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