call flows
DESCRIPTION
GSM, GPRS & WCDMA CALL FLOWTRANSCRIPT
GSM,GPRS,UMTS,HSDPA and HSUPA Protocols and Call flow
ByKiran Koona
Overview
1. GSM Protocols and Call flow2. GPRS Protocols and Call flow3. UMTS Protocols and Call flow4. HSDPA and HSUPA Protocols.
GSM
GSM Architecture-Interfaces
Layer 1 ProtocolTDMA – Time Division Multiple AccessG.703 – ITU PCM frame structureMTP – Message Transfer Part
Layer 2 ProtocolsLAPDm Link Access Protocol D-channel-mobileLAPD Link Access Protocol D-Channel
Layer 3 ProtocolsRR – Radio Resource ManagementMM – Mobility ManagementCM – Connection managementBTSM – Base Transceiver Station ManagementSCCP – Signalling Connection Control PartBSSMAP – Base Station Subsystem MAP-Mobile Application PartDTAP – Direct Transfer Application Part
3-Layer Model
TUP , ISUP
Physical Layer1. Txn of bits2. Error detection and Correction3. Interleaving4. Burst Formating5. Measurements6. Power Control7. Modulation and DemodulationBTS-BSC: 64Kbps BSC-MSC:2Mbps (32*64Kbps)
Physical Layer
Interfaces with Physical Layer
Layer-2: LAPDm and LAPD1. Flow control2. Sequence Numbering3. Duplicate detection4. Frame formatting
Layer-3: RRMProtocols: RR, RSM, BSSAP.1. Cell selection and Reselection Control2. Handover procedure3. Establishing , maintaining, monitoring and releasing the channels4. Monitoring and forwarding of radio connections5. Introduction of encryption6. Change in transmission mode ,Channel coding depending on
channel conditions Advise L1 and L2 7. MS level measurement commands control8. Frequency redefinition Downlink Freq hopping 9. Broadcasting System Information Downlink10. Paging
RRM Messages
Layer-3:MM
Protocols : DTAP,MAP.
1. Authentication request/response2. Ciphering Information/Commands from MSC 3. Abort from MSC Auth Failure4. Normal location Updating request/response5. Periodic location update6. TMSI Reallocation Procedure7. IMSI attach/detach8. IMEI request/response
MM Messages
Layer-3:CM1. Call control (CC) - manages call connections,2. Supplementary service support (SS) - handles special
services3. Short message service support (SMS) - transfers brief texts.CC: Mobile-originating call establishment Setup message Mobile-terminating call establishment PagingCall clearing initiated by the network Call clearing initiated by the MobileDTMFSS:Call ForwardingCall waiting ,Call Hold and ConferenceMulti CallCLIP,CLIR ,COLP and COLRSMS:
CM Messages
SS 7To provide General purpose Signaling system to be used globally.
CCS , Out of Band
ITU-T Q.700 series.
Elements: SSP,STP and SCP.
Access Links: A to F
Analogy: MTP3 IP and SCCPTCP
SCCP: GTT, Ext MTP (Supports CL or CO)
Message Discrimination & distribution
TCAP: Query and Response (CL or CO )
MTP 3: Routing within SPC
MTP2: Node to node delivery
SS 7 Architecture
SSP, STP and SCP
SS 7 Logical Network
MAP
MAP messages are carried by TCAP when dealing with Database centre. MAP Sessions: Open, Close. Message Types: Request, Response, Notification and Confirmation.
GTT
GSM Call flow
GSM Logical Channels
IMSI Attach
Location Update
Authentication and Ciphering
Identity (IMSI) checking
Call Origination
2929
Call Clearing
IMSI Detach
MSRN UsageOur HLR Knows where our Customer is,
Only our GMSC can inquire our HLR
GPRS
GPRS Architecture-Interfaces
GPRS Protocol Stack
Packet Fragmentation
MAC
1. MAC arbitrates access to the shared medium between multiple MSs and GPRS network.
2. Uplink: Managing limited resourcesSlotted Aloha3. Downlink: Queuing and Scheduling of access attempts.4. Priority handling between data flows of one UE5. Priority handling between UEs by means of dynamic
scheduling—Downlink6. Channel mapping7. Traffic Volume monitoring
RLC
1. SAR2. Concatenation3. Padding4. Error Correction---CRC, ARQ (For AM)5. In-Sequence delivery of SDUs6. Duplicate detection7. Flow control8. Sequence number check---UM9. Suspend/resume functionality10. SDU discard
LLCProvide a reliable logical link between MS and SGSN.
LLC messages are transparent to RAN.
Transmission in Asynchronous Disconnected Mode and
Asynchronous Balanced Mode
Ciphering.
Transfer of PDUs of Higher Layers
C-Plane: attach, authentication and PDP activation
U-Plane: carry actual data.
Can be AM or UM
SNDCP• Transparent over BSS. Used only in U-Plane•multiplexing of PDPs. Can be AM or UM
•compression of user data (including IP header compression) RFC 1154 & 2507
•segmentation of data packets to be passed to the LLC layer.
Frame Relay
Meshed N/W Frame Relay
Frame Relay
Speed up to 2 Mbps.
Simple.
Superseded by ATM
BSSGPTransport both control and User data.
Provide the required QoS.
One-to-one mapping of BSSGP between SGSN and BSS.
BSSGP Data Frames
GTP1. GTP-U and GTP-C.2. Uses TCP for Reliable link 3. Uses UDP for non-Reliable link
IP, TCP and UDPIP: IPv4 or IPv6. Datagram Service. Class full or Class less Addressing.
TCP: Connection Oriented.
Ack ARQ. Sequence Number Checking.
Three-way handshake. Point-to-Point Add
Flow Control and Congestion Control.
UDP: Connection less.
Used for Delay Sensitive applications.
Supports Multicast Addressing.
GPRS Callflow
GPRS Logical Channels
GPRS Attach
PDP Context Activation
PDP
Data Transfer from MS
Data Transfer to MS
Web Access in GPRS
PDP Context Deactivation
Security
GPRS Detach
UMTS
Architecture-Interfaces
R99 Protocol Stack
Access Stratum
MACLogical to Transport Conversion
Mac-b located at Node-B
Mac-c/sh and Mac-d are at SRNC.
MAC functionalities
1. Mapping between logical channels and transport channels2. Selection of appropriate TF (from the TFCS) for each Transport
Channel, depending on the instantaneous source rate3. Priority handling between data flows of one UE4. Priority handling between UEs by means of dynamic scheduling—
Downlink5. Identification of UEs on common transport channels6. Multiplexing/demultiplexing of higher layer protocol data units
(PDUs)7. Traffic volume monitoring—Down link8. Dynamic Transport Channel type switching9. Ciphering—RLC (TM)10. Access Service Class (ASC) selection for RACH transmission
RLC1. Transparent mode (Tr) , Unacknowledged Mode (UM) or
Acknowledged Mode (AM)2. Tr and UM RLC entities are defined to be unidirectional, whereas the
AM-mode entities are described as bidirectional3. Tr—Voice Call Video Call, UM—VOIP, Streaming
RLC functionalities
1. Segmentation and reassembly2. Concatenation3. Padding4. Transfer of user data5. Error correction----ARQ6. In-sequence delivery of higher layer PDUs7. Duplicate detection8. Flow control9. SN check (unacknowledged data transfer mode).10. Ciphering is performed in the RLC layer for acknowledged and
unacknowledged modes.11. Suspend/resume function for data transfer
RLC Dataflow
RRC
1. Broadcast of system information2. Paging and notification3. Initial cell selection and reselection4. Establishment, maintenance and release of an RRC
connection 5. Establishment and release of Radio bearers6. Control of ciphering 7. Integrity protection of signalling messages8. UE measurement reporting and control of the reporting9. RRC connection mobility functions10. Support of SRNS relocation11. Support for downlink outer loop power control in the UE12. Open-loop power control13. CBS-related functions (BMC)14. Handovers---preparation and execution15. Control of requested QoS16. Routing of Higher layer PDUs (Direct transfer)17. MBMS control
RRC States
BMC
BMC: Broadcast/Multicast Control ProtocolSMS-CB service
1. Storage of CB2. Traffic volume monitoring and radio resource request for
CBS3. Scheduling of BMC messages4. Transmission of BMC messages to UE
PDCP
PDCP: Packet Data Convergence Protocol
1. PS Domain 2. PDCP contains compression methods, which are needed to get
better spectral efficiency over radio interface.3. IP Packet header compression. Eg: 40 bytes for IPv4 and at least
60 bytes for IPv6. (RFC 2507)4. Transfer of user data
Non Access Stratum
Protocol Interworking architectureTransport : Carry Signaling and User data.
Radio N/W : Establish, maintain and Release RB.
System: Create Communication with Core network.
Transport Network protocols
Radio network protocols
System network protocols
UMTS Call flow
R99 Channels
Basic Model of Network transactions
RRC Connection Setup
RRC Connection CCCH (By passing Node-B)
PagingPaging Type 1 through PCCH
Paging Type-2 through DCCH
RRC Connection CCCH
Authentication and Security Control
DCCH Channel and MM messages
Transaction setup and RAB allocation (CS)
Setup : DCCH Call Proceeding: DTCH
Transaction setup and RAB allocation (PS)
Transaction Clearing with RAB release
RRC Connection release
LU in CS domain
RU in PS domain
HSDPA and HSUPA
R99 RRM Architecture
HSDPA and HSUPA RRM Architecture
New Functionalities
HSDPA and HSUPA Channels
R99 Protocol Stack
HSPA Protocol stack
HSDPA Protocol Stack
HSDPA user plane Protocol Architecture
Fast Node-B Scheduling
H-ARQ ,Incremental Redundancy
Soft Buffer at Node-B and UE
Retransmission at N/W borders No Soft Handover
HSUPA Protocol Stack
HSUPA user plane protocol ArchitectureMac-es/e : Uplink Scheduling
Mac-e: Hybrid ARQ , Buffer
Mac-es : In-sequence delivery (Soft Handover)
RLC re transmissions may take place if Physical layer re transmissions is exceeded initiated by RNC.
References1. 3G TS 25.321, MAC Protocol Specification.2. 3G TS 25.322, RLC Protocol Specification.3. 3G TS 25.323, PDCP Protocol Specification4. 3G TS 25.331, RRC Protocol Specification5. 3G TS 25.324, Broadcast/Multicast Control Protocol (BMC)
Specification6. 3G TS 25.302, Services Provided by the Physical Layer7. 3GPP TS 25.331 RRC specification8. 3GPP TS 25.413 RANAP9. 3GPP TS 25.423 RANSAP10. 3GPP TS 25.433 NBAP11. GSM.System.Engineering.-.Artech BOOK, by Asha Mehrotra.12. GPRS BOOK-MC-HIL by R.J. Bates.13. WCDM for UMTS-Wiley –H.Holma and A.Toskala14. SS7 –MC-HILL by Travel Russel
Datagram
Virtual Circuit