Default_bearer_setup_LTE

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Default Bearer Setup In LTE

By: Zunaira TahirNetwork Performance Optimization Trainee Engineer at Ericsson

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Contents of Presentation: Identifiers Used in LTE

Radio Bearers in LTE

Default Bearer Setup in LTE

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LTE ARCHITECTURE

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IDENTIFIERS USED IN LTE

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Identifiers Used in LTE

PLMN IDIdentify the network

MCC+MNC

MMEGIIdentify MME group in pool

areas

MMECIdentify MME within MME group

MMEIIdentify MME within PLMN

MMEC+MMEGI

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MME Pool Area:

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Benefits of MME Pool Area:

Region A Region B

MME Pool Area 1MME 1 and MME 2

MME Pool Area 2MME 3 and MME 4

Down town

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Identifiers Used in LTE

M TMSIIdentify the mobile to serving

MME

GUMMEIIdentify MME anywhere in the

worldMMEI+PLMN-ID

GUTI To identify a UE between the UE and the MME on behalf of

IMSI for security reasonGUMMEI+ M-TMSI

S TMSIUsed for paging and service

requestM TMSI+ MMEC

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Comparison of GUTI and S-TMSI:

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Identifiers Used in LTE

RNTIUsed to differentiate one user

from other

LBIIdentify default bearer linked

with dedicated bearer

P-GW IDAssigned by HSS to identify a

specific PDN GW (P-GW)

eNB IDIdentify eNodeB within PLMN

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PopUp:

How many types of RNTIs are available in the network?

Who issues RNTI?

How can PHY layer know which RNTI it has to use?

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RADIO ACCESS BEARERS IN LTE

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What is the difference between RRC and RAB?

PopUp:

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Hey, I want to buy some

things from store

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Okay, tell me what do you want to buy

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Buyer will write the items on paper, wrap the paper

around stone and throws the stone towards

seller

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Seller will send the list to store via robot car to confirm

whether all items are

available in store or not

Assume the positive Response from store

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How to do shipment? There is no path to deliver the order

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Let us assume that seller has some carriers and some iron

rods.

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The seller will put the rods and will

establish the path for delivery

of order. The establishment of path for shipment

is called RRC

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The seller then chooses the carrier

according to the type of material which

needs to be delivered. The carrier which is

delivering the order is called RAB

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Definitions of RRC and RAB

RRCA signaling link established as the result of allocation of resources

RABA signaling link that carriers the actual information satisfying the QOS demands

of user

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Lets map the analogy to available technologies !

GSM Network:• Buyer : MS• Seller : BTS• Store: BSC• Robot Car: Abis interface• SD Assignment: RRC • Traffic flow over TCH: Radio bearer

LTE Network:• Buyer : UE• eNode B is the only manager of radio resources in LTE • There is no concept of robot car• We can assume that seller is sitting in the store and receiving the order via telephone

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Radio Bearers in LTE

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DEFAULT BEARER SETUP

IN LTE

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Random Access Procedure in LTE

Random Access Preamble

UE sends one of the 64 preambles,

RA-RNTI

How the UE will come to know when it has to transmit RACH Preamble?

UE will listen the system information type 2

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System Information Type 2:

Number of Rach Preambles: 4-64

Preamble TransMax

Ra-Response Window

Prach_configindex

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Random Access Procedure in LTE

Random Access Preamble

Random Access Response

RRC Setup Request

RRC Setup

UE sends one of the 64 preambles,

RA-RNTI

DL-SCH, RA-RNTI, TA, Uplink resource grant,

TC-RNTI UL-SCH, C-RNTI,

Establishment cause

This message will establish signaling

connection

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ATTACH PROCEDURES IN LTE

Using IMSI

Using GUTI (MME Unchanged)

Using GUTI (MME Changed)

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Attach Procedure Using IMSI

Attach Request

Initial UE message

RRC Connection setup

complete+Attach req

NAS-PDU, ECGI, TAI

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Authentication Procedure

Authentication info req

HSS

Generates AV(RAND, AUTN, XRES, KASME)

Authentication response

IMSI, PLMN ID

Auth. Req.

RAND, AUTN,

KSIASME

AUTNue=AUTNhss

Auth. Response (RES)

RES=XRES

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Security Setup Procedure

Generates Security keys

Security mode Command

Selected ciphering algorithm

Generates Security keys

Security Mode Complete

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Location Update Procedure

Location Update Answer

IMSI, MMEI Location Update Request

HSS

APN, PGW-ID,

QOS Profile, IMSI

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Attach Procedure Using GUTI (MME Unchanged)

Attach Request (GUTI)

Authentication

Security Setup

Location Update

Identity Request

Identity Response

IMSI, GUTI, KSIasme, NAS MAC, NASKeys

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Attach Procedure Using GUTI (MME Changed)

UE N-MME

Attach Request

Authentication

Security Setup

Location Update

Identity Request

Identity Response

O-MME

Attach Request (GUTI)

Identity Request

Identity Response

Fail

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Default Bearer Setup

UES-

GW

Session request

P-GW

EPS Bearer ID, IMSI, PGW ID,

APN, QOS Profile, ECGI, TAI

S5 S-GW TEID (DL)

Session request

EPS Bearer ID, IMSI, PGW ID,

APN, QOS Profile, ECGI, TAI,

S5 S-GW, TEIDUE IP Address

P-GW TEID (UL)

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Default Bearer Setup

UES-

GWP-GW

S5 Bearer

Response

EPS Bearer ID,UE IP, PGW ID, APN, QOS

Profile, S5 P-GW TEID, Charging

info

S1 S-GW TEID

Response

EPS Bearer ID,UE IP, APN, QOS Profile, S5 P-GW TEID, S1

S-GW TEID Charging info

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Default Bearer Setup

UES-

GWP-GW

Receive S1 TEID (UL)

Initial context setup

E-RAB ID, E-RAB QOS, S1 S-GW

TEID (UL), Kenb, GUTI, UE IP, UE

security algo.

Sec mode cmd

Sec Mode comp.

DRB ID

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Default Bearer Setup

UES-

GWP-GW

RRC Re configEPS Bearer ID, DRB ID

Initial contxt res.

DRB Bearer

E RAB ID, S1 enb TEID

(DL)

S1 enb TEID (DL)

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Default Bearer Setup

UES-

GW

Modify bearer request

P-GW

EPS Bearer ID, S1 enb TEID (DL)

Response

S1 Bearer Established

S1 Bearer EstablishedDRB

Established

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THANK YOU