VoLTE and the IMS

1. IMS Architecture and SIP Proxies

• Components: HSS, Proxy-CSCF, Serving-CSCF, Interrogating-CSCF, and Policy Decision Function
• IMS Identifiers
• IMS Message Paths Introduction (Via and Record-Route)
• The Service Path
• Initial Filter Criteria Introduction

2. IMS Identifiers

• IMSI
• UICC
• Home Network, Public ID, and Private ID
• SIP URI Format

3. SIP Architecture

• Requests and Responses
• SIP Message Flow
• SDP Introduction

4. SIP Via Paths

• The Via: Header
• Establishing the Response Path
• Forking—Response Merging
• Loops and Spirals
• Max Forwards

5. SIP Route Headers

• Route Path vs. Via Path
• Record-Route and Route Headers
• Establishing the Route Path
• The Role of the S, I, and P Proxies

6. IMS Service Path

• The Service Path
• Path Header (RFC 3327)
• Service-Route (RFC 3608)

7. DIAMETER

• DIAMETER vs. RADIUS
• AVPs
• SCTP vs. TCP
• IMS Command Values
• IMS DIAMETER Example

8. Initial Filter Criteria

• The User Profile
• How the iFC Is Used
• Understanding XML
• Disjunctive and Conjunctive Normal Form

9. Basic SIP and IMS Specific Headers

• Via, Branch, Max-Forwards
• SIP Dialog (To, From, tag= fields, Call-ID:)
• CSeq, Contact: Expires:
• Proxy-Authenticate:, Proxy-Authorize:
• User-Agent:, Allow:, Supported:
• Content-Type:, Content-Length:
• P-Access-Network-Info
• P-Charging-Vector:, P-Preferred-Identity:, P-Asserted-Identity:, Authorization:
• Security-Client:, Security-Server:
• IMS Signaling Compression (SigComp Architecture)

10. Session Description Protocol (SDP)

• Session Parameters
• SDP Format
• Extending SDP
• SDPng
• Media Negotiation
• Changing Session Parameters

11. QoS, Real Time Media, and RTP

• How Packet Loss, Jitter, and Latency Affects Voice
• Making Voice and Data Coexist Efficiently
• QoS Explained: What It Is and How It Works
• QoS Criteria
• QCI Table: 1-4 vs. 5-9
• Dedicated Bearer When We Need to Change QoS
• Dedicated Bearers
• Dedicated Bearer Establishment
• Sketch Network View of UE with Both Default and Dedicated Bearers
• GBR or Non-GBR
• MBR
• Scheduling Resources for GBR Bearers vs. Not Scheduling for Non-GBR
• Signaling for a Dedicated Bearer (E/W Diagram)
• Channel Quality Indicator (CQI)
• Mechanism for Sending Data to UE in Downlink
• How Uplink Scheduling Differs from Downlink
• Uplink and Downlink Operations to the Associated LTE Physical Channels
• Uplink and Downlink Data Scheduled Every Subframe

12. Presence

• SIMPLE: SIP for Instant Messaging and Presence Leveraging Extensions
• Terminology
• Framework
• Resource List Manipulation Requirements
• Authorization Policy Manipulation
• Acceptance Policy Requirements
• Notification Requirements
• Content Requirements
• General Requirements

13. Charging and New Services within the IMS

• Charging Entities and Functions
• P-Headers Related to Charging
• Diameter and How It Is Used for Ro Interface

14. IMS Call Flow Examples

• LTE Attach Based on an Actual Trace
• Open-IMS Register
• Open-IMS Invite
• Open-IMS Chat Message
• Open-IMS Instant Message
• IMS SIP Register from an Actual Trace
• IMS Invite from an Actual Trace

15. IMS and the DNS

• DNS Basics
• A-Record
• The SRV Record (RFC2782)
• How SIP Uses the SRV Record (RFC3263: Locating SIP Servers)
• How to Configure a SRV Record
• The NAPTR Record (RFC 2915)
• How the P-CSCF Locates the I-CSCF
• Introduction to ENUM (RFC 3761: ENUM Protocol)
• How the S-CSCF Uses ENUM

16. SIP Timers

• UDP and TCP Behavior
• Session-Expires

17. IMS Access Using VoLTE

• IMS Flow Using VoLTE
• IMS Flow VoLTE to CS
• User Plane and Control Plane

18. User Equipment and Radio Frequency

• What Is User Equipment?
• It Is All about Mobility!
• New Requirements of 4G LTE
• Control Signaling Overview (SIP, RCC, Diameter)
• Information Encapsulation Methods: TLV, AVP, XML, ASN.1
• Physical Layer Discussion
• Types of Radio Signaling (History to LTE)
• Types of Radio Architecture
• Non Access Stratum Signaling
• Signaling: OFDMA
• SC-FDMA
• 2G / 3G Fallback to LTE

19. The LTE E-UTRAN

• E-UTRAN
• GSM/WCDMA View
• CDMA View
• Single Component: eNodeB Function and Purpose
• Interfaces: Uu, X2, S1-MME, S1-U
• Separation of Control Plane and User Plane
• Introduction to Paging, Idle and Power Saving
• Introduction to Tracking Areas

20. The UE Power Up Process

• Frequency Scanning on Power-On
• Steps after Power-On
• Uplink Sync on PRACH Channel
• System Information Blocks (SIBS and Types)
• Channel Bandwidth, MIBs, and System Frame Number (SFN)
• Cell Selection Steps
• Random Access Response
• RRC Connection Request
• RRC Connection Setup
• RRC Connection Setup Complete
• RRC Idle State: Re-established and Released
• UE Capability Enquiry from eNB and UE Capability Information Response
• LTE Device Categories (1–5)
• SIB 1 and SIB 2

21. The LTE Attach, GTP, APNs, and Default Bearers

• Initial System Acquisition Steps
• Key System Information Broadcast Messages
• PRACH Channel
• Synchronize with LTE Cell (Downlink and Uplink)
• Request RRC Connection
• Built in Features vs. Configured Features (IMSI, PLMN, Subscriber Info)
• The Attach, GTP, APNs, and Default Bearer Assignment
• Describe Network Attachment in LTE
• Piggybacking Messages
• Establishment of PDN Connectivity from LTE Air Interface
• Attachment to MME: Manage Authentication and Security
• Default Bearer (Connection to PDN)
• SIP Signaling into the IMS

22. Downlink and Uplink Behavior

• Downlink
• Channel Quality Indicator (CQI)
• Dynamic CQI Signaling and QAM
• Reference Signal
• CQI Report (PUCCH)
• CQI Report and Data (PUSCH)
• Periodic and Operator Defined CQI Reporting
• CQI Index Table
• PDCCH
• DCIs
• Uplink
• Uplink Operation (UE to eNodeB)
• Uplink Signaling
• Scheduling Request on PUCCH
• DL Control Information (DCI) on PDCCH
• Buffer Status Report (BSR) on PUSCH
• eNodeB Scheduler
• UL Grand on PDCCH
• Send Data on PUSCH

23. Idle Mode Within and Beyond the UE

• Current Battery Technologies and How They Work
• Saving the Battery and Operator Resources
• Power Saving Features
• Inactivity Timer
• RRC_IDLE
• EMM-REGISTERED
• EMM-IDLE
• Default Bearers Maintained in EPC During Idle
• Contexts Removed in EU-TRAN During Idle
• UE Context Release Request
• UE Context Release Command
• RRC Connection Release
• UE Context Release Complete
• State of EPC Bearers During Idle Mode with S-GW Buffering
• Why Paging Is Necessary
• Idle Mode "Always On" Activities (Cell Reselection, Tracking Area Update, Monitor for Paging, and Exit Idle Mode)

24. Tracking and Paging a UE

• Why Tracking and Paging Is Necessary
• Entities Involved in Tracking and Paging a UE
• Tracking Areas (TAIs)
• Tracking Area Update (TAU)
• Paging to TAIs
• TAU Keep Alive for UE
• TAU Request, Authentication, EPC bearers, TAU response, TAU complete
• T3450 Timer
• GUTI
• Paging Process from E-UTRAN
• Bearer States During Idle Mode
• S-GW Buffering During Idle Mode
• RSRP
• RRC_Idle
• Service Request
• Cell Reselection

25. Handover Between eNodeBs

• The Need for UE Mobility and Cell Reselection
• Cell Reselection Criteria
• Home network Cell
• PLMN Identity
• "Barring" Status Check
• Handover Between eNodeB
• Identify Types of Handover in LTE
• Measurements and Measurement Reporting (Event Driven vs. Periodic Driven)
• Stages of Handover
• Handover Coverage Areas
• LTE Hard Handover: Serving Cells and Target Cells
• RRC Connection Reconfiguration Message: Measurement Criteria (Absolute or Relative) and Measurement Reports
• Handover Prep, Execution, and Completion
• Handover Packet Buffering by SGW
• Handover Data Forwarding Tunnel

Lab 1: Start the IMS
Lab 2: How to Bounce Your IMS (Reference)
Lab 3: Manage Your IMS
Lab 4: Alice IMS User Addition
Lab 5: Bob IMS User Addition
Lab 6: Configure Linksys Phone as Bob
Lab 7: Using IMS Droid with the IMS
Lab 8: How to Use Wireshark (Reference)
Lab 9: Wireshark Call Flow – REGISTER
Lab 10: Wireshark Call Flow
Lab 11: Service Profile Walkthrough
Lab 12: iFC for TAS
Lab 13: DNS Configuration Walkthrough
Lab 14: ENUM