UMTS LTE
Network, Services, Technologies,
and Operation
Author: Lawrence Harte
ISBN: 1-93281315-2
Page Size: 7.5" x 9.25" soft cover book
Copyright: 2008
Number of Pages: 116
Number of Diagrams: 37
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25 Slide UMTS LTE Tutorial
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Description
This book explains the basic components, technologies used, and operation of UMTS LTE systems. You will discover why mobile telephone service providers are upgrading their 2nd and 3nd generation digital mobile to a more efficient and feature rich UMTS LTE generation system.
Discover the key features that LTE systems provide that go beyond the capabilities of existing 2G and 3G mobile systems such as ultra high-speed internet (100 Mbps+), television (multicast video), and low latency services (packet voice).
Explained are the physical and logical radio channel structures of the LTE systems along with the basic frame and slot structures. Described are the fundamental capabilities and operation of the LTE radio channel including channel coding, modulation types, and low latency transmission processes.
You will discover the key functional sections of a LTE network component and how they communicate with each other. Learn how and why LTE systems separate control signing channel from user data channels. You will also discover how LTE systems can interoperate with existing mobile systems which simplify the migration plan from less efficient mobile systems to more cost effective and capable LTE systems.
Learn LTE systems can evolve into 4th generation ultra broadband systems using spatial division multiple access (SDMA) technology which will eventually able to provide up to 1 Gbps data transfer rates. Some of the most important topics featured in this book are:
· How LTE systems operate
· New LTE services such as multicast video
· The LTE radio channel structure
· Types of physical and logical channels
· LTE network components
· Network components and their connections
· How GSM and UMTS WCDMA can be upgraded to LTE technology
Sample Diagrams
There are 37 explanatory diagrams in this book
LTE Key Features
This figure shows that some of the key features of the UMTS LTE system include increased data transmission rate, spectrum flexibility, reduced latency, and lower costs. Increased data transmission rates are possible through the use of wider radio channels and efficient modulation types. Spectrum flexibility allows for the use of variable channel bandwidth and channel duplexing types. Reduced latency is enabled by the use of more efficient channel control assignment processes. Lower cost is provided from the ability to serve more customers using a reduced number of radio channels and through automated system configuration processes.
Upgrading GSM and 3G to LTE
This figure shows how a 3G and GSM system can be upgraded to offer UMTS LTE services. This diagram shows that typically 1 to 4 wide WCDMA or 2 or more narrow GSM channels are typically removed to allow a very wide 20 MHz UMTS LTE channel to be added. This example also shows that a separate base station assembly is added to communicate with a UMTS evolved packet core (EPC).
Table of Contents
UMTS Long Term Evolution
UMTS LTE Industry Specifications
Key LTE Features
Increased Data Transmission Rates
- More Efficient Modulation Technologies
Reduced Transmission Delay (Faster Response Time)
Self Configuration and Optimization
All IP Backbone Network
Voice Call Continuity (VCC)
Multiple Input Multiple Output (MIMO) Radio
Multibeam Radio
Evolution of UMTS
Global System for Mobile Communication (GSM)
General Packet Radio Service (GPRS)
Evolved UMTS Terrestrial Radio Access Network (E-UTRAN)
High Speed Packet Access (HSPA)
Evolved High Speed Packet Access (HSPA+)
UMTS LTE Services
Voice Services
Data Services
- Circuit Switched Data
- Packet Switched Data
- Messaging
Group Services
Multicast Services
- Group Call Service (GCS)
- Voice Broadcast Services (VBS)
Location Based Services (LBS)
UMTS LTE Products (Radio Devices)
Network Termination Units (NTU)
Mobile Telephones
PCMCIA Air Cards
External Radio Modems
Embedded Radio Modules
Digital Media Players
Location Devices
RF Power Classification
- User Equipment Classes (UE Classes)
UMTS LTE Radio Channels
Orthogonal Frequency Division Multiplexing (OFDM)
Single Carrier Frequency Division Multiple Access (SC-FDMA)
- Peak to Average Power Ratio (PAPR)
Multiple Input Multiple Out (MIMO)
- Antenna Ports
Frequency Bands
RF Channel Bandwidth
- Channel Raster
Resource Blocks
Physical Downlink Channels
- Physical Downlink Shared Channel (PDSCH)
- Physical Multicast Channel (PMCH)
- Physical Downlink Control Channel (PDCCH)
- Physical Broadcast Channel (PBCH)
- Physical Control Format Indicator Channel (PCFICH)
- Physical Hybrid ARQ Indicator Channel (PHICH)
Physical Uplink Channels
- Physical Random Access Channel (PRACH)
- Physical Uplink Shared Channel (PUSCH)
- Physical Uplink Control Channel (PUCCH)
Frame Structure
- Frequency Division Duplex (FDD)
- Time Division Duplex (TDD)
- Type 1 Frame
- Type 2 Frame
Transport Channels
- Broadcast Channel (BCH)
- Downlink Shared Channel (DL-SCH)
- Paging Channel (PCH)
- Multicast Channel (MCH)
- Uplink Shared Channel (UL-SCH)
- Random Access Channel (RACH)
Logical Channels
- Broadcast Control Channel (BCCH)
- Paging Control Channel (PCCH)
- Common Control Channel (CCCH)
- Multicast Control Channel (MCCH)
- Dedicated Control Channel (DCCH)
- Dedicated Traffic Channel (DTCH)
- Multicast Traffic Channel (MTCH)
Channel Mapping
Radio Characteristics
Peak Data Rate
Control Plane Latency
Control Plane Capacity
User Plane Latency
User Data Throughput
Spectrum Flexibility
- Frequency Bandwidth Allocation
- Duplex Flexibility
Spectrum Efficiency
Mobility
- Full Mobility
- Seamless Mobility
Coverage
Modes of Operation
- Bandwidth Configuration
- Transmission Bandwidth
- Guard Bands
Duplex Operating Modes
- Frequency Division Duplexing (FDD)
- Time Division Duplexing (TDD)
Co-Existence
Modulation Types
- Quadrature Phase Shift Keying (QPSK)
- 16-QAM
- 64-QAM
Channel Coding
- Convolution Coding
- Turbo Codes
- Interleaving
RF Power Control
Time Alignment
- Timing Advance (TA)
Beamforming
- Spatial Division Multiple Access (SDMA)
UMTS Network
- User Plane
- Control Plane (C-Plane)
- Access Stratum (AS)
- Non-Access Stratum (NAS)
- Global Multimedia Mobility (GMM)
Radio Access Technology (RAT)
Evolved Packet Cores (EPC)
Evolved Node B (eNB)
Mobile Management Entity (MME)
Serving Gateway (S-GW)
Packet Gateway (P-GW)
Network Interfaces
X2 Interface
S1 Interface
S2A Interface
S2B Interface
Iuant Interface
S3 Interface
S4 Interface
S5 Interface
S6A Interface
S7 Interface
SGi Interface
Radio Protocol Layers
Radio Resource Control (RRC)
Packet Data Convergence Protocol (PDCP)
Broadcast and Multicast Control Protocol (BMC)
Radio Link Control (RLC)
- Unacknowledged Mode (UM)
- Acknowledged Mode (AM)
- Transparent Mode (TM)
Medium Access Control (MAC) Layer
Physical Layer (PHY)
- Signaling Radio Bearer (SRB)
- Data Radio Bearer (DRB)
IP Multimedia Subsystem (IMS)
Call Session Control Function (CSCF)
Home Subscriber Server (HSS)
UMTS LTE System Operation
Initialization
- Authentication
- Paging
Registration
Tracking Area (TA)
User Equipment Context (UE Context)
Mobility States
- Detached State
- Idle State
- Active State
Access Control
Handover (HO)
- Intra-System Handover
- Inter-System UMTS LTE to GERAN Handover
- Inter-Radio Access Technology Handover (Inter-RAT Handover)
- Backward Handover
Discontinuous Reception (DRx)
Discontinuous Transmission (DTx)
Speech Coding
Addressing
Radio Network Temporary Identifier (RNTI)
- System Information Radio Network Temporary Identifier (SI-RNTI)
- System Change Radio Network Temporary Identifier (SC-RNTI)
- Cell Radio Network Temporary Identifier (C-RNTI)
- Paging Radio Network Temporary Identifier (P-RNTI)
- Random Access Radio Network Temporary Identifier (RA-RNTI)
Mobile Station ISDN (MSISDN)
International Mobile Subscriber Identity (IMSI)
International Mobile Equipment Identifier (IMEI)
Temporary Mobile Station Identity (TMSI)
S-Temporary Mobile Subscriber Identity (S-TMSI)
Local Mobile Station Identity (LMSI)
IP Address
- Static IP Addressing
- Dynamic IP Addressing
- Subscriber Profile Identifier (SPID)
Location Based Services (LBS)
Positioning Methods
Commercial Location Services (Commercial LCS)
Internal Location Services (Internal LCS)
Emergency Location Services (Emergency LCS)
Lawful Intercept Location Services (Lawful Intercept LCS)
Evolved Multimedia Broadcast Multicast Services (E-MBMS)
MBMS Architecture
- eNB MBMS
- MBMS Gateway
- Multi-Cell/Multicast Coordination Entity (MCE)
- M1 Interface
- M2 Interface
- M3 Interface
eNB Synchronization
UMTS Billing
Offline Charging
- Charging Data Function (CDF)
- Charging Gateway Function (CGF)
Online Charging
- Policy Control and Charging Function (PCRF)
- Policy and Charging Enforcement Point (PCEP)
Billing System
Upgrading 3G and GSM to UMTS LTE
Appendix 1 Acronyms
16-QAM - 16 Level Quadrature Amplitude Modulation
3GPP - 3rd Generation Partnership Project
3GPP System - 3rd Generation Partnership Project System
64 - QAM - 64 Level Quadrature Amplitude Modulation
AC - Access Class
AC Barring - Access Class Barring
AGW - Access Gateway
AN - Access Network
AS - Access Stratum
AM - Acknowledged Mode
ACK - Acknowledgment
ARB - Active Resource Blocks
ACLR - Adjacent Carrier Leakage Ratio
ACS - Adjacent Channel Selectivity
AWS - Advanced Wireless Services Spectrum
AMBR - Aggregate Maximum Bit Rate
AIPN - All Internet Protocol Network
ARP - Allocation and Retention Priority
ADC - Analog to Digital Conversion
AF - Application Function
AP ID - Application Protocol Identity
ARQ - Automatic Repeat Reqeust
BSC Area - Base Station Controller Area
Beamforming - Beam Forming
BS - Bearer Services
Beyond 3G - Beyond 3rd Generation
BER - Bit Error Rate
Blacklist - Black List
Blind HO - Blind Handover
BCCH - Broadcast Control Channel
BSR - Buffer Status Reports
CAP - CAMEL Application Part
C - RNTI - Cell Radio Network Temporary Identifier
CRH - Cell Reselection Hysteresis
CQI - Channel Quality Indicator
Kc - Cipher Key
CSG - Closed Subscriber Group
CDMA2000 - Code Division Multiple Access 2000
Commercial LCS - Commercial Location Services
CCCH - Common Control Channel
CEPT - Conference Of European Postal And Telecommunications Administrations
CMC - Connection Mobility Control
CC - Convolutional Coding
CN - Core Network
CAMEL - Customized Applications For Mobile Enhanced Logic
CP - Cyclic Prefix
CRC - Cyclic Redundancy Check
DRB - Data Radio Bearer
DTCH - Dedicated Traffic Channel
DFTS - DFT Spread OFDM
DRx - Discontinuous Reception
DTx - Discontinuous Transmission
DPC - Downlink Power Control
DL - SCH - Downlink Shared Channel
DR - Dynamic Range
DRA - Dynamic Resource Allocation
DTA - Dynamic Time Alignment
Emergency LCS - Emergency Location Services
ECM - EPS Connection Management
EMM - EPS Mobility Management
EQ - Equalization
EIR - Equipment Identity Register
EVM - Error Vector Magnitude
EEC - Ethernet Equipment Clock
ETSI - European Telecommunications Standards Institute
HSPA+ - Evolved High Speed Packet Access
E - MBMS - Evolved Multimedia Broadcast Multicast Service
eNBS - Evolved Network Base Station
eNB - Evolved Node B
EPC - Evolved Packet Cores
ePDG - Evolved Packet Data Gateway
EPS - Evolved Packet System
EPS Bearer - Evolved Packet System Bearer
EPS Bearer Identity - Evolved Packet System Bearer Identity
E - UTRAN - Evolved UMTS Terrestrial Radio Access Network
E - UTRA - Evolved Universal Terrestrial Radio Access
EGSM - Extended GSM
FRAND - Fair Reasonable and Non - Discriminatory
FFS - For Further Study
FPC - Forward Power Control
FDD - Frequency Division Duplex
FDMA - Frequency Division Multiple Access
FH - Frequency Hopping
GGSN - Gateway GPRS Support Node
GPRS - General Packet Radio Service
GUP Server - General User Profile Server
GUP - Generic User Profile
GMM - Global Multimedia Mobility
GNSS - Global Navigation Satellite Systems
GSM - Global System For Mobile Communications
gprsSSF - GPRS Service Switching Function
GCR - Group Call Register
GERAN - GSM EDGE Radio Access Network
gsmSSF - GSM Service Switching Function
GBR - Guaranteed Bit Rate
GP - Guard Period
HR - Half Rate
HANDO - Handover
HRPD - High Rate Packet Data
HSDPA - High Speed Downlink Packet Access
HSPA - High Speed Packet Access
HSPD - High Speed Packet Data
HSUPA - High Speed Uplink Packet Access
HE - Home Environment
HLR - Home Location Register
HPLMN - Home Public Land Mobile Network
HSS - Home Subscriber Server
HARQ - Hybrid Automatic Repeat Request
IPR - Intellectual Property Rights
IN - IVR - Intelligent Network Interactive Voice Response System
IN - Triggering - Intelligent Network Triggered Charging
ICIC - Inter - Cell Interference Coordination
Inter - RAT Handover - Inter - Radio Access Technology Handover
IVR - Interactive Voice Response
Internal LCS - Internal Location Services
IMEI - International Mobile Equipment Identifier
IMSI - International Mobile Subscriber Identity
IMT - International Mobile Telephony
IP Address - Internet Protocol Address
IWF - Interworking Function
IMS - IP Multimedia Subsystem
ISUP - ISDN User Part
Lawful Intercept LCS - Lawful Intercept Location Services
LMSI - Local Mobile Station Identity
LA - Location Area
LAC - Location Area Code
LBS - Location Based Services
LM - Location Management
LR - Location Register
LCS Client - Location Services Client
LCS Server - Location Services Server
L_CH - Logical Channel
LTE - Long Term Evolution
LCR - Low Chip Rate
MIB - Master Information Block
MBR - Maximum Bit Rate
MOP - Maximum Output Power
MPR - Maximum Power Reduction
MSAP - MCH Subframe Allocation Pattern
MGCF - Media Gateway Control Function
MAHO - Mobile Assisted Handoff
MCC - Mobile Country Code
ME - Mobile Equipment
MME - Mobile Management Entity
MNC - Mobile Network Code
MRI - Mobile Reported Interference
MSRN - Mobile Station Roaming Number
MSISDN - Mobile Subscriber ISDN
MSC - Mobile Switching Center
MSC Area - Mobile Switching Center Area
MTSMS - Mobile Terminated Short Message Service
MVNO - Mobile Virtual Network Operator
MVPN - Mobile Virtual Private Network
MM - Mobility Management
MCS - Modulation and Coding Scheme
MCE - Multi - Cell/Multicast Coordination Entity
Multifunction SIM - Multi - Function Subscriber Identity Module Card
MCH - Multicast Channel
MCCH - Multicast Control Channel
MTCH - Multicast Traffic Channel
MC - Multichannel Carrier
MTCH - Multimedia Broadcast Multicast Service Traffic Channel
MBMS - Multimedia Broadcast Multicast Services
MBMS Session - Multimedia Broadcast Multicast Services Session
MBSFN - Multimedia Broadcast Service Multicast Single Frequency Network
MMOG - Multimedia Online Gaming
MRFC - Multimedia Resource Function Controller
MRFP - Multimedia Resource Function Processor
MIMO - Multiple Input Multiple Output
MU - MIMO - Multiple User MIMO
NDC - National Destination Code
NACK - Negative Acknowledgement
NCL - Neighbor Cell List
NACC - Network Assisted Cell Change
NI - Network Interface
NSS - Network Switching Subsystem
NTU - Network Termination Unit
NGMN - Next Generation Mobile Networks
NAS - Non - Access Stratum
OTS - One Tunnel Solution
OCS - Online Charging System
OFDM - Optical Frequency Division Multiplexing
OFDMA - Orthogonal Frequency Division Multiple Access
PDCP - Packet Data Convergence Protocol
PDCP SN - Packet Data Convergence Protocol Sequence Number
P - GW - Packet Data Network Gateway
PDP Context - Packet Data Protocol Context
P - GW - Packet Gateway
PRACH - Packet Random Access Channel
PSC - Packet Scheduling
PCCH - Paging Control Channel
P - RNTI - Paging Radio Network Temporary Identifier
PAPR - Peak to Average Power Ratio
PCS - Personal Communication Services
PCMCIA - Personal Computer Memory Card International Association
PDA - Personal Digital Assistant
PN - Personal Network
PBCH - Physical Broadcast Channel
PhCH - Physical Channel
PCFICH - Physical Control Format Indicator Channel
PDCCH - Physical Downlink Control Channel
PDSCH - Physical Downlink Shared Channel
PHICH - Physical Hybrid ARQ Indicator Channel
PHY - Physical Layer
PMCH - Physical Multicast Channel
PRACH - Physical Random Access Channel
PRB - Physical Resource Block
PUCCH - Physical Uplink Control Channel
PUSCH - Physical Uplink Shared Channel
PCEF - Policy and Charging Enforcement Function
PCEP - Policy and Charging Enforcement Point
PCRF - Policy Control and Charging Function
PSD - Power Spectral Density
PBR - Prioritized Bit Rate
PDU - Protocol Data Unit
PLMN - Public Land Mobile Network
PLMN Code - Public Land Mobile Network Code
PPDN - Public Packet Data Network
PTT - Push To Talk
QPP - Quadratic Permutation Polynomial
QPSK - Quadrature Phase Shift Keying
QCI - Quality Class Identifier
QoS Profile - Quality of Service Profile
RAT - Radio Access Technology
RAT Handover - Radio Access Technology Handover
RB - Radio Bearer
RBC - Radio Bearer Control
RBG - Radio Bearer Group
Um - Radio Interface
RLC - AM - Radio Link Control Acknowledged Mode
RLC - UM - Radio Link Control Unacknowledged Mode
RNC Area - Radio Network Controller Area
RNL - Radio Network Layer
RNS - Radio Network System
RNTI - Radio Network Temporary Identifier
RRM - Radio Resource Management
RAB - Random Access Burst
RACH - Random Access Channel
RA - RNTI - Random Access Radio Network Temporary Identifier
RSSI - Received Signal Strength Indicator
RPOA - Recognized Private Operating Agency
RSRP - Reference Symbol Received Power
RPE - LTP - Regular Pulse Excitation - Long Term Prediction
RET - Remote Electrical Tilting
RAF - Repository Access Function
RF Power Classes - RF Power Classification
RPLMN - Roaming Public Land Mobile Network
ROHC - Robust Header Compression
RA - Routing Area
S - TMSI - S - Temporary Mobile Subscriber Identity
S1 - AP - S1 Application Protocol
S1 - MME - S1 Interface Mobile Management Entity
S1 - U - S1 Interface User Plane
SR - Scheduling Request
SU - Scheduling Unit
SAP - Service Access Point
SDF - Service Data Flow
SDU - Service Data Unit
SOA - Service Oriented Architecture
S - GW - Serving Gateway
SGSN - Serving General Packet Radio Service Support Node
SGSN Area - Serving General Packet Radio Service Support Node Area
Shared PLMN - Shared Public Land Mobile Network
SSD - Shared Secret Data
Sharing PLMN - Sharing Public Land Mobile Network
SMS - Short Message Service
SG - Signaling Gateway
SRB - Signaling Radio Bearer
SRES - Signed Response
SID - Silence Insertion Description
SC - FDMA - Single Carrier Frequency Division Multiple Access
SU - MIMO - Single User MIMO
SMS - GMSC - SMS Gateway Mobile Switching Center
SMS - IWMSC - SMS Interworking Mobile Switching Center
Source eNB - Source Evolved Node B
Subframe - Sub - Frame
SIM - Subscriber Identity Module
SPID - Subscriber Profile Identifier
Sync Protocol - Synchronization Protocol
SAE - System Architecture Evolution
SC - RNTI - System Change Radio Network Temporary Identifier
SFN - System Frame Number
SI - System Information
SIB - System Information Block
SI - 1 - System Information Block Type 1
S1 - RNTI - System Information Change - Radio Network Temporary Identifier
SI - M - System Information Master
SI - RNTI - System Information Radio Network Temporary Identifier
TB - Tail Bits
Target eNB - Target Evolved Node B
TDD - Time Division Duplex
TDMA - Time Division Multiple Access
TDM - Time Division Multiplexing
Timeslot - Time Slot
Timestamp - Time Stamp
TA - Timing Advance
TA - Tracking Area
TAC - Tracking Area Code
TAI - Tracking Area Identity
TCH - Traffic Channel
TFT - Traffic Flow Template
TA - Transfer Adapter
TAP - Transferred Account Procedures
TCP - Transmission Control Protocol
TCP/IP - Transmission Control Protocol And Internet Protocol
TTI - Transmission Time Interval
TM - Transparent Mode
TA - Transport Address
TB - Transport Block
TNL - Transport Network Layer
TAC - Type Allocation Code
UMB - Ultra Mobile Broadband
UMTS LTE - UMTS Long Term Evolution
UTRAN - UMTS Terrestrial Radio Access Network
UTRA FDD - UMTS xxx
UM - Unacknowledged Mode
UTRA - Universal Terrestrial Radio Access
UL - SCH - Uplink Shared Channel
UDP - User Datagram Protocol
UE - User Equipment
UE Assisted Handover - User Equipment Assisted Handover
UE Class - User Equipment Class
UE Context - User Equipment Context
UPE - User Plane Entity
Virtual MIMO - Virtual Multiple Input Multiple Output
VRB - Virtual Resource Block
VLR - Visitor Location Register
VLR Area - Visitor Location Register Area
VAD - Voice Activity Detection
VBS - Voice Broadcast Service
VCC - Voice Call Continuity
VGCS - Voice Group Call Service
WCDMA - Wideband Code Division Multiple Access
WTLS - Wireless Transport Layer Security
WAG - WLAN Access Gateway
About the Author
Mr. Lawrence Harte is a communications expert with over 29 years technical and business experience. As of 2008, he has authored over 100 books and is an inventor of several communication patents. His many degrees and certificates include an Executive MBA from Wake Forest University and a BSET from the University of the State of New York
Global Worldwide Office in Orlando Florida - US. Branch Office in Anaheim California - US.
Minggu, 11 April 2010
UE access the network
Network Attach
http://beyond-3g-wireless.blogspot.com/
When a UE is turned on it needs to attach to the network so that it can able receive or initiate communication. Until the attach operation is not completed, UE will not be able to access the network.
In order to Attach UE is allocated with Uplink/Downlink Signal thru which it can able to read the System Information sent by the network.It is essential for terminals to understand which kind of network is present in terms of available technology, operators,and which channels and parameters shall be used to connect to the network in order to attempt a registration procedure.
After UE is able to read the System Information the next step would be Cell Selection. This procedure is same as it is done in other technologies.
UE sends the NAS PDU as a part of RRC message to eNB. This NAS PDU is then extracted by eNB and sent to MME as a part of S1AP message(Initial UE message)
Let us take a look at IE's in Attach Request NAS PDU mentioned below
(IMSI or old GUTI, last visited TAI (if available), UE Core Network Capability, UE Specific DRX parameters, PDN Type, Protocol Configuration Options, Ciphered Options Transfer Flag, Attach Type, KSIASME, NAS sequence number, NAS-MAC, additional GUTI, P-TMSI signature)
IMSI is International Mobile Subscriber Identity #.
Because the IMSI uniquely addresses each subscriber, it is seen as critical information from a security point of view and its transmission clearly has to be avoided as much as possible. By spying on and monitoring the IMSI, attackers could, for example, track a subscriber’s location,movement and activity, determine user home country and operator.
IMSI shall be included if the UE does not have a valid GUTI or a valid P TMSI available.NAS procedures make use of the GUTI for temporary identity as much as possible instead of the IMSI.
If available, the last visited TAI shall be included in order to help the MME produce a good list of TAIs for any subsequent Attach Accept message. Selected Network indicates the PLMN that is selected for network sharing purposes.
The UE network capabilities indicate also the supported NAS and AS security algorithms
PDN type indicates the requested IP version (IPv4, IPv4/IPv6, IPv6)
For EUTRAN attach, NAS message is PDN Connectivity request. This message is used by UE to inform network that it needs a bearer to transmit data
NAS sequence number and NAS-MAC are included if the UE has valid EPS security parameters. NAS sequence number indicates the sequential number of the NAS message
MME reads this NAS message and understands that UE needs a default bearer and an IP address. MME creates a GTP message Create Session Request and forwards it to SGW. At this point MME assigns and EPS bearer ID to the bearer.Then S-GW responds to GTP Create Session response message with SGW FTEID for user plane, EBI, and Bearer level QoS values. SGW communicates to PCRF to pull the QOS values.
MME receives the session response. It takes the SGW FTEID, EBI and QoS values and places it in Activate Default Bearer Context Request DL_NAS message(Attach Accept) and sends it to eNB in S1AP Initial Context Setup Request message. At this point EPS bearer is established and a Radio Bearer has to be established so that UE can start transmitting the data.
eNB receives the S1AP message, pulls out the NAS message places it in RRC RECONFIGURATION REQ and sends it UE.
UE responds with RRC_RECONFIGURATION_COMPLETE message. It also starts procession the NAS message. Initial Context Setup Response message is attached to the RRC message. At this point UE knows the Bearer ID, an IP address and corresponding QoS values.
eNB informs that UE accepted the default bearer to MME in a S1-AP UL NAS Transport message -Attach Complete-(EPS Bearer Identity, NAS sequence number, NAS-MAC message). Also eNB indicates its FTEID for user plane communication to MME.
MME now has to indicate the eNB user plane info to SGW. It does the same in GTP message Modify bearer request. SGW learns the eNB user plane info from it. After this the user plane data shall flow on the default bearer
http://beyond-3g-wireless.blogspot.com/
When a UE is turned on it needs to attach to the network so that it can able receive or initiate communication. Until the attach operation is not completed, UE will not be able to access the network.
In order to Attach UE is allocated with Uplink/Downlink Signal thru which it can able to read the System Information sent by the network.It is essential for terminals to understand which kind of network is present in terms of available technology, operators,and which channels and parameters shall be used to connect to the network in order to attempt a registration procedure.
After UE is able to read the System Information the next step would be Cell Selection. This procedure is same as it is done in other technologies.
UE sends the NAS PDU as a part of RRC message to eNB. This NAS PDU is then extracted by eNB and sent to MME as a part of S1AP message(Initial UE message)
Let us take a look at IE's in Attach Request NAS PDU mentioned below
(IMSI or old GUTI, last visited TAI (if available), UE Core Network Capability, UE Specific DRX parameters, PDN Type, Protocol Configuration Options, Ciphered Options Transfer Flag, Attach Type, KSIASME, NAS sequence number, NAS-MAC, additional GUTI, P-TMSI signature)
IMSI is International Mobile Subscriber Identity #.
Because the IMSI uniquely addresses each subscriber, it is seen as critical information from a security point of view and its transmission clearly has to be avoided as much as possible. By spying on and monitoring the IMSI, attackers could, for example, track a subscriber’s location,movement and activity, determine user home country and operator.
IMSI shall be included if the UE does not have a valid GUTI or a valid P TMSI available.NAS procedures make use of the GUTI for temporary identity as much as possible instead of the IMSI.
If available, the last visited TAI shall be included in order to help the MME produce a good list of TAIs for any subsequent Attach Accept message. Selected Network indicates the PLMN that is selected for network sharing purposes.
The UE network capabilities indicate also the supported NAS and AS security algorithms
PDN type indicates the requested IP version (IPv4, IPv4/IPv6, IPv6)
For EUTRAN attach, NAS message is PDN Connectivity request. This message is used by UE to inform network that it needs a bearer to transmit data
NAS sequence number and NAS-MAC are included if the UE has valid EPS security parameters. NAS sequence number indicates the sequential number of the NAS message
MME reads this NAS message and understands that UE needs a default bearer and an IP address. MME creates a GTP message Create Session Request and forwards it to SGW. At this point MME assigns and EPS bearer ID to the bearer.Then S-GW responds to GTP Create Session response message with SGW FTEID for user plane, EBI, and Bearer level QoS values. SGW communicates to PCRF to pull the QOS values.
MME receives the session response. It takes the SGW FTEID, EBI and QoS values and places it in Activate Default Bearer Context Request DL_NAS message(Attach Accept) and sends it to eNB in S1AP Initial Context Setup Request message. At this point EPS bearer is established and a Radio Bearer has to be established so that UE can start transmitting the data.
eNB receives the S1AP message, pulls out the NAS message places it in RRC RECONFIGURATION REQ and sends it UE.
UE responds with RRC_RECONFIGURATION_COMPLETE message. It also starts procession the NAS message. Initial Context Setup Response message is attached to the RRC message. At this point UE knows the Bearer ID, an IP address and corresponding QoS values.
eNB informs that UE accepted the default bearer to MME in a S1-AP UL NAS Transport message -Attach Complete-(EPS Bearer Identity, NAS sequence number, NAS-MAC message). Also eNB indicates its FTEID for user plane communication to MME.
MME now has to indicate the eNB user plane info to SGW. It does the same in GTP message Modify bearer request. SGW learns the eNB user plane info from it. After this the user plane data shall flow on the default bearer
Quality Of Service
Quality Of Service in EPS
http://beyond-3g-wireless.blogspot.com/
It has been a long time not blogging anything. Now it is time to give a kick start once again. Let us continue our discussion from the place where we left 2 months back
In previous topic we discussed about What is default Bearer & Dedicated Bearer?
Now let us try to understand about the various QOS parameters
An EPS Bearer is characterized by various QOS Parameters
* ARP (Allocation Retention Priority): The primary responsibility of ARP is to decide whether bearer establishment or modify request can be accepted or rejected during resource limitation. In this is case the priority level information of ARP is used to decide
In addition eNB uses ARP mechanism to decide which bearer to drop during resource limitations(for eg. Handover).
Refer Spec 23.401 /Sec 4.7.3
a) Video telephony is one use case where it may be beneficial to use EPS bearers with different ARP values for the same UE. In this use case an operator could map voice to one bearer with a higher ARP, and video to another bearer with a lower ARP. In a congestion situation (e.g. cell edge) the eNB can then drop the "video bearer" without affecting the "voice bearer". This would improve service continuity
b) The ARP may also be used to free up capacity in exceptional situations, e.g. a disaster situation. In such a case the eNB may drop bearers with a lower ARP priority level to free up capacity if the pre-emption vulnerability information allows this.
* GBR (Guranteed Bit Rate)
This parameter is applicable only for dedicated bearer services like voice or streaming.GBR is nothing but the guranteed bit rate that is expected by a dedicated bearer service
* MBR (Maximum Bit Rate)
This is to limit the bit rate that can be expected to be provided by dedicated bearer
From sec 4.7.4 /Spec 23.401
Neither the EPC nor the E-UTRAN supports any explicit feedback to trigger a rate adaptation scheme at the application / service / transport layer.
The MBR of a particular GBR bearer shall be set equal to the GBR.
NOTE: Support for "MBR > GBR" bearers may be introduced in a future release.
The EPC does not support E-UTRAN-initiated "QoS re-negotiation". That is, the EPC does not support an eNodeB initiated bearer modification procedure. If an eNodeB can no longer sustain the GBR of an active GBR bearer then the eNodeB should simply trigger a deactivation of that bearer.
* QCI (QOS Class Indicator)
QCI which is used as a reference to a set of Access Network related
Quality of Service (QoS) parameters, for the transmission between the terminal and the eNodeB.
The purpose of the QCI, and associated parameters, is to provide a representation of QoS parameters to be shared between Core and Access parts of the network.
http://beyond-3g-wireless.blogspot.com/
It has been a long time not blogging anything. Now it is time to give a kick start once again. Let us continue our discussion from the place where we left 2 months back
In previous topic we discussed about What is default Bearer & Dedicated Bearer?
Now let us try to understand about the various QOS parameters
An EPS Bearer is characterized by various QOS Parameters
* ARP (Allocation Retention Priority): The primary responsibility of ARP is to decide whether bearer establishment or modify request can be accepted or rejected during resource limitation. In this is case the priority level information of ARP is used to decide
In addition eNB uses ARP mechanism to decide which bearer to drop during resource limitations(for eg. Handover).
Refer Spec 23.401 /Sec 4.7.3
a) Video telephony is one use case where it may be beneficial to use EPS bearers with different ARP values for the same UE. In this use case an operator could map voice to one bearer with a higher ARP, and video to another bearer with a lower ARP. In a congestion situation (e.g. cell edge) the eNB can then drop the "video bearer" without affecting the "voice bearer". This would improve service continuity
b) The ARP may also be used to free up capacity in exceptional situations, e.g. a disaster situation. In such a case the eNB may drop bearers with a lower ARP priority level to free up capacity if the pre-emption vulnerability information allows this.
* GBR (Guranteed Bit Rate)
This parameter is applicable only for dedicated bearer services like voice or streaming.GBR is nothing but the guranteed bit rate that is expected by a dedicated bearer service
* MBR (Maximum Bit Rate)
This is to limit the bit rate that can be expected to be provided by dedicated bearer
From sec 4.7.4 /Spec 23.401
Neither the EPC nor the E-UTRAN supports any explicit feedback to trigger a rate adaptation scheme at the application / service / transport layer.
The MBR of a particular GBR bearer shall be set equal to the GBR.
NOTE: Support for "MBR > GBR" bearers may be introduced in a future release.
The EPC does not support E-UTRAN-initiated "QoS re-negotiation". That is, the EPC does not support an eNodeB initiated bearer modification procedure. If an eNodeB can no longer sustain the GBR of an active GBR bearer then the eNodeB should simply trigger a deactivation of that bearer.
* QCI (QOS Class Indicator)
QCI which is used as a reference to a set of Access Network related
Quality of Service (QoS) parameters, for the transmission between the terminal and the eNodeB.
The purpose of the QCI, and associated parameters, is to provide a representation of QoS parameters to be shared between Core and Access parts of the network.
LTE packet services
Eps Bearer & PDP Context
http://beyond-3g-wireless.blogspot.com/
LTE has been designed to support packet services in a more efficient way than UMTS. The key service, from a wireless data network perspective, is the establishment of the data session that will be used by the mobile device for data services.
In UMTS and GPRS, the key to establishing a data session is the Packet Data Protocol (PDP) Context establishment procedure. In LTE, the procedure has been changed to an Evolved Packet System (EPS) Bearer Setup.
Let us first discuss how PDP context works?
In a UMTS network the data session is established with a PDP Context Activation procedure. But, before the PDP context can be established the UE must do an Attach procedure. The Attach procedure is used to alert the SGSN (Serving GPRS Support Node) that the UE has powered up. The problem is that there isn’t anything the UE can do after an Attach without requesting a PDP Context.
After the Attach procedure is completed the UE will then do a Primary PDP Context that will establish the data session and allocate an IP address to the UE. This PDP Context will have a QoS associated with it based on the needs in the request. If the UE needs to have multiple data sessions, due to various Quality of Service (QoS), the UE will do a Secondary PDP Context activation. For the sake of completeness, it is important to note that there are other reasons to establishing subsequent PDP Context beyond QoS, but that is a good place to start
In a LTE based system, there are two types of data session setups. The first is called a Default EPS Bearer. The second is the Dedicated EPS Bearer. The first is established as part of the Attach procedure. The Default EPS Bearer will only support a nominal QoS, but that should be sufficient for application signaling. When the UE needs to establish a service a Dedicated EPS Bearer will be established. This will have the QoS requirements needed for the service.
As way of comparison, the LTE Attach/Default EPS Bearer will be equivalent to the UMTS Attach and then doing a Primary PDP Context establishment procedure. The Secondary PDP Context Activation is similar to the Dedicated EPS Bearer Setup procedure.
If we were to look at the key parameters in these messages, we would see that both the UMTS procedures and the LTE procedures still use parameters like an Access Point Name (APN), IP address type, and QoS parameters. Therefore, the only real difference between the two types of procedures is that there has been an optimization in LTE that reduces the number of signaling messages that need to be sent over the air.
An EPS bearer is actually composed of the three following elements:
a) An S5 bearer – implemented by a tunnel which transports packets between the Serving & PDN Gateways.
b) An S1 bearer – implemented by a tunnel which transports packets between the ServingGW & eNodeB.
c) A Radio Bearer – implemented by a RLC connection between the eNodeB & the
UE. There is one RLC protocol machine per Radio Bearer
From the Specs:
1) What is EPS bearer?
As per the doc 23.401-800, Section 4.7.2.1
An EPS bearer is a logical aggregate of one or more Service Data Flows (SDFs), running between a UE and a PDN GW in case of GTP-based S5/S8, and between UE and Serving GW in case of PMIP-based S5/S8. An EPS bearer is the level of granularity for bearer level QoS control in the EPC/E-UTRAN. That is, SDFs mapped to the same EPS bearer receive the same bearer level packet forwarding treatment (e.g. scheduling policy, queue management policy, rate shaping policy, RLC configuration, etc.). Providing different bearer level QoS to two SDFs thus requires that a separate EPS bearer is established for each SDF.
2) What is difference between Default EPS bearer and Dedicated EPS bearer?
As per the doc 23.401-800, Section 4.7.2.1
One EPS bearer is established when the UE connects to a PDN, and that remains established throughout the lifetime of the PDN connection to provide the UE with always-on IP connectivity to that PDN. That bearer is referred to as the default bearer. Any additional EPS bearer that is established to the same PDN is referred to as a dedicated bearer.
The initial bearer level QoS parameter values of the default bearer are assigned by the network, based on subscription data (in case of E-UTRAN the MME sets those initial values based on subscription data retrieved from HSS). The
PCEF may change those values based in interaction with the PCRF or based on local configuration.
3) What is TFT(Traffic Flow Template) ?
TFT is a set of all Packet filters associated with a EPS Bearer. Every dedicated EPS bearer is associated with a TFT. Every EPS bearer is associated with an UL TFT in the UE and a DL TFT in the PCEF.
Maximum number of TFT that can be allocated per UE is 10(assuming one default bearer and 10 dedicated bearers).
Refer Spec 24.007/11.2.3.1.5/Eps Bearer Identity
A L3 protocol may define that bits 5 to 8 of octet 1 of a standard L3 message of the protocol contain the EPS bearer identity. The EPS bearer identity is used to identify a message flow.
From other sources: http://www.lteuniversity.com/blogs/chrisreece/archive/2009/02/06/bearers-questions.aspx
4) Default Bearers are created per UE basis or PDN GW basis?
Default bearers are created on a per PDN basis. So if a UE is connecting to two PDNs it will need to establish two default bearers. The best example that I can come up with for why a subscriber may want to connect to multiple PDNs is if subscriber wants to connect to an IP Multimedia Subsystem (IMS) network and the Internet. The first default bearer will be established during the Attach process when the UE first powers up and the second will be done using Activate default EPS bearer context request procedure. When the second default bearer is established will be dependent on the service and the UE.
http://beyond-3g-wireless.blogspot.com/
LTE has been designed to support packet services in a more efficient way than UMTS. The key service, from a wireless data network perspective, is the establishment of the data session that will be used by the mobile device for data services.
In UMTS and GPRS, the key to establishing a data session is the Packet Data Protocol (PDP) Context establishment procedure. In LTE, the procedure has been changed to an Evolved Packet System (EPS) Bearer Setup.
Let us first discuss how PDP context works?
In a UMTS network the data session is established with a PDP Context Activation procedure. But, before the PDP context can be established the UE must do an Attach procedure. The Attach procedure is used to alert the SGSN (Serving GPRS Support Node) that the UE has powered up. The problem is that there isn’t anything the UE can do after an Attach without requesting a PDP Context.
After the Attach procedure is completed the UE will then do a Primary PDP Context that will establish the data session and allocate an IP address to the UE. This PDP Context will have a QoS associated with it based on the needs in the request. If the UE needs to have multiple data sessions, due to various Quality of Service (QoS), the UE will do a Secondary PDP Context activation. For the sake of completeness, it is important to note that there are other reasons to establishing subsequent PDP Context beyond QoS, but that is a good place to start
In a LTE based system, there are two types of data session setups. The first is called a Default EPS Bearer. The second is the Dedicated EPS Bearer. The first is established as part of the Attach procedure. The Default EPS Bearer will only support a nominal QoS, but that should be sufficient for application signaling. When the UE needs to establish a service a Dedicated EPS Bearer will be established. This will have the QoS requirements needed for the service.
As way of comparison, the LTE Attach/Default EPS Bearer will be equivalent to the UMTS Attach and then doing a Primary PDP Context establishment procedure. The Secondary PDP Context Activation is similar to the Dedicated EPS Bearer Setup procedure.
If we were to look at the key parameters in these messages, we would see that both the UMTS procedures and the LTE procedures still use parameters like an Access Point Name (APN), IP address type, and QoS parameters. Therefore, the only real difference between the two types of procedures is that there has been an optimization in LTE that reduces the number of signaling messages that need to be sent over the air.
An EPS bearer is actually composed of the three following elements:
a) An S5 bearer – implemented by a tunnel which transports packets between the Serving & PDN Gateways.
b) An S1 bearer – implemented by a tunnel which transports packets between the ServingGW & eNodeB.
c) A Radio Bearer – implemented by a RLC connection between the eNodeB & the
UE. There is one RLC protocol machine per Radio Bearer
From the Specs:
1) What is EPS bearer?
As per the doc 23.401-800, Section 4.7.2.1
An EPS bearer is a logical aggregate of one or more Service Data Flows (SDFs), running between a UE and a PDN GW in case of GTP-based S5/S8, and between UE and Serving GW in case of PMIP-based S5/S8. An EPS bearer is the level of granularity for bearer level QoS control in the EPC/E-UTRAN. That is, SDFs mapped to the same EPS bearer receive the same bearer level packet forwarding treatment (e.g. scheduling policy, queue management policy, rate shaping policy, RLC configuration, etc.). Providing different bearer level QoS to two SDFs thus requires that a separate EPS bearer is established for each SDF.
2) What is difference between Default EPS bearer and Dedicated EPS bearer?
As per the doc 23.401-800, Section 4.7.2.1
One EPS bearer is established when the UE connects to a PDN, and that remains established throughout the lifetime of the PDN connection to provide the UE with always-on IP connectivity to that PDN. That bearer is referred to as the default bearer. Any additional EPS bearer that is established to the same PDN is referred to as a dedicated bearer.
The initial bearer level QoS parameter values of the default bearer are assigned by the network, based on subscription data (in case of E-UTRAN the MME sets those initial values based on subscription data retrieved from HSS). The
PCEF may change those values based in interaction with the PCRF or based on local configuration.
3) What is TFT(Traffic Flow Template) ?
TFT is a set of all Packet filters associated with a EPS Bearer. Every dedicated EPS bearer is associated with a TFT. Every EPS bearer is associated with an UL TFT in the UE and a DL TFT in the PCEF.
Maximum number of TFT that can be allocated per UE is 10(assuming one default bearer and 10 dedicated bearers).
Refer Spec 24.007/11.2.3.1.5/Eps Bearer Identity
A L3 protocol may define that bits 5 to 8 of octet 1 of a standard L3 message of the protocol contain the EPS bearer identity. The EPS bearer identity is used to identify a message flow.
From other sources: http://www.lteuniversity.com/blogs/chrisreece/archive/2009/02/06/bearers-questions.aspx
4) Default Bearers are created per UE basis or PDN GW basis?
Default bearers are created on a per PDN basis. So if a UE is connecting to two PDNs it will need to establish two default bearers. The best example that I can come up with for why a subscriber may want to connect to multiple PDNs is if subscriber wants to connect to an IP Multimedia Subsystem (IMS) network and the Internet. The first default bearer will be established during the Attach process when the UE first powers up and the second will be done using Activate default EPS bearer context request procedure. When the second default bearer is established will be dependent on the service and the UE.
LTE Protocol Stack
LTE Protocol Stack
http://beyond-3g-wireless.blogspot.com/
After a long break ....
By reading my earlier chapter LTE Architecture Overview,I hope everyone would be familiar with different network elements and their functionality to some extent.
Before we dive into LTE Protocol stack, we will have look at different interfaces connecting the LTE network elements
1) S1-MME:Reference point for the control plane protocol between E-UTRAN and MME.
2) S1-U:Reference point between E-UTRAN and Serving GW for the per bearer user plane tunnelling and inter eNodeB path switching during handover.
3) S3: It enables user and bearer information exchange for inter 3GPP access network mobility in idle and/or active state.(eg. GSM/UMTS network)
4) S4: It provides related control and mobility support between GPRS Core and the 3GPP Anchor function of Serving GW. In addition, if Direct Tunnel is not established, it provides the user plane tunnelling.
5) S5: It provides user plane tunnelling and tunnel management between Serving GW and PDN GW. It is used for Serving GW relocation due to UE mobility and if the Serving GW needs to connect to a non-collocated PDN GW for the required PDN connectivity.
6) S6a: It enables transfer of subscription and authentication data for authenticating/authorizing user access to the evolved system (AAA interface) between MME and HSS.
7) S8: Inter-PLMN reference point providing user and control plane between the Serving GW in the VPLMN and the PDN GW in the HPLMN. S8 is the inter PLMN variant of S5.
8) S9: It provides transfer of (QoS) policy and charging control information between the Home PCRF and the Visited PCRF in order to support local breakout function.
9) S10: Reference point between MMEs for MME relocation and MME to MME information transfer.
10) S11:Reference point between MME and Serving GW
11) S12:Reference point between UTRAN and Serving GW for user plane tunnelling when Direct Tunnel is established. It is based on the Iu-u/Gn-u reference point using the GTP-U protocol as defined between SGSN and UTRAN or respectively between SGSN and GGSN. Usage of S12 is an operator configuration option.
12) S13:It enables UE identity check procedure between MME and EIR.
SGi: It is the reference point between the PDN GW and the packet data network. Packet data network may be an operator external public or private packet data network or an intra operator packet data network, e.g. for provision of IMS services. This reference point corresponds to Gi for 3GPP accesses.
13) Rx: The Rx reference point resides between the AF and the PCRF in the TS 23.203 [6].
14) SBc:Reference point between CBC and MME for warning message delivery and control functions.
15) Gx: It provides transfer of (QoS) policy and charging rules from PCRF to Policy and Charging Enforcement Function (PCEF) in the PDN GW.
We would be discussing mostly on those highlighted in bold font.
This Interface information is taken from 3gpp Spec 23.401/4.2.3/Reference Points
LTE Protocol stack is split into two communication path: Control Plane & User Plane(carry actual user payload)
LTE Control Plane Stack
The control plane consists of protocols for control and support of the user plane functions:-
a) controlling the E-UTRA network access connections, such as attaching to and detaching from E-UTRAN;
b) controlling the attributes of an established network access connection, such as activation of an IP address;
c) controlling the routing path of an established network connection in order to support user mobility;
d) controlling the assignment of network resources to meet changing user demands.
When a mobile is turned ON,the UE communicates to Network by performing Attach Procedure. This where the control plane communication begins.
UE communicates to eNB via Radio Resource Control protocol.This is where all the attach request/response etc are created. RRC is way to communicate to with eNB.
The RRC performs broadcast, paging, RRC connection management, Radio Bearer control, Mobility functions, UE measurement reporting and control.
You can find more information from 3gpp Spec 36.331.
Above RRC we have something called Non Access Stratum Protocol which terminates at MME.
All NAS Messages are sent as a part of RRC message.
Main functions of NAS Protocol:
a) Support of mobility of the user equipment (UE); and
b) Support of session management procedures to establish and maintain IP connectivity between the UE and a packet data network gateway (PDN GW).
c) Also NAS security
e.g. integrity protection and ciphering of NAS signalling messages.
To know more about Non Access Stratum Refer Spec 24.301
LTE User Plane Stack
The Data from UE goes to eNB and eNB maps this data over GTP tunnel and sends it to SGW over S1_U.
MAC, RLC and PDCP are at Layer 2 in UE and eNB
Just below MAC is Physical Layer this where actual concepts of high speed comes into picture, because of sophisticated physical layer. Its no secrete on what technology used here? OFDMA.
Currently I dont have any knowledge over the lower layer(Phy,MAC,RLC,PDCP). So not much discussion on this right now
Below picture shows the interface with protocol used between network elements
Thatz it for now
bye from
Sree
http://beyond-3g-wireless.blogspot.com/
After a long break ....
By reading my earlier chapter LTE Architecture Overview,I hope everyone would be familiar with different network elements and their functionality to some extent.
Before we dive into LTE Protocol stack, we will have look at different interfaces connecting the LTE network elements
1) S1-MME:Reference point for the control plane protocol between E-UTRAN and MME.
2) S1-U:Reference point between E-UTRAN and Serving GW for the per bearer user plane tunnelling and inter eNodeB path switching during handover.
3) S3: It enables user and bearer information exchange for inter 3GPP access network mobility in idle and/or active state.(eg. GSM/UMTS network)
4) S4: It provides related control and mobility support between GPRS Core and the 3GPP Anchor function of Serving GW. In addition, if Direct Tunnel is not established, it provides the user plane tunnelling.
5) S5: It provides user plane tunnelling and tunnel management between Serving GW and PDN GW. It is used for Serving GW relocation due to UE mobility and if the Serving GW needs to connect to a non-collocated PDN GW for the required PDN connectivity.
6) S6a: It enables transfer of subscription and authentication data for authenticating/authorizing user access to the evolved system (AAA interface) between MME and HSS.
7) S8: Inter-PLMN reference point providing user and control plane between the Serving GW in the VPLMN and the PDN GW in the HPLMN. S8 is the inter PLMN variant of S5.
8) S9: It provides transfer of (QoS) policy and charging control information between the Home PCRF and the Visited PCRF in order to support local breakout function.
9) S10: Reference point between MMEs for MME relocation and MME to MME information transfer.
10) S11:Reference point between MME and Serving GW
11) S12:Reference point between UTRAN and Serving GW for user plane tunnelling when Direct Tunnel is established. It is based on the Iu-u/Gn-u reference point using the GTP-U protocol as defined between SGSN and UTRAN or respectively between SGSN and GGSN. Usage of S12 is an operator configuration option.
12) S13:It enables UE identity check procedure between MME and EIR.
SGi: It is the reference point between the PDN GW and the packet data network. Packet data network may be an operator external public or private packet data network or an intra operator packet data network, e.g. for provision of IMS services. This reference point corresponds to Gi for 3GPP accesses.
13) Rx: The Rx reference point resides between the AF and the PCRF in the TS 23.203 [6].
14) SBc:Reference point between CBC and MME for warning message delivery and control functions.
15) Gx: It provides transfer of (QoS) policy and charging rules from PCRF to Policy and Charging Enforcement Function (PCEF) in the PDN GW.
We would be discussing mostly on those highlighted in bold font.
This Interface information is taken from 3gpp Spec 23.401/4.2.3/Reference Points
LTE Protocol stack is split into two communication path: Control Plane & User Plane(carry actual user payload)
LTE Control Plane Stack
The control plane consists of protocols for control and support of the user plane functions:-
a) controlling the E-UTRA network access connections, such as attaching to and detaching from E-UTRAN;
b) controlling the attributes of an established network access connection, such as activation of an IP address;
c) controlling the routing path of an established network connection in order to support user mobility;
d) controlling the assignment of network resources to meet changing user demands.
When a mobile is turned ON,the UE communicates to Network by performing Attach Procedure. This where the control plane communication begins.
UE communicates to eNB via Radio Resource Control protocol.This is where all the attach request/response etc are created. RRC is way to communicate to with eNB.
The RRC performs broadcast, paging, RRC connection management, Radio Bearer control, Mobility functions, UE measurement reporting and control.
You can find more information from 3gpp Spec 36.331.
Above RRC we have something called Non Access Stratum Protocol which terminates at MME.
All NAS Messages are sent as a part of RRC message.
Main functions of NAS Protocol:
a) Support of mobility of the user equipment (UE); and
b) Support of session management procedures to establish and maintain IP connectivity between the UE and a packet data network gateway (PDN GW).
c) Also NAS security
e.g. integrity protection and ciphering of NAS signalling messages.
To know more about Non Access Stratum Refer Spec 24.301
LTE User Plane Stack
The Data from UE goes to eNB and eNB maps this data over GTP tunnel and sends it to SGW over S1_U.
MAC, RLC and PDCP are at Layer 2 in UE and eNB
Just below MAC is Physical Layer this where actual concepts of high speed comes into picture, because of sophisticated physical layer. Its no secrete on what technology used here? OFDMA.
Currently I dont have any knowledge over the lower layer(Phy,MAC,RLC,PDCP). So not much discussion on this right now
Below picture shows the interface with protocol used between network elements
Thatz it for now
bye from
Sree
LTE General Architecture Overview Part-2
LTE General Architecture Overview Part-2
http://beyond-3g-wireless.blogspot.com/
2G/3G Network Architecture
Please take a look at above picture for comparing LTE Architecture with 2G/3G network Architecture.
Let us continue the discussion on the EPC network elements listed in the previous topic
S-GW primary function is to manage the user plane mobility.It maintains the data path between eNodeB's and PDN GW. When UE moves around eNodeBs in E-UTRAN network, the S-GW servers as a anchor for local mobility. The data packets are routed via S-GW during E-UTRAN mobility or when UE moves from E-UTRAN network to other 3GPP network(GSM,UMTS etc.)
PDN GW servers as an anchor for sessions towards the external packet data networks.
MME performs signalling and control functions to manage the UE access to network connections, assignment of network resources,paging,roaming,handovers etc.
In short the control & signalling path in LTE are managed by MME whereas the user data path is managed by S-GW.
Regarding PCRF not much idea but in general it supports flow based charging.
http://beyond-3g-wireless.blogspot.com/
2G/3G Network Architecture
Please take a look at above picture for comparing LTE Architecture with 2G/3G network Architecture.
Let us continue the discussion on the EPC network elements listed in the previous topic
S-GW primary function is to manage the user plane mobility.It maintains the data path between eNodeB's and PDN GW. When UE moves around eNodeBs in E-UTRAN network, the S-GW servers as a anchor for local mobility. The data packets are routed via S-GW during E-UTRAN mobility or when UE moves from E-UTRAN network to other 3GPP network(GSM,UMTS etc.)
PDN GW servers as an anchor for sessions towards the external packet data networks.
MME performs signalling and control functions to manage the UE access to network connections, assignment of network resources,paging,roaming,handovers etc.
In short the control & signalling path in LTE are managed by MME whereas the user data path is managed by S-GW.
Regarding PCRF not much idea but in general it supports flow based charging.
LTE General Architecture
LTE General Architecture Overview
http://beyond-3g-wireless.blogspot.com/
Whenever we start discussing about any technology we usually start with Evolution & its Architecture.
So I would like to start my blog with discussion on LTE (Long Term Evolution) which is our next generation wireless
LTE Network Architecture
In this chapter to make it more interesting I tried to compare LTE network elements with existing 2G/3G networks, so that it would be easy for us to understand their functionalities.
In general the LTE Architecture is functionally split into two parts namely
*
E-UTRAN -Evolved-UMTS Terrestrial Radio Access Network (eNB)
*
EPC-Evolved Packet Core (MME,S-GW,PDN GW,HSS)
Figure2 from 3GPP Spec 36.300
The E-UTRAN consists of eNBs, which provides termination of control plane & user plane towards the UE &EPC network.Currently no need to bother much about what is control/user plane.
eNode B is nothing but combination of both RNC+Node B's in case of a UMTS network or BTS+BSC in case of a GSM network.The eNBs are interconnected with each other by means of the X2 interface. The eNBs are also connected by means of the S1 interface to the EPC (Evolved Packet Core), more specifically to the MME (Mobility Management Entity) by means of the S1-MME and to the Serving Gateway (S-GW) by means of the S1-U.
The S1 interface supports a many-to-many relation between MMEs / Serving Gateways and eNBs
E-UTRAN typically does Radio Resource Management towards UE, Selection of an MME based on the information provided by UE for routing Control Plane data,Selection of S-GW to route User Plane data, Scheduling etc.
You can refer 3GPP Spec 36.300 for more information on E-UTRAN functionalities.
The EPC provides mobile core functionality that, in previous mobile generations (2G, 3G), has been realized through two separate sub-domains: circuit-switched (CS) for voice and packet-switched (PS) for data.
In LTE, these two distinct core sub-domains, which are used voice and data, are unified as a single IP domain(Packet Switch Domain). Which means in LTE there in no more circuit switched voice call is possible.In LTE voice call is supported through VOIP(Voice Over IP)
With all this features LTE failed to satisfy the operators world wide for not having CS LTE network. So there is a recent development happening in LTE market to support Voice Over LTE via Generic Access Network(VOLGA)
Please follow the below mentioned link to get more info on VoLGA
http://www.volga-forum.com/
LTE will be end-to-end all-IP(ie. from mobile handsets and other terminal devices with embedded IP capabilities, over IP-based Evolved NodeBs).
As discussed earlier EPC consists of four components
*
MME (Mobility Management Entity) [similar to SGSN]
*
S-GW (Serving Gateway) [similar to GGSN]
*
PDN GW (Packet Data Network Gateway)
*
PCRF(Policy and Charging Rules Function)
We will discuss each of its functionality later on.
Until then bye from Sridhar.
http://beyond-3g-wireless.blogspot.com/
Whenever we start discussing about any technology we usually start with Evolution & its Architecture.
So I would like to start my blog with discussion on LTE (Long Term Evolution) which is our next generation wireless
LTE Network Architecture
In this chapter to make it more interesting I tried to compare LTE network elements with existing 2G/3G networks, so that it would be easy for us to understand their functionalities.
In general the LTE Architecture is functionally split into two parts namely
*
E-UTRAN -Evolved-UMTS Terrestrial Radio Access Network (eNB)
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EPC-Evolved Packet Core (MME,S-GW,PDN GW,HSS)
Figure2 from 3GPP Spec 36.300
The E-UTRAN consists of eNBs, which provides termination of control plane & user plane towards the UE &EPC network.Currently no need to bother much about what is control/user plane.
eNode B is nothing but combination of both RNC+Node B's in case of a UMTS network or BTS+BSC in case of a GSM network.The eNBs are interconnected with each other by means of the X2 interface. The eNBs are also connected by means of the S1 interface to the EPC (Evolved Packet Core), more specifically to the MME (Mobility Management Entity) by means of the S1-MME and to the Serving Gateway (S-GW) by means of the S1-U.
The S1 interface supports a many-to-many relation between MMEs / Serving Gateways and eNBs
E-UTRAN typically does Radio Resource Management towards UE, Selection of an MME based on the information provided by UE for routing Control Plane data,Selection of S-GW to route User Plane data, Scheduling etc.
You can refer 3GPP Spec 36.300 for more information on E-UTRAN functionalities.
The EPC provides mobile core functionality that, in previous mobile generations (2G, 3G), has been realized through two separate sub-domains: circuit-switched (CS) for voice and packet-switched (PS) for data.
In LTE, these two distinct core sub-domains, which are used voice and data, are unified as a single IP domain(Packet Switch Domain). Which means in LTE there in no more circuit switched voice call is possible.In LTE voice call is supported through VOIP(Voice Over IP)
With all this features LTE failed to satisfy the operators world wide for not having CS LTE network. So there is a recent development happening in LTE market to support Voice Over LTE via Generic Access Network(VOLGA)
Please follow the below mentioned link to get more info on VoLGA
http://www.volga-forum.com/
LTE will be end-to-end all-IP(ie. from mobile handsets and other terminal devices with embedded IP capabilities, over IP-based Evolved NodeBs).
As discussed earlier EPC consists of four components
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MME (Mobility Management Entity) [similar to SGSN]
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S-GW (Serving Gateway) [similar to GGSN]
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PDN GW (Packet Data Network Gateway)
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PCRF(Policy and Charging Rules Function)
We will discuss each of its functionality later on.
Until then bye from Sridhar.
3G LTE eNodeB
3G LTE eNodeB Showcased
www.3g.co.uk
31st March, 2009
US : Motorola will showcase its Wireless Broadband Radio (WBR) 500r Long-Term Evolution (LTE) eNodeB at CTIA Wireless 2009. The WBR 500r is Motorola’s latest advancement in bringing to market a very agile zero footprint LTE solution that addresses the full scope of wireless carriers’ deployment needs to provide an advanced LTE RAN solution that meets size, and deployment cost criteria.
Motorola’s flexible eNodeB LTE base stations will support Frequency Division Duplex (FDD) or Time Division Duplex (TDD) and will be available in a range of frequencies from 700MHz to 2.6GHz with bandwidths from 1.4 MHz to 20MHz. The eNodeB features enhanced coverage and capacity for improved performance, superior power efficiency for reduced energy consumption and lower total cost of ownership, and advanced self organizing network (SON) implementation that help operators build and operate their LTE networks at a lower cost.
“Motorola is actively involved in LTE trials and is committed to research and development of both TDD and FDD LTE solutions with lab facilities in China, North America and our new demonstration lab in the U.K.,” said Darren McQueen, vice president, wireless broadband networks, Motorola Home & Networks Mobility. “We remain on track for the first commercial release of our LTE solutions for 700Mhz and 2.6GHz – including the WBR 500r – later this year.”
Since 2003, Motorola has shipped more than 87,000 Orthogonal Frequency Division Multiplexing (OFDM) radios and more than one million OFDM CPEs. As a result Motorola has gained significant deployment and operations experience with OFDM broadband networks. Using Motorola’s field-proven OFDM technology and platforms, the WBR 500 series LTE base station is built to increase coverage and capacity in even the most challenging RF environments.
Motorola’s LTE solution includes the WBR 500 series eNodeB, evolved packet core (EPC), high-speed backhaul, network and device management solutions, and a complete portfolio of professional services. Motorola’s flexible LTE Radio Access Network (RAN) portfolio features various combinations of frame-based radios and remote radio units with a tower top option that can support a wide variety of LTE deployment scenarios across existing and new virgin spectrum.
Motorola’s LTE RAN solution incorporates a field-proven intelligent RF scheduler, support for advanced antenna techniques such as Multiple Input, Multiple Output (MIMO) and beamforming, and an advanced receiver design to further increase site capacity and improve subscriber experience. In addition, Motorola’s LTE WBR 500 series platform features integrated SON - built leveraging years of research at Motorola’s autonomics lab and expertise in implementation in mission critical public safety networks - to reduce the cost to deploy and maintain the wireless broadband network.
www.3g.co.uk
31st March, 2009
US : Motorola will showcase its Wireless Broadband Radio (WBR) 500r Long-Term Evolution (LTE) eNodeB at CTIA Wireless 2009. The WBR 500r is Motorola’s latest advancement in bringing to market a very agile zero footprint LTE solution that addresses the full scope of wireless carriers’ deployment needs to provide an advanced LTE RAN solution that meets size, and deployment cost criteria.
Motorola’s flexible eNodeB LTE base stations will support Frequency Division Duplex (FDD) or Time Division Duplex (TDD) and will be available in a range of frequencies from 700MHz to 2.6GHz with bandwidths from 1.4 MHz to 20MHz. The eNodeB features enhanced coverage and capacity for improved performance, superior power efficiency for reduced energy consumption and lower total cost of ownership, and advanced self organizing network (SON) implementation that help operators build and operate their LTE networks at a lower cost.
“Motorola is actively involved in LTE trials and is committed to research and development of both TDD and FDD LTE solutions with lab facilities in China, North America and our new demonstration lab in the U.K.,” said Darren McQueen, vice president, wireless broadband networks, Motorola Home & Networks Mobility. “We remain on track for the first commercial release of our LTE solutions for 700Mhz and 2.6GHz – including the WBR 500r – later this year.”
Since 2003, Motorola has shipped more than 87,000 Orthogonal Frequency Division Multiplexing (OFDM) radios and more than one million OFDM CPEs. As a result Motorola has gained significant deployment and operations experience with OFDM broadband networks. Using Motorola’s field-proven OFDM technology and platforms, the WBR 500 series LTE base station is built to increase coverage and capacity in even the most challenging RF environments.
Motorola’s LTE solution includes the WBR 500 series eNodeB, evolved packet core (EPC), high-speed backhaul, network and device management solutions, and a complete portfolio of professional services. Motorola’s flexible LTE Radio Access Network (RAN) portfolio features various combinations of frame-based radios and remote radio units with a tower top option that can support a wide variety of LTE deployment scenarios across existing and new virgin spectrum.
Motorola’s LTE RAN solution incorporates a field-proven intelligent RF scheduler, support for advanced antenna techniques such as Multiple Input, Multiple Output (MIMO) and beamforming, and an advanced receiver design to further increase site capacity and improve subscriber experience. In addition, Motorola’s LTE WBR 500 series platform features integrated SON - built leveraging years of research at Motorola’s autonomics lab and expertise in implementation in mission critical public safety networks - to reduce the cost to deploy and maintain the wireless broadband network.