A Cell Outage Management Framework for Dense Heterogeneous Networks | IEEE Journals & Magazine | IEEE Xplore

A Cell Outage Management Framework for Dense Heterogeneous Networks


Abstract:

In this paper, we present a novel cell outage management (COM) framework for heterogeneous networks with split control and data planes-a candidate architecture for meetin...Show More

Abstract:

In this paper, we present a novel cell outage management (COM) framework for heterogeneous networks with split control and data planes-a candidate architecture for meeting future capacity, quality-of-service, and energy efficiency demands. In such an architecture, the control and data functionalities are not necessarily handled by the same node. The control base stations (BSs) manage the transmission of control information and user equipment (UE) mobility, whereas the data BSs handle UE data. An implication of this split architecture is that an outage to a BS in one plane has to be compensated by other BSs in the same plane. Our COM framework addresses this challenge by incorporating two distinct cell outage detection (COD) algorithms to cope with the idiosyncrasies of both data and control planes. The COD algorithm for control cells leverages the relatively larger number of UEs in the control cell to gather large-scale minimization-of-drive-test report data and detects an outage by applying machine learning and anomaly detection techniques. To improve outage detection accuracy, we also investigate and compare the performance of two anomaly-detecting algorithms, i.e., k-nearest-neighbor- and local-outlier-factor-based anomaly detectors, within the control COD. On the other hand, for data cell COD, we propose a heuristic Grey-prediction-based approach, which can work with the small number of UE in the data cell, by exploiting the fact that the control BS manages UE-data BS connectivity and by receiving a periodic update of the received signal reference power statistic between the UEs and data BSs in its coverage. The detection accuracy of the heuristic data COD algorithm is further improved by exploiting the Fourier series of the residual error that is inherent to a Grey prediction model. Our COM framework integrates these two COD algorithms with a cell outage compensation (COC) algorithm that can be applied to both planes. Our COC solution utilizes an actor-critic-b...
Published in: IEEE Transactions on Vehicular Technology ( Volume: 65, Issue: 4, April 2016)
Page(s): 2097 - 2113
Date of Publication: 08 May 2015

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I. Introduction

Recently, extensive research and standardization efforts have been channeled toward the definition of the paradigm of self-organizing networks (SONs), which aim at achieving a substantial reduction in capital and operational expenditures (CAPEX and OPEX) by reducing human involvement in network operational tasks, while optimizing network coverage, capacity, and quality of service [1], [2]. SONs aim to replace the manual operational processes that have been executed in legacy cellular networks since their conception, such as configuration, postdeployment optimization, and troubleshooting, with autonomous functions called SON functions, such as self-configuration, self-optimization, and self-healing [1]– [3]. The main task within the self-healing functionality is autonomous cell outage detection (COD) and its compensation. Traditionally, cell outages have been manually detected. In some cases, cell outage can be detected by the manual analysis of fault alarms at the operations and maintenance center (OMC), whereas other detections require site visits or drive testing. This is an expensive process. In addition, it may take hours or days for the cell outage to be detected, thus resulting in pronounced reduction in capacity and quality of service and coverage gap [4], [5]. Once detected, the outage is compensated in an ad hoc and manual fashion, making the whole process extremely inefficient and unreliable. With an increasing scale of networks, automatic detection and compensation of cell outage has become a necessity, and it has been included in recent Third-Generation Partnership Project (3GPP) releases [6]. Therefore, the SON paradigm aims to replace these manual tasks with an autonomous process that is referred to as cell outage management (COM) [7]– [12]. COM can be further subdivided into COD and cell outage compensation (COC). COD aims to autonomously detect outage cells, i.e., cells that are not properly operating due to possible failures, e.g., external failure such as power supply or network connectivity, or even misconfiguration [4]– [6], [13]. On the other hand, COC refers to the automatic mitigation of the degradation effect of the outage by appropriately adjusting suitable radio parameters, such as pilot power, antenna tilt, and azimuth of the surrounding cells. The degree of compensation is usually dictated by the operator's policies, which also specify the level of performance that must be satisfied in the outage region [9].

References

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