Heterogeneous Networks

In 2020, mobile access networks will experience significant challenges as compared to the situation of today. Traffic volumes are expected to increase 1000 times, and the number of connected devices will be 10-100 times higher than today in a networked society with unconstrained access to information and sharing of data available anywhere and anytime to anyone and anything. One of the big challenges is to provide this 1000-fold capacity increase to billions of devices in an affordable and sustainable way. Low energy consumption is the key to achieve this. This paper takes as starting point the situation of today, and tries to pinpoint important focus areas and potential solutions when designing an energy efficient 5G mobile network architecture. These include system architecture, where a logical separation of data and control planes is seen as a promising solution; network deployment, where (heterogeneous) ultra dense layouts will have a positive effect; radio transmission, where the introduction of massive antenna configurations is identified as an important enabler; and, finally, backhauling solutions that need to be more energy efficient than today.

Wireless access networks today consume 0.5 percent of the global energy. Rapidly growing demand for capacity will further increase the energy consumption. Thus, improving energy efficiency has a great importance not only for environmental awareness but also to lower the operational cost of network operators. However, current networks which are optimized based
on non-energy related objectives introduce challenges towards green wireless access networks. In this thesis we investigate the solutions at the deployment level and handle energy efficiency assessment issues in wireless access networks.

The precise characterization of the power consumption of the whole network has a crucial importance in order to obtain consistent conclusions from any proposed solution at the network level. For this purpose, we propose a novel power consumption model  considering  the impact of backhaul for two established
technologies, i.e., fiber and microwave, which is often ignored in the literature. We show that there is a tradeoff between the power saved by using low power base stations and the excess power that has to be spent for backhauling their traffic which therefore needs to carefully be included into energy efficiency analysis. Furthermore, among the solutions that are analyzed, fiber-based backhaul solution is identified to outperform microwave regardless of the considered topology. The proposed model is then used to gain a general insight regarding the important design parameters and their possible impact on energy- and cost oriented network design. To this end, we present a  high-level framework to see the main tradeoffs between energy, infrastructure cost, spectrum and show that future high-capacity systems are increasingly limited by infrastructure and energy costs where spectrum has a strong positive impact on both.

We then investigate different network deployment strategies to improve the energy efficiency where we focus on the impact of various base station types, cell size, power consumption parameters and the capacity demand. We propose a refined power consumption model where the parameters are determined in accordance with cell size. We show that network densification can only be justified when capacity expansion is anticipated and over-provisioning of the network is not plausible for greener network. The improvement through heterogeneous networks is indicated to be highly related to the traffic demand where up to 30\% improvement is feasible for high area throughput targets.

Furthermore, we consider the problem of energy efficiency assessment at the network level in order to allow operators to know their current status and quantify the potential energy savings of different solutions to establish future strategies. We propose elaborate metric forms that can characterize the efficiency and a methodology that indicate how to perform a reliable and accurate measurement considering the complexity of wireless networks. We show the weakness of the current metrics reporting the "effectiveness" and how these might indicate disputable improvement directions unless they are properly revised. This illustrates the need for a standardized network level energy efficiency evaluation methodology towards green wireless access.

The integration of the heterogeneous network may increase the performance of the network.  Thanks
to  the  superposition  of  the  various  cellular  layers  the  heterogeneous  network  offers  more
performance to each user.  It increases the capacity of the network and by the same occasion the
traffic forwarding in the network.  In this fact,  the capacity of the mobile backhaul network must
also grow with the flow of the heterogeneous cells to guarantee the routing of the data.

Wireless access networks today consume 0.5 percent of the global energy. Rapidly growing demand for new services and ubiqutious connectivity, will further increase the energy consumption. This situation imposes a big challenge for mobile operators not only due to soaring cost of energy, but also increasing concern for global warming and sustainable development.

This thesis focuses on the energy efficiency issue at the system level and studies how to incorporate energy-awareness into the design of future wireless access networks. The main contributions have been given in the areas of energy efficiency assessment, architectural and operational solutions, and total cost of investment analysis.

The precise evaluation of energy efficiency is the first essential step to determine optimized solutions where  metrics and models constitute the two key elements.
We show that maximizing energy efficiency is not always equivalent to minimizing energy consumption which is one of the main reasons behind the presented contradictory and disputable conclusions in the literature. Further we indicate that in order to avoid the debatable directions, energy efficient network design problems should be formulated with well defined coverage and capacity requirements. Moreover, we propose novel backhaul power consumption models considering various technology and architectural options relevant for urban and rural environments and show that backhaul will potentially become a bottleneck in future ultra-high capacity wireless access networks.


Second, we focus on clean-slate network deployment solutions satisfying different quality of service requirements in a more energy efficient manner. We identify that the ratio between idle- and transmit power dependent power consumption of a base station as well as the network capacity requirement are the two key parameters that affect the energy-optimum design.
While results show that macro cellular systems are the most energy efficient solution for moderate average traffic density, Hetnet solutions prevail homogeneous deployment due to their ability to increase the capacity with a relatively lower energy consumption and thus enable significant energy savings in medium and high capacity demand regions.
%Considering the fact that orders of magnitude of more mobile data traffic will be generated at indoors in the near future, \emph{blasting the signals over the walls} is neither energy efficient nor feasible to satisfy the growing capacity demand.
Moreover, we investigate the energy saving potential of short-term energy aware management approach, i.e., cell DTX, taking advantage of low resource utilization in the current networks arising from strict QoS requirements. With the help of developed novel quantitative method, we show that Cell DTX  brings striking reduction in energy consumption and further savings are achievable if the networks are designed taking into account the fact that network deployment and operation are closely related.

Finally, we develop a general framework for investigating the main cost elements and for evaluating the viability of energy efficient solutions.
We first reveal the strong positive impact of spectrum on both energy and infrastructure cost and further indicate that applying sustainable solutions might also bring total cost reduction, but the viability highly depends on unit cost values as well as the indirect cost benefits of energy efficiency.

Results obtained in this dissertation might provide guidelines for the network designers to achieve future high-capacity and sustainable wireless access networks.

Machine to Machine communication or M2M, refers to a model of communication where devices communicate directly with each other using the available wired or wireless channels. M2M is a new concept proposed under 3GPP(3 rd Generation Partnership Project); several research are working on providing solutions for M2M communication for the 5G networks. Challenges associated with M2M communication are the lack of standards, security, poor infrastructure, interoperability and diverse architecture. In this paper, we propose a new mechanism called TM2M5G (The Machine to Machine for 5G) based on SOFTNET platform which results in support of 5G heterogeneous network. In this paper, we propose the architecture for M2M communication based on SOFTNET and provide new features support like security algorithms for data transmission among devices and scheduling algorithm for seamless transmission of data packets over the network. Finallysimulation results ofthis algorithm based on a system level simulator, considering two different approaches for analyzing the parameters such as delay, throughput and bandwidth are presented.

Information and Communication Technology (ICT) is being provided to the variety of end-users demands, thereby providing a better and improved management of services is crucial. Therefore, Service Level Agreements (SLAs) are essential and play a key role to manage the provided services among the network entities. This survey identifies the state of the art covering concepts, approaches and open problems of the SLAs establishment, deployment and management. This paper is organised in a way that the reader can access a variety of proposed SLA methods and models addressed and provides an overview of the SLA actors and elements. It also describes SLAs' characteristics and objectives. SLAs' existing methodologies are explained and categorised followed by the Service Quality Categories (SQD) and Quality-Based Service Descriptions (QSD). SLA modelling and architectures are discussed, and open research problems and future research directions are introduced. The establishment of a reliable, safe and QoE-aware computer networking needs a group of services that goes beyond pure networking services. Therefore, within the paper this broader set of services are taken into consideration and for each Service Level Objective (SLO) the related services domains will be indicated. The purpose of this survey is to identify existing research gaps in utilising SLA elements to develop a generic methodology, considering all quality parameters beyond the Quality of Service (QoS) and what must or can be taken into account to define, establish and deploy an SLA. This study is still an active research on how to specify and develop an SLA to achieve the win-win agreements among all actors.

In a ‘knowledge-based society’ (Machlup, 1962), we expect the U.S. counterterrorism response to rely on evidence-based research. Yet, numerous evaluations of terrorism studies literature conducted in the 1980s, 1990s, and early 2000s demonstrate that a majority of studies on terrorism are not evidence-based. To address this issue, the aim of this dissertation is to: (1) assess the main trends in the field of terrorism research from 1992-2013 and to characterize the evolution of the knowledge base over the last decade; (2) determine the descriptive and structural characteristics of the terrorism studies knowledge production system that correlate with evidence-based policy research in the knowledge base; (3)  empirically evaluate a scientific network of authors collaborating over books, comparing it with a network of authors collaborating over journal articles in terms of collaboration patterns, heterogeneity, organizational diversity, and research type.

Drawing on models of knowledge production and social network analysis, a list of propositions is developed and examined in regard to a terrorism research knowledge base consisting of 5,121 publications on terrorism between 1992 and 2013 by the means of regression analysis and social network analysis. Next, a modified list of propositions is examined in regard to a scientific collaboration network of a purposeful sample of the 19 contributing authors in the field of terrorism, identified through their terrorism research publications count as well as a scientific collaboration network of authors whose books on terrorism receive over 900 citations in Google Scholar. The findings indicate that as the terrorism studies field matures the network of authors becomes more connected, less fragmented and more heterogeneous. Further, inviting researchers from different countries to contribute their research and engaging authors and organizations in scientific collaboration has a positive effect on increasing the proportion of evidence-based studies in a knowledge base. While the state of terrorism research has undergone a profound transformation since the September 11, 2001 attacks on the U.S. with a greater proportion of studies in the knowledge base becoming evidence-based, to reach the normative standard, the terrorism studies knowledge base needs to become more heterogeneous in terms of contributing countries.

This paper presents a priority approach for censorious real-time traffic which flows particularly for low data rate wireless sensor and actor network (LR-WSAN). In the recent years, the demand for low rate wireless data transmission has been increased drastically in small scale industrial and non-industrial applications. The different traffic flows are increased by incorporating a variety of distinct sensing devices. In particular, injection of different traffic into network makes the communication system unstable and unreliable because of unnecessarily resource utilization, wasting energy for surplus delivery management and violation of time constraints. This paper aims to presents the new priority-based algorithm at actuator node for appropriate classification and categorization of data packets for delay sensitive and delay-tolerant applications. A novel real-time priority-based scheduler (RTPS) is proposed to handle heterogeneous data flows simultaneously according to their transmission type. The priority-based data delivery is an essential research topic for low rate multi-event IEEE 802.15.4 sensor networks. A priority metric is designed to dynamically control various types of traffic based flows with considerations of packet type, delay, and buffer processing rate. TestBed results describe significant improvements in data reporting mechanism for delay sensitive and delay-tolerant applications over various topologies. The high priority transient traffic suffers less delay and presents effective packet delivery ratio compared with traditional approaches.

A vast majority of current wireless cellular networks are deployed using the homogeneous deployment scenario. The homogeneous cellular system is essentially a network base stations and user terminals with standards power level profiles and similar technical characteristics. All base stations in the network are similar and carefully planned for compatibility. This deployment scenario is complex, rigid, and expensive. Hence the need for a more flexible, cost-effective and ubiquitous deployment model capable of broadband delivery. This need informed the advent of heterogeneous networks, which allow for the deployment of non-homogeneous base stations, with the attendant advantage of improved spectral efficiency per unit area. One of the most important features of next generation networks is the roaming possibility of end user equipments across different access networks. The Session Initiation Protocol (SIP) makes this experience achievable, it also describes other different mobility management solutions and compares the suitability of SIP for roaming across General Packet Radio Service (GPRS), Universal Mobile Telecommunication System (UMTS) and wireless Local Area Networks (WLAN). We present in this paper an overview of the various wireless networking implementations vis-à-vis interworking architectures. The paper also discusses the three generic interworking architectures for WLAN 802.11 and 3GPP networks among others.

Cellular mobile networks have evolved from offering a basic mobile
telephony service to supporting high speed mobile broadband multi-media communications. But, can they continue to advance in order to
cope with the ever increasing demands being placed on network
capacity? This paper explores the concept of small cells within a heterogeneous network and how such an implementation can significantly increase area capacity density.

6th  International  Conference  on  Networks  and  Communications  (NET  2022)  looks  for
significant  contributions  to  the  Computer  Networks,  Communications,  wireless  and  mobile
computing  for  wired  and  wireless  networks  in  theoretical  and  practical  aspects.  Original
papers  are  invited  on  computer  Networks,  network  protocols  and  wireless  networks,  Data
communication Technologies, network security and mobile computing.

When setting up technical measures to protect sensitive communication flows, one factor is generally underestimated: indirect costs of protection versus addressed risk. Direct costs include money spent for the acquisition, installation and management of the systems. Indirect costs are costs resulting from unexpected unwanted consequences, such as downgraded communication reliability that may lead to loss of productivity or even loss of market shares due to damages to an organization’s image.
Enabling communications between trusted and untrusted networks has become a must in our connected world. Many new applications, data types, like encapsulation, are becoming availa-ble every week. New network protocols and transport methods are also created. And they al-most all come with new vulnerabilities, as the threats discovered every day show very clearly.
Not so long ago, a packet filtering firewall was enough to isolate any “protected” network. While control of network transport layers is not anymore enough, specific protection is re-quired today to control specific protocols and/or applications, or simply to respond to particu-lar threats.
When a service located in an internal and controlled part of a corporate network (called a “Trusted network”), needs to be reachable from un-trusted networks, like Internet, organization-al, technical and architectural measures have to be taken to allow a right balance between iso-lation of and connectivity to systems. These measures are selected to address specific avail-ability, integrity and confidentiality requirements of the published applications.
As the perfect solution doesn’t exist, those protection measures induce various side effects, that may affects the reliability of communication flows – ranging from the well-known  delays in transmission to data losses and the like, when not cumulating them. Finding the right bal-ance between a good protection and a limited impact on communication proves to be a chal-lenging effort.
As protection systems are often the first visible part in the communication flow, they are fre-quently pointed as the root cause of communication issues between a client and a server, even before any investigation is started.

This paper presents theoretical and numerical analysis of interference and throughput for Long Term Evolution Advanced (LTE-A) outdoor small cells using a detailed simulation. In the simulation program, the downlink from base station to mobile user was studied and results are shown

"Energy efficiency in mobile radio networks has recently gained great interest due to escalating energy cost and environmental concerns. Rapidly growing demand for capacity will require denser and denser networks which further increase the energy consumption. In this regard, the deployment of small cells under macro-cellular umbrella coverage appears a promising solution to cope with the explosive demand in an energy efficient manner. In this paper, we investigate the impact of joint macro-and femtocell deployment on energy efficiency of wireless access networks, based on varying area throughput requirements. We take into account the the co-channel interference, fraction of indoor users, femto base station density and backhaul power consumption. It is shown that utilizing indoor base stations provide significant energy savings compared to traditional macro only network in urban areas with medium and high user demand where the gain increases up to 75 percent as more data traffic.
is offloaded to femtocells"

A heterogeneous network (HetNet), typically a combination of macrocells and small cells, is a popular solution for Long Term Evolution (LTE) based 4G or 5G technologies as it can provide ubiquitous and cost-effective broadband user experience with higher network capacity. However, the interference issues are more complicated in LTE HetNets. The mobile and unknown locations of the User Equipment (UEs) add further difficulties to interference management in uplink spectrum where this uplink spectrum is a separate range from downlink for LTE FDD and the same range but on specific time slots for LTE TDD. Since the major source of this interference is the high power transmission from UEs, located in neighboring cells but far away from their serving eNodeBs, limiting this power can be greatly helpful. To mitigate interference in uplink spectrum by reducing power transmission from those UEs, a scheme is proposed in this paper for HetNets. The proposed scheme shifts the handover boundary from its conventional location for UEs, performing data transfer only in uplink. It can additionally help increase the battery life for these UEs and also, it limits a drop in uplink data rate due to clipping off power transmission level by the UE capability. Simulation has been performed to demonstrate the reduction in uplink power transmission in the proposed scheme.

The development and deployment of several wireless
and cellular networks mean that users will demand to be always
connected as they move around. Mobile nodes will therefore have
several interfaces and connections will be seamlessly switched
among available networks using vertical handover techniques.
Proactive handover mechanisms can be combined with the
deployment of a number of location-based systems that provide
location information to a very high degree of accuracy in different
contexts. Furthermore, this new environment will also allow
contextual information such as user profiles as well as the
availability of local services to be combined to provide optimal
communications for mobile users. The goal of this paper is
therefore to explore the development of a comprehensive framework
for achieving optimal communication in heterogeneous
wireless environments using location and contextual information
to provide efficient handover mechanisms. Using location-based
techniques, it is possible to demonstrate that the Time Before
Handover as well as the Network Dwell Time can be accurately
estimated. These techniques are dependent on accurately estimating
the handover radius. This paper investigates how location and
context awareness can be used to estimate the best handover
radius. The paper also explores how such techniques may be
integrated into the Y-Comm architecture which is being used to
explore the development of future mobile networks. Finally, the
paper highlights the use of ontological techniques as a mechanism
for specifying and prototyping such systems.

Machine to Machine communication or M2M, refers to a model of communication where devices
communicate directly with each other using the available wired or wireless channels. M2M is a new
concept proposed under 3GPP(3rd Generation Partnership Project); several research are working on
providing solutions for M2M communication for the 5G networks. Challenges associated with M2M
communication are the lack of standards, security, poor infrastructure, interoperability and diverse
architecture. In this paper, we propose a new mechanism called TM2M5G (The Machine to Machine for
5G) based on SOFTNET platform which results in support of 5G heterogeneous network. In this paper, we
propose the architecture for M2M communication based on SOFTNET and provide new features support
like security algorithms for data transmission among devices and scheduling algorithm for seamless
transmission of data packets over the network. Finallysimulation results ofthis algorithm based on a system
level simulator, considering two different approaches for analyzing the parameters such as delay,
throughput and bandwidth are presented

Abstract—Device-to-Device (D2D) communications, which al-
low direct communication among mobile devices, have been
proposed as an enabler of local services in 3GPP LTE-Advance
(LTE-A) cellular networks. This work investigates a hierarchical
LTE-A network framework consisting of multiple D2D operators
at the upper layer and a group of devices at the lower layer.
We propose a cooperative model that allows the operators to
improve their utility in terms of revenue by sharing their devices, and the devices to improve their payoff in terms of end-to-end throughput by collaboratively performing multi-path routing. To help understanding the interaction among operators and devices, we present a game-theoretic framework to model the cooperation behavior, and further, we propose a layered coalitional game (LCG) to address the decision making problems among them. Specifically, the cooperation of operators is modeled as an overlapping coalition formation game (CFG) in a partition form, in which operators should form a stable coalitional structure. Moreover, the cooperation of devices is modeled as a coalitional graphical game (CGG), in which devices establish links among each other to form a stable network structure for multi-path routing. We adopt the extended recursive core, and Nash network, as the stability concept for the proposed CFG and CGG, respectively. Numerical results demonstrate that the proposed LCG yields notable gains compared to both the non-cooperative case and a LCG variant and achieves good convergence speed.

The continuous innovations and advances in both high-end mobile devices and wireless communication technologies have increased the users demand and expectations for anywhere, anytime, any device high quality multimedia applications provisioning. Moreover, the heterogeneity of the wireless network environment offers the possibility to the mobile user to select between several available radio access network technologies. However, selecting the network that enables the best user perceived video quality is not trivial given that in general the network characteristics vary widely not only in time but also depending on the user location within each network. In this context, this paper proposes a user location-aware reputation-based network selection solution which aims at improving the video delivery in a heterogeneous wireless network environment by selecting the best value network. Network performance is regularly monitored and evaluated by the currently connected users in different areas of each individual network. Based on the existing network performance-related information and mobile user location and speed, the network that offers the best support for video delivery along the user’s path is selected as the target network and the handover is triggered. The simulation results show that the proposed solution improves the video delivery quality in comparison with the case when a classic network selection mechanism was employed.

This paper deals with the planning of two-layer long-term evolution-advanced cellular systems, taking both the co-tier and cross-tier interference into account. In particular, we propose the novel multi-level soft frequency reuse (MSFR) scheme, where the users in three different regions of a macro/micro cell adopt distinct frequency segments and different transmission power levels. The optimization of power control parameters and cell association with MSFR results in a non-convex problem. We present the iterative-MSFR (I-MSFR) scheme, where the main optimization problem is divided into two sub-problems that can be subsequently solved by means of classical optimization methods. Finally, we propose two simplified schemes that achieve a comparable performance as I-MSFR in terms of utility, cell capacity, and outage conditions. I-MSFR and the simplified schemes have shown better performance than other schemes in the literature. Index Terms— Long term evolution-advanced (LTE-A), soft frequency reuse, heterogeneous networks, load balancing, convex optimization.

Wireless cellular industry has hardly seen more thrilling times, capacity demands by cellular users will continue to increase due to accelerating demands of high speed data application like social networking, Machine to machine communication and high speed video streaming. In order to meet high demands of data hungry devices cellular networks are going through major infrastructure reforms. In traditional networks, capacity demands are full filled by placing planned sets of homogeneous high power macro Base Stations (BS). However, addition of BS is not always feasible due to high opex and capex which forces network operators to install Low Power Nodes (LPNs) to meet this capacity crunch. This infrastructure change in traditional network is known as Heterogeneous Network. This paradigm shift in basic homogeneous network brings major challenges in design and analysis of traditional cellular networks. Recognizing these demands, this research work proposes a tractable approach to key performance metrics that are used to rate the performance of state of the art Heterogeneous Cellular Networks sometimes referred as multi-tier network. Advance probability concepts and stochastic geometry are used to get some significant insights.