Aspects of Critical Communications in Disturbance Scenarios

Infrastructures are the foundations of modern societies. The most important ones are the so-called critical infrastructures: mobile networks and electricity networks. If these networks are damaged or otherwise unavailable, the functionality of the whole society is at risk and can result even in public safety hazards. Furthermore, people expect all the time ubiquitous access to internet through mobile networks as many services rely on these wireless networks. The dependence is growing all the time as the number of worldwide subscriptions has already exceeded the world population and the amount of internet of things (IoT) and other connected devices continues to increase exponentially.This thesis focuses on the critical communications aspects of mobile networks during disturbance scenarios. These are defined as situations where, e.g. there is a power blackout in the electricity network, which affects the functionality of the mobile network.The contributions of this thesis can be divided into three main themes. The first one is the actual functionality of mobile networks during disturbance scenarios. This includes finding out how the behavior of subscribers changes when there is an uncommon disturbance scenario in the mobile network and how to prolong the disturbance time functionality of the existing networks. The results show that subscribers utilize mobile networks more than usual already before the power blackout starts when they try to find out information about the status of an upcoming storm. Immediately after the disturbance scenario starts, the subscribers within the blackout area are more active as the statistics show 73 % increase in the number of new calls and 84 % in the amount of short message service (SMS) messages. The results show also that the majority of mobile network availability is lost after 3–4 hours from the start of the incident. In order to prolong this availability time, simulations are performed to find out how utilizing only a portion of the available base station (BS) sites affects the service coverage. The results show that around 20 % of BS sites would be enough to cover 75 % of the original service coverage. Therefore, the operational time of the so-called mobile network backup coverage could be increased several times given that core network (CN) and backhaul network are also operational.The second main theme in this thesis presents a new developed situation awareness system (SAS) that combines the outage information of both mobile and electricity networks. This is an important tool for monitoring the networks and performing disaster and disturbance management. The user interface of the developed SAS is a map view showing the outage information, i.e. the faults, in both networks. It utilizes operational data from both networks such as the coverage outage areas of the mobile network and the outages of transformers in the electricity network in near real-time. The developed SAS helps to prioritize maintenance and repair work to the most critical areas as well as help to form a better overall situation awareness that fire and rescue services and authorities could utilize for improving public safety actions.The last main theme in the thesis considers innovative solutions in order to find out methods to improve the performance, i.e., to mitigate the outage of mobile networks in disturbance scenarios. The three different approaches presented are the indirect guidance of subscribers, the concept of a temporary low altitude platform (LAP) network with the help of drones, and the concept of a macro sensor network (MSN). First, the energy and capacity aspects of mobile networks can be improved when the subscribers are indirectly guided to self-optimize their location in the serving cell area. This can result in serving more user equipment (UEs) within a cell or to decrease the amount of energy needed for transmissions. Next, the coverage aspects of a LAP system are studied in order to find out the suitability of forming a temporary emergency coverage with a wireless local area network (WLAN) equipped drones. The results show that this kind of approach could provide a suitable emergency coverage for a limited area with a reasonable number of drones. Finally, a framework for MSN is studied to investigate the possibility of bringing wireless sensor network (WSN) functionalities into mobile networks. The results show that the concept of MSN could remarkably improve the resilience of mobile networks in situations where the backhaul connection is broken. However, implementing and further developing this kind of functionality will require changes in the 3rd Generation Partnership Project (3GPP) specifications and self-organizing network (SON) features within the network.Overall, this thesis provides insight on how to develop the current and future mobile networks toward more resilient infrastructures. It highlights the importance of critical communications as a fundamental part of modern societies. Thus, securing the functionality and performance of mobile networks in all situations is crucial. As a result, the contributions in this thesis can be utilized as a starting point in the future research to develop new functionalities for mobile networks. One of such approaches can be a safety mode, which would improve the mobile network resiliency during disasters and disturbance scenarios

Evaluation of Maximum Range for Backscattering Communications Utilising Ambient FM radio signals

The objective of this article is to evaluate the maximum range of ambient backscattering communications (AmBC). FM radio signals operating at 100 MHz are selected as the ambient signal due to their large communication ranges. The FM radio signals operate in one of the lowest commercially available frequency bands that can be utilized for AmBC. Additionally, due to the extensive deployment of FM radio, this technology is readily available worldwide. Simulations are performed in a rural highway environment to analyse the suitability of FM radio as an ambient signal for backscattering communications. The FM transmitter and receiver antenna are located in approximately the same area representing a monostatic form of operation for backscattering communications. The sensors are located in more or less the line of sight (LOS) of the TX/RX antenna. The FM signal is reflected back from the sensor towards the receiver for detection. The ray-tracing technique and the radar equation are utilized to perform the simulations. Based on the ray-tracing simulations, a distance of 14.5 km was obtained between the TX/RX antenna and the sensor. The achievable distances utilising the radar equation depend significantly on the cross-section of the sensor and different sizes were utilised in the simulations.acceptedVersionPeer reviewe

Maximum Receiver Harvesting Area of Backscatter Signals from Ambient Low-Frequency Mobile Networks

The purpose of this paper is to estimate the maximum achievable range for ambient backscattering communications (AmBC) by utilizing one of the lowest available frequency bands for mobile networks. Long term evolution (LTE) networks operating at 700 MHz (LTE-700, also referred to as LTE band 28) use the frequency division duplexing (FDD) technique for communications and are utilised as the ambient signals to perform the simulations. The simulations are carried out in urban macro-cellular and suburban highway environments. For the simulations, the sensors are placed in the line-of-sight (LOS) path of the LTE-700 transmitter and receiver antenna as this ensures the maximum applicability of the AmBC technology. Two propagation models, the ray tracing approach and the radar equation are leveraged to determine the maximum range of communication when the signal is reflected by the sensor. It is observed from the analysis that distances of a few hundred meters are achievable utilising both propagation models. The size of the sensor has a pivotal role in determining the maximum range of communication while utilising the radar equation. Therefore, a thorough analysis is performed using real-world sensor sizes deployed for the internet of things (IoT) wireless communication.acceptedVersionPeer reviewe

Agile 5G Network Measurements : Operator Benefits of Employing Aerial Mobility

This article discusses a flexible method of assessing 5G networks in connection to aerial mobility and for the benefits of mobile network operators. Two scenarios are considered. The first one features a commercial-grade 5G test network. Here, agile antenna pattern measurements are performed over known configurations with a smartphone attached to an unmanned aerial vehicle (UAV) having different flying speeds. The second scenario presents agile measurements for all mobile network operators in Finland to quickly estimate 5G network availability with respect to a particular area and altitude. The results collected in Scenario 1 indicate that aerial measurements are a prompt method to estimate 5G network antenna patterns, which is important for the operators to validate their new 5G antenna equipment. The results of Scenario 2 show how the existing operator-owned 5G networks perform, which is essential to evaluate the suitability of different services related to aerial mobility. Therefore, agile aerial network measurements are beneficial for the operators to assess the maintenance and optimization needs across their 5G deployments and thus complement traditional drive tests, and as the means to ensure that the deployments are UAV-ready.acceptedVersionPeer reviewe

Aspects of Critical Communications in Disturbance Scenarios

Infrastructures are the foundations of modern societies. The most important ones are the so-called critical infrastructures: mobile networks and electricity networks. If these networks are damaged or otherwise unavailable, the functionality of the whole society is at risk and can result even in public safety hazards. Furthermore, people expect all the time ubiquitous access to internet through mobile networks as many services rely on these wireless networks. The dependence is growing all the time as the number of worldwide subscriptions has already exceeded the world population and the amount of internet of things (IoT) and other connected devices continues to increase exponentially.This thesis focuses on the critical communications aspects of mobile networks during disturbance scenarios. These are defined as situations where, e.g. there is a power blackout in the electricity network, which affects the functionality of the mobile network.The contributions of this thesis can be divided into three main themes. The first one is the actual functionality of mobile networks during disturbance scenarios. This includes finding out how the behavior of subscribers changes when there is an uncommon disturbance scenario in the mobile network and how to prolong the disturbance time functionality of the existing networks. The results show that subscribers utilize mobile networks more than usual already before the power blackout starts when they try to find out information about the status of an upcoming storm. Immediately after the disturbance scenario starts, the subscribers within the blackout area are more active as the statistics show 73 % increase in the number of new calls and 84 % in the amount of short message service (SMS) messages. The results show also that the majority of mobile network availability is lost after 3–4 hours from the start of the incident. In order to prolong this availability time, simulations are performed to find out how utilizing only a portion of the available base station (BS) sites affects the service coverage. The results show that around 20 % of BS sites would be enough to cover 75 % of the original service coverage. Therefore, the operational time of the so-called mobile network backup coverage could be increased several times given that core network (CN) and backhaul network are also operational.The second main theme in this thesis presents a new developed situation awareness system (SAS) that combines the outage information of both mobile and electricity networks. This is an important tool for monitoring the networks and performing disaster and disturbance management. The user interface of the developed SAS is a map view showing the outage information, i.e. the faults, in both networks. It utilizes operational data from both networks such as the coverage outage areas of the mobile network and the outages of transformers in the electricity network in near real-time. The developed SAS helps to prioritize maintenance and repair work to the most critical areas as well as help to form a better overall situation awareness that fire and rescue services and authorities could utilize for improving public safety actions.The last main theme in the thesis considers innovative solutions in order to find out methods to improve the performance, i.e., to mitigate the outage of mobile networks in disturbance scenarios. The three different approaches presented are the indirect guidance of subscribers, the concept of a temporary low altitude platform (LAP) network with the help of drones, and the concept of a macro sensor network (MSN). First, the energy and capacity aspects of mobile networks can be improved when the subscribers are indirectly guided to self-optimize their location in the serving cell area. This can result in serving more user equipment (UEs) within a cell or to decrease the amount of energy needed for transmissions. Next, the coverage aspects of a LAP system are studied in order to find out the suitability of forming a temporary emergency coverage with a wireless local area network (WLAN) equipped drones. The results show that this kind of approach could provide a suitable emergency coverage for a limited area with a reasonable number of drones. Finally, a framework for MSN is studied to investigate the possibility of bringing wireless sensor network (WSN) functionalities into mobile networks. The results show that the concept of MSN could remarkably improve the resilience of mobile networks in situations where the backhaul connection is broken. However, implementing and further developing this kind of functionality will require changes in the 3rd Generation Partnership Project (3GPP) specifications and self-organizing network (SON) features within the network.Overall, this thesis provides insight on how to develop the current and future mobile networks toward more resilient infrastructures. It highlights the importance of critical communications as a fundamental part of modern societies. Thus, securing the functionality and performance of mobile networks in all situations is crucial. As a result, the contributions in this thesis can be utilized as a starting point in the future research to develop new functionalities for mobile networks. One of such approaches can be a safety mode, which would improve the mobile network resiliency during disasters and disturbance scenarios

Maintaining Mobile Network Coverage Availability in Disturbance Scenarios

Disturbance and disaster scenarios prevent the normal utilization of mobile networks. The aim of this study is to maintain the availability of cellular networks in disturbance scenarios. In order to extend the disaster time functionality, energy usage optimization is needed to maintain reasonable coverage and capacity. Simulations performed with different network layouts show the effects of choosing only a portion of evolved node B (eNB) macrosites to operate at a time. Different sets of three to nine three-sectored eNB sites are selected to study how the network would perform with a limited number of eNB sites. Simulation results show how the mobile network availability duration can be sustained by selecting a set of eNB sites to operate at a time and still maintain a reasonable service level and availability in disturbance scenarios. An increase of 100% to 500% can be achieved in the duration of “backup coverage” in cellular networks with backup batteries when the percentage of active eNB sites is reduced down to 20%.publishedVersionPeer reviewe

Mobile Network Service Demand in case of Electricity Network Disturbance Situation

acceptedVersionPeer reviewe

User Guided Energy and Capacity Optimization in UMTS Mobile Networks

acceptedVersionPeer reviewe

Arguments of Innovative Antenna Design and Centralized Macro Sites for 5G

The evolution of mobile networks has been extremely fast during the last decade. However, the advancements in the technological ways of improving the system capacity are not enough for the data revolution we have witnessed in the last couple of years, and for the data traffic forecast made by the professionals for the next decade. Several recent technological enhancements may double the network capacity, or may even increase the system capacity 5–10 times, but still it is far away from the expected “need for a thousandfold more capacity”. The fifth Generation (5G) of mobile networks with a slogan of thousandfold more capacity has compelled the research community to think in an “Innovative Way” and to think “Outside the box”. The aim of this article is first to show the limitations of recent technology solutions for the future demands, and thus to highlight the need for more innovative breakthrough solutions. The excellence of centralized macro sites is argued as a principal capacity layer instead of micro cells, small cells, or femto cells. Moreover, it is also argued that an ultimate need for innovative antenna solutions for macro sites is required instead of traditional antenna array technologies.acceptedVersionPeer reviewe

Applicability of macro sensor network in disaster scenarios

acceptedVersionPeer reviewe