REV-090004



ⓒ 3GPP 2009
<3GPP
LTE-Advanced Evaluation Workshop, Dec. 17-18, 2009> 1
Magnus Lindstrom, Ericsson
3GPP TSG-RAN WG2
LTELTE--AdvancedAdvanced
Radio Layer 2 and RRC aspectsRadio Layer 2 and RRC aspects

Outline



E.UTRA
overview


. LTE
Advanced
features
. E.UTRAN
architecture
. User
plane
protocol
stack
. Control
plane
protocol
stack
User
plane


. Reliable
transport
. U.plane
data
flow
. Scheduling
. DRX
. Security
Control
plane


. System
information
. Connection
control
. RRC
state
model
. IDLE
mode
mobility
. CONNECTED
mode
mobility
. Radio
Link
Failure
handling
. Random
Access
. Priority
access
Performance


. U.plane
latency
. C.plane
latency
. HO
interruption
ⓒ 3GPP 2009 <3GPP LTE-Advanced Evaluation Workshop, Dec. 17-18, 2009>

2

LTE
Advanced
features



LTE
Advanced
supports:


. Reliable,
high
rate,
high
capacity
and
low
latency
data
transfer
.
suitable
for
a
wide
range
of
services
. Mobility
. seamless
and
lossless
(using
packet
forwarding)
. optimized
for
low
mobile
speed
from
0
to
15
km/
h
.
higher
mobile
speed
between
15
and
120
km/
h
also
supported
with
high
performance
.
mobility
across
the
cellular
network
can
be
maintained
at
speeds
from
120
km/
to
350
km/
(or
even
up
to
500
km/h
depending
on
the
frequency
band)
. Relays
.
to
improve
e.g.
the
coverage
of
high
data
rates,
temporary
network
deployment,
cell.edge
throughput
and/or
to
provide
coverage
in
new
areas
.
relay
node
wirelessly
connected
to
donor
cell
of
donor
eNB
. Carrier
and
spectrum
aggregation
. to
support
wider
transmission
bandwidths
up
to
100MHz
and
spectrum
aggregation
. aggregation
of
both
contiguous
and
non.contiguous
component
carriers
is
supported
. Coordinated
Multi.Point
transmission
and
reception
.
to
improve
the
coverage
of
high
data
rates,
the
cell.edge
throughput
and/or
to
increase
system
throughput
ⓒ 3GPP 2009 <3GPP LTE-Advanced Evaluation Workshop, Dec. 17-18, 2009>

3

LTE
Advanced
features
(cont’d)



LTE
Advanced
further
supports:


. Emergency
Calls
.
Provisioning
of
emergency
call
service
to
user
equipment
in
both
normal
service
mode
(authenticated)
and
limited
service
mode
(unauthenticated)
. Positioning
.
UE
location
determination
through
user
plane
and
control
plane
based
solutions;
e.g.
,
A.GNSS,
OTDOA,
cell
level
granularity
location
reporting
. Public
warning
systems
(PWS)
.
Provisioning
of
timely
and
accurate
alerts,
warnings
and
critical
information
regarding
disasters
and
other
emergencies
through
Earthquake
and
Tsunami
Warning
System
(ETWS)
and
Commercial
Mobile
Alert
System
(CMAS)
. Home
eNB
(HeNB)
.
Provisioning
of
LTE
service
through
customer.premises
equipment
using
operator’s
licenced
spectrum
. Multimedia
Broadcast/Multicast
Service
(MBMS)
.
Multi.cell
broadcast
of
multimedia
services
through
efficient
Single
Frequency
Network
(SFN)
mode
of
operation
ⓒ 3GPP 2009 <3GPP LTE-Advanced Evaluation Workshop, Dec. 17-18, 2009>

4

E.UTRAN
architecture



ⓒ 3GPP 2009 <3GPP LTE-Advanced Evaluation Workshop, Dec. 17-18, 2009> 5
eNodeB
Cells
eNodeB
Cells
P-GW(s)
MME
S-GW(s)
External IP networks (internet, corporate
networks, operator services)
EPC
E-UTRAN
S1-MME S1-U
X2
Relay Node
Cells
IP Transport Network
PDCP
NAS
RRC
RLC
MAC
eNodeB
PHY
S-GWMME
Control
Plane
User
Plane
Non-Access
Stratum
(NAS)
Access
Stratum
(AS)

User
plane
protocol
stack



TS 36.323

PDCP
(Packet
Data
Convergence
Protocol)


.
Header
compression
using
the
RoHC
protocol†
.
In.sequence
delivery
and
retransmission
of
PDCP
SDUs
for
AM
Radio
Bearers
at
handover;
.
Duplicate
detection;
.
Ciphering;
.
Integrity
protection‡
.
TS 36.322
RLC
(Radio
Link
Control)


.
Transfer
of
upper
layer
PDUs
supporting
AM,
UM
and
TM
data
transfer;
.
Error
Correction
through
ARQ;
.
Segmentation
according
to
the
size
of
the
TB;
.
Re.segmentation
of
PDUs
that
need
to
be
retransmitted;
.
Concatenation
of
SDUs
for
the
same
radio
bearer;
.
Protocol
error
detection
and
recovery;
. In.sequence
delivery
MAC
(Media
Access
Control)
.
Multiplexing/demultiplexing
of
RLC
PDUs
TS 36.321
.
Scheduling
Information
reporting;
.
Error
correction
through
HARQ;
.
Logical
Channel
Prioritisation;
.
Padding;
†) for U-plane ‡) for C-plane
ⓒ 3GPP 2009 <3GPP LTE-Advanced Evaluation Workshop, Dec. 17-18, 2009>
6

Channel
Mapping



Transport
Channels:
Logical
channels:
. PCH:
Paging
Ch.
. PCCH:
Paging
Control
Ch.
. BCH:
Broadcast
Ch.
. BCCH:
Broadcast
Control
Ch.
. MCH:
Multicast
Ch.
. CCCH:
Common
Control
Ch.
. DL.SCH:
Downlink
Shared
Ch.
. DCCH:
Dedicated
Control
Ch.
. UL.SCH:
Uplink
Shared
Ch.
. DTCH:
Dedicated
Traffic
Ch.
. MCCH:
Multicast
Control
Ch.
. MTCH:
Multicast
Traffic
Ch.
PCCH BCCH CCCH DCCH DTCH MCCH MTCH CCCH DCCH DTCH

Uplink
Logical channels

Downlink

Logical channels

Downlink

Uplink

Transport channels

Transport channels

PCH BCH DL-SCH MCH


RACH UL-SCH


ⓒ 3GPP 2009 <3GPP LTE-Advanced Evaluation Workshop, Dec. 17-18, 2009>

7

Control
plane
protocol
stack



RLC
and
MAC
sublayers
perform
the
same


functions
as
for
the
user
plane.
PDCP
sublayer
performs
ciphering
and
integrity
protection.



RRC
(Radio
Resource
Control)
TS 36.331
protocol
performs:


.
Broadcast
of
System
Information
related
to
NAS
and
AS;
.
Establishment,
maintenance
and
release
of
RRC
connection;
.
Establishment,
configuration,
maintenance
and
release
of
Signalling
and
Data
Radio
Bearers
(SRBs
and
DRBs)
.
Security
functions
including
key
management;
.
Mobility
functions
including,
e.g.
.
Control
of
UE
cell
selection/reselection;
Paging;
UE
measurement
configuration
and
reporting;
Handover;
.
QoS
management
functions;
.
UE
measurement
reporting
and
control
of
the
reporting;
.
Notification
for
ETWS,
CMAS
and
MBMS;
.
NAS
direct
message
transfer
between
UE
and
NAS.
ⓒ 3GPP 2009 <3GPP LTE-Advanced Evaluation Workshop, Dec. 17-18, 2009>
8

User
plane


E.UTRA
overview



Control
plane
. LTE
Advanced
features
. E.UTRAN
architecture
. User
plane
protocol
stack
. Control
plane
protocol
stack
User
plane


. Reliable
transport
. U.plane
data
flow
. Scheduling
. System
information
. Connection
control
. RRC
state
model
. IDLE
mode
mobility
. CONNECTED
mode
mobility
. Radio
Link
Failure
handling
. Random
Access
. Priority
access
. DRX
Performance
. Security
. U.plane
latency
. C.plane
latency
. HO
interruption
ⓒ 3GPP 2009 <3GPP LTE-Advanced Evaluation Workshop, Dec. 17-18, 2009>

9

Reliable
transport
Retransmission
protocols



L1
applies
24
bit
CRC
protection
to
transport
blocks
(MAC
PDUs)


. Erroneous
transport
blocks
are
discarded
on
L1
Hybrid
ARQ
protocol
in
MAC
complemented
by
ARQ
protocol
in
RLC† for
high
reliability
and
radio
efficiency


. HARQ
feedback
sent
on
L1/L2
control
channel
. Single,
uncoded
bit
(low
overhead)
. Sent
for
each
scheduled
subframe
(fast)
. Retransmissions
are
soft.combined
with
previous
attempt
(efficient)
. ARQ
status
report
sent
as
MAC
data
. protected
by
CRC
and
HARQ
retransmissions
. RLC
Status
is
sent
on
demand
(poll,
timer,
gap
detection)
Both
HARQ
and
ARQ
protocols
terminated
in
the
eNB


. fast
handling
of
residual
HARQ
errors
†) RLC AM (Acknowledged Mode)
Ensures
low
latency
and
high
reliability
only. No retransmissions in RLC
UM (Unacknowledged mode).
ⓒ 3GPP 2009 <3GPP LTE-Advanced Evaluation Workshop, Dec. 17-18, 2009>



Reliable
transport
Lossless
and
in.sequence
delivery



Lossless
and
in.sequence
delivery
of
data
provided
by:


.
RLC
retransmission
(ARQ)
and
re.ordering
functions
for
normal
operation
(based
on
RLC
SNs)
.
PDCP
forwarding,
retransmission
and
reordering
functions
for
handover
cases
(based
on
PDCP
SNs)
. For
RLC
AM
data
radio
bearers
only
. PDCP
SNs
are
maintained
across
handovers
. Lower
layers
(RLC/MAC)
are
reset
RLC SDU RLC SDU RLC SDU RLC SDU
n+3n+2n+1n
RLC header RLC header
RLC PDU



Duplicate
detection
provided
by
PDCP


.
Duplicates
may
disturb
TCP
performance
.
Detects
and
removes
duplicates
based
on
PDCP
Sequence
Numbers
(SNs)
ⓒ 3GPP 2009 <3GPP LTE-Advanced Evaluation Workshop, Dec. 17-18, 2009> 11

User
Plane
data
flow
(downlink)



IP PDU

IP

RLC

ⓒ 3GPP 2009 <3GPP LTE-Advanced Evaluation Workshop, Dec. 17-18, 2009>
PDCP SDU
IP Payload H
H
PDCP
(Header Compression
& Ciphering)
PDCP
header
IP PDU
Radio Bearer 1
RLC SDU
(multiplex.)
MAC SDU
CRCTransport Block
MAC
header
IP PDU
IP PayloadH IP Payload H
Radio Bearer 1
Radio Bearer 2
H H
PDCP SDUPDCP
header PDCP SDUPDCP
header
RLC
header
RLC
header
RLC SDU
RLC
header
RLC SDU
MAC SDUMAC
header
CRCTransport Block
RLC PDU RLC PDU RLC PDU
MAC PDU
(segmentation &
concatenation)
Multiplexing
Concatenation Segmentation
MAC SDU
MAC

PHY

12

Scheduling



Scheduler
residing
in
eNB
with
objective
of:


.
Fulfilling
of
\"QoS
Contracts“
;
.
Maximising
cell
throughput;
. Providing
Fairness,
based
on
measurements,
scheduling
information
and
QoS
parameters.
Scheduling
Information
from
UE,
e.g.
:


.
Channel
Quality
Indication;
Buffer
Status
Report;
Power
Headroom
Report;
Uplink
Sounding.
QoS
framework
with
per
bearer
granularity


.
Bearers
associated
with
several
QoS
parameters,
e.g.
:
.
QoS
Class
Identifier
(QCI)
;
Guaranteed
Bit
Rate
(GBR)
;
Allocation
and
Retention
Priority
(ARP)
Logical
Channel
Priority;
Prioritised
Bit
Rate
(PBR)
;
Aggregate
Maximum
Bitrate
(AMBR)
.
Supports
wide
range
of
services,
e.g.
:
.
Basic
conversational
service
class,
rich
conversational
service
class
and
conversational
low
delay
service
class;
.
Also
interactive
high
delay,
interactive
low
delay,
streaming
live,
streaming
non.live
and
background.
ⓒ 3GPP 2009 <3GPP LTE-Advanced Evaluation Workshop, Dec. 17-18, 2009>

13

Scheduling
Dynamic
&
Semi.Persistent
&
TTI
Bundling



Scheduling
decisions
dynamically
signaled
on
L1L2
control
channel
PDCCH


.
1ms
Transmission
Time
Interval
(TTI)
for
DL.SCH
and
UL.SCH
.
PDCCH
provides
physical
resource
allocation,
Modulation
and
Coding
scheme,
New.Data
indicator,
Transport
Block
size,
Redundancy
version,
HARQ
Process
ID
.
DL:
adaptive
HARQ
.
All
(re.)transmissions
are
indicated
on
PDCCH
.
Synchronous
HARQ
feedback,
asynchronous
retransmissions
.
UL:
adaptive
and
non.adaptive
HARQ
.
First
transmission
indicated
on
PDCCH
.
Retransmissions
can
be
indicated
on
PDCCH
or
be
derived
from
previous
transmission
parameters
and
HARQ
feedback
.
Synchronous
HARQ
feedback,
synchronous
retransmissions
Semi.Persistent
Scheduling
(SPS)


.
Reduced
L1/L2
control
signalling
for
traffic
with
periodic
transmissions
.
UL/DL
resources
configured
to
occur
at
specific
interval
.
Only
first
assignment/grant
need
to
be
signalled
.
Subsequent
transmissions
use
the
same
resources
as
the
first
transmission
. Can
be
deactivated
with
a
special
assignment/grant
TTI
Bundling
.
Improved
coverage
at
lower
delay
.
UE
performs
multiple
HARQ
transmission
attempts
in
consecutive
TTIs
before
receiving
HARQ
feedback
.
Less
HARQ
signalling
reduces
risk
of
HARQ
failure
ⓒ 3GPP 2009 <3GPP LTE-Advanced Evaluation Workshop, Dec. 17-18, 2009>

14

UE
battery
efficiency
Discontinuous
Reception .DRX



Configurable
Sleep
Mode
for
UE’s
receiver
chain
Periodic
repetition
of
an
“On
Duration”
followed
by
a
possible
period
of
inactivity



“Active
time”
defines
periods
of
mandatory
activity:


.
In
configured
On
Duration
(e.g.
2
ms
per
20
ms)
;
.
While
receiving
assignments
or
grants
for
new
data;
(an
Inactivity
Timer
is
(re.)started
and
the
UE
is
prepared
to
be
scheduled
continuously)
.
When
expecting
a
retransmission
of
a
Downlink
HARQ
transmission
(one
HARQ
RTT
after
receiving
an
unsuccessful
DL
transmission)
;
.
When
expecting
HARQ
feedback
for
an
Uplink
HARQ
transmission;
.
After
transmitting
a
Scheduling
Request.
Two.level
DRX
scheme


.
Long
DRX
for
very
power
efficient
operation
during
periods
of
low
activity
.
Short
DRX
for
low
latency
during
periods
of
more
activity
.
autonomous
transitions
between
states
ⓒ 3GPP 2009 <3GPP LTE-Advanced Evaluation Workshop, Dec. 17-18, 2009>

15

ⓒ 3GPP 2009 <3GPP LTE-Advanced Evaluation Workshop, Dec. 17-18, 2009> 16 ⓒ 3GPP 2009 <3GPP LTE-Advanced Evaluation Workshop, Dec. 17-18, 2009> 16
Security
Ciphering
and
Integrity
Protection


ASsecurityfunctionsprovidedbyPDCPcontrolledbyRRC. Alwaysactivatedearly. Oncestarted,alwayson. BasedonSNOW3GandAESalgorithms. Keyschangedathandover;backwardandforwardsecurity. Countersplitintwopartsforhighradioefficiency:
. HyperFrameNumber(HFN):maintainedlocally. SequenceNumber(SN):signalledovertheairIntegrityprotection. forC.planeradiobearers(SignallingRadioBearers)
. 32.bitMessageAuthenticationCode(MAC.I)
. MAC.IplacedatendofPDUCiphering(confidentialityprotection)
. forC.planeradiobearers(SignallingRadioBearers)
. forU.planeradiobearers(DataRadioBearers)
. PDCPControlPDUs(RoHCfeedbackandPDCPstatusreports)notcipheredPackets not
associated to aPDCP SDU

Control
plane


E.UTRA
overview



. LTE
Advanced
features
. E.UTRAN
architecture
. User
plane
protocol
stack
. Control
plane
protocol
stack
User
plane


. Reliable
transport
. U.plane
data
flow
. Scheduling
. DRX
. Security
Control
plane


. System
information
. Connection
control
. RRC
state
model
. IDLE
mode
mobility
. CONNECTED
mode
mobility
. Radio
Link
Failure
handling
. Random
Access
. Priority
access
Performance


. U.plane
latency
. C.plane
latency
. HO
interruption
ⓒ 3GPP 2009 <3GPP LTE-Advanced Evaluation Workshop, Dec. 17-18, 2009>

17

System
Information



System
Information
is
provided
by
RRC,
structured
in
MIB
and
SIBs
MIB
.transmitted
in
fixed
location


. Includes
parameters
essential
to
find
SIB1
scheduled
on
DL.SCH
(e.g.
DL
bandwidth
and
System
Frame
Number)
SIB1
.
scheduled
in
the
frequency
domain
(fixed
timing)
on
DL.SCH


. Contains
information
relevant
when
evaluating
if
a
UE
is
allowed
to
access
cell
and
defines
the
scheduling
of
other
system
information
Other
SIBs
are
multiplexed
in
SystemInformationMessages


. Scheduled
in
time
and
frequency
domains
as
defined
by
SIB1
. SIB2
.
contains
resource
configuration
information
that
is
common
for
all
UEs;
needed
before
accessing
a
cell
.
SIB3,
SIB4,
..
.
. other
system
information
grouped
according
to
functionality
ⓒ 3GPP 2009 <3GPP LTE-Advanced Evaluation Workshop, Dec. 17-18, 2009>

18

Connection
Management



Connection/session
management
is
performed
by:


.
the
RRC
protocol
between
the
UE
and
E.UTRAN
. the
NAS
protocol
between
the
UE
and
CN
The
NAS
protocol
performs
e.g.
:
.
authentication,
registration,
bearer
context
activation/
deactivation
and
location
registration
management
RRC
messages
are
used
e.g.
,
to:


.
establish
connection,
configure
the
radio
bearers
and
their
corresponding
attributes,
and
to
control
mobility
The
RRC
protocol
has
two
states:


.
RRC_IDLE
and
RRC_CONNECTED
ⓒ 3GPP 2009 <3GPP LTE-Advanced Evaluation Workshop, Dec. 17-18, 2009>

19

Mobility
and
RRC
State
Models



RRC_CONNECTEDRRC_IDLE
Dormant Active
IDLE:


.
UE
known
in
EPC
and
has
IP
address;
.
UE
not
known
in
E.UTRAN/eNB;
.
UE
location
known
on
Tracking
Area
level;
.
Unicast
data
transfer
not
possible;
.
UE
reached
by
paging
in
tracking
areas
controlled
by
EPC;
.
UE.based
cell.selection
and
tracking
area
update
to
EPC.
CONNECTED:


.
UE
known
in
EPC
and
E.
UTRAN/eNB;
”context”
in
eNB;
.
UE
location
known
on
cell
level;
.
Unicast
data
transfer
possible;
.
DRX
supported
for
power
saving;
.
Mobility
is
controlled
by
the
network.
ⓒ 3GPP 2009 <3GPP LTE-Advanced Evaluation Workshop, Dec. 17-18, 2009> 20

Idle
Mode
Mobility


ⓒ 3GPP 2009 <3GPP LTE-Advanced Evaluation Workshop, Dec. 17-18, 2009> 21
UEknownonTrackingArea(TA)
levelUEreachedbypaginginTAsTA1
TA2
TA3 TA4
MME
TA list 1
-TA1
-TA2
-TA3
Page in TA1, TA2, TA3

Idle
Mode
Mobility



ⓒ 3GPP 2009 <3GPP LTE-Advanced Evaluation Workshop, Dec. 17-18, 2009> 22
1area(3inWCDMA)
. Trackingarea,TATA1
TA2
TA3 TA4
MME
TA Update
request TA Update
TA list 2
-TA2
-TA3
-TA4
TA list 1
-TA1
-TA2
-TA3

ConnectedStateMobilitySourceeNodeBconfiguresUEmeasurementsandreportingSourceeNBreceivesUEmeasurementreporteNode B eNode B
Measurement Reports
MME S-GW
X2
ConnectedStateMobilitySourceeNodeBconfiguresUEmeasurementsandreportingSourceeNBreceivesUEmeasurementreporteNode B eNode B
Measurement Reports
MME S-GW
X2
ⓒ 3GPP 2009 <3GPP LTE-Advanced Evaluation Workshop, Dec. 17-18, 2009> 23

ⓒ 3GPP 2009 <3GPP LTE-Advanced Evaluation Workshop, Dec. 17-18, 2009> 24
ConnectedStateMobilityHOrequestfromsourcenodeAdmissioncontrolHOAckfromtargetnodeeNode B eNode B
HO Request
MME S-GW
HO Request ACK
ⓒ 3GPP 2009 <3GPP LTE-Advanced Evaluation Workshop, Dec. 17-18, 2009> 24
ConnectedStateMobilityHOrequestfromsourcenodeAdmissioncontrolHOAckfromtargetnodeeNode B eNode B
HO Request
MME S-GW
HO Request ACK

Connected
State
Mobility


eNode B eNode B HO Command
MME S-GW
HO
Command
from
source
node



ⓒ 3GPP 2009 <3GPP LTE-Advanced Evaluation Workshop, Dec. 17-18, 2009> 25

Connected
State
Mobility


eNode B eNode B
Data Forwarding
MME S-GW
Data
forwarding
initiated


ⓒ 3GPP 2009 <3GPP LTE-Advanced Evaluation Workshop, Dec. 17-18, 2009> 26

Connected
State
Mobility


eNode B eNode B
HO confirm
MME S-GW
Handover
confirm
to
target
node


ⓒ 3GPP 2009 <3GPP LTE-Advanced Evaluation Workshop, Dec. 17-18, 2009> 27

ConnectedStateMobilityRequestEPCtoswitchdatapathS.GWswitchesdatapathHOcompletedeNode B eNode B
MME S-GW
ConnectedStateMobilityRequestEPCtoswitchdatapathS.GWswitchesdatapathHOcompletedeNode B eNode B
MME S-GW
ⓒ 3GPP 2009 <3GPP LTE-Advanced Evaluation Workshop, Dec. 17-18, 2009> 28

Radio
Link
Failure
handling



1st
phase:


. Layer
1
monitors
downlink
quality
and
indicates
problems
to
RRC
. RRC
filters
L1
indications
and
starts
a
timer
. if
no
recovery
within
1st
phase,
triggers
2nd
phase
. Layer
2
monitors
random
access
attempts
and
indicates
problems
to
RRC
. RRC
triggers
2nd
phase
2nd
phase
.Radio
Link
Failure
(RLF)
:


. Possible
recovery
through
an
RRC
Connection
Reestablishment
procedure
. reestablishment
may
be
performed
in
any
cell
to
which
the
UE’s
context
is
made
available
. If
no
recovery
within
2nd
phase,
UE
goes
autonomously
to
IDLE
ⓒ 3GPP 2009 <3GPP LTE-Advanced Evaluation Workshop, Dec. 17-18, 2009>

29

Random
Access
procedure



Four.step
procedure
to…
UE


. …establish
uplink
synchronization
. …obtain
UL.SCH
resources
. …obtain
identity
(C.RNTI)
1.
Preamble
transmission
on
PRACH
.
Timing
estimation
at
eNodeB
2.
Random
access
response
.
Timing
Advance
command
.
UL.SCH
resource
assignment
for
step
3
.
Temporary
C.RNTI
3.
Contention
resolution
.
transmit
terminal
identity
.
also
other
data
4.
Contention
resolution
.
Echo
terminal
identity
from
step
3
.
also
other
signaling/data
Also
support
for
contention.free
random
access
procedure
.
only
step
1
and
2
used
1
3
eNB

RA Preamble
RA Response
(Timing Advance, UL grant, etc.)
RA Message 3
(UE Identity, BSR, etc.)
RA Contention Resolution
(UL grant, DL assignment)
Further uplink/downlink transmissions
2
4
ⓒ 3GPP 2009 <3GPP LTE-Advanced Evaluation Workshop, Dec. 17-18, 2009>

30

Priority
access



Access
classes
used
to
differentiate
admittance
in
accessing
a
cell


.
UE
associated
to
an
access
class
for
normal
use
.
UE
may
also
belong
to
an
access
class
in
the
special
categories,
e.g.
PLMN
staff,
social
security
services,
government
officials
Access
class
barring


.
Access
load
can
be
controlled
by
use
of
access
barring
.
For
normal
use,
access
barring
rate
and
barring
time
could
be
broadcast
in
case
of
congestion
.
For
the
special
categories,
1.bit
barring
status
could
be
broadcast
for
each
access
class
.
Barring
parameters
could
be
configured
independently
for
mobile
originating
data
and
mobile
originating
signaling
attempts
.
For
emergency
calls,
a
separate
1.bit
barring
status
is
indicated
ⓒ 3GPP 2009 <3GPP LTE-Advanced Evaluation Workshop, Dec. 17-18, 2009>

31

Performance



E.UTRA
overview


. LTE
Advanced
features
. E.UTRAN
architecture
. User
plane
protocol
stack
. Control
plane
protocol
stack
User
plane


. Reliable
transport
. U.plane
data
flow
. Scheduling
. DRX
. Security
Control
plane


. System
information
. Connection
control
. RRC
state
model
. IDLE
mode
mobility
. CONNECTED
mode
mobility
. Radio
Link
Failure
handling
. Random
Access
. Priority
access
Performance


. U.plane
latency
. C.plane
latency
. HO
interruption
ⓒ 3GPP 2009 <3GPP LTE-Advanced Evaluation Workshop, Dec. 17-18, 2009>

32

User
plane
latency



UE
eNB

TTI

1.5 ms
1.5 ms
HARQ RTT
8 ms
1.5 ms
1.5 ms 1ms
1ms
UE eNB TTI
User
plane
latency
(FDD
RIT)


.
4ms
when
HARQ
retransmission
is
not
needed
FDD RIT


User
plane
latency
(TDD
RIT)


.
Depends
on
UL/DL
configuration
and
on
whether
UL
or
DL
transmission
TDD RIT

.
4.9ms
possible
for
uplink
and
downlink
jointly
when
HARQ
retransmission
is
not
needed
1ms+FAt1.5ms 1ms
HARQ RTT
1.5ms 1ms+FAt 1 ms
ⓒ 3GPP 2009 <3GPP LTE-Advanced Evaluation Workshop, Dec. 17-18, 2009> 33

Control
plane
latency .IDLE..CONNECTED



Step
LTE Advanced
Description Time [ms]
1 Average delay due to RACH scheduling period (1ms
RACH cycle)
0.5
2 RACH Preamble 1
3-4 Preamble detection and transmission of RA response
(Time between the end RACH transmission and UE’s
reception of scheduling grant and timing adjustment)
3
5 UE Processing Delay (decoding of scheduling grant,
timing alignment and C-RNTI assignment + L1 encoding
of RRC Connection Request)
5
6 Transmission of RRC and NAS Request 1
7 Processing delay in eNB (L2 and RRC) 4
8 Transmission of RRC Connection Set-up (and UL grant) 1
9 Processing delay in the UE (L2 and RRC) 12
10 Transmission of RRC Connection Set-up complete 1
11 Processing delay in eNB (Uu →S1-C)
12 S1-C Transfer delay
13 MME Processing Delay (including UE context retrieval of
10ms)
14 S1-C Transfer delay
15 Processing delay in eNB (S1-C
→
Uu) 4
16 Transmission of RRC Security Mode Command and
Connection Reconfiguration (+TTI alignment)
1.5
17 Processing delay in UE (L2 and RRC) 16
Total delay 50

NOTE:
LTE
Rel.
8
supports
IDLE..CONNECTED
latency
of
around
80ms
and,


hence,
already
meets
the
ITU
requirement
on
C.plane
latency
for


IDLE..CONNECTED
transition


ⓒ 3GPP 2009 <3GPP LTE-Advanced Evaluation Workshop, Dec. 17-18, 2009>

34

Control
plane
latency
.Dormant
.
Active



Uplink
initiated
transition
from
dormant
state
(DRX
substate)
to
active
state
(non.
DRX
substate)
for
synchronised
UE;
including
first
uplink
data
transmission.



Step
LTE Advanced
Description Time [ms]
1 Average delay to next SR opportunity (1ms
PUCCH cycle)
0.5
2 UE sends Scheduling Request 1
3 eNB decodes Scheduling Request and
generates the Scheduling Grant (+ delay for
nearest DL subframe)
3
4 Transmission of Scheduling Grant 1
5 UE Processing Delay (decoding of scheduling
grant + L1 encoding of UL data)
3
6 Transmission of UL data 1
Total delay 9.5

ⓒ 3GPP 2009 <3GPP LTE-Advanced Evaluation Workshop, Dec. 17-18, 2009>

35

Handover
interruption



Intra.LTE
inter.eNB
handover


Target
cell
already
identified
and
measured
by
the
UE


.
Fast
radio
synchronisation
to
target
aided
by
previous
measurement
Data
forwarding
initiated
before
radio
synchronisation
to
target
cell
and
backhaul
faster
than
radio


.
Forwarded
data
available
in
target
when
UE
is
ready
to
receive
.
Data
forwarding
does
not
affect
UE Source Target
HO Preparation
HO Command
Processing
Data Forwarding
4. Processing
5. Grant
1. Radio Synch
3. Preamble
2. RACH Waiting
interruption
7. Data
6. Processing
overall
delay


ⓒ 3GPP 2009 <3GPP LTE-Advanced Evaluation Workshop, Dec. 17-18, 2009> 36

Handover
interruption
(cont’d)



UE Source Target
HO Preparation
HO Command
Processing
Data Forwarding
4. Processing
5. Grant
1. Radio Synch
3. Preamble
2. RACH Waiting
interruption
7. Data
6. Processing
Step
LTE Advanced
Description Time [ms]
1 Radio Synchronisation to the target cell 1
2 Average delay due to RACH
scheduling period (1ms
periodicity)
0.5
3 RACH Preamble 1
4-5 Preamble detection and transmission
of RA response (Time between
the end RACH transmission and
UE’s reception of scheduling
grant and timing adjustment)
5
6 Decoding of scheduling grant and
timing alignment
2
7 Transmission of DL Datta 1
Total delay 10.5

Note: This delay does not depend on the
frequency of the target in the typical case where
the cell has already been measured by the UE

ⓒ 3GPP 2009 <3GPP LTE-Advanced Evaluation Workshop, Dec. 17-18, 2009> 37

References



TR
36.912:
Feasibility
study
for
Further
Advancements
for
E.UTRA
(LTE.Advanced)


TS
36.300:
E.UTRA
and
E.UTRAN
Overall
description


TS
36.304:
E.UTRA
User
Equipment
(UE)
procedures
in
idle
mode


TS
36.321:
E.UTRA
Medium
Access
Control
(MAC)
protocol
specification


TS
36.322:
E.UTRA
Radio
Link
Control
(RLC)
protocol
specification


TS
36.323:
E.UTRA
Packet
Data
Convergence
Protocol
(PDCP)
specification


TS
36.331:
E.UTRA
Radio
Resource
Control
(RRC)
Protocol
specification


Latest
versions
of
these
specifications
can
be
acquired
from:
http://www.3gpp.org/ftp/Specs/html.info/36.series.htm


ⓒ 3GPP 2009 <3GPP LTE-Advanced Evaluation Workshop, Dec. 17-18, 2009>

38