lte system overview - additional materials
DESCRIPTION
Here are some additional materials from LTE System Overview course delivered in October 2012 in Amsterdam, The Netherlands. If you are interested in attending top in class LTE/LTE-Advanced courses, please have a look http://is-wirelesstraining.com/course-map-2 or contact us directly: [email protected].TRANSCRIPT
LTE System Overview Additional Materials
LTE Radio Frames Examples LTE PHY Lab Generations
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Subframe
12 SCs
Guardband
Downlink Radio Frame
5 MHz channel BW
4.5 MHz measured BW Guardband
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Downlink Radio Frame
Subframe
12 SCs
Guardband
5 MHz channel BW
4.5 MHz measured BW Guardband
Copyright by IS-Wireless. All rights reserved. www.is-wireless.com
Downlink Radio Frame
PDSCH
PDCCH
P-SS, S-SS
PBCH
RS
Subframe
12 SCs
Guardband
5 MHz channel BW
4.5 MHz measured BW Guardband
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Uplink Radio Frame
Subframe
Guardband
5 MHz channel BW
4.5 MHz measured BW Guardband
12SCs
Copyright by IS-Wireless. All rights reserved. www.is-wireless.com
Uplink Radio Frame
Subframe
Guardband
5 MHz channel BW
4.5 MHz measured BW Guardband
12 SCs
Copyright by IS-Wireless. All rights reserved. www.is-wireless.com
Uplink Radio Frame
PUSCH
PUCCH
SRS
PRACH
Subframe
Guardband
5 MHz channel BW
4.5 MHz measured BW Guardband
12SCs
LTE SON
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E-UTRA Rel. 9 Self Organizing Networks
SON
Self Configuration Self Optimization Self Healing
SON Objective
minimization of manual changes of RAN configuration and optimization SON reduces the need for centralized planning and human intervence
3GPP approach for SON (3GPP TS 32.500):
”SON algorithms themselves will not be standarized in 3GPP”
”3GPP standarizes measurements, procedures and open interfaces to support SON”
eNB
Network
Plug in
Self Configuration example features: • Plug and play eNB (e.g. HeNB)
• Before eNB switches transmitters
• Downloading configuration:
(IP address, Cell IDs, powers, etc)
• Secure connection establishment
Configuration
downloading
eNB
eNB
Optimize powers
HO params
PRACH params
Self Optimization example features: • Based on UE/eNB measurements:
(e.g. throughputs, HO failures, etc)
• Based on NW performance meas.
(e.g. RLFs, Drops, etc)
• Aim – maximize NW performance
and provide cost savings
• Optimization of parameters for:
HO, RACH, ICIC, TxPower
eNB
eNB
restart
RF failure
Ala
rm
Recovery
actions
take
over UEs
Self Healing example features: • Automatic detection and locatization
of NW failures and faults
• Performing recovery actions
(e.g. reconfiguration, restart, reload,
load fallback software)
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E-UTRA Rel. 9 SON Architecture Options
Centralized SON Distributed SON Hybrid SON
SON O&M
SON
Operation
Cou
nte
rs, K
PIs
(e.g
. a
larm
s, ca
ll d
rop
s)
eN
B s
pe
cific
se
ttin
gs
SON
SON O&M
Hig
h L
eve
l R
ep
ort
s
Hig
h le
ve
l S
ON
po
licie
s
SON
SON
SON
SON O&M
Hig
h L
eve
l R
ep
ort
s
Co
un
ters
, K
PIs
Hig
h le
ve
l S
ON
po
licie
s
eN
B s
pe
cific
se
ttin
gs
SON
SON
SON
SON
• > 2 cells involved
• Long term statistics
• Slower update rate
Cri
teri
a
• One or two cells involved
• Fast update rate
• Short term statistics
• Auto-configuration with
dynamic self planning
• Coverage and capacity
optimization Ex
am
ple
s
• Automated Neighbor relation
• Handover and ICIC optimization
• Link optimization
• RACH optimization
• Both from the other two
architectures
• Both from the other two
architectures
High level network tuning
RAN self optimization
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E-UTRA Rel. 9 Self Configuration Procedure Example
eNB
eNB
eNB
Backhaul
MME
DHCP
Server O&M
1. Auto connect to
backhaul
2. Get the IP address
4. Autosetup the
S1 connection
3. Auto software
and configuration download
(e.g. PCIs, neighbors)
5. Auto X2 with neighbor setup
6. Configure
the PCIs for
cells
7. Set the neighbor
cells (ANR)
New eNB
Already deployed eNB
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E-UTRA Rel. 9 Self Optimization Algorithm (High Level View)
Monitor input data
Analyse input data with
optimization algorithms
Execute corrective actions
One time self-optimization
procedure ends
Fallback
mechanism
Meet the
targets?
System state better after the
corrective actions execution?
Yes
No
Yes
No
Keep monitoring
Restore the system to
the previous state
(before the corrective
actions were executed)
UE measurements
UE signalling (e.g. RLF)
Cell global counters
Apply optimization
algorithm and
parameter adaptation
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E-UTRA Rel. 9 SON Self Optimization (Mobility Load Balancing)
Mobility Load Balancing Procedure example
Overloaded eNB
eNB1
eNB2
Resource status request
Resource status response
Resource status update
Load reporting (e.g. # of
occupied PRBs)
X2
Congestion triggered SON load balancing
(find eNBs to HO user)
Handover procedure (cause: load balancing) Load balancing action
Evaluation of HO situation SON load balancing
(HO params change required)
Mobility change request (cause: load balancing)
Mobility change ACK
Change of HO
setting (+2dB) Change of HO
setting (-2dB)
SON HO params change
(amending mobility configuration:
2dB range change) For the UE not to get back
to the overloaded cell
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E-UTRA Rel. 9 SON Self Optimization Framework in 3GPP Rel. 9/10
SON Functionality Defined by 3GPP SON Feature
Load Balancing
Handover Optimization
RACH Optimization
Energy Saving
Load and capacity reporting
• Allocated load
• Available capacity
Mobility configuration negotiations
• Information about change of handover trigger on own side
• Request to change handover trigger in neighbor cell
• Possible rejection of the request
RLF and handover reporting
• Detection of RLF cause
• Fetching UE measurements and passing to neighbor
PRACH information exchange
• Fetching UE statistics (e.g. # of RACH attempts before
succesful, contention resolution failure indication)
• Exchanging PRACH configuration between eNBs
Cell status information
• Cell switch on request
LTE Voice Solutions CS Fallback and SR-VCC
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Voice Solutions Signalling Procedures CS Fallback Procedure – Message Flow
eNB MME MSC/ VLR
RNC/ BSC
RRC connection est
IDLE-to-connected
Incoming
voice call Paging Request
(IMSI, TMSI, etc)
Paging
(STMSI, incl CS indicator) Paging
(STMSI, incl CS indicator)
Service Request
(incl CS fallback indicator) Service Request
(incl CSFB ind.)
Initial UE ctx setup
(UE capabs, CSFB ind)
Handover/eNB assisted cell change/Release with redirect
eNB selects suitable cell (e.g. by triggering UE meas of 2G/3G neighbours)
Using RRC: Mobility from E-UTRA Command
Paging Response
Paging Response
CS connection establishment
• MME determines S-TMSI related to
received TMSI
• MME pages user in all TAs
• Bearer ctx activation with indication to
perform fallback to 2G/3G
Radio conn est.
with target RAN
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Voice Solutions Signalling Procedures SR-VCC – Procedure Overview (Example With PS Data Suspension)
eNB
UTRAN/ GERAN
SGW/ PGW
MSC Serv
IMS MME
Measurement Reports
(GERAN/UTRAN) HO to UTRAN/GERAN
Required (SRVCC ind)
Voice/nonVoice
Bearer splitting
Initialization of SRVCC for Voice Bearer
CS HO Preparation PS nonVoice
bearer suspension
IMS Service Continuity Procedures
PS Voice and PS Data
CS HO Response
(CS resources est.)
IMS voice translation
HO Command
(Target cell config.) Mobility from EUTRA Cmd
(Target cell config.)
Handover execution
PS data
suspended
CS Voice
After CS call is ended UE might perform TAU and
get back to LTE to resume PS data bearers
If target RAT supports both
CS/PS, the PS data bearer
will be rerouted via SGSN