**1. Introduction**

Polycystic ovary syndrome (PCOS) is a common endocrinophaty disorder that affecting reproductive aged women [1]; it becomes frequently manifest during early reproductive age [2]. It is a heterogeneous disorder, with multiple reproductive, cosmetic and metabolic complexities which is characterized by dysfunction in ovulation and clinical or biochemical hyperandrogenism and the presence of polycystic ovarian morphology. It is the most common endocrine cause of infertility and increased the risk of adverse pregnancy outcome, metabolic syndrome, type 2 diabetes mellitus, and some carcinoma [2-5]. However, there is not a consensus on its definition [6]. At the first time, PCOS was described by Stein and Leventhal in 1935 [6] as the presence of bilaterally enlarged ovaries with multiple cysts in seven women with infertility, menstrual irregularity and hyperandrogenism [7]. The National Institutes of Health (NIH) in 1990 introduced NIH standard criteria in PCOS for applying in researches and clinics [3]. This definition relied on clinical or biochemical evidence of hyperandrogenae‐ mia (in the absence of adrenal hyperplasia and hyperprolactinemia and thyroid dysfunction) in combination of oligomenorrhoea or amenorrhea. Therefore, PCOS was diagnosed in the absence of an ultrasound appearance of polycystic ovaries morphology [8]. In 2003, a consen‐ sus workshop in Rotterdam in the Netherlands presented new diagnostic criteria [3]. Rotter‐ dam criteria describe PCOS as persistence of PCO and hyperandrogenism in women with normal menstrual cycles and especially women presenting with PCO and ovulatory disturb‐ ance without hyperandrogenism [9].

In 2009, the Androgen Excess and PCOS Society (AE-PCOS Society) introduced criteria for PCOS. Based on AE-PCOS Society criteria, PCOS should be define by the presence of hyper‐ androgenism (clinical and /or biochemical), ovarian dysfunction (ovulation disturbance and or polycystic ovary morphology), and the exclusion of other androgen excess or related

© 2015 The Author(s). Licensee InTech. This chapter is distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/3.0), which permits unrestricted use, distribution, and eproduction in any medium, provided the original work is properly cited.

disorders [10]. These criteria reflected differences in defining PCOS which could affect reporting, diagnosis and treatment of it.

#### **1.1. Epidemiology**

Despite PCOS being considered the most common endocrine disorder, the estimation of its prevalence is highly variable, ranging from 2.2% to 26.7% [11-13], due to differences in the presentation of PCOS phenotype methods [12]. In a study in Iran, a total of 646 reproductiveage women were assessed by Rotterdam, Androgen Excess Society, and NIH criteria, the prevalence of PCOS were 14.1%, 12%, and 4.8% respectively [14]. In a study from china, levels of luteinizing hormone and higher luteinizing hormone/follicle-stimulating hormone ratios were used for defining PCOS for 915 women in reproductive age, the results demonstrated 2.2 % prevalence [14]. In a study from china, levels of luteinizing hormone and higher luteinizing hormone/follicle-stimulating hormone ratios were used for defining PCOS for 915 women in reproductive age, the results demonstrated 2.2 % prevalence [11]. The prevalence based on NIH criteria in an unselected population black and white women in the southeastern United States were 3.4% and 4.7% respectively [15]. Using same criteria, the prevalence of PCOS was almost 6.5% between Caucasian and Greek women [16, 17].


*2.2. Nanocomposite Films and Thermoplastic Composites Fabrication*

The nanocomposite films (MWCNT/PP) were manufactured with a heated laboratory press (Dake, Grand Haven, MI, USA). During compression molding, PTFE (polytetrafluoroethylene)-coated fiberglass release films and steel shims were placed between the heated platens to produce a consistent surface finish and to control the films' final thickness. Based on previous work on the effect of ED thickness on USW of TPCs [10,16,46], shims with thicknesses equal to 0.06 mm, 0.25 mm and 0.50 mm were selected. The molded nanocomposite films were cut into rectangular specimens and stored in sealed bags. For thermo-electrical characterization, the films dimensions were 50 mm × 15 mm, while they were 30 mm × 25 mm for ultrasonic welding.

GF/PP substrates were manufactured by compression molding with a laboratory press (Dake, Grand Haven, MI, USA). Eight unidirectional prepreg layers, measuring 254 mm × 254 mm, were stacked in a [0]8 sequence between steel plates, then placed between the press' heated platens. The laminate was consolidated under 1 MPa at 180 ◦C for approximately 15 min. During compression molding, a thermocouple was placed at one edge of the laminate to monitor the temperature between the plies. After demolding, a laminate with a final thickness between 1.8 mm and 1.9 mm was obtained. Prior to welding, the laminate was cut into rectangular specimens (101.6 mm × 25.4 mm) with a water-cooled diamond saw (PICO 155 from Pace Technologies). The longer side was cut along the direction of the glass fibers.


**Abstract**

The deployment of 4G/LTE (Long Term Evolution) mobile network has solved the major challenge of high capacities, to build real broadband mobile Internet. This was possible mainly through very strong physical layer and flexible network architecture. However, the bandwidth hungry services have been developed in unprecedented way, such as virtual reality (VR), augmented reality (AR), etc. Furthermore, mobile networks are facing other new services with extremely demand of higher reliability and almost zero-latency performance, like vehicle communications or Internet-of-Vehicles (IoV). Using new radio interface based on massive MIMO, 5G has overcame some of these challenges. In addition, the adoption of software defend networks (SDN) and network function virtualization (NFV) has added a higher degree of flexibility allowing the operators to support very demanding services from different vertical markets. However, network operators are forced to consider a higher level of intelligence in their networks, in order to deeply and accurately learn the operating environment and users behaviors and needs. It is also important to forecast their evolution to build a pro-actively and efficiently (self-) updatable network. In this chapter, we describe the role of artificial intelligence and machine learning in 5G and beyond, to build cost-effective and adaptable performing next generation mobile network. Some practical use cases of AI/ML in network life cycle are discussed.

**Keywords:** Next Generation mobile Networks, 5G, Artificial Intelligence, Machine Learning, Deep Learning, Physical Layer, Big Data, Network Control

### **1. Introduction**

The massive deployment of LTE (Long Term Evolution) or 4G mobile network has solved one of the major challenges of wireless communications, which is high capacities, to build real broadband mobile Internet. This was possible mainly through very strong physical layer, based on orthogonal frequency division multiplexing (OFDM) and multiple input multiple output (MIMO) among others, and flexible network architecture. However, new bandwidth-hungry services have been developed in unprecedented way, reaching capacities up to 1 Gbps, such as virtual reality (VR), augmented reality (AR), etc. Furthermore, mobile networks are facing other new services with extremely demand of higher reliability and

almost zero-latency performance, like vehicle communications or Internet-of-Vehicles (IoV).

The 5G systems solved the major problems related to the capacity through use of new radio interface, massive MIMO, beamforming, high modulation orders, etc. Furthermore, 5G is planned to include a high level of flexibility to optimize the network utilization by integrating software defined networking (SDN) and network function virtualization (NFV) technologies. This should allow the network operators to support current and new more demanding future services. The main challenge is to be ready to support services for customers in completely different vertical markets/industries, like e-health, Internet-of-Vehicles (IoV), Industry 4.0, smart grids, etc. Furthermore, the network operators have to establish more partnerships on multiple layers for sharing of the 5G infrastructure through network sharing relationship among different mobile operators, delivery of Infrastructure as a Service, Platform as a Service or Network as a Service by assets providers. Facilitating such partnerships may act as catalyst for the deployment of 5G networks, considering the large investments for mobile network operators (MNOs) in capital expenditure CAPEX and operational expenditure OPEX are still not being followed by significant revenue increase, [1]. Network operators are also forced to consider a higher level of intelligence in their networks, in order to deeply and accurately learn the operating environment and users behaviors and needs. The adoption of Artificial Intelligence (AI), and Machine Learning (ML) approaches as core part of AI, is crucial to forecast the evolution of the environment and users/ services behavior/demand to build a pro-actively and efficiently (self-) optimizing and (self-) updating networks. This is true for each layer of the system and each level of the network. For example, AI/ML are crucial for massive MIMO to identify dynamic change and forecast the user distribution by analyzing historical data, dynamically optimize the weights of antenna elements using the historical data or to improve the coverage in a multi-cell scenario considering the inter-site interference between multiple 5G massive MIMO cell sites, etc.

In this chapter, we describe the role and the integration method of AI and different ML approaches as core part of AI in the next generation mobile networks. The rest of the chapter is built by giving a short overview on AI and ML definitions, historic and (sub-) classes in second section. The third section shows the role of big data as prerequisite for a full exploitation of AI/ML advantages. The components of 5G are described in fourth section and how to make AI/ML a main component of next generation mobile networks. Practical use cases are illustrated and discussed in fifth section.

#### **2. AI and ML in mobile communications networks**

#### **2.1 Overview on AI and ML**

#### *2.1.1 What is AI?*

AI is the scientific field that deals with programming machines to mimic human behavior in solving tasks that humans are good at (natural language, speech, image recognition, etc.). AI involves the intersection of many fields of computer science and applied mathematics. The position of artificial intelligence is rather to consider that we, as human beings, have an intuitive understanding of what intelligence is and therefore we can judge whether a machine is intelligent or not. This operational definition of AI was promoted by Alan Turing in 1950, who introduced his famous "Turing test". The Turing test is an operational test; according to which a machine

**49**

**Figure 1.**

*Artificial Intelligence and Machine Learning in 5G and beyond: A Survey and Perspectives*

is considered intelligent if it can converse in such a way that (human) interrogators

Initial efforts at AI involved modeling the biological neurons in the brain. In 1943 McCulloch and Pitts [3] modeled for the first time the artificial neural as a binary variable that is switched to either on or off. Later in 1949, Donald Hebb developed an algorithm for learning neural networks. In 1951, Marvin Minsky and Dean Edmonds built the Stochastic Neural Analog Reinforcement Calculator (SNARC), the first neural network computer. Following this accomplishment, a small group of scientists interested in the study of intelligence met in a 2-month workshop at Dartmouth University in 1956. According to common belief, the term AI was first introduced and defined by John McCarthy at this workshop, as:" AI involves machines that can perform tasks that are characteristic of human

Over the last few decades, AI has gained increasing interest among researchers and industry. This is due to the wide variety of applications in which AI has been used, such for example, natural language processing (e.g. broadcast news transcription, speech-to-speech translation), healthcare (e.g. assisting in surgeries, computer aided diagnosis), smart cars and drones (e.g. self-driving cars, obstacle detection) and also mobile networks (e.g. performance optimization, traffic prediction).

Today AI is a collection of different technologies working together to enable machines to sense, comprehend, act, and learn with human-like levels of intelligence. Rule-based techniques as well as expert system are the first approaches to AI. Technologies such as ML, Deep Learning, and Big Data are all part of the AI landscape, as illustrated in **Figure 1**. As the most recent advances in AI have been in the field of machine learning, people often mistakenly conflate AI with ML. Eventually, the field of MML was created from the desire to design AI with the ability to learn

ML is a subset of AI, which aims to give the ability for a computer to perform tasks without being given explicit instructions on how to solve it. It is a paradigm that aims to build a computer that can learn, just like humans do. The learning

*Connection and overlap between machine learning, deep learning, and artificial intelligence.*

*2.1.2 The connection between machine learning, deep learning and AI*

*DOI: http://dx.doi.org/10.5772/intechopen.98517*

intelligence".

and acquire knowledge.

cannot distinguish it from a human being [2].

*Artificial Intelligence and Machine Learning in 5G and beyond: A Survey and Perspectives DOI: http://dx.doi.org/10.5772/intechopen.98517*

is considered intelligent if it can converse in such a way that (human) interrogators cannot distinguish it from a human being [2].

Initial efforts at AI involved modeling the biological neurons in the brain. In 1943 McCulloch and Pitts [3] modeled for the first time the artificial neural as a binary variable that is switched to either on or off. Later in 1949, Donald Hebb developed an algorithm for learning neural networks. In 1951, Marvin Minsky and Dean Edmonds built the Stochastic Neural Analog Reinforcement Calculator (SNARC), the first neural network computer. Following this accomplishment, a small group of scientists interested in the study of intelligence met in a 2-month workshop at Dartmouth University in 1956. According to common belief, the term AI was first introduced and defined by John McCarthy at this workshop, as:" AI involves machines that can perform tasks that are characteristic of human intelligence".

Over the last few decades, AI has gained increasing interest among researchers and industry. This is due to the wide variety of applications in which AI has been used, such for example, natural language processing (e.g. broadcast news transcription, speech-to-speech translation), healthcare (e.g. assisting in surgeries, computer aided diagnosis), smart cars and drones (e.g. self-driving cars, obstacle detection) and also mobile networks (e.g. performance optimization, traffic prediction).

#### *2.1.2 The connection between machine learning, deep learning and AI*

Today AI is a collection of different technologies working together to enable machines to sense, comprehend, act, and learn with human-like levels of intelligence. Rule-based techniques as well as expert system are the first approaches to AI. Technologies such as ML, Deep Learning, and Big Data are all part of the AI landscape, as illustrated in **Figure 1**. As the most recent advances in AI have been in the field of machine learning, people often mistakenly conflate AI with ML. Eventually, the field of MML was created from the desire to design AI with the ability to learn and acquire knowledge.

ML is a subset of AI, which aims to give the ability for a computer to perform tasks without being given explicit instructions on how to solve it. It is a paradigm that aims to build a computer that can learn, just like humans do. The learning

**Figure 1.**

*Connection and overlap between machine learning, deep learning, and artificial intelligence.*

process consist of providing a ML algorithm with examples of the task we want to solve (data), and letting the computer finding patterns and making inferences that optimizes the decision making according to a user-defined objective. In general, ML could be used to accomplish different type of tasks including classification, clustering and making predictions about data.

Artificial Neural Networks (ANN), referred also as Neural Networks (NN), are a popular machine learning models inspired by the biological processes of the brain. The first NN algorithm is the Perceptron developed by Rosenblatt in 1958; [4]. This finding was inspired by McCulloch mathematical models of neurons in the human brain [3]. In the following decades, different types and architectures of neural networks have been proposed as well as algorithms to train them effectively. Following these accomplishments, the term Deep Learning was introduced to the ML community. Around the year 2000, Deep Learning is a subcategory of ML focused on parameterizing multilayer (deep) neural networks that can learn representations of the data.

In recent years, deep learning based methods has gained increasing interest. This is due to their high performances in image classification [5], speech recognition [6] and natural language processing tasks [7]. In fact, deep learning techniques have largely outperformed stat-of-the-arts results in these tasks. However, deep learning, and indeed most of ML techniques, have several limitations. The first limitation is the amount of data required during training in order to achieve human like performances. Another limitation is the computational capacities required to train deep learning based models on large datasets.

#### *2.1.3 The categories of machine learning*

As pointed out in the previous paragraphs, ML is a complex landscape. Based on the training strategy, ML can be divided into three classical categories; which different learning approaches are illustrated in **Figure 2**:

**Supervised Learning**: Learning with a labeled training set. This category includes Classification and Regression tasks.

**Unsupervised Learning**: The process of training a model using training data that is unlabeled. The model had to discover patterns in unlabeled data. The widely used task in unsupervised learning is Clustering.

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**Figure 3.**

complexity.

*Artificial Intelligence and Machine Learning in 5G and beyond: A Survey and Perspectives*

**Reinforcement Learning**: The process of training a model on a series of actions that lead to a particular outcome, where the system receives rewards for performing well and punishments for performing poorly directly from its environment.

As one of the worldwide leading mobile systems manufacturers, Ericsson has led a study to analyze the state-of-the-art and the expectation of adopting AI by the mobile network operators and global service providers. The study found that operators have mainly adopted AI as means to enable them to switch to 5G and to guarantee optimized investment; [8]. Furthermore, already with 4G/4.5G there has been an increased complexity in the management of a vast number of devices and huge amount of data. Operators are hoping that AI and ML will help to reduce this

• AI is already being incorporated into networks, with a primary focus on reducing capital expenditure, optimizing network performance and building new revenue streams. Operators from all over the world are already reaping the benefits of integrating AI into their networks. More than half of service providers (53 percent) expect to have fully integrated some aspects of AI into

• AI will be vital for improving customer service and enhancing customer experience, generally referred as "Quality of Experience (QoE)" to. AI is expected to help providers further improve customer experience in many ways, includ-

• AI will help recoup the investments communications service providers (CSPs) are making in their networks to switch to 5G. Lowering operational costs and ensuring returns on network investments are key priorities that service providers are looking to achieve using Artificial Intelligence. **Figure 3** shows the prioritized domains for the integration of AI to optimize the costs as well as the management of the always-increasing network complexity. Network intelligence and automation are crucial to the evolution of 5G, IoT and industrial digitalization. As 5G-enabled technologies develop; operators will need to increase their network capacity. However, the added capacity brings additional

ing improving network quality and providing personalized services.

*DOI: http://dx.doi.org/10.5772/intechopen.98517*

Reinforcement Learning is used in robotics and games.

**2.2 Introducing AI and ML in mobile communications**

*2.2.1 Needs for intelligence in mobile networks prior to 5G*

complexity. Other main findings of the study are as follows; [8]:

their networks by the end of 2020.

*Core areas with the highest potential for returns on AI investments [8].*

**Figure 2.**

*Classification of different ML approaches.*

*Artificial Intelligence and Machine Learning in 5G and beyond: A Survey and Perspectives DOI: http://dx.doi.org/10.5772/intechopen.98517*

**Reinforcement Learning**: The process of training a model on a series of actions that lead to a particular outcome, where the system receives rewards for performing well and punishments for performing poorly directly from its environment. Reinforcement Learning is used in robotics and games.

## **2.2 Introducing AI and ML in mobile communications**

## *2.2.1 Needs for intelligence in mobile networks prior to 5G*

As one of the worldwide leading mobile systems manufacturers, Ericsson has led a study to analyze the state-of-the-art and the expectation of adopting AI by the mobile network operators and global service providers. The study found that operators have mainly adopted AI as means to enable them to switch to 5G and to guarantee optimized investment; [8]. Furthermore, already with 4G/4.5G there has been an increased complexity in the management of a vast number of devices and huge amount of data. Operators are hoping that AI and ML will help to reduce this complexity. Other main findings of the study are as follows; [8]:

#### **Figure 3.**

*Core areas with the highest potential for returns on AI investments [8].*

• Adopting AI is creating new data challenges, even as it solves network complexities. Network providers agree that they need to develop effective mechanisms for collecting, structuring and analyzing the huge volumes of data that AI is capable of amassing.

## *2.2.2 Advantages of using AI in mobile networks*

The history of mobile communication is evolving from one generation to a next one over the last three decades. Nowadays, before to jump to a next generation, i.e. 5G, the mobile network operator need to understand deeply the current situations and future scenarios. The MNO needs to learn more about the real behavior of the subscribers, their profiles, the traffic patterns, wished and possibly adequate services for each profile and how all these will evolve in the future. In the communications market, whether it is network operators, equipment manufacturers or solution providers, etc., the market players hope to take advantage of AI to assist in areas that become very challenging, such as in designing, operating, maintaining and managing communication networks and services. Mainly AI will offer the MNO the ability of learning more about their network and the need of customers, ability of understanding and reasoning to make the ideal decision/actions for different scenarios and environment conditions and finally the ability to collaborate between high heterogeneous widely expanded and densified network infrastructures.

Operators need intelligent decisions to manage complex resources and dynamic traffic. However, so far no one single model has the ability to model accurately the network traffic characteristics. Fortunately, AI has entered into the cognitive age, and deep learning can be used. Through deep learning, the machine system can use the existing training data to process large amounts of data through data mining. AI can also learn the characteristics of data traffic, management, controls and other characteristics automatically and master expert experience of operating, managing and maintaining networks. By these efforts, the accuracy of analysis can be enhanced, and the intelligent management and services of communication networks can be realized. Detailed description can be found in [9].

Due to the high dynamics of the network system, the state information of a resource may have changed when it is transmitted to the network management system. Therefore, the network management can only know the local state information without the knowledge about the system internal state. ML has the strength to deal with this kind of fuzzy logic and uncertainty reasoning. In order to make the classification or prediction of the state easier, deep learning constructs a multi-hidden layer model and uses the hierarchical network structure to transform the feature representation of the sample into a new feature space layer by layer, as detailed in the first sections of the chapter. The major advantage is the fact that AI does not need to describe the mathematical model of the system accurately, and therefore has the ability to deal with uncertainty or even 'unknowability.

Due to the expansion and high densification of the network infrastructure, both in scale and size, the structure complexity of communication networks, and especially for the next generation, are increasing quickly. Concepts such as distribution and hierarchy are often talked about in the network management. Management tasks and controls are distributed to the entire network, in order to avoid centralization of the management functions that requires more data overhead and reliability issues. As a result, network operators have to deal with issues such as tasks' distribution, communication and collaboration between management nodes. The introduction of the multi-agent collaboration of distributed AI into the network management will support the ability to collaborate between network managers distributed in every layer. However, such collaboration requires a high

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*Artificial Intelligence and Machine Learning in 5G and beyond: A Survey and Perspectives*

level of interoperability between the heterogeneous networks building the entire communications infrastructure. Furthermore, this network interoperability is just of the many other factors that must be fulfilled by the environment, in order to take benefits of the above-cited advantages of AI. The other factors allowing taking full

**3. Big data as prerequisite for integrating AI in mobile networks**

network-aware data, social data and cloud data [11].

The integration of intelligent algorithms and learning approaches requires the availability of big data sets, which represent the starting point. However, because the AI and ML can be integrated at different levels of the next generation mobile work, or at least in 5G, different big data sources can be explored and must be selected carefully to be able to extract as much as possible of knowledge/learning. Different ways are proposed in the literature to classify the needed types of big data sets, which should build the basis for the AI and ML, such the ones proposed in [10–12]. For example, a classification of different big data sources is illustrated in **Figure 5**, which contains three pools of big data sets: general wireless data, social

Wireless data: This class represents the big data generated by wireless users, and which contains useful information about the activity patterns in time, frequency and space (locations). For example, this can help to infer from the data traffic/ demand variation over time, the interference power at different frequencies, and the congestion level distribution at different locations, etc. The exploitation of these spectral patterns will allow an efficient management of the wireless resources, at radio resource management/allocation (RRM/RRA) functionalities, for improving the systems spectral efficiency and for enhancing the delivered quality of service experienced by the end-user.  In such context, the network operator

One of the major enablers of a profitable AI integration is the availability of high performing and efficient computing resources. Indeed, 5G systems seek to provide high throughput and ultra-low latency communication services, to improve users QoE. Implementing deep learning to build intelligence into 5G systems, to meet these objectives is expensive. This is because powerful hardware and software is required to support training and inference in complex settings. Several tools are emerging, which make deep learning in mobile networks tangible as discussed in [10]. Authors discussed a hierarchy of advanced computing tools as deep learning integration enablers; namely: (i) advanced parallel computing, (ii) distributed ML systems, (iii) dedicated deep learning libraries, (iv) fast optimization algorithms,

*DOI: http://dx.doi.org/10.5772/intechopen.98517*

potential from AI are depicted in **Figure 4**.

*Factors contributing to a full and efficient AI integration into mobile networks.*

and (v) fog computing.

**Figure 4.**

*Artificial Intelligence and Machine Learning in 5G and beyond: A Survey and Perspectives DOI: http://dx.doi.org/10.5772/intechopen.98517*

#### **Figure 4.**

*Factors contributing to a full and efficient AI integration into mobile networks.*

level of interoperability between the heterogeneous networks building the entire communications infrastructure. Furthermore, this network interoperability is just of the many other factors that must be fulfilled by the environment, in order to take benefits of the above-cited advantages of AI. The other factors allowing taking full potential from AI are depicted in **Figure 4**.

One of the major enablers of a profitable AI integration is the availability of high performing and efficient computing resources. Indeed, 5G systems seek to provide high throughput and ultra-low latency communication services, to improve users QoE. Implementing deep learning to build intelligence into 5G systems, to meet these objectives is expensive. This is because powerful hardware and software is required to support training and inference in complex settings. Several tools are emerging, which make deep learning in mobile networks tangible as discussed in [10]. Authors discussed a hierarchy of advanced computing tools as deep learning integration enablers; namely: (i) advanced parallel computing, (ii) distributed ML systems, (iii) dedicated deep learning libraries, (iv) fast optimization algorithms, and (v) fog computing.

#### **3. Big data as prerequisite for integrating AI in mobile networks**

The integration of intelligent algorithms and learning approaches requires the availability of big data sets, which represent the starting point. However, because the AI and ML can be integrated at different levels of the next generation mobile work, or at least in 5G, different big data sources can be explored and must be selected carefully to be able to extract as much as possible of knowledge/learning. Different ways are proposed in the literature to classify the needed types of big data sets, which should build the basis for the AI and ML, such the ones proposed in [10–12]. For example, a classification of different big data sources is illustrated in **Figure 5**, which contains three pools of big data sets: general wireless data, social network-aware data, social data and cloud data [11].

Wireless data: This class represents the big data generated by wireless users, and which contains useful information about the activity patterns in time, frequency and space (locations). For example, this can help to infer from the data traffic/ demand variation over time, the interference power at different frequencies, and the congestion level distribution at different locations, etc. The exploitation of these spectral patterns will allow an efficient management of the wireless resources, at radio resource management/allocation (RRM/RRA) functionalities, for improving the systems spectral efficiency and for enhancing the delivered quality of service experienced by the end-user.  In such context, the network operator

**Figure 5.**

*Classes of big data in mobile network and their applications [11].*

can adjust the transmit power, frequency or direction, through the beamforming mechanism adopted for 5G or simply through sectorized antennas, of the different base station transmitters relaying on the mobile users distributions. In addition, the operator can dispatch mobile base stations in advance when anticipating a regional surge of data traffic, which could be caused for example by sport events, music concerts, etc. In [10], authors subdivided the mobile big data into classes: Network level-data, which is similar to "wireless data", and App-level data. It is worth to notice that network level-data are further subdivided into sub-classes, namely:

Social data: Nowadays, the main cause of the soaring data volume in the Internet is the online social networks. The penetration of the mobile Internet into our daily lives and behaviors makes convenient multimedia communications easily accessible for everyone, independently of the age or social level. The volume of social data, which represents the data exchanged on social media, has reached an unprecedented astonishing magnitude and it is expected to continue an explosive increase in the next years. On one hand, its strong ties to public events in the physical world feature social network data. So that, an important football game or political event may inspire heated online discussions that may last for day in case of games and some weeks or months in case of an elections year. On the other hand, social network data contains rich information about the context/preferences of individuals or social groups. The mobile network operator can exploit such data to build a social-network-aware wireless concept. For example, operators may offer more bandwidth in touristic sites so that users/tourists can share their tourist-experience on the social media with highly satisfying quality of service even if they have only paid pre-paid service. Example of connecting the social media big data source to a AI learning framework is illustrated in a simple way in **Figure 6**, showing the most promising expected AI applications, like mobile caching, drone-based mobile BS

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*Artificial Intelligence and Machine Learning in 5G and beyond: A Survey and Perspectives*

placement or radio resource allocation in case of adaptive non-orthogonal multiple

*Example of connecting big data source to learning framework before feeding the predicted behavior models to*

Cloud data: one of the major cause for the apparition of the data tsunami in mobile network is the transmission of the multimedia contents stored in the cloud servers. Furthermore, it was found that most contents transferred over Internet are based on its popularity. It is possible therefore to reduce the tele-traffic of the system by exploiting the users' preference for special cloud contents. For example, the most popular videos, for a specific geographic region, can pre-cached at the edge servers so that no real-time backhaul data downloading is needed for frequent request. In addition, individual user's preferences for specific multimedia contents can be used to predict the user's future content demand, based on which the

network operator can perform a pre-feeding or recommendation actions.

While the evolution toward 4G/LTE was driven by more mobile data speed, the 5G system is confronted by more stricter and diverse requirements; as summarized in **Table 1**. The deployment of 5G systems seeks to provide high throughput and ultra-low communications latencies, to improve users' quality of experience (QoE). To meet these requirements, 5G targets three evolution axes to cope with the new applications fields; such autonomous cars/driving, industrial automation/smart manufacturing (Industrie 4.0), virtual reality, e-health, etc. These axes are:

Enhanced mobile broadband (eMBB): Allows for new bandwidth-hungry applications with extreme high data rate demands over a uniform coverage area. Examples include ultra-high-definition video streaming and virtual/augmented reality (VR/AR). Massive machine-type communications (mMTC): A key characteristic of 5G communication services is the scalable connectivity demand for expanding the number of wireless devices with efficient transmission of small amounts of data over extended coverage areas. Applications like body-area networks, smart homes, IoT, and drone delivery will generate this type of traffic. mMTC must be able to support massive new uses and others uses that would appear in the future.

Ultra-reliable low-latency communications (URLLC): Connected healthcare, remote surgery, mission-critical applications, autonomous driving, unmanned aerial vehicles (UAV), vehicle-to-vehicle (V2V) communications, high-speed train

**4. AI and ML as main components for 5G**

**4.1 Main goals and components of 5G**

*DOI: http://dx.doi.org/10.5772/intechopen.98517*

access (NOMA).

*the AI applications layer [11].*

**Figure 6.**

*Artificial Intelligence and Machine Learning in 5G and beyond: A Survey and Perspectives DOI: http://dx.doi.org/10.5772/intechopen.98517*

#### **Figure 6.**

*Example of connecting big data source to learning framework before feeding the predicted behavior models to the AI applications layer [11].*

placement or radio resource allocation in case of adaptive non-orthogonal multiple access (NOMA).

Cloud data: one of the major cause for the apparition of the data tsunami in mobile network is the transmission of the multimedia contents stored in the cloud servers. Furthermore, it was found that most contents transferred over Internet are based on its popularity. It is possible therefore to reduce the tele-traffic of the system by exploiting the users' preference for special cloud contents. For example, the most popular videos, for a specific geographic region, can pre-cached at the edge servers so that no real-time backhaul data downloading is needed for frequent request. In addition, individual user's preferences for specific multimedia contents can be used to predict the user's future content demand, based on which the network operator can perform a pre-feeding or recommendation actions.

## **4. AI and ML as main components for 5G**

#### **4.1 Main goals and components of 5G**

While the evolution toward 4G/LTE was driven by more mobile data speed, the 5G system is confronted by more stricter and diverse requirements; as summarized in **Table 1**. The deployment of 5G systems seeks to provide high throughput and ultra-low communications latencies, to improve users' quality of experience (QoE). To meet these requirements, 5G targets three evolution axes to cope with the new applications fields; such autonomous cars/driving, industrial automation/smart manufacturing (Industrie 4.0), virtual reality, e-health, etc. These axes are:

Enhanced mobile broadband (eMBB): Allows for new bandwidth-hungry applications with extreme high data rate demands over a uniform coverage area. Examples include ultra-high-definition video streaming and virtual/augmented reality (VR/AR).

Massive machine-type communications (mMTC): A key characteristic of 5G communication services is the scalable connectivity demand for expanding the number of wireless devices with efficient transmission of small amounts of data over extended coverage areas. Applications like body-area networks, smart homes, IoT, and drone delivery will generate this type of traffic. mMTC must be able to support massive new uses and others uses that would appear in the future.

Ultra-reliable low-latency communications (URLLC): Connected healthcare, remote surgery, mission-critical applications, autonomous driving, unmanned aerial vehicles (UAV), vehicle-to-vehicle (V2V) communications, high-speed train

#### **Table 1.**

*Summary of major requirements for 5G mobile system [13].*

connectivity, and smart industry applications. These applications prioritize high reliability, low latency, and mobility over data rates.

To achieve the above listed objectives, 5G systems use a very large number different advanced technologies or enablers; such as new PHY layer, new MAC layer, SDN, NFV, etc. To have a structured view of these different enablers, **Figure 7** classifies them into two main categories; the system-level and network-level technologies. More details about of the listed technologies and paradigms can be found in the survey [14]. If we consider the breakthrough of the unprecedented achieved capacities, three enabling technologies can be cited, namely: massive MIMO that allows a new level of bit rates, use of millimeter-wave that finally give a hope to overcome the spectrum scarcity and network densification.

The introduction of MIMO in 4G/LTE was decisive in achieving real broadband speeds for mobile Internet. With the same philosophy, the massive MIMO is bringing the next mobile network to the next level of throughputs up to Gbps. Therefore, massive MIMO is considered as a leading candidate technology for 5G, where the high number of antennas at the base station requires large number of power amplifiers. According to [15], the primary problem with power amplifiers is known as the trade-off between linearity and efficiency: amplifiers can be designed to attain good linearity at the cost of efficiency. As the highly linear power amplifiers are

**57**

*Artificial Intelligence and Machine Learning in 5G and beyond: A Survey and Perspectives*

performance of the intended receiver and thus the entire network.

expensive and power inefficient, the excessive use number of antennas at the base station makes the use of inexpensive elements strongly targeted to keep the overall network costs, capital expenditure and operational expenditure, manageable. However, emerging energy and spectrum-efficient wideband wireless communications systems are vulnerable to non-linear distortions that are attributed to the radio frequency front-ends. For example, those types of high-power amplifier affect the

Furthermore, because the 5G systems should operate in more dynamic environments and in different bands (extending from cm-wave to mm-waves), the dynamic range requirements will likely become more demanding. Therefore, the power amplifiers need to meet stricter linearity specifications while at the same time maintaining an acceptable efficiency for the overall systems. The aimed high efficiency of power amplifiers is achievable when constantly feeding the amplifier at the limit of its high-power linear zone. However, this is not realistic for 5G base station, because this is not feasible solution for the peak-to-average power ratio. The previously cited 5G enablers have a direct contribution in the network performance; however, an operative and efficient 5G network cannot be complete without AI. For example, 5G enables simultaneous connections to multiple IoT devices, generating massive amounts of data that must be processed using ML and AI. When ML and AI are integrated within, wireless providers can, for example [16]:

• Identify dynamic change and forecast the user distribution by analyzing

• Forecast the peak traffic, resource utilization and application types; and optimize and fine tune network parameters for capacity expansion,

• Eliminate coverage holes by measuring the interference and using the inter-site

• High level of automation from the distributed ML and AI architecture at the

• Application-based traffic steering and aggregation across heterogeneous access

With the increasing advances and advantages of ML in the wireless communications, each research community has tried to evaluate the impact of ML on 5G in its discipline. As result, we have several publication for ML impact on physical layer, security aspects, radio resource managements, etc. This makes it very difficult to give short overview on the utilization and the impact of AI/ML in 5G. Therefore, we can summarize the works applying ML to 5G according to two principles: a "general ML categorization", where we consider all possible ML approaches from the literature, and a "Deep Learning-based Categorization", which focuses only the deep learning, because several leading publications consider deep learning as the most

• Dynamic network slicing to address varied use cases with different QoS

• ML/AI-as-a-service offering for end users, etc.

promising approach of ML for the high complexity of 5G.

**4.2 Machine learning/deep learning in 5G**

*DOI: http://dx.doi.org/10.5772/intechopen.98517*

historical data,

network edge,

requirements,

networks,

distance information,

#### **Figure 7.**

*Classification of major enabling technologies of 5G systems and networks.*

#### *Artificial Intelligence and Machine Learning in 5G and beyond: A Survey and Perspectives DOI: http://dx.doi.org/10.5772/intechopen.98517*

expensive and power inefficient, the excessive use number of antennas at the base station makes the use of inexpensive elements strongly targeted to keep the overall network costs, capital expenditure and operational expenditure, manageable. However, emerging energy and spectrum-efficient wideband wireless communications systems are vulnerable to non-linear distortions that are attributed to the radio frequency front-ends. For example, those types of high-power amplifier affect the performance of the intended receiver and thus the entire network.

Furthermore, because the 5G systems should operate in more dynamic environments and in different bands (extending from cm-wave to mm-waves), the dynamic range requirements will likely become more demanding. Therefore, the power amplifiers need to meet stricter linearity specifications while at the same time maintaining an acceptable efficiency for the overall systems. The aimed high efficiency of power amplifiers is achievable when constantly feeding the amplifier at the limit of its high-power linear zone. However, this is not realistic for 5G base station, because this is not feasible solution for the peak-to-average power ratio.

The previously cited 5G enablers have a direct contribution in the network performance; however, an operative and efficient 5G network cannot be complete without AI. For example, 5G enables simultaneous connections to multiple IoT devices, generating massive amounts of data that must be processed using ML and AI. When ML and AI are integrated within, wireless providers can, for example [16]:

### **4.2 Machine learning/deep learning in 5G**

With the increasing advances and advantages of ML in the wireless communications, each research community has tried to evaluate the impact of ML on 5G in its discipline. As result, we have several publication for ML impact on physical layer, security aspects, radio resource managements, etc. This makes it very difficult to give short overview on the utilization and the impact of AI/ML in 5G. Therefore, we can summarize the works applying ML to 5G according to two principles: a "general ML categorization", where we consider all possible ML approaches from the literature, and a "Deep Learning-based Categorization", which focuses only the deep learning, because several leading publications consider deep learning as the most promising approach of ML for the high complexity of 5G.

#### **Table 2.**

*Learning approaches and their 5G applications for the three ML classes.*

A general ML categorization in case of 5G follows the general structure of ML as seen in the first sections, which uses three classes of ML: supervised learning, unsupervised learning and reinforcement learning. **Table 2** shows an example of such classification giving the used learning approaches from each class and a concrete example of application in 5G, [17]. In the next section, some 5G use cases will be described and solution for AI/ML integration in mobile network operators will be proposed.

Some research works focus only on the deep learning, because it is considered as most powerful learning approach of AI/ML. This gives a very large spectrum of applications in 5G and its different aspects, as detailed in the most recent surveys from examples [10, 18]. **Figure 8** shows just a small part of possible applications in

**59**

*Artificial Intelligence and Machine Learning in 5G and beyond: A Survey and Perspectives*

5G systems and classify them according to each system layer where AI/ML is integrated. Furthermore, some works have focused on of the application of some very promising sub-variants of deep learning, like the application of Deep Q-learning for caching/offloading, network security and connectivity preservation, traffic engineering/resource scheduling, [19]. Deep learning presents several strengths to cope with the challenges in wireless communications, and especially in case of 5G, which

• Feature extraction: Deep neural networks can automatically extract high-level features through layers of different depths. This allows reducing the expensive hand-crafted feature engineering in processing heterogeneous and noisy

• Big data exploitation: Unlike traditional ML tools, the performance of deep learning usually grow significantly with the size of training data. Therefore, it can efficiently utilize huge amounts of mobile data generated at high rates.

• Unsupervised learning: Deep learning is effective in processing un−/semilabeled data, enabling unsupervised learning. This is very important in handling large amounts of unlabeled data, which are common in mobile system.

• Multi-task learning: Features learned by neural networks through hidden layers can be applied to different tasks by transfer learning. This reduces computational and memory requirements when performing multi-task learning in

• Geometric mobile data learning: Dedicated deep learning architectures exist to model geometric mobile data, which revolutionize geometric mobile data

The life cycle of a communication network starts with its planning, dimensioning and deployment in a first life phase. Here, the network operator aims an investment optimization, minimal capital expenditure (CAPEX), while respecting the design

**5. Use cases: network planning, optimisation and management**

**5.1 AI in network life cycle: from planning to control and management**

are explained in detail in [10] and can be summarized as follows:

*Applications of deep learning in different layers of 5G systems (extended version of [18]).*

mobile big data.

**Figure 8.**

mobile systems.

analysis.

*DOI: http://dx.doi.org/10.5772/intechopen.98517*

*Artificial Intelligence and Machine Learning in 5G and beyond: A Survey and Perspectives DOI: http://dx.doi.org/10.5772/intechopen.98517*

**Figure 8.**

*Applications of deep learning in different layers of 5G systems (extended version of [18]).*

5G systems and classify them according to each system layer where AI/ML is integrated. Furthermore, some works have focused on of the application of some very promising sub-variants of deep learning, like the application of Deep Q-learning for caching/offloading, network security and connectivity preservation, traffic engineering/resource scheduling, [19]. Deep learning presents several strengths to cope with the challenges in wireless communications, and especially in case of 5G, which are explained in detail in [10] and can be summarized as follows:


**1. Introduction**

This is a review about the concept of quality of life: today this notion is very important and its definition is really complex; as a matter of fact, it has evolved over the years and become an increasingly articulated idea (i.e., it is specified by the perception of one's physical, psychological, and emotional health, by the degree of independence, by social relations, and by the type of interaction with one's context). We also can note that the quality of life construct is broader than that of health, it is not a synonym of it (as we will analyze). In this sense, being healthy is considered a dimension of quality of life and health-facilitating behaviors are considered the predictors of the quality of life itself [1]. These aspects and many other features are going to be analyzed in depth and clarified in this narrative review.

## **2. Historical overview: the concept's evolution and scientific assessment**

The debate regarding quality of life is quite ancient. Starting from early Greece, Plato had devoted several years of his life in developing a perfect government where quality of life for citizens is a mainstream. The precise term "quality of life" however had not yet been coined at that time; actually, it was introduced later, in the 1970s. We can synthetically define the quality of life as a person's judgment about various aspects of his/her own physical, social, and psychological wellbeing. The growing importance of personal evaluation of life aspects supported the development of a more precise definition of this concept and the need of a scientific assessment using psychometric standardized tests: thus, an initiative to develop a scientific quality of life assessment was born. The World Health Organization has therefore started a specific research aimed to create a rigorous measurement of this construct. The specific need to develop this research arose for several reasons. First, during recent years, beyond traditional health indicators (such as morbidity and mortality), there has been a broadening focus on the measurement of health outcomes [2], on the inclusion of measures of perceived health, on the impact of disease and impairment about daily activities and behavior [3], and on functional status/disability status measures. Furthermore, it is important to remember that it was also noted that while these questionnaires were beginning to provide a general measure of the impact of the disease, they did not actually assess the specific quality of the disease. This is the reason why, later, some specific questionnaires were developed to measure quality of life in the context of distinguishing diseases. A criticity arose because many measures of health status have been developed in the United Kingdom and in North America, the translation of which for their use in other settings appearing quite unsatisfactory and timeconsuming [4]. A third important reason was the need to go beyond the increasingly mechanistic model of medicine that deals only with the eradication of disease and symptoms. The awareness that this model is obsolete reinforced the need for the introduction of a new humanistic perspective into health care. It is widely recognized that health care is essentially a humanistic transaction where the patient's well-being is the primary aim; it no longer stops just at making the symptoms disappear, but it is more inclusive and complete. To deal with these reasons, the World Health Organization created the initiative to develop a quality of life assessment promoting a holistic approach to health and health care, as emphasized in the World Health Organization's definition of health as the "state of physical, mental and social well-being and not merely as the absence of disease and infirmity." Precisely in 1995, this organization defined in an extensive and articulated way the

**5**

*Quality of Life and Biopsychosocial Paradigm: A Narrative Review of the Concept and Specific…*

quality of life as the subjective perception that individuals have of their position in life, in their life context, culture and value system, and in relation to the achievement of their goals and their expectations, reference standards, and concerns. The result is a very complex concept in which the quality of life refers to various dimensions: the perception of one's physical, psychological, and emotional health, the degree of independence of the individual, social relations and the type of interaction with their own life context. As we have anticipated, the concept of quality of life therefore appears broader than that of "health," being not synonymous with "health" [5] but at the same time being intertwined with this notion and with the concept of a biopsychosocial paradigm. The definition of quality of life given by the World Health Organization links together a huge amount of studies [6–14], and in this way being in a state of good health is considered only one dimension of quality of life, and behaviors facilitating health are considered predictors of the quality of life itself. An acknowledgement of these aspects is necessary in order to distinguish the notion of quality of life from the notion of health. It is important to point that the definition of quality of life always includes a reference to the physical state of the subject, but it is not enough to describe the quality of a person's functionality. The latter can be detected with standardized parameters, since it is mostly correlated to the degree of satisfaction perceived with respect to these

standardized parameters and the level of physical functionality.

In this chapter, we present a definition of quality of life that shifts the emphasis from the scope of objectively definable functionality to the focus on subjectivity. In the field of objectivity, the disease is described as a defined clinical and physical state (the disease) and as the different areas of functionality (work area, psychological area, social area, etc.). It is also important to consider that quality of life refers to a subjective point of view, which is embedded in a cultural, social, and environmental context. In different geographic areas, there can be different concepts and different cultural values that can influence people's perception. It is also important to state that the World Health Organization's quality of life definition focuses on the respondents' "perceived" quality of life; it does not require a measure of any detailed symptoms, conditions, or diseases, nor disability as objectively judged, but rather the perceived effects of disease and health interventions on the person's quality of life. Starting from this point of view, an assessment of this multidimensional concept was developed, incorporating the individual's perception of health status, psychosocial status, and other aspects of life. For several years, the importance of going beyond an observation of the quality of life from an individual point of view was also underlined, and already in 2003 an Italian researcher, Ingrosso, encouraged a collective and social research in this field. In particular, he states that the topic of quality of life can characterize the perspective about a local community and its dynamics. In this broader definition of quality of life, Ingrosso refers to the evaluation that individuals of a population make about the correspondence of certain personal and collective endowments with respect to their own scale of needs and values, based on their own orientations and experiences. He put as example how citizens of a specific local community can express judgments about the adequacy or inadequacy of policies or complexes of interventions that are implemented in a specific geographic territory [15]. He also pointed out that in recent years the debate about the quality of life has partially gotten lost in generalities. The debate was also divided between the extendibility of the objective component and the subjective one, thus losing the perspective about the sense of collective, contextual, relational, and operational evaluation with which the term was originally used as from the 1970s. Scientific research can thus modify the collective knowledge about this topic, to stimulate the citizens, whether directly or indirectly, to think about some

*DOI: http://dx.doi.org/10.5772/intechopen.91877*

#### *Quality of Life and Biopsychosocial Paradigm: A Narrative Review of the Concept and Specific… DOI: http://dx.doi.org/10.5772/intechopen.91877*

quality of life as the subjective perception that individuals have of their position in life, in their life context, culture and value system, and in relation to the achievement of their goals and their expectations, reference standards, and concerns. The result is a very complex concept in which the quality of life refers to various dimensions: the perception of one's physical, psychological, and emotional health, the degree of independence of the individual, social relations and the type of interaction with their own life context. As we have anticipated, the concept of quality of life therefore appears broader than that of "health," being not synonymous with "health" [5] but at the same time being intertwined with this notion and with the concept of a biopsychosocial paradigm. The definition of quality of life given by the World Health Organization links together a huge amount of studies [6–14], and in this way being in a state of good health is considered only one dimension of quality of life, and behaviors facilitating health are considered predictors of the quality of life itself. An acknowledgement of these aspects is necessary in order to distinguish the notion of quality of life from the notion of health. It is important to point that the definition of quality of life always includes a reference to the physical state of the subject, but it is not enough to describe the quality of a person's functionality. The latter can be detected with standardized parameters, since it is mostly correlated to the degree of satisfaction perceived with respect to these standardized parameters and the level of physical functionality.

In this chapter, we present a definition of quality of life that shifts the emphasis from the scope of objectively definable functionality to the focus on subjectivity. In the field of objectivity, the disease is described as a defined clinical and physical state (the disease) and as the different areas of functionality (work area, psychological area, social area, etc.). It is also important to consider that quality of life refers to a subjective point of view, which is embedded in a cultural, social, and environmental context. In different geographic areas, there can be different concepts and different cultural values that can influence people's perception. It is also important to state that the World Health Organization's quality of life definition focuses on the respondents' "perceived" quality of life; it does not require a measure of any detailed symptoms, conditions, or diseases, nor disability as objectively judged, but rather the perceived effects of disease and health interventions on the person's quality of life. Starting from this point of view, an assessment of this multidimensional concept was developed, incorporating the individual's perception of health status, psychosocial status, and other aspects of life. For several years, the importance of going beyond an observation of the quality of life from an individual point of view was also underlined, and already in 2003 an Italian researcher, Ingrosso, encouraged a collective and social research in this field. In particular, he states that the topic of quality of life can characterize the perspective about a local community and its dynamics. In this broader definition of quality of life, Ingrosso refers to the evaluation that individuals of a population make about the correspondence of certain personal and collective endowments with respect to their own scale of needs and values, based on their own orientations and experiences. He put as example how citizens of a specific local community can express judgments about the adequacy or inadequacy of policies or complexes of interventions that are implemented in a specific geographic territory [15]. He also pointed out that in recent years the debate about the quality of life has partially gotten lost in generalities. The debate was also divided between the extendibility of the objective component and the subjective one, thus losing the perspective about the sense of collective, contextual, relational, and operational evaluation with which the term was originally used as from the 1970s. Scientific research can thus modify the collective knowledge about this topic, to stimulate the citizens, whether directly or indirectly, to think about some

*Quality of Life - Biopsychosocial Perspectives*

This is a review about the concept of quality of life: today this notion is very important and its definition is really complex; as a matter of fact, it has evolved over the years and become an increasingly articulated idea (i.e., it is specified by the perception of one's physical, psychological, and emotional health, by the degree of independence, by social relations, and by the type of interaction with one's context). We also can note that the quality of life construct is broader than that of health, it is not a synonym of it (as we will analyze). In this sense, being healthy is considered a dimension of quality of life and health-facilitating behaviors are considered the predictors of the quality of life itself [1]. These aspects and many other features are going to be analyzed in depth and clarified in this narrative review.

**2. Historical overview: the concept's evolution and scientific assessment**

Plato had devoted several years of his life in developing a perfect government where quality of life for citizens is a mainstream. The precise term "quality of life" however had not yet been coined at that time; actually, it was introduced later, in the 1970s. We can synthetically define the quality of life as a person's judgment about various aspects of his/her own physical, social, and psychological wellbeing. The growing importance of personal evaluation of life aspects supported the development of a more precise definition of this concept and the need of a scientific assessment using psychometric standardized tests: thus, an initiative to develop a scientific quality of life assessment was born. The World Health Organization has therefore started a specific research aimed to create a rigorous measurement of this construct. The specific need to develop this research arose for several reasons. First, during recent years, beyond traditional health indicators (such as morbidity and mortality), there has been a broadening focus on the measurement of health outcomes [2], on the inclusion of measures of perceived health, on the impact of disease and impairment about daily activities and behavior [3], and on functional status/disability status measures. Furthermore, it is important to remember that it was also noted that while these questionnaires were beginning to provide a general measure of the impact of the disease, they did not actually assess the specific quality of the disease. This is the reason why, later, some specific questionnaires were developed to measure quality of life in the context of distinguishing diseases. A criticity arose because many measures of health status have been developed in the United Kingdom and in North America, the translation of which for their use in other settings appearing quite unsatisfactory and timeconsuming [4]. A third important reason was the need to go beyond the increasingly mechanistic model of medicine that deals only with the eradication of disease and symptoms. The awareness that this model is obsolete reinforced the need for the introduction of a new humanistic perspective into health care. It is widely recognized that health care is essentially a humanistic transaction where the patient's well-being is the primary aim; it no longer stops just at making the symptoms disappear, but it is more inclusive and complete. To deal with these reasons, the World Health Organization created the initiative to develop a quality of life assessment promoting a holistic approach to health and health care, as emphasized in the World Health Organization's definition of health as the "state of physical, mental and social well-being and not merely as the absence of disease and infirmity." Precisely in 1995, this organization defined in an extensive and articulated way the

The debate regarding quality of life is quite ancient. Starting from early Greece,

**1. Introduction**

**4**

aspects regarding the lines of intervention consistent with their own expectations. Therefore, not only quantitative methods like indicators and surveys, but also qualitative surveys and dynamic surveys, such as participatory research-process methods, are useful for the purposes of these surveys. These methodologies are often indicated as the first fundamental step when carrying out interventions in a city or territory [15]. Today the social aspect of quality of life is increasingly present, so the concept of quality of life now is often strictly related to the terms "livable" and "livability," referring to the more or less desirable economic and social environment of a town, a metropolis, or a country: nowadays, these terms have become part of the common language.