Raphael Romeikat

Policy-based coordination and management of SON functions

Future wireless networks (LTE and beyond) will experience a continuous growth regarding the number of network elements with increasingly complex interrelations between the configuration of multiple network elements (NEs). A related trend is the seamless integration of multiple radio technologies into a single heterogeneous wireless network. Both developments increase network management complexity and require new management concepts with a very high degree of automation such as Self-Organizing Network (SON) concepts, which are currently discussed in the network operator (NGMN), research, and standardization (3GPP) communities. SON functions have to be coordinated and supervised in an automated way in order to enable a stable system operation with tight control over the system behavior by the network operator together with a high degree of automation. Based on a detailed analysis of the requirements for the coordination, a policy-based approach to realize the coordination-related decision making based on the network configuration and SON function context is presented. Results for two use cases (fully automatic hardware to site mapping and coverage & capacity optimization) are presented to show the applicability of the developed approach to diverse SON use cases.

Translation of QVT Relations into QVT Operational Mappings

Model transformations play a key role in Model-Driven Engineering solutions. To efficiently develop, specify, and manage model transformations, it is often necessary to use a combination of languages that stand for different transformation approaches. To provide a basis for such hybrid model transformation specification solutions, we developed and implemented a translation of the declarative QVT Relations into the imperative QVT Operational Mappings language.

An Experimental System for SON Function Coordination

Through the introduction of Self-Organizing Net- works (SON) into mobile networks, a potentially large number of SON functions are available. These SON functions automatically perfom management actions. There will be SON functions for many aspects of fault, configuration, accounting, performance, and security (FCAPS) management. The functions are executed based on monitored network behavior, which may lead to several functions being active concurrently in the same network area. Simultaneous execution of different functions with contradicting goals may lead to oscillating function execution and service degra- dation in the worst case. Therefore, SON function coordination is indispensable for SON-enabled networks in order to align the executed SON funtions and thus assure that they take full effect (improved performance and fault handling). Coordination mechanisms need to be developed and verified before they are deployed into the network. For this purpose, an experimental sys- tem realizes SON function coordination based on flexible policy- based decisions. Coverage and Capacity Optimization (CCO) is presented as use case to demonstrate succesful coordination of multiple independent SON functions.

Policy-driven workflows for mobile network management automation

Future wireless networks will experience a continuous growth regarding the number of network elements with increasingly complex interrelations between the configuration of multiple network elements. Another trend is the seamless integration of multiple radio technologies into a single wireless network. Both developments increase network management complexity and require new management concepts with a very high degree of automation. For this purpose, a novel management approach based on a combination of workflow and policy technologies is presented. The goal is to simplify and automate management tasks in mobile networks in order to raise the state of self-organization while the network still remains under control of the operator. The approach provides the means for a dynamic system to automatically adapt to context changes. Moreover, an experimental system is presented for the purposes of concept validation and evaluation along with a real world use case.

Optimized network configuration parameter assignment based on graph coloring

The trend for future mobile networks is to move away from Network Elements (NEs) delivered with specially tailored configurations towards off-the-shelf products. The configurations of NEs are automatically created with respect to their context including information on location and configuration of neighboring NEs. To minimize time-consuming and error-prone human interaction, automatic behavior is required for all stages of a NEs life cycle. The possibility to pre-assess the effects of configuration changes is inevitable in order to avoid service degradation caused by unnecessary reconfigurations. Graph coloring-based Physical Cell ID (PCID) assignment for LTE networks was introduced previously. The foundation on graph coloring theory allowed to transfer knowledge from this domain to the task of PCID assignment in order to pre-asses if an assignment is possible and how many PCIDs are required. Now the focus lies on adaptations of the basic approach to satisfy additional operator requirements such as safety margins. Those adaptations should provide equally good results in terms of used PCIDs with only minimal impact on costs and operation and maintenance tasks. Variations of the basic PCID assignment approach are discussed to address other types of problems.

Transformation of Graphical ECA Policies into Executable PonderTalk Code

Rules are becoming more and more important in business modeling and systems engineering and are recognized as a high-level programming paradigma. For the effective development of rules it is desired to start at a high level, e.g. with graphical rules, and to refine them into code of a particular rule language for implementation purposes later. An model-driven approach is presented in this paper to transform graphical rules into executable code in a fully automated way. The focus is on event-condition-action policies as a special rule type. These are modeled graphically and translated into the PonderTalk language. The approach may be extended to integrate other rule types and languages as well.

Towards Semantically-Enhanced Distributed Service Discovery

In this paper, we present a new approach for service discovery combining semantic web and peer-to-peer techniques. A reference ontology is used to describe and discover services in our approach. We do not need a central point of control at any time. All information required for service description and discovery is completely distributed across the nodes of a peer-to-peer overlay network. We describe the design of a Semantically- enhanced Distributed Discovery System (SDDS) allowing dynamic and efficient registration and discovery of services. We also present performance analysis and discuss open issues of our system.

Formal Specification of Domain-Specific ECA Policy Models

Policy-based management allows to adapt systems to changed requirements in a flexible and automated way. Policy development usually starts with the specification of high-level policies, which are then refined into a low-level representation. We use models to specify event-condition-action (ECA) policies at different levels of abstraction and consequently separate domain and policy aspects from each other. Domain-specific concepts are used within policies in their event, condition, and action parts. We present a formal specification of the models by means of a relational algebra. The algebra is used to validate the models at each level. Finally, executable policy code is generated from the low-level models.

Automated refinement of policies for network management

Policy-based management is a flexible approach for the management of networks as policies make context-sensitive and automated decisions. For their effective development it is desired to specify policies at a high level of abstraction initially and to refine them until they are represented in a machine-executable way. We present an approach that uses models to specify event-condition-action (ECA) policies at different abstraction layers and that uses model transformations to refine them in an automated way. A relational algebra is used to formally validate the models and define the semantics of the refinement process. One benefit of the approach is the automated policy refinement at runtime. Changes at the high-level models are automatically reflected in their low-level implementation through refinement. This allows to manage a system at a high level of abstraction. The approach is applied to the network management domain and demonstrated with policies for physical cell identification (PCI) in a mobile network. It can also be applied to other domains and supports a flexible number of abstraction layers.

Specification and Refinement of Domain-Specific ECA Policies

Policy-based management is a flexible approach for the management of complex systems as policies make context-sensitive and automated decisions. For the effective development of policies it is desired to specify policies at a high level of abstraction initially, and to refine them until they are represented in a machine-executable way. We present an approach for the specification and the automated refinement of domain specific event-condition-action (ECA) policies. Domain-specific policies use domain-specific concepts within their event, condition, and action parts. The approach is generic as it can be applied to any domain and supports a flexible number of abstraction layers. It is applied to the network management domain and demonstrated with policies for signal quality management in a mobile network.