8.2 NMS Basic Principle


8.2.1  Introduction to the TMN

1. Basic Concepts of the TMN

TMN is the abbreviation of Telecommunication Manager Network. The TMN supports the management of telecommunication networks and services by transmitting/storing/processing information.
The TMN can manage various types of telecommunication networks and the network elements such as analog/digital network, the public network/private network, the switching system/transmission system, the telecommunication software, the network logic resources (like the circuit/route/service) and auxiliary supporting systems (like the power system and the air-conditioning system).
The TMN is the telecommunication network management standard presented by ITU-T. As a part of the telecommunication supporting network, TMN is separate from the telecommunication service in principle.

2. Basic Model and Features of the TMN

1)      Introduction to the TMN architecture
The TMN consists of multiple layers with each layer corresponding to a different management mode. 

NEF: Network Element Function

EML: Element Manager Layer

NML: Network Manager Layer

SML: Service Manager Layer

BML: Business Manager Layer

According to the figure above, the TMN consists of different management layers, interconnected via an interface. The TMN is a bottom-up network system with products as the core. The layers are described as follows:
l   Business Management Layer
Providing support for service-oriented decision functions, such as report statistics and performance trend analysis.
l   Service Management Layer
Providing the customer-oriented management functions to manage the services offered to the customer and to collect the accounting information and the feedback information of the network service quality.
l   Network Management Layer
Providing network-oriented operation and management, such as network traffic monitoring and fault monitoring.
l   Network Element Management Layer
Delivering equipment-oriented operation and maintenance.
l   Network Element Function
As the basis of the TMN O&M system, the OM system at the NE side provides NE operation and maintenance, and upper interfaces with the TMN.
2)      Features of the TMN Architecture
l   Built from bottom up with products as the core;
l   Based on interoperation between devices with the ultimate objective of unified management over the equipment of different vendors;
l   Defines corresponding interface and information model;
l   Focuses on the NEF-EML-NML relationship, giving priority to OMS (operation & maintenance system) support in terms of service, while the SML and the BML in the model are not addressed.

8.2.2  Introduction to the TOM Model


In 3GPP, the description of the NMS is based on the TMN model of ITU-T as well as ideas of the TOM model presented by TMF. Especially in versions higher than 3GPP (R5), it comes even closer to the TOM model. The following is about the model.
TOM (Telecom Operations Map) is a new generation of the NMS model put forward by the TMF (Telecommunication Management Forum), which is a non-profitable organization committed to providing leading, strategic and practical solutions to improve the communication service management and operation quality. In addition, it develops the programmed market-based solutions to address the major problems arising in connection with OSS integration and business procedure automation. It has 384 members from large companies, organizations and associations, including service providers, software solution suppliers, computer/network equipment suppliers and customers using communication services.
Simply speaking, the TOM involves such vertical processes as service implementation, service assurance and service billing as well as one cross-carrier process. Horizontally, it also includes such layers as care, service development & operation, and network development & operation. The customer care layer includes five parts: sales, order processing, troubleshooting, customer QoS management and bill payment (i.e. billing). The layer for service development and operation also comprises five parts: service planning and development, service configuration, service problem management, service QoS management and rating/discounting. The layer for network development and operation consists of another five parts: network planning and development, network provisioning, network inventory management, network maintenance & restoration and network data management.

In the WCDMA NMS, the O&M layer relies heavily on the building of the TMN O&M network system (NMF-EMS-NMS), while the accounting management, the business forecast and the network service provision are based on the TOM model.

8.2.3  Introduction to the WCDMA NMS

1. Goals of the WCDMA NMS

l   To manage the equipment of different vendors, including the management system itself;
l   To simplify the UMTS network management;
l   To support the communication between the UMTS NE and the UMTS OS or between the UMTS OSs via the standard interfaces;
l   To reduce the cost of the UMTS network management;
l   To provide the capability of flexible and fast service configuration;
l   To provide comprehensive fault management capability;
l   To simplify the operation and maintenance with local or remote O&M functions;
l   To allow for the exchange of the network management and the accounting information between the network manager and the service provider, and the exchange of information with different networks, including other UMTS networks and non-UMTS networks;
l   To support and control the growth of resources, and with scalability, to satisfy the requirements of smooth expansion according to the development of network services;
l   To provide a security management mechanism based on the whole UMTS NMS;
l   To provide flexible billing and accounting management, and to support the account settlement between the UMTS and the non-UMTS networks;
l   To provide transaction notification; for example, the change in the property of an NE may cause some changes to this NE or other NEs. These changes are one-time changes and should be reported as events;
l   To provide the capability of restoring the UMTS system.

2. Introduction to the 3G NMS architecture

With a good operation support system, the operator can fully understand the operation status of the network equipment and the network service quality, and deploy the services efficiently, thus improving its operation and maintenance efficiency and service quality as well as the competitiveness.
Based on the TMN and TOM architectures, the WCDMA NMS provides relevant NMS frameworks.
The basic framework of the NMS described in 3GPP is shown as the figure below. The UMTS Operation System in the figure also adopts a hierarchical structure (LA, logic layer architecture), which may be considered an equivalent to the equipment system at the EML/NML layer of the TMN framework. The Enterprise systems is the information system used in the communications system, which has no direct or substantial connection with communication services. It includes the call center, the fraud detection and prevention system and the billing system.

Interface 1: The interface between the NE and the OS. Generally, it means the interface between the NE and the EML. If the NE itself provides a network management interface, it also refers to the interface between the EML and the NML.
Interface 2: The interface between the OS and the Enterprise system. It may be considered as the interface between the OS layer and the service provisioning system, similar to the interface between the NML layer and the upper layers in TMN.
Interface 3: It means the interface between OSs. It may be the OS interface between the UMTS networks, or the interface between a UMTS network and a non-UMTS network, such as the PSTN or other networks;
Interface 4: It indicates the interface among the layers of an OS, similar to the interface between the EML and the NML.
According to the figure above, the 3G NMS is designed to provide a complete, open and scalable operation support system to support the UMTS network and develop services.

3. Comparisons between the 3G NMS and the 2G NMS

The NM functions of a traditional 2G mobile network are based on the TMN network management framework, and focused on the service functions of the equipment O&M layers. In the main, it provides management functions in five areas as defined by ITU:
l   Performance Management
l   Fault Management
l   Configuration Management
l   Accounting Management
l   Security Management
As a network management product, it must provide centralized operation and maintenance based on the network-wide equipment, so the NMS generally needs to provide such functions as centralized topology management and centralized operation & maintenance. These are the basic functions of the OMS of the 2G NMS.
According to the management objectives of the 3G NMS above, there is no substantial difference between the 3G NMS and the 2G NMS. In terms of architecture and service functions, the 3G NMS adheres to the characteristics of the 2G NMS. However, the WCDMA network is more complex than the 2G network. Below are some differences between the 2G NMS and the 3G NMS.
1)      The architecture of the 3G NMS is more reasonable than that of the 2G NMS
The 2G NMS is designed based on the idea of TMN network management, so the operation and maintenance layer (O&M layer) is fairly perfect. However, it is deficient in the entire operation layer (OSS layer), where services are not well integrated.
The 3G NMS is intended to deliver an integrated operation network based on numerous management theories such as TMN and TOM, combining the features such as network maintenance, management, service deployment and operation, to develop an integrated support system solution.
2)      More openness between networks
In the 2G NMS, the standards of the interfaces between the NE and the EMS, between the EMS and the NMS, and among different networks vary largely, making it difficult to develop an integrated O&M network system. As a result, it is difficult for operators to keep fully informed about the NMS operation status and deploy services quickly by establishing an unified O&M network system given multiple equipment vendors, different standards and complex structures.
The 3G NMS pays more attention to interface standardization and normalization, guiding the standardization of the interfaces between the NE and the EMS, or between the EMS and the NMS, and between the O&M layer and the OSS layer, to develop an integrated O&M solution.
In addition, the sharing of information among UMTS networks, or between a UMTS network and a non-UMTS network is also addressed in the 3G NMS. All this relies on interface standardization.
3)      Wide application and recommendation of the CORBA technology
In the 3G NMS construction, it is strongly recommended to adopt a CORBA technology-based architecture with an object-based description of the network structure, to shape a unified O&M idea. It is also recommended to take the CORBA interface standard as the standard for NMS interface on the layers of the O&M network system for the normalization of the interfaces.
In addition, the CORBA technology brings a distributed network structure in real sense, making it easier for future network expansion and service development.
4)      More perfect service features
In addition to the 2G NMS feature, the 3G NMS provides more service features such as network-wide software management, OoS management and location management. The details will be described in the introduction below.

4. The 3G NMS serves to manage a diversity of service areas through different layers

Overall management over the operation of 3G services calls for a large amount of complicated systems engineering. Its features include:
l   Multiple managed network layers, each of which has a variety of devices, and these devices may be provided by different vendors;
l   The business mode of the 3G service is much more complicated than that of the traditional voice service, involving varied services and service providers and multi-vendors;
l   The network structure and the equipment type varies with the network system, and even the same kind equipment in different systems calls for different services;
l   Different vendors use different technologies on their equipment, for example, some vendors adopt the ATM technology, while some adopt the IP technology;
l   The wireless service itself has some complex features, such as cell management, roaming management and mobility management. All these features make the 3G service management intricate;
l   Each network equipment layer of the 3G service environment comprises five parts: access equipment (i.e. mobile phone/terminal), wireless access network, core network, service release network and content & service. To fully support the 3G service operation, we need to manage these devices;
Thus, the 3G NMS manages various service areas through different layers.

In addition, mobile network management must attain the objectives of greater customer satisfaction but lower cost:
l   - Providing highly-personalized communication service
l   - The growth of individual subscribers exceeding that of enterprise subscribers
l   - Segregating the roles of service provider and network operators between the home environment and the service network entity.
l   - One-stop charging for all services

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