The document describes network identities and procedures used in LTE attach flows. It discusses identifiers like GUTI, RNTI, and bearers. The attach flow involves the UE sending an attach request to the eNB which triggers authentication and establishment of default bearer towards the PGW, after which the UE receives an attach accept. Timers are involved at different nodes during this process.
It is a handbook of UMTS/LTE/EPC CSFB call flows.
This document is originally edited by Justin MA and it is free to share to everyone who are interested.
All reference/resource are from internet. If there is any copy-right issue, please kindly inform Justin by majachang@gmail.com.
Thanks for your reading!
It is a handbook of UMTS/LTE/EPC CSFB call flows.
This document is originally edited by Justin MA and it is free to share to everyone who are interested.
All reference/resource are from internet. If there is any copy-right issue, please kindly inform Justin by majachang@gmail.com.
Thanks for your reading!
An introduction to Cellular communications Signaling, Specifically LTE Signaling.
Introducing 3GPP approach to handover and handoff mechanisms.
LTE architecture by alcatel-lucent included in this presentation.
This presentation focuses on mobility management protocols such as GTP-C and GTP-U.
Simplified Call Flow Signaling: Registration - The Attach Procedure3G4G
This presentation/video provides an example of the registration procedure. The device or UE needs to let the core network(s) know that it is switched on and active. This procedure is known as registration. The UE can register individually to the CS and PS core networks. Most modern networks allow combined registration (or combined attach) whereby the UE registers only to the PS network and the PS network informs the CS network that the UE is active.
This second webinar discusses LTE Air Interface, the link between a mobile device and the network, and a fundamental driver of the quality of the network.
An introduction to Cellular communications Signaling, Specifically LTE Signaling.
Introducing 3GPP approach to handover and handoff mechanisms.
LTE architecture by alcatel-lucent included in this presentation.
This presentation focuses on mobility management protocols such as GTP-C and GTP-U.
Simplified Call Flow Signaling: Registration - The Attach Procedure3G4G
This presentation/video provides an example of the registration procedure. The device or UE needs to let the core network(s) know that it is switched on and active. This procedure is known as registration. The UE can register individually to the CS and PS core networks. Most modern networks allow combined registration (or combined attach) whereby the UE registers only to the PS network and the PS network informs the CS network that the UE is active.
This second webinar discusses LTE Air Interface, the link between a mobile device and the network, and a fundamental driver of the quality of the network.
LTE network: How it all comes together architecture technical posterDavid Swift
Mobile network operators that want to deploy LTE now want to do so on their own terms. They want to roll out ultrafast mobile broadband safe in the knowledge that one vendor’s solution will work efficiently with another, while delivering the high level of service that subscribers expect. A standards-based network will ensure the goal is met and help drive down cost for operators, but understanding how to pull it all together can be a challenge. So how does it all come together?
Main purpose of this document is to discuss LTE basic call flows.
It also introduces LTE network architecture, Nodes, their functionality as well as interfaces that
connect these network nodes.
A brief description of UE states is also given.
In this presentation file, High level structure of the LTE/SAE system is presented. Main resource for the presentation is chapter 2 of Christopher Cox-An Introduction to LTE_ LTE, LTE-Advanced, SAE, VoLTE and 4G Mobile Communications-Wiley (2014).
This third webinar discusses the fundamentals of LTE Carriers and how LTE mobiles communicate with the network including what factors affect performance.
June 3, 2024 Anti-Semitism Letter Sent to MIT President Kornbluth and MIT Cor...Levi Shapiro
Letter from the Congress of the United States regarding Anti-Semitism sent June 3rd to MIT President Sally Kornbluth, MIT Corp Chair, Mark Gorenberg
Dear Dr. Kornbluth and Mr. Gorenberg,
The US House of Representatives is deeply concerned by ongoing and pervasive acts of antisemitic
harassment and intimidation at the Massachusetts Institute of Technology (MIT). Failing to act decisively to ensure a safe learning environment for all students would be a grave dereliction of your responsibilities as President of MIT and Chair of the MIT Corporation.
This Congress will not stand idly by and allow an environment hostile to Jewish students to persist. The House believes that your institution is in violation of Title VI of the Civil Rights Act, and the inability or
unwillingness to rectify this violation through action requires accountability.
Postsecondary education is a unique opportunity for students to learn and have their ideas and beliefs challenged. However, universities receiving hundreds of millions of federal funds annually have denied
students that opportunity and have been hijacked to become venues for the promotion of terrorism, antisemitic harassment and intimidation, unlawful encampments, and in some cases, assaults and riots.
The House of Representatives will not countenance the use of federal funds to indoctrinate students into hateful, antisemitic, anti-American supporters of terrorism. Investigations into campus antisemitism by the Committee on Education and the Workforce and the Committee on Ways and Means have been expanded into a Congress-wide probe across all relevant jurisdictions to address this national crisis. The undersigned Committees will conduct oversight into the use of federal funds at MIT and its learning environment under authorities granted to each Committee.
• The Committee on Education and the Workforce has been investigating your institution since December 7, 2023. The Committee has broad jurisdiction over postsecondary education, including its compliance with Title VI of the Civil Rights Act, campus safety concerns over disruptions to the learning environment, and the awarding of federal student aid under the Higher Education Act.
• The Committee on Oversight and Accountability is investigating the sources of funding and other support flowing to groups espousing pro-Hamas propaganda and engaged in antisemitic harassment and intimidation of students. The Committee on Oversight and Accountability is the principal oversight committee of the US House of Representatives and has broad authority to investigate “any matter” at “any time” under House Rule X.
• The Committee on Ways and Means has been investigating several universities since November 15, 2023, when the Committee held a hearing entitled From Ivory Towers to Dark Corners: Investigating the Nexus Between Antisemitism, Tax-Exempt Universities, and Terror Financing. The Committee followed the hearing with letters to those institutions on January 10, 202
A Strategic Approach: GenAI in EducationPeter Windle
Artificial Intelligence (AI) technologies such as Generative AI, Image Generators and Large Language Models have had a dramatic impact on teaching, learning and assessment over the past 18 months. The most immediate threat AI posed was to Academic Integrity with Higher Education Institutes (HEIs) focusing their efforts on combating the use of GenAI in assessment. Guidelines were developed for staff and students, policies put in place too. Innovative educators have forged paths in the use of Generative AI for teaching, learning and assessments leading to pockets of transformation springing up across HEIs, often with little or no top-down guidance, support or direction.
This Gasta posits a strategic approach to integrating AI into HEIs to prepare staff, students and the curriculum for an evolving world and workplace. We will highlight the advantages of working with these technologies beyond the realm of teaching, learning and assessment by considering prompt engineering skills, industry impact, curriculum changes, and the need for staff upskilling. In contrast, not engaging strategically with Generative AI poses risks, including falling behind peers, missed opportunities and failing to ensure our graduates remain employable. The rapid evolution of AI technologies necessitates a proactive and strategic approach if we are to remain relevant.
Biological screening of herbal drugs: Introduction and Need for
Phyto-Pharmacological Screening, New Strategies for evaluating
Natural Products, In vitro evaluation techniques for Antioxidants, Antimicrobial and Anticancer drugs. In vivo evaluation techniques
for Anti-inflammatory, Antiulcer, Anticancer, Wound healing, Antidiabetic, Hepatoprotective, Cardio protective, Diuretics and
Antifertility, Toxicity studies as per OECD guidelines
Macroeconomics- Movie Location
This will be used as part of your Personal Professional Portfolio once graded.
Objective:
Prepare a presentation or a paper using research, basic comparative analysis, data organization and application of economic information. You will make an informed assessment of an economic climate outside of the United States to accomplish an entertainment industry objective.
Honest Reviews of Tim Han LMA Course Program.pptxtimhan337
Personal development courses are widely available today, with each one promising life-changing outcomes. Tim Han’s Life Mastery Achievers (LMA) Course has drawn a lot of interest. In addition to offering my frank assessment of Success Insider’s LMA Course, this piece examines the course’s effects via a variety of Tim Han LMA course reviews and Success Insider comments.
Acetabularia Information For Class 9 .docxvaibhavrinwa19
Acetabularia acetabulum is a single-celled green alga that in its vegetative state is morphologically differentiated into a basal rhizoid and an axially elongated stalk, which bears whorls of branching hairs. The single diploid nucleus resides in the rhizoid.
Embracing GenAI - A Strategic ImperativePeter Windle
Artificial Intelligence (AI) technologies such as Generative AI, Image Generators and Large Language Models have had a dramatic impact on teaching, learning and assessment over the past 18 months. The most immediate threat AI posed was to Academic Integrity with Higher Education Institutes (HEIs) focusing their efforts on combating the use of GenAI in assessment. Guidelines were developed for staff and students, policies put in place too. Innovative educators have forged paths in the use of Generative AI for teaching, learning and assessments leading to pockets of transformation springing up across HEIs, often with little or no top-down guidance, support or direction.
This Gasta posits a strategic approach to integrating AI into HEIs to prepare staff, students and the curriculum for an evolving world and workplace. We will highlight the advantages of working with these technologies beyond the realm of teaching, learning and assessment by considering prompt engineering skills, industry impact, curriculum changes, and the need for staff upskilling. In contrast, not engaging strategically with Generative AI poses risks, including falling behind peers, missed opportunities and failing to ensure our graduates remain employable. The rapid evolution of AI technologies necessitates a proactive and strategic approach if we are to remain relevant.
30. 30
Samsung Confidential and Proprietary Information. All Contents Copyright ⓒ 2011 Samsung Electronics Co., Ltd.
RJIL PDN Connectivity Request (APN=ims)
OCS
4.1 CCR & CCA to/from PCRF, APN=ims)
PCRF
4.2 CCR & CCA to/from OCS, APN=ims)
PCO : Protocol
Configuration Option is
used to allocate the PCSCF
domain name /IP address
DNS : Domain Name
Server translates
hostname into IP address
PCO option is used
by UE during PDP
context activation
to request for
P_CSCF address,
DNS server details
etc
Steps after
Modify
Bearer are :
1. PDN
Request
2. Create
Session
3. Activate
Bearer
4. Modify
Bearer
Modify Bearer Request
Modify Bearer Response
Not
configured
PCAM
36. LTE Attach Messages
FromeNB to MME
UE Capabilities for E-UTRAN
IMS PS Voice preferred and
CS voice as secondary
37. Message Details in brief (UE messages shown in Red Font)
Attach Request – UE to MME over 102 VLAN (RRC Connection Set Up); contains
S1AP ID allocated from eNB, Contains PDN connectivity request for Jionet APN, with
IMS Voice as preferred and CS Voice as secondary
1. Authentication – MME to DRA to HSS using Diameter ID for S6a, contains IMSI,
HSS replies using same Diameter Session ID with Authentication Vectors , MME
sends Authentication Request (EPS Challenge Request) to UE using same S1AP
ID received from eNB during Attach Request and allocates the MME end S1AP
ID. Now both S1AP ID allocated (eNB side and MME side). UE then sends
Authentication Response computed by it using the same S1AP IDs.
2. Security Mode – MME to UE over S1AP interface; MME sends Security Mode
Command to UE using the same S1AP ID, UE replies with Security Mode
Response which also includes IMEI.
3. Identity Check – MME to DRA to EIR over S13 interface; MME sends IMSI &
IMEI to EIR for Identity Check through Diameter. New Diameter ID created. EIR
replies stating IMEI as “white listed”
4. Update Location – MME to HSS over S6a; In case MME does not have context
information of UE, Update Location is sent to HSS which then sends Cancel
Location Message to old MME. HSS sends Update Location Answer to new MME
using same Diameter Session ID as contained in the request – this reply contains
APN details (Jionet and IMS) and three PDN types IPv4, IPv6 and IPv4/IPv6
38. Message Details in brief (UE messages shown in Red Font)
5. Create Session: MME to SAEGW over S11 interface; This is first GTP C message
for the subscriber. GPTC TeID from MME side added. SAEGW sends CCR-I
request over Gx interface to PCRF. CCA-I is received from PCRF containing the
charging rules & the triggers for CCR-U towards PCRF. SAEGW sends CCR-I
towards OCS over Gy interface with details of session related information. OCS
replies with CCA-I. After receiving reply from both PCRF and OCS, SAEGW sends
Create Session Response to MME and adds the GTPC TeID for the S11 interface
(now both ends TeID created for GTPC over S11) and IPv4 and IPv6 Address
allocated to UE for Jionet APN, indicates the AMBR values, adds the GTPU
TeID for eNB for S1-U interface
6. Attach Accept: MME to UE using the same S1AP ID created earlier. Contains
GTPU TeID for S1-U interface received from SAEGW, contains GUTI & S-TMSI.
7. UE capability: eNB to MME using already existing S1AP ID; sends UE capability
for UTRAN and GERAN; eNB sends Initial Context Set Up Response to UE
(Activate Default EPS Bearer Context Request) which includes the GTPU TeID
for S1-U interface towards SAEGW; UE sends Attach Complete Message
towards MME
8. Modify Bearer: MME sends Modify Bearer Request towards SAEGW which
contains the GTPU TeID received from eNB (Now both ends TeID of GTPU are
with SAEGW); SAEGW acknowledges by sending Modify Bearer Response to
MME
40. eNB S1AP ID which was allocated by eNB for this UE
NAS-PDU content received from UE.
InitialUEMessage, Attach Request (1/2) S1AP/NAS message from UE
S1AP message from eNB
Message in Hex
Attach Request from UE to MME
VLAN 102
41. Attach Request – Voice Preference (2/2)
FromUE to MME
IMS PS Voice preferred and
CS voice as secondary
VLAN 102
42. Authentication Information Request from MME to HSS
AIR message from
MME DRA HSS
Diameter session ID for S6a Interface
IMSI
Authentication Request from MME to HSS
44. EPS Challenge towards UE
Authentication Request
Same eNB S1AP ID as
received in Attach Request
MME sends
the Allocated
MME S1AP
ID
Authentication Request from MME to UE
Now both UE S1AP
Ids are created from
eNB side and MME
side
45. eNB and MME S1AP ID’s
Response calculated by UE
Authentication Response
Authentication Response from UE to MME
Same UE S1AP Ids
created from eNB
side and MME side
are used
48. IMEI Check
MME DRA EIR
ME Identity Check Request
Diameter Session
ID for S 13
IMSI
IMEI
ME Identity from MME to EIR
49. IMEI Check Response
EIR -> DRA -> MME
ME Identity Check Answer
White Listed
ME Identity Response from EIR to MME
Same Session
ID
50. ULR message from
MME -> DRA -> HSS
Update Location Request
Update Location Request is sent
when MME does not have the
context information for the UE
Diameter Session
ID for S6a
Update Location Request from MME to HSS
IMSI
51. CLR to Old MME to delete the UE Context
HSS-> DRA -> Old MME
Cancel Location Request to old MME
52. ULA message with subscription data
HSS -> DRA -> new MME
Update Location Answer to new MME
APN Information is
sent
Same Diameter
Session ID for S6a as
contained in request
53. APN Profile in Update Location Answer
Jionet
IMS APN
Three PDN types IpV4,
IpV6 and IPv4v6
54. S11 MME GTP-C Teid
Create Session Request
First GTP-C message for this subscriber, so GW GTP-C Teid is ‘0’
From MME to Gateway (SAEGW)
IMSI
Can contain - Three PDN
types IpV4, IpV6 and
IPv4v6
55. CCR-I
SAEGW(PCEF) -> DRA -> PCRF
Credit Control Request –Gx(CCR - I)
From PGW to PCRF over Gx
Diameter Gx Session ID
Subscription ID contains
IMSI
56. CCA-I
PCRF -> DRA -> SAEGW(PCEF)
Credit Control Answer – Gx(CCA-I)
Event Triggers for CCR-U towards PCRF
Charging Rule Names
Trigger for ECGI
change can be
added
Same Session ID
57. CCR –I (Gy)
SAEGW -> DRA -> OCS
Credit Control Request – Gy(CCR-I)
Session Related Info Sent to OCS
Gy Interface
Diameter Session ID for Gy Interface
59. IPv4 and IPv6 Address allocated to UE
Create Session Response
SGW GTP-c Teid
SGW GTP-U Teid
From SAEGW to MME after receipt of CCA from OCS
TeID already received by SAEGW
SAEGW adds its GTP C TeID
GTP C both ends
TeID complete
SAEGW adds its GTP U TeID to eNB
Aggregate MBR values for
Jionet APN
60. S1AP Attach Accept
S1AP Attach Accept
MME -> eNB
GUTI Value Allocated
To UE
GW GTP U TeID
S-TMSI
Allocated =
MME Code + M-
TMSI
61. UE Capability Info Indication
FromeNB to MME
UE Capabilities for E-UTRAN
UE Capabilities for geran-cs
UE Capabilities for geran-ps
67. Message Details in brief (UE messages shown in Red Font)
1. PDN Connectivity Request for IMS APN – UE to MME; uses the same S1 AP
ID already created ; indicates PDN connectivity type as IPv4 or IPv6 or
IPV4/IPv6; requests details of P CSCF and DNS Server;
2. Create Session: MME to SAEGW using the GTPC TeID already defined; This
contains the GTPC TeID from MME; SAEGW sends CCR U message to PCRF
over Gx interface; New Diameter Session ID created for IMS APN; This message
contains details of IMSI & MSISDN and the IPv4 & IPv6 address allotted to IMS
APN; PCRF replies with CCA I which contains charging rule and event triggers
to sent CCR U; SAEGW then sends Create Session Response to MME with
GTPC TeID of SGW & PGW for QCI 5 and the Primary & Secondary IPv4 &
IPv6 address of P-CSCF and the IP Address of DNS and the IPv4 & IPv6
address allocated to IMS APN and the SAEGW TeIDs for S1-U traffic
3. Attach Accept: MME to ENB ; MME sends S1 ERAB Set Up Request to eNB
and Activate Default Bearer Context Request to UE; Message also contains
the the IP address for IMS APN for UE and AMBR values for IMS APN. The eNB
sends ERAB Set Up Response containing the GTPU TeIDs for S1 U for QCI 5;
Now both ends of GTPU TeID defined for QCI 5; UE sends Activate Default
Bearer Context Accept.
4. Modify Bearer: MME to SAEGW; MME sends Modify Bearer Request which
contains details of the eNB GTP TeID for S1 U for QCI 5; SAEGW sends Modify
Bearer Accept. Now QCI 5 bearer is established and data can start flowing.
69. S1AP PDN Connectivity Request [1/2]
Same
MME- UE-S1AP-ID
Same
ENB- UE-S1AP-ID
S1AP PDN Connectivity Request for IMS APN
UE to MME
70. S1AP PDN Connectivity Request [2/2]
S1AP PDN Connectivity Request for IMS APN
APN: IMS
Requesting Details of DNS
and P-CSCF Address
UE to MME
Three PDN types IpV4,
IpV6 and IPv4v6
71. Create Session Request for IMS APN
GTPv2 Create Session Request
APN: IMS
IMSI: same
GTP-C Teid of MME
GW GTP-C Teid
allocated before
MME to SAEGW
72. CCR-I for IMS Session on Gx Interface
CCR-I for IMS Apn on Gx Interface
SAEGW(PCEF) DRA PCRF
Subscription ID contains IMSI
and MSISDN
Diameter Gx Session ID
for IMS APN
IPv4 and V6 Address
allocated to IMS APN
This is new Diameter Session ID
allocated for IMS. This is not the same
ID which has been used for Jionet
SAEGW to PCRF
73. CCA-I for IMS Session on Gx Interface
CCA-I for IMS Apn in Gx Interface
PCRF DRA PCEF(SAEGW)
Charging
Rule Name
Event Triggers about
when to send CCR-U
Same IMS Diameter Session ID of Gx Interface
used in Request message(CCR-I)
74. Create Session Response for IMS APN [1/3]
GTPv2 Create Session Response
Bearer ID for IMS
EBI - 6
GTP-C Teid of SGW and
PGW
MME GTP-C Teid
allocated before
SAEGW to MME
EBI 5 is allocated to Jionet and EBI 6 for IMS
based on availability
75. Create Session Response for IMS APN [2/3]
GTPv2 Create Session Response
Primary and Secondary IPV4 P-
CSCF Address (since only IPv4
configured)
IPv4 and IPv6 Address
allocated for IMS APN
If available, IPv6 P-CSCF
address can also be given
by SAEGW
SAEGW to MME
UE is allocated two sets of IP Addresses – one for Jionet APN and second for IMS APN
The UE would be allocated IPv4 or IPv6 or IPv4v6 based on initial request,
configuration in HSS and PGW. Final decision on allocation by PGW . For usage
Ipv6 would be preferred if available on both UE and Network side
DNS IP which UE has
to Use
76. Create Session Response for IMS APN [3/3]
GTPv2 Create Session Response
S1-U SGW and S5/S8 PGW GTP-
U Teid’s for User Plane Packet's
QOS for EBI-6 bearer
QCI -5
SAEGW to MME
77. S1AP E-RAB Setup, Activate default EPS… [1/3]
S1AP E-RAB Setup Request
S1AP E-RAB Setup Request which
contains
EBI-6
QOS details
One message contains
S1AP E-RAB Setup Request &
NAS Activate default EPS bearer Context Request
MME to eNode B
78. S1AP E-RAB Setup, Activate default EPS… [2/2]
NAS Activate default EPS bearer Context Request
NAS PDU
towards UE
QCI -5
EBI-6
Only last 64 bits of IPv6
Address and IPv4 Address
Aggregate MBR values for
IMS APN
MME to UE
79. S1AP E-RAB Setup Response
S1AP E-RAB Setup Response
S1AP Message from eNB
EBI-6
GTP-U Fteid details of eNB
eNode B to MME
80. S1AP/NAS Activate default EPS bearer context accept
Activate Default EPS bearer context accept
NAS Message from UE
Accept message from UE
UE to MME
81. Gtpv2 Modify Bearer Request for Ebi-6
Modify Bearer Request
GTP-U Fteid of eNB
MME to SAEGW
82. Gtpv2 Modify Bearer Response for Ebi-6
Modify Bearer Response
GTP-U Fteid of SGW
Request Accepted
Now the GTP-U teid’s of eNB and
GW are known at both sides.
User data transfer can flow now.
SAEGW to MME
84. TCP 3-Way Handshake
A three-way-handshake is a method used in a TCP/IP network to create a Reliable Connection
between a client and server. It is a three-step method that requires both client and server to
exchange SYN and ACK (acknowledgment) packets before actual data communication begins.
A three-way-handshake is also known as a TCP handshake.
85. TCP SYN
When Client wants to initiate a connection with Server, Client sends a segment with
SYN(Synchronize Sequence Number). This segment will inform the Server that Client would like
to start a communication with Server and informs that with what sequence number it will
start its segments with.
Note: Sequence Numbers are mainly used to keep data in order.
86. TCP SYN –ACK
Now Server will respond to Client with "Acknowledgment" (ACK) and SYN bits set.
Here Servers ACK segment does two things; they are as below
1. It acknowledges Client’s SYN segment.
2. It informs Client that what sequence number it will start its data with.
87. TCP ACK
Now finally Client Acknowledges Server’s initial sequence Number and in its ACK signal.
And then Client will start the actual data transfer.
Note: Initial Sequence Numbers are randomly selected while initiating connections between
two machines.
88. IMS REGISTRATION using
QCI 5 Bearer already created
A different subscriber taken as example
CCR: Credit Control Request , CCA: Credit Control Answer
UAR : User Authorization Request, UAA : User Authorization Answer
MAR : Multimedia Authorization Request, MAA : Multimedia Authorization Answer
UDR : Update Data Request, UDA : Update Data Answer
SAR : Server Authorization Request, SAA : Server Authorization Answer
89. Message Details in brief(UE messages shown in Red Font)
1. REGISTER: UE to P CSCF; contains the IP Address allocated for IMS APN to UE and IP
address of P CSCF received via PCO Options and the SIP Call ID used for Registration;
P CSCF sends REGISTER Message to ICSCF : contains the Public User Identity which
generally starts with sip: or tel:
2. Authorization: ICSCF sends UAR message to HSS; HSS replies with UAA to I CSCF; I-
CSCF forwards the SIP Register message to the S-CSCF address received from HSS; S
CSCF then sends MAR to HSS requesting Authentication Vectors for Multimedia
session from HSS. HSS replies with MAA;
3. 401 Unauthorized: From S CSCF to P CSCF to SAEGW to UE; Contains SIP
Authorization parameters received from HSS and uses the same Call ID as received in
the REGISTER Message;
4. REGISTER: UE sends second REGISTER to SAEGW to P CSCF to S CSCF using same
Call ID; This contains the Authentication Response based on the keys received in 401
Unauthorized
5. Authorization: S-CSCF Sends the REGISTER Message to I CSCF; I-CSCF (SCFX in NSN)
sends UAA to HSS and again asks HSS about which S CSCF (S-CFX) to use; HSS replies
with UAA to I CSCF; I-CSCF forwards the SIP Register message to the S-CSCF address
received from HSS; S CSCF sends SAR to HSS and Updates HSS that the user is
authenticated and asks to provide the subscription Information; S-CSCF request HSS
to map the subscriber to the mentioned S-CSCF server name; HSS replies with SAA
which contains charging information and identities present in HSS for the subscriber;
6. 200 OK: S- CSCF to P CSSF to SAEGW to UE; uses the same Call ID; After this
message is received we can see the two Horizontal BARS symbols for IMS in UE
91. SIP REGISTER (Unprotected)
SIP Register(Unprotected)
SIP Call ID used for Registration
process
P-CSCF Address received i
PCO options
IPv6 Address allocated to
IMS APN
SIP “Via” header contains Transport,
Last SIP hop and transaction ID
Expiry Value for SIP Transaction
Private Identity of the user
Used in Authentication Request
A different subscriber taken as example
UE to P CSCF
92. SIP REGISTER (Unprotected) from P-CSCF to I-CSCF
SIP Register(Unprotected)
REGISTER message
One more “Via” header
added about p-cscf route
Content of the Message will not
be modified, rather new
headers like Via and IMS related
will be added.
From: contains the Public User Identity
Generally starts with sip: or tel:
93. User Authorization Request (I-CSCF to HSS)
User Authorization Request
SCFX DRA HSS
New Diameter Session ID allocated by
I-CSCF
User Name Contains IMSI
94. User Authorization Answer (HSS to I-CSCF)
User Authorization Response
HSS DRA SCFX
S-CSCF address
Result as
Diameter Subsequent Registration
I-CSCF forwards the SIP
Register message to the S-CSCF
address received from HSS
95. Multimedia Auth Request (S-CSCF to HSS)
Requesting Authentication Vectors for Multimedia
session from HSS.
Requested Authentication Vectors : 5
New diameter Session ID allocated by S-CSCF
96. Multimedia Auth Answer (HSS to S-CSCF)
Received
SIP Auth Items : 1
Same diameter session ID used for MAR
97. SIP 401 Unauthorized (S-CSCF P-CSCF SAEGW UE)
SIP Auth parameters
Received from HSS
Same SIP Call ID used in
REGISTER message
“Via” header used for routing
purposes
98. SIP Register (2nd ) (UE -> SAEGW -> PCFX -> SCFX)
Same SIP
Call ID
Authentication Response based on the
keys received in 401 Unauthorized
99. User Authorization Request ( 2nd time)
New Diameter Session ID again
I-CSCF(SCFX in NSN) again asks
HSS about which S-CFX to use
100. User Authorization Answer(HSS I-CSCF)
S-CSCF Server name
I-CSCF forwards the SIP
Register message to the S-CSCF
address received from HSS
101. Server Assignment Request (S-CSCF DRA HSS)
S-CSCF Server name
S-CSCF Updates HSS that user is authenticated and
asks to provide the subscription Information
102. Server Assignment Answer (HSS DRA S-CSCF)
Identities present in HSS for this
subscriber
S-CSCF request HSS to map the
subscriber to the mentioned
S-CSCF server name
Charging Information
103. 200 Ok for SIP Register (S-CSCF P-CSCF SAEGW UE)
SIP Call ID
Used for registration process
After this message is received
we can see the two Horizontal
BARS symbols for IMS in UE
Public Identity
for the user for next transactions
104. Modify bearer request *is initiated by MME/S4-SGSN and/or from S-GW to P-GW*
Here you are not adding or deleting any resources/bearers.
This message is used when there is no change on allocated bearers, Only the cause is
user is moving from one place to another. Basically Radio Part is changing. This
information MME should inform to all Core Network Elements (S-GW) and it helps
them to attain the resources and handovers case too. It will just modify the bearers.
After getting the response of Modify Bearer Request it indicates that User Plane is
ready to carry the user data as Control plane is done and now data can flow in between
E-UTRAN and S-GW.
Update Bearer Request: *is initiated by P-GW to S-GW and/or from S-GW to MME/S4-
SGSN*
I want to explain here with example. Suppose you are playing a online game in your
Mobile. It requires a promised speed to avoid the delay and you are subscribed for that
too. Now suddenly you got to know that you have to send a mail to your boss but you
don't want to close your game. For this purpose you need more resources.
Here Update Procedure will come.
You already have dedicated bearers with you. Your packet forwarding is happening
through P-GW but you need more resources. In this case P-GW will initiate the
message Update Bearer Request.