321
A/N ACK/NACK
BSR Buffer Status Report
CQI Channel Quality IndicatorC-RNTI Cell RNTI
DL-SCH Downlink Shared Channel
HARQ Hybrid Automatic Repeat RequestLogCH Logical Channel
MCS Modulation and Coding Scheme
PDCCH Physical Downlink Control ChannelPDU Protocol Data Unit
PHICH Physical HARQ Indicator Channel
PHR Power Headroom Report
• Channel and QoS aware • Dynamic scheduling:
UE monitors PDCCH each TTI
• Semi - Persistent scheduling:
Preconfigured periodic resource
• Random access: Initial access,
HO access, TA update (UE init)
• Addressing: x-RNTI
• TA Update: eNB init when needed,
UE init when TA timer expires
• Buffer Status Reporting (BSR) Periodic, new higher prio data,
# padding bits > BSR size
• Power Headroom Reporting (PHR)
Periodic, when pathloss change > X
MAC Control Procedures
RA-PREAMBLE
PDCCH: RA-RNTI
RA-RESPONSE:
UL grant, TA, C-RNTI
C-RNTI/ P-RNTI/ SI-RNTI
DATA/ PAGING/ SYS INFO
DATA [ TA UPDATE ]
DATA [ BSR/PHR ]
Scheduling
PDCCH: MCS & PRBs
DL-SCH
PUCCH/PUSCH: A/N
UL-SCH
PHICH: A/N
HARQ Operation
• 8-process Stop-and-Wait HARQ
• DL: Asynchronous, Adaptive
• UL: Synchronous, eNB controlled
MAC Architecture (eNB)
LogCHs
De-multiplexing LogCH
Multiplexing
DL assign.
UL grants
Schedulers
DL & UL
CQI, SR
HARQ
(8 proc)
UL-SCH
HARQ A/NHARQ A/N
LogCHs QoS parameters
UE capabilities
DL-SCH
1 Transport Block (= MAC PDU)
per TTI to PHY
HARQ
(8 processes)
PUCCH?
Use Grant!
RESP?
GRANT?
Send SR!
Initiate RA!N
YY
N
Y
N
Scheduling Request Sequence(UL Grant needed)
SR is repeated until an
UL Grant is received PRB Physical Resource Block
P-RNTI Paging RNTI
PUCCH Physical Uplink Control ChannePUSCH Physical Uplink Shared Channe
RA Random Access
RA-RNTI Random Access RNTIRNTI Radio Network Temporary Ident
SI-RNTI System Information RNTI
SR Scheduling RequestTA Timing Advance
TTI Transmission Time Interval
UL-SCH Uplink Shared Channel
BSR
PHR
Medium Access Control Protocol
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Layer 1 Information Processing - Part 1
P2 Parity 2 bits
PhyCH Physical Channel
RV Redundancy VersionS Systematic bits
TB Transport Block
TTI Transmission Time Interv
CONV Convolutional Coder
CRC Cyclic Redundancy Check
DL-SCH Downlink Shared ChannelFDD Frequency Division Duplex
MIMO Multiple Input Multiple Output
P1 Parity 1 bits
DL-SCH Channel Coding
CRC 24(bit error
detection)
Code Block
Segmentation
Turbo CodingR=1/3
(bit error
correction)
Sub-block
Interleaving
ScramblingModulation
Antenna &
resource mapping
Code Block
Concatenation
Rate matching
(circular buffer)
Example:
Fixed Reference Channel
R.11 FDD
If input > 6144 bits
CRC24 added per block
Parity bits are
interlaced
MIMO:
1 or 2
TB/TTI
Depends on:
- Wanted code rate
- Available PhyCH bits
- Redundancy version
12960 bits 12984
4352 /block
(3 blocks) 13068/ block
Includes 12
termination bits
Described in 36.2
3 blocks: 26400 bits
= 1 Code Word
8800 /block
1 TB
S
P1
P2
Circular Buffer Rate Matching
S S
P1
.
.
.
P2P1
P2
.
.
.
Redundancy version 0 (RV0)
always contains ALL
systematic bits
RV1
Convolutional
coder 1
CONV
coder 2
Inter
leaver
Turbo Coder
1 code block
(4352 bits)
Systematic bits (S) + 3 bits
Parity 1 bits (P1) + 3
Parity 2 bits (P2) + 3
3Termination bits
RV2
36.212
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Layer 1 Information Processing - Part 2DL-SCH Scrambling and Modulation
RE Resource Element
RNTI Radio Network TemporaTB Transport Block
Tx Transmission/Transmit
XOR Exclusive-Or
DL-SCH Downlink Shared Channel
IFFT Inverse Fast Fourier TransformOFDM Orthogonal Frequency Division Multiplex ing
QAM Quadrature Amplitude Modulation
QPSK Quadrature Phase Shift Keying
36.211
Cell-specific
Scrambling
Modulation
(QPSK/xQAM)
LayerMapping
(symbols
1-4 layers)
Precoding(mapping to
1,2 or 4
antennas)
RE Mapping
.
.
.
.
.
.
RE Mapping
OFDM (IFFT)
OFDM (IFFT)
.
.
.
.
.
.
Code Word q1
(if MIMO)
Code Word
q0
Depends on Tx mode:
- Single antenna tx
- Tx diversity
- Spatial multiplexing
- Beamforming
Pseudo-random
bit sequence
’Mixing’ data,
control channels
and reference
signals
Not standardised
6600 16QAM
symbols
2 layers26400 bits
(3 code blocks)2 antenna
ports
6600 REs needed
(8400 available/port)
Mod. symbol RE
Xi Yi
Extend to
desired
length
Initiate
sequence
Cinit Cn
Cinit = (RNTI × 214 ) + (q × 213 ) + ns/ 2 × 29 + PhyCell-ID
Purpose
dependent
Fixed rules
in specs
Code Word
number
Slot
number
Code
Word
Scrambling Sequence
Randomizes inter-cell interference
Phy Cell IDPhy Cell ID
RNTI
UE ’de-masks’ all DL signals
with cell-specific scrambling seq.
Sequence Generation
(PDSCH example)
D li k T i i P d
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NACK P1
Minimum HARQ RTT = 8 subframes
need 8 Processes
DL
UL
1 subframe
DL Retransmissions:
Always scheduled
(may be adaptive)
PDCCH: DL Assignment
• UE-ID: RNTI
• PRBs: bitmap/RIV
• MCS (TB size implicit)
• HARQ info: RV, NDI
• HARQ Process Id
• PUCCH TPC
PUCCH
DATA
P1
Re-Tx
P1
DATA
P5
PDSCH
• On PUCCH: Periodic (2-128ms)
• PUSCH: Aperiodic (on eNB request)
• Both: Wideband or subband
PCFICH
CQI: downlink channel quality
PMI: preferred precoding
RI: preferred # layers
PMI Precoding Matrix IndicationPRB Physical Resource Block
PUCCH Physical Uplink Control CH
PUSCH Physical Uplink Shared CH
RI Rank IndicatonRIV Resource Indication Value
MIMO Multiple Input Multiple OutputNDI New Data Indicator
P (HARQ) Process
PCFICH Physical Control Format Indicator CH
PDCCH Physical Downlink Control CHPDSCH Physical Downlink Shared CH
RNTI Radio Network Temporary Id.RTT Round-Trip Time
RV Redundancy Version
SPS-RNTI Semi Persistent Scheduling RN
TB Transport BlockTPC Transmit Power Command
CQI Channel Quality IndicatonC-RNTI Cell RNTI
CSR Channel Status Reporting
DCI Downlink Control Informat ion
HARQ Hybrid Automatic Repeat RequestMCS Modulation & Coding Scheme
DL/UL Scheduling
Dynamic (C-RNTI):
- PDCCH read each TTISemi-persistent (SPS-RNTI):
- Preconfigured resource
- ’PDCCH-less’
Bitmap allowsDistributed
PRB allocation
CSR
(A/N)
PUSCH
ACK P5DATA P7
CSR
PUCCH PUCCH
Physical
Resource Blockpair
Downlink Transmission ProceduresScheduling and HARQ
U li k T i i P d
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Scheduling Request
• TA valid: SR on PUCCH
• TA invalid: SR on PRACH
• TA timer: 500-10240 ms
UL Retransmissions
PHICH: non-adaptiv
With PDCCH: adaptiv
DCI Format 0
• UE-ID: RNTI
• PRBs: RIV
• MCS, RV, NDI
• PUSCH TPC
• CQI request ind.
PUSCH withUL control info
PHICH
NACK for P1
(acts as
implicit grant)
DL
UL
1 subframe
PUSCH
Scheduling
Request
DATA
P7
DATA P1Re-Tx P1
A/N (CSR)
PUSCH
DATA P5
PHICH
A/N for P5
DCI 0 & DCI 1/2
UL grant &
DL assignm.
DCI 3
Transmit Power
Commands to
multiple UEs
UCI Formats:
1: Scheduling Request
1a: ACK/NACK, 1 TB
1b: ACK/NACK, 2 TB
2: CQI/PMI/RI2a: CQI..., 1 A/N
2b: CQI..., 2 A/N
PUCCH
region
PUSCH
for all
UEs
PUCCH
Sounding RS (SRS)
• Periodic SRS (2-160ms) used for:
- UL CH quality estimation
- input for TA regulation
- input for power control
• Wideband or hopping narrowband
PUSCH transmission
forbidden in all
SRS symbols
PUCCH Physical Uplink Control CHPUSCH Physical Uplink Shared CH
RI Rank Indicaton
RIV Resource Indication Value
RNTI Radio Network Temporary Id.RV Redundancy Version
NDI New Data IndicatorPDCCH Physical Downlink Control CH
PHICH Physical HARQ Indication CH
PMI Precoding Matrix Indication
PRACH Physical Random Access CHPRB Physical Resource Block
SR Scheduling RequestSRS Sounding Reference Sig
TA Timing Advance
TB Transport Block
TPC Transmit Power CommanUCI Uplink Control Informat io
CQI Channel Quality IndicatonCSR Channel Status Reporting
DCI Downlink Control Informat ion
HARQ Hybrid Automatic Repeat Request
MAC Medium Access ControlMCS Modulation & Coding Scheme
Uplink Transmission ProceduresScheduling and HARQ