The paper deals with mobility prediction in small cell and femtocell networks, which is important for automatic resource allocation schemes in$5 \mathrm{G} / 6 \mathrm{G}$. For a long time, the way to approach mobility predictions in cellular networks has been mainly through the coordinate-based trajectory. However, this approach has encountered many drawbacks, especially the drifting effect, which can significantly affect the prediction accuracy. In the cases of small cell networks, where the coverage radius of the cells is very small compared to the micro- and macrocells, such drawbacks can lead to an increase in the next cell's prediction error. To overcome this flaw, this research proposes using cell-based trajectory prediction, a potential solution for mobility prediction, and comparing it with traditional coordinatebased trajectory approaches. The experiment in our contribution shows remarkably better performance and accuracy of the cell-based mobility approach compared to the coordinate-based trajectory approaches.

Mobility prediction has been a popular research topic for many decades. With the advent of new generation technologies (5G and beyond) and smaller coverage cells, hand-over operations have become more frequent. Cellular system companies are therefore taking increasing interest in using the available predictive information on node movements to optimize and manage their bandwidth resources. In particular, the main challenging scope of our contribution consists in solving the issue of reliable next-cell prediction, aimed to call dropping probability minimization. In addition, our proposal is based on the innovative concept of mobility data to image encoding. The scheme is able to a-priori determine the next visited cells during host movements by applying a convolutional neural approach to mobility images. The power of machine learning is used to advantage, and highly accurate image classification is achieved for mobility prediction. We performed numerous simulation campaigns related to next-cell prediction in mobile cellular environments, obtaining very satisfactory results by the application of convolutional neural networks, which have an impressive history of effectiveness with image classification problems. The trained network has been associated to each coverage cell and the prediction accuracy has been evaluated.

With the low integration costs and quick development cycle of all-IP-based 5G+ technologies, it is not surprising that the proliferation of IP devices for residential or industrial purposes is ubiquitous. Energy scheduling/management and automated device recognition are popular research areas in the engineering community, and much time and work have been invested in producing the systems required for smart city networks. However, most proposed approaches involve expensive and invasive equipment that produces huge volumes of data (high-frequency complexity) for analysis by supervised learning algorithms. In contrast to other studies in the literature, we propose an approach based on encoding consumption data into vehicular mobility and imaging systems to apply a simple convolutional neural network to recognize certain scenarios (devices powered on) in real-time and based on the Non-Intrusive Load Monitoring (NILM) paradigm. Our idea is based on a very cheap device and can be adapted at a very low cost for any real scenario. We have also created our own dataset, taken from a real domestic environment, contrary to most existing works based on synthetic data. The results of the study’s simulation demonstrate the effectiveness of this innovative and low-cost approach and its scalability in function of the number of considered appliances.

In this study, we investigate the trade-off between reliability and security in unmanned aerial vehicle (UAV) communications systems, considering a UAV-terrestrial network aided by a relay powered by a dedicated power beacon. For this system, we derive the outage probability (OP) under both exact and approximate frameworks and compute the approximations in the closed-form expressions. For the security aspect, we also derive the intercept probability (IP) under exact and approximated frameworks. To minimize the IP, a friendly jamming technique is employed whereby the power beacon constantly broadcasts artificial noise (AN) toward an eavesdropper. Based on the derived mathematical framework, we then formulate a bi-objective optimization problem by jointly minimizing the OP and IP with respect to the UAV’s position and the time-switching (TS) ratio. A suitable algorithm, named non-dominated sorting genetic algorithm version II (NSGA-II), is deployed to obtain the sub-optimal solution. Finally, numerical results are presented to verify the accuracy of the proposed mathematical framework and the superiority of jointly minimizing both the OP and IP using only the channel statistics.

In the last decade, the investigation of mobility features has gained enormous significance in many scenarios as a result of the significant diffusion and deployment of mobile devices covered by high-speed technologies (e.g., 5G). Many contributions in the literature have attempted to discover mobility properties, but most studies are based on the time features of the mobility process. No study has yet considered the effects of setting a proper sampling frequency (generally set to 1 s), in order to avoid information loss. Following our previous works, we propose a novel predictive spectral approach for mobility sampling based on the concept of a predictive wavelet. With this method, the choice of sampling frequency is governed by the current spectral components of the mobility process and derived from an analysis of future, predicted components. To assess whether our proposal may yield a helpful method, we conducted several simulation campaigns to test sampling accuracy and obtained results that confirmed our expectations.

Free Space Optics (FSO) represent a promising technology for secure communications in several types of architectures: from Quantum Key Distribution Networks (QKDNs) to satellite communications. In this paper, in particular, we take into account terrestrial point-to-point laser communications and evaluate the performance in terms of Signal-to-Noise Ratio (SNR) and Bit Error Rate (BER), taking into account different scenarios, that can reflect real situations in which long distances can be reached in a secure way, guaranteeing an acceptable level of BER. So, after a huge campaign of simulations, we would like to let the scientific community know which are the theoretical limits that such kind of communications can reach. We take into account standard telescopes parameters (available today in the market), while configuring several real situations, in function of, for example, bit-rate, visibility, link distance, etc. A brief survey of the existing works is given, then a clearer performance evaluation of terrestrial FSO links is proposed.

We propose a network-based approach to mission planning for a swarm of robots. We model a search and rescue mission with a fleet of aquatic robots, coordinated with a computing central on a rowing boat, to minimize the environmental impact and avoid noticeable waves. We develop a theoretical yet implementable model for the mission management, taking into account energy and multi-robot communication issues. The considered mathematical tools come from network theory and multi-layered graphs. The chosen mission is aquatic cleaning, and in particular trash detection in canals of Venice. We schematize a specific canal as an example, the "Rio di Ca’ Foscari." Computing centers are located in gondolas, and each of them is coordinated with a swarm of aquatic robots. In this context, we consider a newly-designed floating robot, RoboWood, equipped with GPS sensors, distance sensors, and an underwater camera to observe the ground of the canal and store images, to be analyzed onboard and offline. Finally, we discuss a sonification strategy to obtain human-friendly, auditory feedback from the robotic movements.

Nowadays, mobile computing has become a key component of telecommunication systems, and the Open Systems Interconnection (OSI) layer operations are affected by the effects of node movements along the roads, from the physical to the routing/transport layers. In particular, routing approaches have been investigated from many years, trying to optimize the performance of the whole considered system, under different points of view. In this paper we are focusing the attention on the analysis of the mobility grade trend for a mobile ad-hoc network environment, as well as on the way it can be a-priori known, in order to have the possibility to study how the dynamics of mobile nodes can be described and in-advance known, with a predicted knowledge of nodes stability (in terms of mobility). Our simulations considered mobility in real geographical maps, and the obtained results confirmed the goodness of our proposed study.

Many studies in literature have shown that the bandwidth of an ongoing flow can dynamically change during multimedia sessions and an efficient bandwidth prediction scheme must be employed in order to guarantee the needed Quality of Service. Many contributions in literature focused on some specific reservation schemes for cellular systems, 3G/4G/5G networks, WLAN and so on. However, few of them exploited the trade-off between resource prediction error and bandwidth wastage through a general prediction technique based both on the analysis of Cell Stay Time and on the direction probabilities of hand-in and hand-out events of mobile nodes among wireless cells. Our proposed scheme is based on the stochastic computation and characterization of user movements and it is absolutely general. Two novel metrics such as prediction error e and resource wastage u are defined. Moreover, predictive reservation schemes, admission prediction and resource wastage probabilistically associated to the stochastic hand-in/hand-out movement directions are proposed, with an optimization problem for the optimal pre-reservation of bandwidth in wireless system. A threshold-based reservation scheme has been considered and it has been evaluated in terms of reservation prediction errors and resource wastage, in order to prove the practical effectiveness and consistence of the defined theoretical bounds.

Mobility is a key aspect of modern networking systems. To determine how to better manage the available resources, many architectures aim toa prioriknow the future positions of mobile nodes. This can be determined, for example, from mobile sensors in a smart city environment or wearable devices carried by pedestrians. If we consider infrastructure networks, frequently changing the coverage cell may lead to service disruptions if a predictive approach is not deployed in the system. All predictive systems are based on the storage of old mobility samples to adequately train the model. Our focus is based on the possibility to determine an approach for adaptively sampling mobility patterns based on the intrinsic features of the human/node behavior. Several works in the literature examine mobility prediction mobile networks, but all of them are dedicated to the study of time features in mobility traces: none took into account the spectral content of historical mobility patterns for predictive purposes. In contrast, we take into account this spectral content in mobility samples. Through a set of wavelet transforms, we adapted the sampling frequency dynamically and obtained a considerable set of advantages (space, energy, accuracy, etc.). In fact, this issue covers an important role in the IoT paradigm, where energy consumption is one of the main variables requiring optimization (frequent and unnecessary mobility samplings can disrupt battery life). We performed several simulations using real-world traces to confirm the merit of our proposal.

A key role in the modern telecommunication networks is played by routing aspects as the great number of works present in literature proves. In particular, in the mobile ad-hoc networks routing is a fundamental aspects because the mobile devices nature and their elevate dynamism. In fact, it is important to have the possibility of finding the minimum overhead for connectivity in the network and, calculate the communication potential through the analysis of different parameters. The focus of this paper is represented by the analysis of the entropy in this type of mobile networks. The entropy gives the possibility of studying and predicting the dynamics of mobile nodes. The knowledge of these aspects can help to optimise some key features of wireless mobile communications, such as nodes stability, channel failures, and routing costs. Many simulation campaigns have been carried out by taking into account the movement of the real nodes, obtaining beneficial results, which confirm the effectiveness of the proposed study.

In the modern telecommunication systems, mobility is one of the key advantage of wireless communications, given that it is possible to transmit/receive data, without caring of having a static position into the network. Of course, mobility poses special issues such as degradations, channel quality fluctuations, fast topology changes, and so on. Modern researches focus their attention on predicting mobile future node positions, in order to a-priori know, for example, what the evolution of the network topology will be or which level of stability each node will reach. Each prediction scheme is based on the storage and analysis of several historical mobility trajectories, in order to train the proper prediction algorithm. In this paper, we focus our attention on the optimization of the space needed to store historical mobility samples, encoding their values and evaluating the conversion error, comparing different encoding functions. Several simulation campaigns have been carried out in order to evaluate the goodness and feasibility of our proposal.

With the proliferation of connected vehicles, new coverage technologies and colossal bandwidth availability, the quality of service and experience in mobile computing play an important role for user satisfaction (in terms of comfort, security and overall performance). Unfortunately, in mobile environments, signal degradations very often affect the perceived service quality, and predictive approaches become necessary or helpful, to handle, for example, future node locations, future network topology or future system performance. In this paper, our attention is focused on an in-depth stochastic micro-mobility analysis in terms of nodes coordinates. Many existing works focused on different approaches for realizing accurate mobility predictions. Still, none of them analyzed the way mobility should be collected and/or observed, how the granularity of mobility samples collection should be set and/or how to interpret the collected samples to derive some stochastic properties based on the mobility type (pedestrian, vehicular, etc.). The main work has been carried out by observing the characteristics of vehicular mobility, from real traces. At the same time, other environments have also been considered to compare the changes in the collected statistics. Several analyses and simulation campaigns have been carried out and proposed, verifying the effectiveness of the introduced concepts.

In recent years, noticeable progress has been made in the development of quantum equipment, reflected through the number of successful demonstrations of Quantum Key Distribution (QKD) technology. Although they showcase the great achievements of QKD, many practical difficulties still need to be resolved. Inspired by the significant similarity between mobile ad-hoc networks and QKD technology, we propose a novel quality of service (QoS) model including new metrics for determining the states of public and quantum channels as well as a comprehensive metric of the QKD link. We also propose a novel routing protocol to achieve high-level scalability and minimize consumption of cryptographic keys. Given the limited mobility of nodes in QKD networks, our routing protocol uses the geographical distance and calculated link states to determine the optimal route. It also benefits from a caching mechanism and detection of returning loops to provide effective forwarding while minimizing key consumption and achieving the desired utilization of network links. Simulation results are presented to demonstrate the validity and accuracy of the proposed solutions.

Unmanned aerial vehicles are devices able to perform many different tasks that can help human activity in many processes. One of the most important use regards the possibility of giving wireless connectivity to user in a specific area. These new typologies of networks are called Flying Adhoc Network. Their use benefit all those situations of emergency where the traditional communications may have many issues, due to the specific event. Different types of natural disasters (such as climatological, meteorological, hydrological, geophysical) can result in many deaths and many economic damages. In these situations, drones can provide an additional or complementary access network, supporting web services and multimedia traffic, helping people involved in the rescue. Hence, it is clear that the possibility of using a simulator can result in a huge help to the research community. So, in this work, a Flying Ad-hoc Network simulator is proposed, able to simulate different scenarios with different coverage areas. In particular, emphasis is given to new coverage and human mobility models, in order to support more realistic situations. Some simulations have been led out to show how the simulator works.

In this paper, the attention is focused on the design of a hybrid platoon system capable of minimising energy consumption in the vehicular environment. In this paper, we focused our attention on the design of a Intelligent Transportation System (ITS) system which offers support to the platooning management to achieve a global optimisation of the groups. In this way, new formations help vehicles to reduce energy consumption exploiting platooning. In this work, we propose a novel algorithm based on Gray Wolf Optimization (GWO) to perform the search of the best platoon. Moreover, in this work we propose a protocol to accomplish platoon tasks. We evaluated the system performances of the platoon formation by considering several constraints such as platoon size, platoon speed, average platoon energy consumption, and so on. For the analysis of the results, we use the Omnet++ framework for protocol issues and Matlab tools for carrying out algorithm performances.

In this paper a simulator for the management of a team of Unmanned Aerial Vehicles (UAVs) and drones has been proposed. This new network is known as Fly Ad-Hoc Network (FANET), and it is a particular type of Mobile Ad-Hoc Network (MANET) but with some specific aspects that allow to provide new services in future generation networks. One of the possible applications is emergency situations or scenario where drones can provide an additional or complementary access networks supporting web services and multimedia traffic. In this paper a simulator for FANET deploying has been proposed providing the possibility to simulate different scenarios with different coverage areas. New coverage model has been included in the features and also interesting human mobility model to support more realistic users mobility. Moreover, additional modules for traffic pattern generation have been implemented to create scenario where mobile users can activate multimedia calls and traffic on FANET. Some simulations have been led out to show how the simulator works.

When the connection to Internet is not available during networking activities, an opportunistic approach exploits the encounters between mobile human-carried devices for exchanging information. When users encounter each other, their handheld devices can communicate in a cooperative way, using the encounter opportunities for forwarding their messages, in a wireless manner. But, analyzing real behaviors, most of the nodes exhibit selfish behaviors, mostly to preserve the limited resources (data buffers and residual energy). That is the reason why node selfishness should be taken into account when describing networking activities: in this paper, we first evaluate the effects of node selfishness in opportunistic networks. Then, we propose a routing mechanism for managing node selfishness in opportunistic communications, namely, SORSI (Social-based Opportunistic Routing with Selfishness detection and Incentive mechanisms). SORSI exploits the social-based nature of node mobility and other social features of nodes to optimize message dissemination together with a selfishness detection mechanism, aiming at discouraging selfish behaviors and boosting data forwarding. Simulating several percentages of selfish nodes, our results on real-world mobility traces show that SORSI is able to outperform the social-based schemes Bubble Rap and SPRINT-SELF, employing also selfishness management in terms of message delivery ratio, overhead cost, and end-to-end average latency. Moreover, SORSI achieves delivery ratios and average latencies comparable to Epidemic Routing while having a significant lower overhead cost.

Vehicular ad hoc networks (VANETs) represent a particular mobile technology that permits communication between vehicles, offering security and comfort. Nowadays, distributed mobile wireless computing is becoming a very important communication paradigm, due to its flexibility to adapt to different mobile applications. In this work, an interference aware metric is proposed in order to reduce the level of interference between each pair of nodes at the MAC and routing layer. In particular, this metric with a prediction algorithm is proposed to work in a cross-layered MAC and an on-demand routing scheme in multi-radio vehicular networks, wherein each node is equipped with two multi-channel radio interfaces. The proposed metric is based on the maximization of the average signal-to-interference ratio (SIR) level of the connection between source and destination. In order to relieve the effects of the cochannel interference perceived by mobile nodes, transmission channels are switched on a basis of a periodical SIR evaluation. Our solution has been integrated with an on-demand routing scheme but it can be applied to other routing strategies. Three on-demand interference aware routing schemes integrating IEEE 802.11p Multi-channel MAC have been tested to assess the benefits of the novel metric applied to a vehicular context. NS-3 has been used for implementing and testing the proposed idea, and significant performance improvements were obtained: in particular, the proposed policy has resulted in an enhancement of network performance in terms of throughput and packet delivery ratio.

In wireless networking, the main desire of end-users is to take advantage of satisfactory services, in terms of QoS, especially when they pay for a required need. Many efforts have been made to investigate how the continuity of services can be guaranteed in QoS networks, where users can move from one cell to another one. The introduction of a prediction scheme with passive reservations is the only way to face this issue; however, the deployment of in-advance bandwidth leads the system to waste resources. This work consists of two main integrated contributions: a new pattern prediction scheme based on a distributed set of Markov chains, in order to handle passive reservations, and a statistical bandwidth management algorithm for the reduction of bandwidth wastage. The result of the integration is the Distributed Prediction with Bandwidth Management Algorithm (DPBMA) that is independent from the considered technology and the vehicular environment. Several simulation campaigns were conducted in order to evaluate the effectiveness of the proposed idea. It was also compared with other prediction schemes, in terms of system utilization, accuracy, call dropping, and call blocking probabilities.

Vehicular networking is rapidly growing in the last years, due to its ability of enhancing users everyday-life, in terms of comfort, security and QoS. New services are being implemented and the research activity on the topic is embracing different OSI layers, like the network and application ones. Many efforts have been also given at the PHY layer. In this paper we focus our attention on a new approach for modeling the wireless channel of VANETs communications. In the literature many channel models have been proposed, but most of them work at the bit level or they investigate only some aspects of channel interaction. In this work we provide a high level IEEE802.11p channel model based on Discrete Time Markov Chain (DTMC) modeling, useful in every simulation context. The proposed model is called Markovian Vehicular Channel Model (MVCM) and it is based on the concept of Packet Error Rate (PER) discretization: we do not consider the performance analysis at the bit level, but we derive the proposed model by computing the PER, associated to different observation times. The effectiveness of the proposed idea has been evaluated through a deep campaign of simulations.

In this work a new protocol for Voice over IP (VoIP) transmissions in wireless ad-hoc networks is proposed. Distributed architecture is necessary when dealing with dynamic environments, such as ports or battlefields, where creating infrastructures becomes expensive or impossible. Mobile ad-hoc networks (MANETs) are based on a peer-to-peer approach and each node participates in the organization of the whole network. VoIP over MANETs is a challenging issue due to the intrinsic distributed nature of the existing peer-to-peer paradigm. This paper proposes a new protocol, capable of ensuring a quality of service (QoS) level for VoIP calls over a MANET and to manage a large number of calls in the system. Novel metric and utility functions are proposed to perform the best path selection from source to destination nodes, respecting the QoS parameters for VoIP quality. In particular, an objective metric such as R-factor is considered, and a flexibility index is defined in order to maximize the number of acceptable VoIP calls. Performance evaluation shows that the proposed approach led to better network management in terms of admitted calls and respected QoS constraints.

In last years, wireless networking is becoming very popular because it is able to satisfy user requests in terms of Quality of Service (QoS); when mobility is present, perhaps, hand-over issues are relevant when hosts change coverage areas during their active sessions. It is very important to mitigate mobility effects, employing an appropriate bandwidth management policy. In our work, we propose two integrated schemes: the first one is based on Markov theory and is aimed at the prediction of mobile hosts movements (in terms of future cells), while the second one is based on statistical theory and is aimed at the minimization of the wasted bandwidth used for passive reservations. So, the proposed Pattern Prediction and Passive Bandwidth Management Algorithm (3P-BMA) is the result of the integration of the Markov predictor and the statistical bandwidth management scheme. 3P-BMA is completely independent on the considered technology, mobility model and vehicular environment. We do not care if the coverage is made by UMTS or WLAN technologies, if hosts are pedestrians or mobile users, etc. Some campaigns of simulation have been led-out in order to confirm the effectiveness of the proposed idea in terms of prediction accuracy, Call Dropping/Blocking probabilities and system utilization.

In last years, the challenge of providing end-to-end service where end-to-end forwarding paths do not exist is faced by the new emerging approach of Delay Tolerant Networks (DTNs), that support interoperability of “regional networks” by accommodating long delay between and within regional networks, such as space communications, networking in sparsely populated areas, vehicular ad-hoc networks and underwater sensor networking. The common issue of these environments consists in the absence of guarantees about the existence of continuous end-to-end paths between source and destination nodes. In this paper we consider epidemic schemes to solve this problem, proposing an extended approach aimed at the routing optimization in terms of energy consumption and message delivery probability. The performance of our idea have been evaluated through a deep campaign of simulations, verifying that the proposed extended epidemic approach leads the system to an overall enhancement.

The utilization of the Return Channel Satellite (RCS) in DVB systems allows a bi-directional communication via satellite. With this particular characteristic, DVB-RCS systems promoted its enormous diffusion in the commercial area and the academic research interest and, in this context, it is very important to test DVB-RCS systems using an efficient satellite channel model. Many channel models have been proposed in the literature, but most of them work at the bit level or they investigate only some aspects of channel interaction. In this paper we present a high level satellite channel model based on Markov Chains (MCs) modeling, useful in every simulation context: the proposed Markovian Satellite Channel Model (MSCM) is based on the concept of windowed observations and the idea is not to analyze a single packet, but fixing an observation window to evaluate the degradation level of the link, computing the PER associated to the specific window. The model has been verified through a deep campaign of simulations, which demonstrate how the introduced error is minimized.

Satellite communications represent an important slice of the global communications sector thanks to their broadcast nature. Unfortunately, TCP used on satellite links suffers from a number of well-known performance issues, especially for high altitude satellites with longer delays. In this paper, a new TCP protocol is proposed. This new protocol arises after a careful study of the various protocols present in literature that try to resolve the typical satellite issues. Our TCP protocol is called Available bandwidth adaptable Transport Protocol (ATP) and it takes the advantages of two TPC protocols proposed in literature: Satellite Transport Protocol (STP) and TCP Jersey. In particular, it consists of a reviewed version of STP protocol with the addition of the TCP Jersey Bandwidth Estimation algorithm called Available Bandwidth Estimation (ABE). In order to show the goodness of the proposed protocol we have performed some comparisons between ATP, STP, TCP Jersey and another TCP protocol called Satellite Communication Transmission Protocol (SCPS-TP).

DVB-RCS is an open satellite communications standard allowing a bi-directional communication via satellite. These characteristics certainly promoted its enormous diffusion in the commercial area and the academic research interest. In this context, it is very important to test DVB-RCS systems using an efficient satellite channel model. In the literature many channel models have been carried out, but most of them work at the bit level or they investigate only some aspects of channel interaction. In this work we provide a high level satellite channel model based on Discrete Time Markov Chain (DTMC) modeling, useful in every simulation context. Our model, called Quality Degree-DTMC (QD-DTMC), is based on the concept of Quality Degree (QD) of a given observation windows: the idea is not to analyze a single packet, but fixing an observation window and evaluating the QD of the link, computing the Packet Error Rate (PER) associated to the specific window. The effectiveness of the proposed idea has been evaluated through a deep campaign of simulations.

In these last years, many studies have focalized on the design of reliable under water acoustic communication systems. However, the ocean acoustic communication channel exhibits strong amplitude and phase fluctuations and the phenomena of diffraction, refraction and reflection. Due to the complexity of environment, the motions of transducers, sea surface, etc., the underwater acoustic signals exhibit random temporal and spatial frequency fluctuations in both amplitude and phase. These highly space, time and frequency dependent features introduce numerous obstacles for any attempts to establish reliable and long-range underwater acoustic communications. Therefore, it is very important to model a so complex channel. In this paper, we propose a new multipath channel model for shallow underwater acoustic communications. In particular, our model takes into account the effects due to spreading loss, scattering and reflections.

In recent years, mobile hosts desire to benefit a good level of satisfaction for the received services in wireless networks, with adequate quality of service guarantees. In this work the attention is focused on wireless services in cellular networks, where the hand-over effects need to be mitigated, through an appropriate reservation policy. Passive resources are used to ensure service continuity when mobile hosts are moving among different coverage cells. The system is modeled through a distributed set of Hidden Markov Chains and the related theory is used to design a mobility predictor (in terms of future probably visited cells), as the main component of the proposed idea, that does not depend on the considered transmission technology (GSM, UMTS, WLAN, etc.), mobility model or vehicular scenario (urban, suburban, etc.). MRSVP has been used in order to realize the active/passive bandwidth reservation in the considered network topology and a severe simulation campaign has been led-out in order to appreciate the robustness of the reservation scheme.

In wireless networking, users mobility has a heavy impact on QoS parameters and the existing architectures for real-time services with motionless hosts become inadequate for QoS management. In particular Doppler shift and multipath fading introduce some degradations in wireless transmissions. For these reasons, the management of real-time flows and handover events (in terms of bandwidth guarantee and service continuity) when the system is dealing with Mobility Independent Predictive (MIP) services is mandatory, if QoS constraints need to be satisfied. In order to offer a soft QoS increasing the total system utilization, a bandwidth reallocation algorithm has been considered for dynamic resource adaptation, based on wireless channel modeling, in order to take into account the degradations related to the channel state conditions. The main idea of this proposal is the utilization of a pre-reservation phase in the admission control through a Markovian approach, in order to predict the amount of bandwidth needed by a mobile host during its movements among active and passive cells. The performance evaluation of the proposed idea has been made in terms of total admitted/dropped MIP flows, assigned bandwidth and system utilization.

In the last years, there has been a lot of research and development in wireless networking and mobility management. We focus our attention on the management of real-time flows, in particular on the management of hand-over events, in terms of bandwidth guarantee and service continuity when the system is dealing with Mobility Independent Predictive (MIP) services, defined in Integrated Services (IS) for mobile wireless environment. The main idea of this proposal is the utilization of a pre-reservation phase in the admission control through a Markovian approach, in order to predict the amount of bandwidth needed by a mobile host during its movements among the probably visited cells. The performance evaluation of the proposed idea has been made in terms of total assigned bandwidth, system utilization and admitted/dropped MIP flows.

Vehicular communication systems represent one of the most desirable technologies when the safety, efficiency and comfort of everyday road travel need to be improved. The main advantage is the absence of an infrastructure, typical of centralized networks, that makes them very scalable and adequate for highly-variable network topologies. Vehicular Ad-hoc NETworks (VANETs) are able to provide wireless networking capability in situations where no fixed infrastructure exists and the communication among nodes can be either direct or made via relaying nodes, as in the classical ad-hoc networks. In this paper, the attention is focused mainly on the network layer of VANETs, proposing a novel approach to reduce the interference level during mobile transmission, also considering the minimization of path lengths. We propose an interference aware routing scheme for multi-radio vehicular networks and a new metric is also proposed, based both on the maximization of the average Signal to Interference level and on the minimization of the path length of the connection between source and destination. Our solution has been integrated with the AODV routing protocol to design a new MIMO Distance Vector Protocol. NS-2 has been used for implementing and testing the proposed idea, and significant performance improvements have been obtained.

An important suggestion of the standard for DVB-RCS+M is the possibility of using a continuous carrier operation mode in the return channel beyond the classical MF-TDMA mode. In order to realize it a mechanism for switching between these two modalities has to be used. In this paper, after showing the typologies of applications considered in the simulation, a proposal of a novel switching mechanism is presented and the simulation results are reported in order to provide some guidelines to the satellite operators that want to adopt in their satellite system this hybrid mode. The simulation results provide good indications and this study is the base for more depth researches.

Energy awareness for computation and protocol management is becoming a crucial factor in the design of protocols and algorithms. On the other hand, in order to support node mobility, scalable routing strategies have been designed and these protocols try to consider the path duration in order to respect some QoS constraints and to reduce the route discovery procedures. Often energy saving and path duration and stability can be two contrasting efforts and trying to satisfy both of them can be very difficult. In this paper, a novel routing strategy is proposed. This proposed approach tries to account for link stability and for minimum drain rate energy consumption. In order to verify the correctness of the proposed solution a biobjective optimization formulation has been designed and a novel routing protocol called Link-stAbility and Energy aware Routing protocols (LAER) is proposed. This novel routing scheme has been compared with other three protocols: PERRA, GPSR, and E-GPSR. The protocol performance has been evaluated in terms of Data Packet Delivery Ratio, Normalized Control Overhead, Link duration, Nodes lifetime, and Average energy consumption.

Mobile computing and vehicular communications are becoming a very important paradigm for wireless communications, mainly because of their ability to adapt to different mobile applications. In this paper, we propose a new scheme for reducing the interference level during mobile transmissions in the VehiculAr inter-NETworking (VANET) environment, taking the advantage of the multi-channel nature of IEEE802.11p standard. In order to relieve the effects of the co-channel interference perceived by mobile nodes, transmission channels are switched on a basis of a periodical Signal-to-Interference Ratio (SIR) evaluation. The attention is focused on the routing level of VANET and we propose an interference aware routing scheme for multi-radio vehicular networks, wherein each node is equipped with a multi-channel radio interface. A new metric is also proposed, based on the maximization of the average SIR level of the connection between source and destination. Our solution has been integrated with the AODV routing protocol to design an enhanced Signal-to-Interference-Ratio-AODV (SIR-AODV). NS-2 has been used for implementing and testing the proposed idea, and significant performance enhancements were obtained, in terms of throughput, packet delivery and, obviously, interference.

Vehicular mobile communications are attracting much attention in wireless communications field. In this paper a new routing protocol for the reduction of interference level during mobile transmissions in VANET environment is proposed, considering the availability of different channels in the DSRC spectrum. The attention is mainly focused on the routing level of VANET and we propose an interference aware routing scheme for multi-radio vehicular networks based on a new metric, for the maximization of the average SIR level of the connection between source and destination. The proposed idea has been integrated with the AODV routing protocol to design an enhanced Dynamic-Frequency-Interference-Aware-AODV (DFIA-AODV). The proposed idea has been tested and significant performance enhancements were obtained.

Nowadays, in wireless computing, guaranteeing a certain grade of Quality of Service (QoS) during wireless sessions is an important issue, especially when non-tolerant applications are running into the system. Mobility and channel quality often affect system performance, depending on the grade of mobility of hosts. In this paper, providing QoS to mobile hosts belonging to a certain service class (Mobility Independent Predictive - MIP) is the main issue and a statistical multiplexing algorithm is proposed, in order to save an enormous amount of resources; it is based on the Cell Stay Time (CST) distribution analysis for a 2- dimensional (2D) wireless environment under the Smooth Random Mobility Model (SRMM). There are many works in literature about resource pre-reservation: they offer good QoS guarantees, but a very low system utilization, because they do not care about the fact that a passive reservation can remain unused for long time. With the help of the CST statistical multiplexing introduced in this paper, better results are obtained in terms of system utilization, while the Quality of Service and prediction error are maintained at acceptable levels. The proposed idea has been validated through many simulation campaigns, with a good performance analysis in terms of some interesting parameters, like bandwidth system utilization or prediction errors.

Ultra wideband (UWB) is a promising technology thanks to its unique physical characteristics. For this purpose, many works have already treated issues regarding UWB system. Most of them analyzed only first two ISO/OSI levels, that are physical and MAC layers, while too few investigations are yet spent on the routing layer of UWB systems. However, traditional approaches are not valid for UWB systems because they do not take into account of interference between nodes, that is not a trivial problem in these networks. The main goal of our work is to propose a new on demand routing protocol, called interference aware-based ad-hoc on demand distance vector (IA-AODV), based on the concept of interference perceived by the nodes: so, the optimum route is chosen on the basis of the minimum perceived interference, improving in this way the general system performance. To test the proposed protocol a ns-2 based simulator was realized. The protocol was compared with the AODV and IBOR protocols in terms of packet delivery ratio, end-to-end delay and normalized overhead. Simulation results show as our protocol outperforms the others protocols in all considered scenarios: only in few cases IA-AODV presents an overhead slightly higher than AODV.

QoS guarantee is a very important issue in wireless communications, when mobile nodes move among different coverage areas. This paper presents a novel 2D reservation scheme for WLAN environments. A general prediction technique based both on the analysis of Cell Stay Time (CST) and on the direction probabilities of hand-in and hand-out events of mobile nodes from wireless cells is outlined. In particular, a threshold-based algorithm is presented, trying to take into account the mobility behavior of mobile users, through the analysis of a directional probabilities matrix. An integrated architecture able to make active and passive reservations has been employed as a possible application of the proposed approach. Many simulations have been carried out and a performance analysis has been performed, finding a good tradeoff between bandwidth utilization and prediction error.

Recently there has been a lot of research and development in wireless networking and mobility management, with the main purpose of connection handling between mobile hosts and base stations or access points. QoS guarantee is a very important issue in wireless communications, when mobile nodes move among different coverage areas. This paper presents a general prediction technique based both on the analysis of cell stay time and on the direction probabilities of hand-in and hand-out events of mobile nodes from wireless cells. User mobility has been analyzed, in order to reduce passive resource reservations, with a high gain in system utilization. In particular, a threshold-based algorithm is presented, trying to take into account the mobility behavior of mobile users, through the analysis of a directional probabilities matrix. The performances of the 2D wireless system have been evaluated in terms of prediction error and system utilization; in addition, some comparisons with older prediction schemes have been made.

Multi-mode satellite terminals are actually the most desired devices on the market, thanks to their flexibility and suitability. A multi-mode radio communication terminal is a terminal allowing two or more transmission mode. In the last few years many research resources have been invested in the study of this new type of terminal In this work, we define a multi-mode terminal as a terminal capable of communicating both with a bent-pipe (BP) satellite and with an on-board processor (OBP) satellite and dynamically setting its transmission parameters (e.g. transmission power and code rate). In order to realize this multi- mode functionality, the most suitable technology is the software defined radio (SDR). The SDR is a set of hardware and software technologies that allow one to obtain reconfigurable architectures for network and wireless terminals. The goal of our work is to plan a satellite system based on digital video broadcast with the return channel satellite (DVB-RCS) standard in which the return channel satellite terminals (RCSTs) are able to adapt it to the channel state, configuring the transmission chain via software, respecting a certain quality of service (QoS) constraint on the packet error rate (PER).

Ultra-wideband (UWB) radio is a viable candidate for short-range multiple access communications in dense multipath environments. This paper analyzes the efficiency of direct sequence - UWB physical layer standard proposal in a indoor environment with fixed transmitters and receiver positions. The performance evaluation is carried out using the UWB channel model provided by the IEEE 802.15 channel modelling subcommittee to model the dense multipath indoor environment typical of the UWB system. DS-UWB architecture has been implemented using a Matlab Simulink tool and simulation results are evaluated in terms of bit error rate (BER) vs. transmitter-receiver distance and noise power spectral density. Moreover, a polynomial regression analysis is carried out on simulation results in order to obtain a closed formula to describe, for different scenarios, the BER as a function of data rates, noise power spectral density (PSD) and distance between the transmitter and receiver.

In last years there has been a lot of research and development in wireless communications and mobility management, with the main purpose of connections handling between mobile hosts and base stations or access points, when different coverage areas are visited. This paper presents a novel 2D reservation scheme for WLANs; a general prediction technique based both on the analysis of cell stay time (CST) and on the direction probabilities of hand-in and hand-out events of mobile nodes from wireless cells is outlined. In particular, a threshold-based algorithm is presented, trying to take into account the mobility behavior of mobile users, through the analysis of a hand-off directional probabilities (HDP) matrix. Users' mobility has been analyzed, in order to reduce passive resource reservations, with a high gain in system utilization. In particular, an integrated architecture able to make active and passive reservations has been employed as a possible application of the proposed approach. The performances of the 2D wireless system have been evaluated in terms of prediction error and system utilization; in addition, some comparisons with older prediction schemes have been made.

A multi-mode radio communication terminal is a tunable terminal for passing and/or receiving bands in at least two radio communication systems. In the last few years many research resources have been invested in the study of this new type of terminal. This study is intended for a multi-mode terminal is a terminal capable of communicating both with a bent-pipe satellite and with an on-board processor satellite. In the literature different technologies are presented and they can be used to realize the multi-mode capability of a terminal, but, the most suitable technology is the software defined radio (SDR). The SDR is a set of hardware and software technologies that allow one to obtain reconfigurable architectures for network and wireless terminals. The goal of this work is to plan a satellite system based on digital video broadcast with the return channel satellite (DVB-RCS) standard in which the return channel satellite terminals (RCSTs) are able to adapt to the channel state, configuring the transmission chain via software, respecting a certain quality of service (QoS) constraint on the packet error rate (PER).

The low cost of devices and the possibiliy of achieving higher data rates without increasing transmitter power make Ultra-Wideband (UWB) radio a viable candidate for short-range multiple access communications in dense multipath environments. This paper analyses the efficiency of the Direct Sequence - Spread Spectrum (DS-SS) physical layer standard proposal in an indoor environment with fixed transmitters and receiver positions. The modelling and the performance evaluation of a new channel model, where impulse response is also distance-dependent, are outlined. Packet Error Rate (PER) analysis has been carried out by using a polynomial regression technique, through the Matlab tool, on simulation results obtaining an expression for the PER as function of distance and packet length. Simulation results are evaluated in terms of PER vs transmitter-receiver distance.

This papers presents a 2D reservation scheme in WLAN environment. A two-dimensional wireless mobility model called smooth random mobility model (SRMM) has been considered, because it makes the movement of users smoother and more realistic than well-known in literature random mobility models. A general prediction technique based both on the analysis of cell stay time and on the direction probabilities of hand-in and hand-out events of mobile nodes from wireless cells is outlined. Three different reservation policies are considered: the first scheme reserves a fixed number of cells for each hand-off; the second one permits to reserve on a greater number of cells in the first hand-off and a lower number of cells in the next hand-off events; the last policy uses an increasing adaptive reservation scheme, trying to take advantage of the lower prediction error for the first hand-off and the greater prediction error for the next hand-off. Many simulations have been carried out and a comparison between the three reservation schemes has been performed.

The low cost of devices and the possibility of achieving higher data rates without increasing transmitter power make ultra-wideband (UWB) radio a viable candidate for short-range multiple access communications in dense multipath environments. This paper analyses the efficiency of the direct sequence-spread spectrum (DS-SS) physical layer standard proposal in an indoor environment with fixed transmitters and receiver positions. The modelling and the performance evaluation of a new channel model, where impulse response is also distance- dependent, are outlined. Moreover, the performance evaluation of an ideal minimum mean square error (MMSE) receiver is exploited in terms of distance, noise and data rates dependence. packet error rate (PER) analysis has been carried out by using a polynomial regression technique, through the Matlab tool, on simulation results. Simulation results are evaluated in terms of bit error rate (BER) and PER vs. transmitter-receiver distance.

This paper presents a novel call admission control (CAC) algorithm based on the statistical multiplexing of VBR traffic. The proposed algorithm is called statistical multiplexing based on discrete bandwidth levels of GOP rate (SMDB) because the solution is based on the discretisation of the GOP rate in a set of bandwidth levels and on the time characteristics of discrete bandwidth levels of MPEG sources. SMDB is compared with another statistical CAC based on the normal/lognormal distribution of the GOP rate (SMND). SMDB overcomes SMND in many situations such as high variance around the average video traffic GOP rate of sources and heavy traffic load. The new CAC has been tested in the new generation satellite platform called digital video broadcasting via return channel satellite (DVB-RCS). A high system utilization and multiplexing gain respecting QoS constraints is obtained

In the past few years, there has been much research in wireless adaptive networking and resource management, in order to examine how to efficiently handle wireless communications between mobile hosts and base stations. In this paper, we focus the attention on the mobile independent predictive (MIP) service class, which provides a passive reservation policy, with the goal of QoS guarantees during hand-off events. We analyzed MIP users' mobility along coverage areas, to obtain a system utilization improvement, by reducing passive resource reservations on cells that users will probably visit. A prediction technique is also proposed and calls are managed in a wireless system by a utility-based algorithm that takes into account the radio-link quality variability by a Markov channel model, based on the IEEE802.11b standard. System performances are evaluated by varying users' speed and system utilization with prediction error percentages are shown. It is observed that the proposed prediction technique causes an increase in system utilization.