Towards autonomic management of communications networks

As communications networks become increasingly dynamic, heterogeneous, less reliable, and larger in scale, it becomes difficult, if not impossible, to effectively manage these networks using traditional approaches that rely on human monitoring and intervention to ensure they operate within desired bounds. Researchers and practitioners are pursuing the vision of autonomic network management, which we view as the capability of network entities to self-govern their behavior within the constraints of business goals that the network as a whole seeks to achieve. However, applying autonomic principles to network management is challenging for a number of reasons, including: (1) A means is required to enable business rules to determine the set of resources and/or services to be provided. (2) Contextual changes in the network must be sensed and interpreted, because new management policies may be required when context changes. (3) As context changes, it may be necessary to adapt the management control loops that are used to ensure that system functionality adapts to meet changing user requirements, business goals, and environmental conditions. (4) A means is required to verify modeled data and to add new data dynamically so that the system can learn and reason about itself and its environment. This article provides an introduction to the FOCALE autonomic network management architecture, which is designed to address these challenges.     

UMTS mobility management

The characteristics of first, second and third generation mobile communication systems are first described. The state of standardisation of the universal mobile telecommunication system (UMTS) is then outlined and the system concept is introduced. A mobility management platform which will provide uniform access to mobility functions for every user or network entity independent of the actual location of the requested function in the network is described. The mobility management platform is based on the intelligent network concept. Mobility management aims to share the processing load in the distributed UMTS environment     

UMTS网络中SRNS重定位机制的研究

对UMTS网络中的SRNS重定位机制进行了分析和研究,针对在硬切换过程中传统SRNS重定位所需时间过长的缺陷,提出了一种新的SRNS重定位机制。该机制中,SGSN使用双播Bicasting技术,使切换后的移动台能够尽快地接入到新的小区,减少了分组的丢失。仿真结果显示,新机制可以将切换过程中的分组丢失率减少15%左右。     

Planning reliable UMTS terrestrial access networks

The Universal Mobile Telecommunication System (UMTS) will play a very important role in the telecommunication market of the near future. Due to the wide range of services and the increased transmission capacity, UMTS will become one of the most important access network types. The proposed topology of the UMTS terrestrial access network is tree-like, but the high amount of carried traffic requires a more reliable network structure. We introduce two types of heuristic algorithms to solve this problem, and we plan network topologies having a low magnitude of traffic loss in case of failures. One of our algorithms solves the problem by modifying the tree-topology, while others expand the network by inserting additional links. We show how to find a good compromise between topology refinement and network expansion in the case of realistic network scenarios, and we confirm our results by detailed tests     

Fast handoff with reducing waste rate approach for wireless resources management in UMTS mobile networks

3G Wideband CDMA systems adopt the Orthogonal Variable Spreading Factor code tree as the channelization codes management for achieving high data rate transmission in personal multimedia communications. It assigns a single channelization code for each accepted connection. Nevertheless, it wastes the system capacity when the required rate is not powers of two of the basic rate. One good solution is to assign multiple codes for each accepted connection but it causes two inevitable drawbacks: long handoff delay and new call setup delay due to high complexity of processing with multiple channelization codes, and high cost of using more number of rake combiners. Especially, long handoff delay may result in more call dropping probability and higher Grade of Service, which will degrade significantly the utilization and revenue of the 3G cellular systems. Therefore, we propose herein an adaptive efficient codes determination algorithm based on the Markov Decision Process analysis approach to reduce the waste rate and reassignments significantly while providing fast handoff. Numerical results demonstrate that the proposed approach yields several advantages, including the lowest GOS, the least waste rate, and the least number of reassignments. Meanwhile, the optimal number of rake combiners is also analyzed in this paper. This research was supported in part by the National Science Council of Taiwan, ROC, under contract NSC-93-2213-E-324-018.     

Performance evaluation of location management in UMTS

The universal mobile telecommunications system utilizes a three-level location-management strategy to reduce the net costs of location update and paging in the packet-switched service domain. Within a communication session, a mobile station (MS) is tracked at the cell level during packet transmission. In the idle period of an ongoing session, the MS is tracked at the UTRAN registration area (URA) level to avoid frequent cell updates while still keeping the radio connection. If the MS is not in any communication session, the MS is tracked at the routing-area (RA) level. The inactivity counter mechanism was proposed in 3GPP 25.331 to determine when to switch between the three location-tracking modes. In this mechanism, two inactivity counters are used to count the numbers of cell and URA updates in an idle period between two packet transmissions. If the number of cell updates reaches a threshold K/sub 1/, the MS is switched from cell tracking to URA tracking. After that, if the number of URA updates reaches a threshold K/sub 2/, the MS is tracked at the RA level. The paper proposes analytical and simulation models to investigate the performance of the inactivity counter mechanism. Our study provides guidelines for K/sub 1/ and K/sub 2/ selection to achieve lower net costs of location update and paging.     

Interoperability between UMTS and cdma2000 networks

In overlaying an existing cdma2000 network with a UMTS network, service transparency and number portability are important requirements for end users and hence the network operator. To support both requirements, one could introduce a protocol conversion node between the two networks; however, such a solution does not fully meet the requirements due to inherent technical constraints imposed by the differing standards. This article describes a network architecture based on the dual stack concept that satisfies the service transparency and number portability requirements across UMTS and cdma2000 networks, and also defines the functionality of the network nodes and the call processing procedures.     

UMTS与cdma 2000网络的融合

2G移动通信系统在向具有统一无线接口,公共先进核心网和提供全球漫游能力的3G系统演进的过程中,面临着下述挑战:* 3GPP和3GPP2分别在已有基础设施上研发了基于GSM的UMTS系统和基于cdma one的cdma 2000系统,已难以使3G成为一个全球统一移动通信系统;* 在各自系统边界范围内的全球漫游仍面临着困难;* 从2G不同系统演进来的3G不同系统间的移动性管理,呼叫转移,辅助业务等互通问题还未解决。从移动终端和网络业务提供者角度看,UMTS和cdma 2000系统的融合应满足下述关键要求。下面分别给予讨论:从移动终端角度看:* 号码便携性:不管移动…     

An all-IP approach for UMTS third-generation mobile networks

This article describes the UMTS all-IP approach for third-generation mobile systems, with emphasis on the core network architecture. Following the introduction of the core network nodes, we elaborate on application-level registration, circuit-switched call origination, packet-switched call origination, and packet-switched call termination.     

Genetic algorithm for autonomic joint radio resource management in end-to-end reconfigurable systems

This article presents the genetic algorithm （GA） as an autonomic approach for the joint radio resource management （JRRM） amongst heterogeneous radio access technologies （RATs） in the end-to-end reconfigurable systems. The joint session admission control （JOSAC） and the bandwidth allocation are combined as a specific decision made by the operations of the genetic algorithm with certain advisable modifications. The proposed algorithm is triggered on the following two conditions When a session is initiated, it is triggered for the session to camp on the most appropriate RAT and select the most suitable bandwidth for the desired service. When a session terminates, it is also used to adjust the distribution of the ongoing sessions through the handovers. This will increase the adjustment frequency of the JRRM controller for the best system performance. Simulation results indicate that the proposed autonomic JRRM scheme not only effectively reduces the handover times, but also achieves well trade-off between the spectrum utility and the blocking probability.     

Functional models of UMTS and integration into future networks

The universal mobile telecommunication system (UMTS) will implement terminal mobility and a form of personal mobility limited to UMTS. The most essential procedures to provide this are related to user registration, location management, handover and security. These mobility procedures are specified using specific functional models. In these models, the required functions are identified and the distribution of the functions in the network is anticipated. In a next step, the specific models are mapped onto a generic functional model. This generic model can be considered as the integration and unification of the specific models. Its structure reflects two important implementation aspects. First, the integration of UMTS into future networks for fixed telecommunications is anticipated. Secondly, the application of the intelligent network architecture for the implementation of the UMTS mobility procedures and service provision is assumed     

一种超密集网络基站分簇管理算法

为了降低超密集网络中基站管理算法的计算复杂度并提升基站的能源使用效率,根据用户密度、网络负载量等信息,提出了一种基于分簇的动态管理基站算法.该算法首先根据用户测量报告计算出理论最小需求基站数,然后对基站进行合理的网络分簇,最终通过粒子群优化算法确定基站休眠组合.仿真结果表明,与未进行分簇的基站管理算法相比,该算法可以降低约60%的计算复杂度,并能有效降低基站能源消耗.     

Location management of correlated mobile users in the UMTS

In this paper, we propose concurrently searching for correlated mobile users in mobile communications networks. Previous work either focuses on locating a single mobile user or assumes that the locations of mobile users are statistically independent. We first propose a mobility model in which the movements of mobile users are statistically correlated. Next, we use the theory of Markov chain to derive the joint probability density function of the locations of mobile users. In addition, we propose a novel approach to discover the correlations among the locations of mobile users without explicitly calculating the joint probability density function. Our simulation results indicate that exploring the correlations among the locations of mobile users could significantly reduce the average paging delay and increase the maximum stable throughput.     

Mobility management: from GPRS to UMTS

This paper describes mobility management for the third‐generation mobile networks. We focus on the evolution from General Packet Radio Service (GPRS) to Universal Mobile Telecommunication System (UMTS). In this evolution, the radio access network UTRAN has been introduced, and radio‐related management is moved from the core network to UTRAN. We elaborate on how this architecture change affects the mobility management functionality, including the attach and detach procedures, location update, serving radio network controller relocation and intersystem change between GPRS and UMTS. Copyright © 2001 John Wiley & Sons, Ltd.     

A cognitive model‐based approach for autonomic fault management in OpenFlow networks

Autonomic network management is an approach to the management of complex networks and services that incorporates the detection, diagnosis and reconfiguration, as well as optimization, of their performance. A control loop is fundamental as it facilitates the capture of the current state of the networks and the reconfiguration of network elements without human intervention. For new networking architectures such as software‐defined networking and OpenFlow networks, in which the control plane is moved onto a centralized controller, an efficient control loop and decision making are more crucial. In this paper, we propose a cognitive control loop based on a cognitive model for efficient problem resolving and accurate decision making. In contrast to existing control loops, the proposed control loop provides reactive, deliberative and reflective loops for managing systems based on analysis of current status. In order to validate the proposed control loop, we applied it to fault management in OpenFlow networks and found that the protection mechanism provides fast recovery from single failures in OpenFlow networks, but it cannot cover multiple‐failure cases. We therefore also propose a fast flow setup (FFS) algorithm for our control loop to manage multiple‐failure scenarios. The proposed control loop adaptively uses protection and FFS based on analysis of failure situations. We evaluate the proposed control loop and the FFS algorithm by conducting failure recovery experiments and comparing its recovery time to those of existing methods. Copyright © 2013 John Wiley & Sons, Ltd.     

Two hybrid ARQ algorithms for reliable multicast communications in UMTS networks

Multicast communications in wireless networks have attracted the interest of the scientific community, since many issues remain open. In this framework, our letter proposes two novel hybrid automatic repeat request (HARQ) algorithms for multicast communications in the UMTS radio link control (RLC) layer. The proposed algorithms exploit the channel autocorrelation in order to dynamically estimate the multicast users' channel conditions and thus reduce the mean service data unit (SDU) delay and increase the SDU throughput.     

Autonomous agents for autonomic networks

This paper deals with a multi-agent technology as a tool to introduce an autonomic behavior in network control and management. In a first section, we describe the autonomic communication paradigm, the characteristics, and the need for new architectures. Then, we focus on the differences between a classical and an autonomic network. Some related works involving the combination of artificial intelligence and telecommunication networks are presented. Then, characteristics of agents and multi-agent systems are presented to provide the network with autonomic behavior. A specific section also analyzes the different proposals in the literature. Then, a network-oriented platform associated with agent capabilities is described. The following section presents an application of the architecture toOspf weight setting optimization. Finally, the paper details two experiments on theOspf weight setting applied to a small network and to a large scale network.     

Performance analysis for UMTS networks with queued radio access bearers

The Universal Mobile Telecommunications System (UMTS) network consists of a core network (CN) and a UMTS terrestrial radio access network (UTRAN). The UTRAN offers radio access bearer (RAB) services between the user equipment (UE) and the CN to support mobile multimedia applications with different quality of service (QoS) requirements. Depending on the requested QoS, different types of RABs can be established at the request of the CN. The UTRAN then has to establish and maintain the RAB with the requested QoS. We study the queueing of RABs as a means for improving the bandwidth utilization while minimizing the RAB blocking probability. We develop an analytical model to study the performance for UTRAN with queued RABs in terms of RAB blocking probability and average queueing time of queued RABs. From an analytic point of view, the main contribution of this paper is the introduction of a novel recursion for the computation of the performance measures.     

Data dissemination in autonomic wireless sensor networks

In this paper, a new data dissemination algorithm for wireless sensor networks is presented. The key idea of the proposed solution is to combine concepts presented in trajectory-based forwarding with the information provided by the energy map of the network to determine routes in a dynamic fashion, according to the energy level of the sensor nodes. This is an important feature of an autonomic system, which must have the capacity of adapting its behavior according to its available resources. Simulation results revealed that the energy spent with the data dissemination activity can be concentrated on nodes with high-energy reserves, whereas low-energy nodes can use their energy only to perform sensing activity or to receive information addressed to them. In this manner, partitions of the network due to nodes that ran out of energy can be significantly delayed and the network lifetime extended.