1. 教育部補助「行動寬頻尖端技術跨校教學聯盟第二期計畫 -- 行動寬頻網路與應用 -- 小細胞基站聯盟中心」 模組名稱： 「LTE-Small Cell 核心網路架構及服務」 單元-A7：LTE-Small Cell 核心網路與網路管理(OAM)
計畫主持人：許蒼嶺 (國立中山大學 電機工程學系)
授課教師：萬欽德 (國立高雄第一科技大學 電腦與通訊工程系)

2. 課程單元目標 了解 Data Services in EPS 了解 IP Connectivity 與 Session Management
了解 Mobility Principles

3. Data Services in EPS

4. Introduction to Mobile Network Management (1/3)
Requirements toward network management of the mobile backhaul network are increasing due to
The vast growth of network capacity
The increasing complexity of the mobile network
Network Management consists of
Element Management System (EMS)
Network Management System (NMS)
The widest definition of network management is typically called the Operations Support System (OSS).
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5. Introduction to Mobile Network Management (2/3)
The Operations Support System (OSS) includes all the necessary systems used by the telecommunication service providers to management their networks.
Either the Operations and Management (OA&M) interface connects the managed network elements directly to the NMS
Or the OA&M interface is provided by the EMS.
Network management serves many user groups in the network operator organization, involving
Planning
Optimization
Configuration
Monitoring and Trouble Shooting
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6. Introduction to Mobile Network Management (3/3)
Network management provides a centralized focal point to
Collect information about the managed mobile backhaul network,
Enable network optimization either manually or automatically.
The typical NMS provides the following functionality
Fault Management
Performance Management
Configuration Management
Optimization
Self-Organizing Network (SON)
[1]

7. NMS Architecture
When looking at the external interfaces, the high-level NMS architecture includes connectivity to
Planning and optimization tools and other external systems (such as trouble ticket systems and inventory systems) through northbound interface,
EMS through southbound interface

8. Layered NMS
Many operators organize management to have a centralized or a country-level system in addition to regional NMS systems, creating a layered NMS configuration.
The centralized NMS provides multiple benefits to
Manage border areas between regions due to mobility management
Enable a single location to provide 24/7 support instead of multiple ones.
Country wide NMS
Regional NMS
Element management
Network elements
[1]

9. NMS for Mobile LTE and Backhaul Networks
The LTE network elements (NEs) includes eNodeBs and S-GW; while the backhaul NEs includes switches and routers.
In addition to LTE radio and core functions, the LTE NEs includes transport functions,
which shares a common
OA&M function with
the mobile part.
[1]

10. Fault Management
The purpose of network fault management is to detect faults in the network and make a notification of the fault.
Fault notification typically means an alarm event is emitted and sent to the NMS.
The alarm contains a standardized set of attributes defined by ITU-T and 3GPP, such as its location, type, severity, cause and time stamp.
The NEs and EMS should reduce the amount of alarms by employing fault correlation to combines alarms which are triggered by the same fault.
Alarm events can trigger automatic recovery actions and optimization algorithms.
[1]

11. Performance Management
Performance management in EMS/NMS collects network performance indicators emitted by NEs.
The amount of collected performance data is reduced with the help of data aggregation, which may apply statistical functions such as averaging and summarizing to raw data.
Performance data analysis includes a functionality to perform automatic actions based on predefined thresholds and profiles.
Data-forwarding function can automatically send data to an external system such as the centralized NMS.
Combined radio and backhaul measurement reporting helps to locate bottlenecks and enhances optimization and planning.
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12. Configuration Management
Configuration management is a central optimization and planning function to monitor and control NE configurations.
The features of configuration management include
Maintaining an up-to-date picture of the network
Recoding configuration history
Configuring network
Policy-based configuration management
Planning interfaces
Network configuration discovery
Configuration management of backhaul network
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13. Policy-Based Configuration Management
Policy-based configuration management introduces a capability to add or change a configuration with templates.
Policy templates contains parameters
which can be defined and changed.
With polices, different parameter
setting can be defined for groups
of similar elements in the network
Grouping criteria can based on location
Feature and layer.
Policies also enable setting for
different services.
[1]

14. Planning Interfaces
In accordance with open policy, the NMS provides a set of well-defined open interfaces for the upper level system.
Examples of interfaces typically used are:
3GPP northbound interface
XML (Extensible Markup Language) interface
CSV (Comma-Separated Values) interface
Web service interface, which is based on SOAP (Simple Object Oriented Access Protocol).
SOAP is used for exchanging structured data in the form of XML.
SOAP protocol uses HTTP or SMTP underneath.
Excel interface
[1]

15. Configuration Management of Backhaul Network (1/2)
NMS-based configuration management provides the following benefits and leads to increased service availability as well as reduced OPEX.
Cross-domain consistency checking between the radio and the backhaul
Auditing leading to less parameter errors
Efficient operations due to mass modification possibilities
Reducing unnecessary variation in configurations by utilizing policy-based configuration management
Quick troubleshooting and combined configuration changes with a radio network
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16. Configuration Management of Backhaul Network (2/2)
The figure shows a single NMS supporting configuration management (CM) functions for both the LTE radio network and the LTE backhaul.
The more the NMS supports CM over various elements, the bigger the benefits achievable in terms of OPEX and quality.
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17. IP Connectivity

18. IP Connectivity Enables Session Management
In conjunction with the evolution of the access networks provided with LTE
Provides a common packet core with appropriate policy, security, charging, and mobility
Provides end-users with ubiquitous access to network services across different access networks
Provides session continuity across various access technologies.
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19. IP Connectivity (1/8)
IPv4 or IPv6
QoS

20. IP Connectivity (2/8) APN (corresponding PDN) : EPS concerns:
user’s subscription profile in the HSS (if not, default)
PDN GW
EPS concerns:
PDN connection layer
associated functions such as IP address management, QoS, mobility, charging, security, policy control, etc.

21. IP Connectivity (3/8)
The user IP connection (the PDN connection) is separate from the IP connection between the EPC nodes (the transport layer).
Transport network in the EPC provides IP transport:
Using different technologies such as MPLS, Ethernet, wireless point-to-point links, etc.
Not aware of the PDN connections.

22. IP Connectivity (4/8)
Trusted Non-3GPP Accesses

23. IP Connectivity (5/8) IP Addresses Can be purely private IP network
IPv4 or IPv6
A terminal with a PDN connection in EPS may request an IPv4 address, an IPv6 prefix, or both
Two alternative ways ( both methods to coexist in EPC)
IPv4 address to the UE during the attach procedure (E-UTRAN) or PDP context activation procedure (GERAN/UTRAN)
DHCPv4
Stateless IPv6 address auto configuration (SLAAC)

24. IP Connectivity (6/8) IP Address Allocation in Other Accesses
Trusted Non-3GPP Accesses
Untrusted Non-3GPP Accesses

25. IP Connectivity (7/8)
Trusted Non-3GPP Accesses

26. IP Connectivity (8/8)
Untrusted Non-3GPP Accesses

27. Session Management

28. Session Management, Bearers, and QoS Aspects (1/13)
The basic functions in EPS to manage the user-plane path between the UE and the PDN GW
EPS bearer in E-UTRAN and EPS
for providing the IP connection
for enabling QoS

29. Session Management, Bearers, and QoS Aspects (2/13)
Default bearer
associated with a default type of QoS
Dedicated bearers
Additional EPS bearers
activated on demand
for example, when an application is started with a specific guaranteed bit rate or prioritized scheduling

30. Session Management, Bearers, and QoS Aspects (3/13)
User-Plane Aspects
The UE and the PDN GW (for GTP-based S5/S8) or Serving GW (for PMIP-base S5/S8) use packet filters to map IP traffic onto the different bearers
Each EPS bearer is associated with a so-called Traffic Flow Template (TFT)

31. Session Management, Bearers, and QoS Aspects (4/13)
This packet filter information is typically an IP 5-tuple defining the source and destination IP addresses, source and destination port, as well as protocol identifier (e.g. UDP or TCP).

32. Session Management, Bearers, and QoS Aspects (5/13)
The filter information may contain the following attributes:
Remote IP Address and Subnet Mask
Protocol Number (IPv4)/Next Header (IPv6)
Local Address and Mask (introduced in Release 11)
Local Port Range
Remote Port Range
IPSec Security Parameter Index (SPI)
Type of Service (TOS) (IPv4)/Traffic Class (IPv6)
Flow Label (IPv6).

33. Session Management, Bearers, and QoS Aspects (6/13)
GTP-U header contains:
a field that allows the receiving node to identify the bearer the packet belongs to
A user-plane packet encapsulated using GTP-U

34. Session Management, Bearers, and QoS Aspects (7/13)

35. Session Management, Bearers, and QoS Aspects (8/13)

36. Session Management, Bearers, and QoS Aspects (9/13)
How the UE, PDN connection, EPS bearer, TFT, and packet filters within the TFT relate to each other

37. Session Management, Bearers, and QoS Aspects (10/13)
Control-Plane Aspects
To activate, modify, and deactivate bearers, to assign QoS parameters, packet filters, etc., to the bearer.
Dedicated bearer
network-requested secondary PDP context activation procedure
If the default bearer is deactivated the whole PDN connection will be closed.

38. Session Management, Bearers, and QoS Aspects (11/13)
Bearers in PMIP- and GTP-Based Deployments
GTP designed to support
all functionality required to handle the bearer signaling
the user plane transport,
PMIP designed by IETF to only handle
functions for mobility and forwarding of the user plane.

39. Session Management, Bearers, and QoS Aspects (12/13)
When PMIP-based S5/S8 is used:
Packet filters are needed to map the downlink traffic onto the appropriate bearer

40. Session Management, Bearers, and QoS Aspects (13/13)

41. Session Management for EPS and GERAN/UTRAN Accesses (1/3)
The SGSN provides the mapping between PDP context and EPS bearer procedures, and maintains a one-to-one mapping between PDP contexts and EPS bearers.
By using PDP context procedures between UE and SGSN, the UE can use similar ways to connect when the 2G/3G access connects to EPC.
By using the EPS bearer in the EPC also for 2G/3G access, it is easier for the PDN GW to handle mobility between E-UTRAN and 2G/3G.

42. Session Management for EPS and GERAN/UTRAN Accesses (2/3)

43. Session Management for EPS and GERAN/UTRAN Accesses (3/3)
SGSN using S4 maps “the UE-initiated PDP context procedures over GERAN/UTRAN” into “corresponding EPS bearer procedures towards the Serving GW”
For example, when the UE is using GERAN/UTRAN and has requested activation of a secondary PDP context, the PDNGW must activate a new EPS bearer corresponding to the PDP context

44. Subscriber Identifiers and Corresponding Legacy Identities (1/3)
Permanent Subscriber Identifiers
Structure of IMSI

45. Subscriber Identifiers and Corresponding Legacy Identities (2/3)
Temporary Subscriber Identifiers
stored in an MME (or SGSN in the 2G/3G case)
The GUTI (Globally Unique Temporary ID) is a worldwide unique identity that points to a specific subscriber context in a specific MME.
The S-TMSI is unique within a particular area of a single network.

46. Subscriber Identifiers and Corresponding Legacy Identities (3/3)

47. Relation to Subscription Identifiers in 2G/3G

48. Mobility Principles

49. Mobility Principles EPS The functionality of mobility management
complete realization of multi-access convergence:
a packet core network that supports full mobility management
access network discovery
and selection for any type of access network.
The functionality of mobility management
the network can “reach” the user
a user can initiate communication towards other users or services
ongoing sessions can be maintained as the user moves

50. Mobility within 3GPP Family of Accesses
Cellular Idle-Mode Mobility Management
Not be practical to keep track of a UE in idle mode every time it moves between different cells.
Not practical to search for the UE in the whole network for every terminating event (incoming call)
Cells are grouped together into “registration areas”

51. Cellular Idle-Mode Mobility Management (1/7)

52. Cellular Idle-Mode Mobility Management (2/7)
Base stations broadcast registration area information.
UE compares the broadcasted registration area information with its own information

53. Cellular Idle-Mode Mobility Management (3/7)
In EPS the registration areas are called Tracking Areas (TAs).
As long as the UE moves within its list of allocated TAs, it does not have to perform a tracking area update.
Periodic updates are used to clear resources in the network for UEs that are out of coverage or have been turned off.

54. Cellular Idle-Mode Mobility Management (4/7)
In GSM/WCDMA there are two registration area concepts:
the PS domain (Routing Areas, RAs)
the CS domain (Location Areas, LAs).
The Routing Areas are a subset of the Location Areas and can only contain cells from the same LA.

55. Cellular Idle-Mode Mobility Management (5/7)
A summary of the idle mobility procedure in EPS:
A TA consists of a set of cells
The registration area in EPS is a list of one or more TAs
The UE performs TA Update when moving outside its TA list
The UE also performs TA Update when the periodic TA Update timer expires.
An outline of the Tracking Area Update procedure is shown in the figure of next slide.

56. Cellular Idle-Mode Mobility Management (6/7)

57. Cellular Idle-Mode Mobility Management (7/7)
Paging is used to search for Idle UEs and establish a signaling connection.

58. References
M. Olsson, Shabnam Sultana, Stefan Rommer, Lars Frid, and C. Mulligan, “EPC and 4G Packet Networks,” Second Edition: Driving the Mobile Broadband Revolution, Elsevier, 2013