lte system overview - additional materials

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



Subframe

12 SCs

Guardband

5 MHz channel BW




PDSCH

PDCCH

P-SS, S-SS

PBCH

RS

Subframe

12 SCs

Guardband

5 MHz channel BW



Uplink Radio Frame

Subframe

Guardband

5 MHz channel BW


12SCs


Uplink Radio Frame

Subframe

Guardband

5 MHz channel BW


12 SCs


Uplink Radio Frame

PUSCH

PUCCH

SRS

PRACH

Subframe

Guardband

5 MHz channel BW


12SCs

LTE SON


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)


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


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


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


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


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


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


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

lte system overview - additional materials

Documents

lte son

son functionality

son algorithms

self optimization example

channel bwcopyright

self optimization criteria

deployed enb new enb

ho failures