Showing papers by "Romano Fantacci published in 2015"

Aggregation and trunking of M2M traffic via D2D connections

Abstract: Machine-to-Machine (M2M) communications is one of the key enablers of the Internet of Things (IoT). Billions of devices are expected to be deployed in the near future for novel M2M applications demanding ubiquitous access and global connectivity. In order to cope with the massive number of machines, there is a need for new techniques to coordinate the access and allocate the resources. Although the majority of the proposed solutions are focused on the adaptation of the traditional cellular networks to the M2M traffic patterns, novel approaches based on the direct communication among nearby devices may represent an effective way to avoid access congestion and cell overload. In this paper, we propose a new strategy inspired by the classical Trunked Radio Systems (TRS), exploiting the Device-to-Device (D2D) connectivity between cellular users and Machine-Type Devices (MTDs). The aggregation of the locally generated packets is performed by a user device, which aggregates the machine-type data, supplements it with its own data and transmits all of them to the Base Station. We observe a fundamental trade-off between latency and the transmit power needed to deliver the aggregate traffic, in a sense that lower latency requires increase in the transmit power.

Resource Allocation Strategies for Network-Coded Video Broadcasting Services Over LTE-Advanced

Abstract: Video service delivery over 3GPP Long Term Evolution-Advanced (LTE-A) networks is gaining momentum with the adoption of the evolved Multimedia Broadcast Multicast Service (eMBMS). In this paper, we address the challenge of optimizing the radio resource allocation process so that heterogeneous groups of users, according to their propagation conditions, can receive layered video streams at predefined and progressively decreasing service levels matched to respective user groups. A key aspect of the proposed system model is that video streams are delivered as eMBMS flows that utilize the random linear network coding (NC) principle. Furthermore, the transmission rate and NC scheme of each eMBMS flow are jointly optimized. The simulation results show that the proposed strategy can exploit user heterogeneity to optimize the allocated radio resources while achieving desired service levels for different user groups.

A novel emergency management platform for smart public safety

Abstract: Summary This paper proposes an efficient architecture of a smart public safety platform that involves public professional operators as well as citizens. The proposed system is compliant with the emerging paradigm of a smart city. Its main features are that of monitoring, forecasting and managing emergency situations, arising from environmental disasters or crimes. The proposed platform performs a smart and functional integration of heterogeneous components as a smart data gathering and analysis system, a novel professional communication system, wireless sensor networks and social networks. Each element acts not only as an information collector but has autonomous capabilities to cooperate with the others in order to increase the system efficiency and to reduce the need of human interactions. Finally, the paper highlights some open research issues that represent critical aspects and require additional investigations in order to further improve the performance of the proposed platform. Copyright © 2013 John Wiley & Sons, Ltd.

Context aware clustering in VANETs: A game theoretic perspective

Abstract: This paper focuses on a particular application of coalitional game theory to Vehicular Ad Hoc Networks (VANET), involving only vehicular-to-vehicular communications. Moreover, networking is performed in an ad hoc basis to pursue full context awareness of vehicles. The proposed approach relies upon the setting up of cluster as soon as convoys temporarily arise in traffic dynamics. First, we define a utility function for each node under the hypothesis of being an ordinary node, cluster head or free node. We further prove that a selfish approach is suboptimal when compared to a game of coalition. Then, the communication between clusters (inter clusters communications) has been implicitly modelled according to this approach. Finally, from the simulation results, it is shown that a coalitional game outperforms a selfish approach for different nodes spatial deployment and mobility patterns.

Buffer-Aided diamond relay network with block fading

Abstract: A simple diamond half-duplex relay network composed of a source, two half-duplex relays, and a destination is considered, where no direct link between the source and the destination is exists. For this network, we investigate the achievable rate when the relays are equipped with buffers. Buffer-aided relays can receive data from the source, store it in their buffers, and forward it to the destination when the channel conditions are more advantageous. Thereby, buffering enables adaptive scheduling of the transmissions and receptions over time, which allows the network to better exploit the diversity offered by the fading channel. For the considered network, because of the half-duplex relays, four transmission modes are employed based on whether the relay nodes receive or transmit. Considering these four transmission modes, in this paper, we derive the optimal transmission mode selection policy such that the received data rate at the destination is maximized. Furthermore, based on numerical examples, we show that the proposed protocol outperforms the existing protocols for the considered network in the literature.

A distributed clustering scheme with self nomination: proposal and application to critical monitoring

Abstract: Clustering is a well known methodology to optimize the use of the resources, to lower the congestion and to improve the reliability in self-organized networks as the wireless sensor networks. This paper deals with the proposal of a novel clustering approach based on a low complexity distributed cluster head election based on a two-stage process. In particular, a suitable objective function is introduced in order to take into account the number of 1-hop neighbours (i.e., node degree) and the residual node energy. It is shown in the paper that the proposed protocol achieves remarkable performance improvements with respect to different alternatives, especially in the case of unpredictable scenarios. Moreover, the proposed protocol exhibits self-organize capabilities that are of special interest for critical monitoring applications, in particular when the effect of nodes mobility is significant.

Aggregation and Trunking of M2M Traffic via D2D Connections

Abstract: Machine-to-Machine (M2M) communications is one of the key enablers of the Internet of Things (IoT). Billions of devices are expected to be deployed in the next future for novel M2M applications demanding ubiquitous access and global connectivity. In order to cope with the massive number of machines, there is a need for new techniques to coordinate the access and allocate the resources. Although the majority of the proposed solutions are focused on the adaptation of the traditional cellular networks to the M2M traffic patterns, novel approaches based on the direct communication among nearby devices may represent an effective way to avoid access congestion and cell overload. In this paper, we propose a new strategy inspired by the classical Trunked Radio Systems (TRS), exploiting the Device-to-Device (D2D) connectivity between cellular users and Machine-Type Devices (MTDs). The aggregation of the locally generated packets is performed by a user device, which aggregates the machine-type data, supplements it with its own data and transmits all of them to the Base Station. We observe a fundamental trade-off between latency and the transmit power needed to deliver the aggregate traffic, in a sense that lower latency requires increase in the transmit power.

An efficient HARQ scheme for applications in multicast communication systems

Abstract: This paper deals with the performance evaluation and optimization of an efficient hybrid automatic repeat request HARQ scheme suitable for applications delivered over lossy multicast communication channels. In particular, different from previously investigated strategies, this paper proposes a modified HARQ scheme based on the symbol combining principle MHARQ-SC where multiple copies of a same packet are consecutively transmitted at each transmission opportunity. By considering as the performance metrics, the mean packet delivery delay, and the energy consumption per information packet, this paper presents suitable performance evaluation and optimization strategies tailored for multicast communications. For the sake of comparisons, it has been also analyzed, under the same operational conditions, the performance of different HARQ schemes optimized for multicast communications. Numerical results have been provided to validate the proposed performance evaluation and optimization approaches in the case of the MHARQ-SC scheme. An important result devised here is that the reported analytical results clearly highlight the performance gain of the proposed strategy in comparison with all the other considered alternatives. Copyright © 2013 John Wiley & Sons, Ltd.

Cognitive Radio Techniques for M2M Environments

Abstract: Machine to Machine (M2M) communications have been recently introduced as a viable paradigm for allowing low cost and efficient communications among devices mainly in an autonomous manner. Even if M2M protocols need dedicated resources, a new paradigm, called Cognitive M2M (CM2M) communications, has been recently considered exploiting cognitive/opportunistic radio communications. After having introduced the problem of applying cognitive techniques in M2M scenarios, the authors focus their attention on the Medium Access Control (MAC) protocols for CM2M scenarios, with a particular attention on the OFDMA-based primary systems. Among other approaches, the authors focus on a data-aided approach for the access of the secondary devices aiming to reduce interference toward the primary system.

Efficient Multicast Beamforming in HetNet with an Opportunistic Cells Activation

Abstract: This paper focuses on coordinated multicell multicast transmissions in Heterogeneous Networks (HetNets). In particular the HetNet Multicast Problem (HMP) is formulated, whose goal is to to improve the quality of the multicast service by maximizing signal to noise ratio (SNR) of the user with the worst channel conditions, but taking into account the energy consumption issue. Indeed, the small cells are activated opportunistically, only when needed, using suitable beamfoming weights. In addition the maximum number of activated small cells can be limited. Then, due to the complexity of the problem a suboptimal iterative solution is proposed and its performance in terms of minimum SNR and energy consumption is validated by means a comparison with other benchmark solutions.

LTE enhancements for Public Safety and Security communications to support Group Multimedia Communications

Abstract: Currently Public Safety and Security communication systems rely on reliable and secure Professional Mobile Radio (PMR) Networks that are mainly devoted to provide voice services. However, the evolution trend for PMR networks is towards the provision of new value-added multimedia services such as video streaming, in order to improve the situational awareness and enhance the life-saving operations. The challenge here is to exploit the future commercial broadband networks to deliver voice and multimedia services satisfying the PMR service requirements. In particular, a viable solution till now seems that of adapting the new Long Term Evolution technology to provide IP-based broadband services with the security and reliability typical of PMR networks. This paper outlines different alternatives to achieve this goal and, in particular, proposes a proper solution for providing multimedia services with PMR standards over commercial LTE networks.

Cognitive Interference Management in Heterogeneous Networks

Abstract: This brief investigates the role of interference management in Heterogeneous Networks (Het Nets), focusing on cognitive approaches and the use of beamforming. Key concepts of Het Nets are introduced and different deployment strategies are examined, such as sharing the same frequency band of the macro cells or using new high frequency bands. Particular attention is devoted to co-channel deployment and to the problem of interference management, addressing various strategies that can be adopted to handle the interference between the cells. In addition, the brief explores cognitive small cells which are able to avoid or limit interference by using suitable beamforming and resource allocation schemes. The suggested solutions are supported by numerical results in terms of performance evaluations and comparisons.

Performance Evaluation of an Adaptive Channel Allocation Technique for Cognitive Wireless Sensor Networks

Abstract: This paper deals with the performance evaluation of a cognitive overlay wireless sensor network relying on a low complexity spectrum sensing technique. In particular, the paper proposes a dynamic channels selection policy in order to improve the performance of a IEEE 802.15.4e sensor overlay network. Further, the paper proposes a suitable analytic model to carry out a performance evaluation analysis, in terms of throughput, packet dropping probability and energy efficiency. The obtained results highlight a remarkable gain with respect to classic approaches, without burdensome cost or complexity.

Sleep period optimization model for layered video service delivery over eMBMS networks

Abstract: Long Term Evolution-Advanced (LTE-A) and the evolved Multimedia Broadcast Multicast System (eMBMS) are the most promising technologies for the delivery of highly bandwidth demanding applications. In this paper we propose a green resource allocation strategy for the delivery of layered video streams to users with different propagation conditions. The goal of the proposed model is to minimize the user energy consumption. That goal is achieved by minimizing the time required by each user to receive the broadcast data via an efficient power transmission allocation model. A key point in our system model is that the reliability of layered video communications is ensured by means of the Random Linear Network Coding (RLNC) approach. Analytical results show that the proposed resource allocation model ensures the desired quality of service constraints, while the user energy footprint is significantly reduced.

Sleep Period Optimization Model For Layered Video Service Delivery Over eMBMS Networks

Abstract: Long Term Evolution-Advanced (LTE-A) and the evolved Multimedia Broadcast Multicast System (eMBMS) are the most promising technologies for the delivery of highly bandwidth demanding applications. In this paper we propose a green resource allocation strategy for the delivery of layered video streams to users with different propagation conditions. The goal of the proposed model is to minimize the user energy consumption. That goal is achieved by minimizing the time required by each user to receive the broadcast data via an efficient power transmission allocation model. A key point in our system model is that the reliability of layered video communications is ensured by means of the Random Linear Network Coding (RLNC) approach. Analytical results show that the proposed resource allocation model ensures the desired quality of service constraints, while the user energy footprint is significantly reduced.

Current and future trends in open source network simulators for wireless systems

Abstract: The impressive standardization activities within the wireless arena require a high degree of interoperability, thus leading to open standards. Even though the benefits are evident for this, the overall system is usually more complex, with tightly coupled protocol interactions. For this reasons, the protocol suite optimization is still an open issue. In particular, it is essential to carefully investigate the overall resulting performance before industrial development and real-world deployment. Since a real testbed is often extremely costly, an Open Source network simulator can represent a valid alternative to real device development and testbed deployment for academic and industrial research goals. In this chapter, the most relevant simulation frameworks are introduced and compared in terms of the following capabilities: • To implement standard protocols in order to optimize the performance for a specific scenario; • To build an approximate (i.e., not overly detailed) model, both analytical or functional, of the scenario; • To allow system parameters modification; • To be capable of going beyond the standards, in order to propose amendments or new standards; • To test and evaluate application-level protocols or, more generally, applications. Afterwards, we focus on the ns-3 framework, describing its actual models for IEEE 802.11, IEEE 802.15.4 and LTE/LTE-A systems and pointing out the most relevant features of the simulator. To conclude, some relevant simulation examples are shown, together with concluding remarks, pointing out ongoing development efforts.

Downlink cross-layer scheduling strategies for long-term evolution and long-term evolution-advanced systems

Abstract: The most recent trend in the Information and Communication Technology world is toward an ever growing demand of mobile heterogeneous services that imply the management of different quality of service requirements and priorities among different type of users. The long-term evolution LTE/LTE-advanced standards have been introduced aiming to cope with this challenge. In particular, the resource allocation problem in downlink needs to be carefully considered. Herein, a solution is proposed by resorting to a modified multidimensional multiple-choice knapsack problem modeling, leading to an efficient solution. The proposed algorithm is able to manage different traffic flows taking into account users priority, queues delay, and channel conditions achieving quasi-optimal performance results with a lower complexity. The numerical results show the effectiveness of the proposed solution with respect to other alternatives. Copyright © 2013 John Wiley & Sons, Ltd.

Enhance the QoE for smartphone applications: An API approach for QoS control in LTE-A

Abstract: In this paper, we propose a novel architecture to address the problem of application Quality of Experience (QoE) management for rapidly evolving and heterogeneous network scenarios. The proposed architecture can be used for mixed Long Term Evolution Advanced (LTE-A) and Wi-Fi systems, and it can be used to enhance the effectiveness of next-generation Software Defined Network (SDN). Thanks to the elements described in this paper, the Applications can interact in a secure and controlled way with the network QoE management entities. This allows to have a better system flexibility, scalability and enables to use advanced QoE support mechanisms for rapidly evolving user scenarios.

MIMO cooperative spectrum sensing in hybrid satellite/terrestrial scenario

Abstract: In a hybrid satellite/terrestrial scenario, the paper analyzes the advantages of using a cooperative scheme combined with Multiple-Input Multiple- Output (MIMO) technologies at each cognitive radio (CR) node for spectrum sensing. In the proposed scenario, the satellite and the terrestrial components use the same band (primary users) and a group of secondary users (sensors or mobile users) want to dynamically share the spectrum without harmful interference on primary user (PU). The satellite can also report measures provided by the group of secondary users to a remote center in an area where the mobile coverage it is difficult to extend or for emergency situations. The joint use of multiple antennas at each CR node and cooperative cognitive radio scheme is analyzed to improve the performance of the conventional energy detector (ED) and to increase the reliability in PU detection. A coordination center (CC) takes the final decision based on the detections carried out by all the CRS. Moreover, the CC can manage a strategy to allow equal and fare share of the radio resources to the group of CR nodes. The use of improved energy detector based on the average power of received samples is also analyzed. Simulation results show that the use of cooperation and MIMO technologies improves the detection even at low value of signal to noise ratio (SNR) and a trade off-it is necessary among the number of multiple antennas, the number of samples and the spectrum usage efficiency and the level of interference on the PU.

User initiated fast identity switch between LTE UEs

Abstract: In the last few years smartphones have increased their capabilities in terms of hardware and software. They are used for many purposes beyond the simple calls and messaging. Presently, industries are focusing on smartphone-devices integration. As a matter of fact, car-smartphone integration is an ever increasing field, even though the car equipments are still used as phone accessories. Our goal is enhancing the user's experience by extending the concept of smartphone interface. We propose a new method where the device itself becomes their new User Equipment (UE) instead of being simply a smartphone interface. Our idea is to transfer all the user profile from the smartphone to the device. In this way, it is possible to use different devices each one having specific characteristics. We are convinced that this paves the way to many new possibilities in term of services. In this paper we propose a method of transferring temporarily the references to the user's identity carried in a Universal Subscriber Identity Module (USIM), from a UE to another one. This is possible by leveraging current interfaces between elements of the Evolved Packet Core (EPC) and by exchanging new messages.

Interference Management in HetNets

Abstract: The capacity and the coverage of any wireless network can be improved in terms of efficiency by moving the transmitter and the receiver closer together. Therefore, the concept of small cells overlapping with traditional macrocells is gaining considerable research attention. However, the mass deployment of HetNets introduces certain challenges that must be addressed to ensure that the expected benefits of the deployment are realized. Among these challenges, interference management is one of the most important when considering co-channel HetNet deployment, where the small cells and the macrocells share the same frequency spectrum. Different approaches can be adopted, depending on several aspects. These include the specific network scenario, the computational capacity of the devices used, the backhaul link and various other factors. This chapter describes the main concepts of interference management in HetNets when they are deployed using a spectrum sharing approach. It also provides an overview of the best known interference management approaches.

Cognitive Resource Allocation with Beamforming

Abstract: As we discussed in depth in the previous Chapters, the dense deployment of cells in HetNets means that the inter-layer interference in these networks must be handled appropriately to realize the actual benefits of HetNets. In particular, it becomes very challenging when there is zero or limited coordination among the cells, and cognitive capabilities and opportunistic use of the available resources are thus required. With that background, this Chapter describes potential cognitive approaches to both reduce the co-channel interference that arises from the coexistence of heterogeneous cells and increase the small cell capacity. The approaches described here consider the use of multiple antenna technology to use the angular dimension as a new spectrum opportunity. The small cell models its transmissions by placing nulls in the directions of the MUEs, thus protecting the macrocell DL transmissions. In addition, the small cell performs an appropriate resource allocation process for its UE to increase its communication capacity. The MuSiC algorithm is used to estimate the DoAs of the UE signal replicas in an indoor environment, assuming a variable number of multipath components that are characterized by a very large angle spread. The quality of the solutions described in this chapter is shown by providing a performance comparison with other benchmark methods in terms of both small cell capacity and the BER of the macrocell DL.