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1 © Nokia Siemens Networks RA41121EN05GLA0
LTE Radio Access System Overview
2 © Nokia Siemens Networks RA41121EN05GLA0
Nokia Siemens Networks Academy
Legal notice
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3 © Nokia Siemens Networks RA41121EN05GLA0
Content
LTE / EPS Architecture and Interfaces
EPS Mobility and Connection States
EPS Bearer Concept
E-UTRAN Functionalities
NSN LTE / EPC Solution
4 © Nokia Siemens Networks RA41121EN05GLA0
NSN Network Architecture Evolution - Summary
Node B RNC SGSN GGSN
Internet
3GPP Rel 6 / HSPA
Direct tunnel
3GPP Rel 7 / HSPA
Internet
Node B RNC
SGSN
GGSN
Direct tunnel
3GPP Rel 7 / Internet HSPA
Internet
Node B
SGSN
GGSN
Node B
(RNC Funct.)
Direct tunnel
3GPP Rel 8 / LTE
Internet
Evolved Node B
MME
SAE GW
5 © Nokia Siemens Networks RA41121EN05GLA0
LTE/EPS Network Architecture Subsystems
• LTE/EPS architecture is driven by the goal to optimize the system for packet data transfer.
• No circuit switched components
• New approach in the inter-connection between radio access network and core network (S1 interface)
•The EPS architecture is made up of an EPC
(Packet Core Network, also referred as SAE)
and an eUTRAN Radio Access Network (also
referred as LTE)
•The EPC provides access to external packet
IP networks and performs a number of CN
related functions (e.g. QoS, security, mobility
and terminal context management) for idle
(camped) and active terminals
•The eUTRAN performs all radio interface
related functions
IMS/PDN
EPC
eUTRAN
LTE-UE
EPS
6 © Nokia Siemens Networks RA41121EN05GLA0
LTE/EPS Network Elements Main references to architecture in 3GPP specs.:
TS23.401,TS23.402,TS36.300
7 © Nokia Siemens Networks RA41121EN05GLA0
TS 36.421
LTE Radio Interface and the X2 Interface
LTE-Uu
• Air interface of EUTRAN
• Based on OFDMA in downlink and SC-FDMA in uplink
• FDD and TDD duplex methods
• Scalable bandwidth: from 1.4 up to 20 MHz
• Data rates up to 150 Mbps(DL), 50Mbps (UL)
• MIMO (Multiple Input Multiple Output) is a major component although optional.
X2
• Inter eNB interface
• Handover coordination without involving the EPC
• X2AP: special signaling protocol
• During HO, Source eNB can use the X2 interface to forward downlink packets still buffered or arriving from the serving gateway to the target eNB.
• This will avoid loss of a huge amount of packets during inter-eNB handover.
(E)-RRC User PDUs
PDCP
RLC
MAC
LTE-L1 (FDD/TDD-OFDMA/SC-FDMA)
TS 36.300
eNB LTE-Uu
eNB
X2
User PDUs
GTP-U
UDP
IP
L1/L2
TS 36.424
X2-UP
(User Plane)
X2-CP
(Control Plane)
X2-AP
SCTP
IP
L1/L2 TS 36.421
TS 36.422
TS 36.423
TS 36.420 [X2 general aspects & principles)
NAS Protocols
Control Plane User Plane
TS 36.323
TS 36.322
TS 36.321
TS 36.331
TS 29.281
TS 24.301
8 © Nokia Siemens Networks RA41121EN05GLA0
S1-MME & S1-U Interfaces
S1-MME
• Control interface between eNB and MME
• MME and UE will exchange non-access stratum signaling via eNB through this interface.
• E.g.: if a UE performs a tracking area update the TRACKING AREA UPDATE REQUEST message will be sent from UE to eNB and the eNB will forward the message via S1-MME to the MME.
• S1AP:S1 Application Protocol
• S1flex 1 eNB to connect to several MME
S1-U
• User plane interface between eNB and serving gateway.
• It is a pure user data interface (U=User plane).
• S1flex-U also supported: a single eNB can connect to several Serving GWs.
• Which Serving GW a user’s SAE bearer will have to use is signaled from the MME of this user.
MME
Serving
Gateway
S1-MME
(Control Plane)
S1-U
(User Plane)
NAS Protocols
S1-AP
SCTP
IP
L1/L2
User PDUs
GTP-U
UDP
IP
L1/L2
TS 36.411
TS 36.411
TS 36.412
TS 36.413
TS 36.414
TS 36.410 [S1 general aspects & principles]
eNB
TS 29.281
TS 36.410 [S1 general aspects & principles]
TS 24.301
9 © Nokia Siemens Networks RA41121EN05GLA0
LTE/EPS Mobility Areas
Two areas are defined for handling of mobility in LTE/EPS:
Tracking Area (TA)
• It is the successor of location and routing areas from 2G/3G.
• When a UE is attached to the network, the MME will know the UE’s position on tracking area level.
• In case the UE has to be paged, this will be done in the full tracking area.
• Tracking areas are identified by a Tracking Area Identity (TAI).
The Cell
• Smallest entity regarding mobility
• When the UE is in connected mode, the MME will know the UE´s position on cell level
• Cells are identified by the Cell Global Identification (CGI), at the system level, and by the Physical Cell Identification (PCI), at the physical layer
10 © Nokia Siemens Networks RA41121EN05GLA0
LTE Mobility & Connection States
• Deregistered
• No location information in MME, no IP address or Default Bearer
• Registered
• MME knows location at cell or tracking area level, Default Bearer and IP address allocated for UE.
1.- EPS* Mobility Management (EMM) states
• ECM Idle
• No NAS connection between UE and MME, mobility is based on tracking area and cell reselection, no E-RAB (S1 and Uu), but EPS Default Bearer is still allocated (S5 / S8).
• ECM Connected
• NAS connection established, E-RAB (S1 and Uu) is allocated, mobility based on handover a cell level.
2.- EPS* Connection Management (ECM) states
11 © Nokia Siemens Networks RA41121EN05GLA0
LTE/EPS Bearer: Identity & Architecture
cell
S1-U LTE-Uu S5/S8
PDN
SGi eNB Serving
Gateway PDN
Gateway
E-UTRAN EPC PDN
•An EPS bearer identity uniquely identifies an EPS bearer for one UE. The EPS Bearer Identity is
allocated by the MME.
•LTE/EPS Bearer spans the complete network, from UE over EUTRAN and EPC up to the connector of
the external PDN.
•The SAE bearer is associated with a quality of service (QoS) usually expressed by a label or QoS
Class Identifier (QCI)
LTE-UE
End-to-End Service
EPS Bearer External Bearer
Radio Bearer S1 Bearer S5/S8 Bearer
12 © Nokia Siemens Networks RA41121EN05GLA0
EPS Bearers Establishment can be triggered by….
cell
S1-U
UE
S5 PDN
SGi
eNB
Serving
Gateway PDN
Gateway
EPS Bearer External Bearer
MME:This happens typically during
the attach procedure of an UE.
Depending on the information coming
from HSS, the MME will set up an
initial bearer, also known as the
Default EPS bearer. This EPS bearer
provides the initial connectivity of the
UE with its external data network or
IMS platform. MME
S1-MME
S11
PDN Gateway: The external data network
can request the setup of an EPS bearer by
issuing this request via PCRF to the PDN
gateway. This request will include the quality
of service granted to the new bearer. Those
are referred as Dedicated EPS bearers.
UE: Note here the differences to GPRS in 2G/3G networks, where only MS/UE initiated PDP context setup is defined.
PCRF
Gx/S7
Rx
Further Reading in Note Page
13 © Nokia Siemens Networks RA41121EN05GLA0
The Default Bearer Concept
•Each UE that is attached to the LTE network has at least one bearer available, that is called the default bearer.
•Its goal is to provide continuous IP connectivity towards the EPC (“always-on” concept)
•From the QoS point of view, the default bearer is normally a quite basic bearer
•If an specific service requires more stringent QoS attributes, then a dedicated bearer should be established.
cell
S1-U
UE
S5 PDN
Sgi
eNB
Serving
Gateway
PDN
Gateway
Default EPS Bearer
MME
S1-MME
S11
14 © Nokia Siemens Networks RA41121EN05GLA0
EPS Bearer QoS Attributes
EPS Bearer QoS Parameters
(To be defined per Bearer)
Default Bearer/Dedicated Bearer
GBR/N-GBR
MBR
UL/DL-TFT
QCI
ARP
EPS Bearer QoS Parameters
(To be defined per User)
AMBR
15 © Nokia Siemens Networks RA41121EN05GLA0
QoS Class Identifier (QCI) Table in 3GPP
GBR 1
Guarantee Delay budget Loss rate Application QCI
GBR
100 ms 1e-2 VoIP
2
GBR
150 ms 1e-3 Video call
3
GBR
300 ms 1e-6 Streaming
4
Non-GBR 100 ms 1e-6 IMS signaling 5
Non-GBR 100 ms 1e-3 Interactive gaming 6
Non-GBR 300 ms 1e-6 TCP protocols : browsing, email, file download
7
Non-GBR 300 ms 1e-6 8
Non-GBR 300 ms 1e-6 9
Priority
2
4
5
1
6
7
8
9
50 ms 1e-3 Real time gaming 3
16 © Nokia Siemens Networks RA41121EN05GLA0
EMM & ECM States Transitions
EMM_Deregistered
ECM_Idle
Power On
EMM_Registered
ECM_Connected
Registration (Attach)
• Allocate C-RNTI, GUTI
• Allocate IP address
• Authentication
• Establish security context
• Release RRC connection
• Release C-RNTI
• Configure DRX for paging
EMM_Registered
ECM_Idle
Release due to
Inactivity
•Establish RRC Connection
•Allocate C-RNTI
New Traffic
TAU Deregistration (Detach)
Change PLMN
• Release C-RNTI, GUTI
• Release IP address
Timeout of Periodic TA
Update
• Release GUTI
• Release IP address
17 © Nokia Siemens Networks RA41121EN05GLA0
E-UTRAN Functionalities
Transfer of user data
Radio channel ciphering and deciphering
Integrity protection
Header compression
Mobility control functions:
Connection setup and release
Load Balancing
Distribution function for NAS messages
NAS node selection function
Synchronization
Radio access network sharing
Subscriber and equipment trace
RAN Information Management
3GPP TS 36.401
Evolved
Node B
(eNB) cell
LTE-Uu
LTE-UE
E-UTRAN consists of one
or more Evolved Node
Bs (eNB)
It replaces the old Node B /
RNC combination
from 3G.
It terminates the complete
radio interface including
physical layer.
It provides all radio
management functions
18 © Nokia Siemens Networks RA41121EN05GLA0
NSN LTE / EPC Portfolio
Flexi Multiradio BTS LTE
• Evolved Node B (eNB)
Flexi Network Server
• Mobility Management Entity (MME)
Flexi Network Gateway
• S-GW and P-GW
19 © Nokia Siemens Networks RA41121EN05GLA0
Flexi Multiradio BTS LTE A complete macro high power outdoor 1+1+1 @ 60 W Flexi Multiradio BTS consists of:
system module
3-sector RF module for 60 W per sector/cell
optional AC/DC and battery module
A complete macro high power outdoor 1+1+1 @ 60 W + 60 W Flexi Multiradio BTS consists of:
system module
two 3-sector RF modules for 60 W + 60 W per sector/cell
optional AC/DC and battery module
The Flexi Multiradio BTS provides very high radio downlink output power when using the Flexi 210W 3-sector Radio Module. In the 3-sector BTS, all RF functions are integrated to one single outdoor installable 3U high module. With two 3-sector RF Modules in 2TX MIMO configuration, TX power is 120W per sector/cell (60 W + 60 W).
20 © Nokia Siemens Networks RA41121EN05GLA0
Flexi Multiradio BTS LTE
Another option especially for feederless and distributed LTE BTS sites is the Flexi Multiradio Remote Radio Head (RRH) that can support one sector with the following integrated features:
two transceivers to support 2TX MIMO
30 W + 30 W output power at antenna connectors
two linear power amplifiers
two RF filters for TX/RX
2 way RX diversity
wide bandwidth support (up to 20 MHz depending on 3GPP band RF variant)
48 V DC input power supply
no fans
OBSAI optical interface to the BTS system module
antenna tilt support
21 © Nokia Siemens Networks RA41121EN05GLA0
Flexi Network Server
Flexi Network Server (Flexi NS) is a high transaction capacity product on top of Advanced TCA (ATCA). It is optimized for all-IP flat architecture, and is used for control plane-only mobility management entity (MME) functionality.
The Flexi NS is an essential part of the Nokia Siemens Networks LTE and EPS end-to-end offering. The MME has a similar role in LTE as 2G/3G SGSN has in 2G/3G networks.
The Flexi NS is designed to serve as a pure control plane element for all-IP flat networks. Therefore, R8 S4 3G SGSN is considered as a natural evolution step for Flexi NS, leveraging the all-IP, control plane only optimized design.
Flexi NS implements high transaction and connectivity capacity to accommodate the increased signaling load and higher service penetration in an operators’ subscriber base. The product footprint is small, so you can install up to three high capacity units in a standard 19” rack. Flexi NS is power efficient, offering reduction in energy consumption.
Innovative control plane-only architecture of Flexi NS allows implementing session redundancy within a single Flexi NS network element. In case of a failure of any single hardware unit, the subscriber session can be preserved.
Nokia Siemens Networks SGSN has demonstrated market leading reliability levels in live networks over a time period of several years. The same DMX software platform is applied also as a basis for the Flexi NS.
22 © Nokia Siemens Networks RA41121EN05GLA0
Flexi Network Gateway
The new Flexi NG product family targets current and future mobile networks as well as converged networks. It is targeted to support high-speed packet access (HSPA), evolved high-speed packet access (HSPA+), Internet high-speed packet access (I-HSPA) and Long Term Evolution (LTE) access networks. Different applications, such as gateway GPRS support node (GGSN) or Evolved Packet Core (EPC) gateway, can be installed on same platform.
Flexi NG provides high throughput and signaling capacity to accommodate the traffic growth in next generation networks. The key to Flexi NG performance is in the use of multi-core packet processor (MPP) technology in the control plane and in the user plane. MPPs are designed for fast networking applications and contain several hardware units that accelerate packet data processing. MPP technology is highly flexible and scalable, and enables faster development cycles.
Flexi NG is based on the Nokia Siemens Networks AdvancedTCA (ATCA) hardware platform and Nokia Siemens Networks FlexiPlatform operating software and middleware. FlexiPlatform is a robust, carrier grade Linux based platform, offering versatile services for operation and maintenance (O&M), networking and platform services using the latest technologies available.
23 © Nokia Siemens Networks RA41121EN05GLA0
NSN O&M Solution – NetAct & iOMS
24 © Nokia Siemens Networks RA41121EN05GLA0
LTE SON has key operational benefits
Self Quality
Capacity
Coverage
Healing • Error self-detection and
mitigation
• Reduced operator effort
• Faster maintenance
• Reduced outage time
Optimization • Error self-detection and
mitigation
• Reduced operator effort
• Faster maintenance
• Reduced outage time
Configuration • Simplified installation
procedures - less prone to errors
• Faster roll-out
• Fewer drive-tests
• More flexibility in logistics (no site specifics)
• Reduced site planning
25 © Nokia Siemens Networks RA41121EN05GLA0
Nokia Siemens Networks’ SON is built on our detailed understanding of how networks operate
• Network automation and optimization for various use cases
• Full end-to-end solution combining distributed and centralized SON
• Multi-technology, multi-vendor solution through open 3GPP interfaces
• Flexible system enabling control and stop points
Nokia Siemens Networks SON Suite
Cell outage detection and compensation
Automated neighbor relat.
Interference optimization
Load balancing
Power saving
Plug and Play
Mobility robustness
Drive test minimization
Self Healing / alarm management
LTE SON
2G/3G SON
Open northbound interfaces
SON
Packet
Core
Other vendor network
26 © Nokia Siemens Networks RA41121EN05GLA0
In all SON use cases the features reside in both element and OSS level
SON Data Multi-vendor Data Network Data CM, FM, PM
WCDMA/GSM LTE Vendor Y Vendor X
• NetAct
Configurator Monitor & Reporter
Optimizer SW Manager
SON Workflow Coordinator
Planning tools
Management Network Engineering
Planning tools Network Operations
… …
Centralized SON
Distributed SON
27 © Nokia Siemens Networks RA41121EN05GLA0
SON Suite Features
Self- healing
Self- optimization
Self- configuration
• SON Plug and Play
• Automated Neighbor Relations
Management
• Automated Neighbor Relations
Management
• Power Saving
• Mobility Load Balancing
• Mobility Robustness Optimization
• Service Quality Optimization
• Minimization of Drive Tests
• Cell Outage Detection, Repair
and Compensation
• Automatic interface alarm
correlation
• SON Plug and Play
• Automated Neighbor Relations
Management
LTE WCDMA & GSM
• Automated Neighbor Relations
Management
• Power Saving
• Interference Optimization
• Load Balancing
• Alarm Triggered Log Correction
(WCDMA)
• Automatic OMS resiliency
(WCDMA)
• OMS Overload Control
(WCDMA)
28 © Nokia Siemens Networks RA41121EN05GLA0
See Notes
Recommended