1,721,055 research outputs found
A Stochastic Approach for Resource Prediction Error and Bandwidth Wastage Evaluation in Advanced Dynamic Reservation Strategies
No full textMany 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
Mitigating DoS attacks in IoT EDGE Layer to preserve QoS topics and nodes' energy
No full textNumerous challenges prevent the securing of IoT devices and their end-to-end communication in an IoT environment. The IoT is currently widely used in many areas such as in smart cities, in advanced logistic systems, in smart home etc. The safety and security of such systems are key aspects to guarantee the quality of their services. The purpose of this work is to model and evaluate a new IoT security system in a fog/edge network where there are lightweight nodes exchanging messages through the Message Queue Telemetry Transport (MQTT) protocol. This work aims to increase the security of this protocol at the application level, particularly mitigating data tampering and eavesdropping by using Elliptic Curve Cryptography (ECC), and applying different security mechanisms to the data topics. This feature allows to apply a threshold-based packet discarding policy for preserving the Quality of Service (QoS) of MQTT topics
DS-SS UWB wireless personal area network: BER and PER evaluation under an MMSE receiver
No full textThis paper focuses on the performance evaluation of a Direct Sequence - Spread Spectrum (DS-SS) Ultra Wideband (UWB) network in an indoor environment where receiver and transmitter positions are fixed. In particular, a novel distance and time dependent impulse response has been obtained and considered for our performance evaluation. Moreover, from receiver side, a Minimum Mean Square Error (MMSE) receiver has been considered in order to get the Bit Error Rate (BER) and Packet Error Rate (PER) estimation in many simulation conditions where distance, data rates and noise level are changed. PER analysis has been carried out by using a polynomial regression technique, through the Matlab tool, on simulation results. BER and PER vs. transmitter-receiver distance and number of users performance evaluations have been outlined
A Predictive Cross-Layered Interference Management in a Multichannel MAC with Reactive Routing in VANET
No full textVehicular 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 co-channel 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
A simulator for drones and Fanet management supporting multimedia traffic under human mobility
Full text linkIn 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
Adaptive reservation in WLAN networks under smooth random mobility model
No full textThis papers presents a novel technique to predict the number of WLAN cells visited by a mobile host during its call holding time. 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 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, as a method for QoS guarantees, lower bandwidth wastage and higher system utilisation. An integrated architecture able to make active and passive reservations has been applied as possible application of the proposed approach. Simulation results have been carried out and an interesting bandwidth management usage has been observed
Bio-inspired routing over FANET in emergency situations to support multimedia traffic
No full textA QoS routing to select the best paths among Drones supporting incoming calls and multimedia traffic in emergency or critical situations is proposed. In situations where drones' teams are requested to cover areas where mobile users can need to communicate under the absence of network infrastructure, a self-organized on-the fly network becomes an essential goal. Cooperating with a critical network infrastructure, deploying a QoS aware path selection strategy supporting QoS requests and multimedia traffic such as VoIP and Video traffic can become a key issue to face. In this paper, a bio-inspired strategy to maintain the drones' network topology in a ligthway manner is proposed. Two metrics considered in a joint unified metric are proposed in order to balance traffic load and, at the same time, select the shortest routes. A comparison with an enhanced Link-State (LS) routing has been performed where the minimum hop count metric has been considered together to a LS routing with maximum available bandwidth metric. Performance evaluation has been evaluated in terms of control overhead, number or admitted calls, average bandwidth utilization
Prediction and QoS Enhancement in New Generation Cellular Networks with Mobile Hosts: A Survey on Different Protocols and Conventional/Unconventional Approaches
No full textNowadays, interest in mobile communications is growing rapidly due to the high level of device development, which permits the achievement of good objectives in terms of quality of service (QoS) for user satisfaction during active data flows. The increasing mobile client populations use different mobile devices to access the wireless medium and many applications are being developed to satisfy eager client requirements. Independently on the considered architecture (WLAN, UMTS, LTE, etc.), mobility represents a great advantage for user comfort, but it needs to be managed in an adequate manner in order to avoid service disruptions or unacceptable degradation of the perceived quality. In this paper, the concept of cell-mobility prediction is considered and we show how the analysis of user behavior, in terms of mobility, can be exploited to enhance QoS levels in current communications among mobile hosts and base stations (coverage cells, in general). This paper surveys different unconventional approaches and protocols, showing how it is possible to consider in-advance bandwidth reservations to achieve service continuity, avoiding call droppings during active sessions. First, we present the importance of in-advance reserving in wireless cellular networks, then we discuss the existing protocols and approaches for determining the most suitable future cells
Interference Aware-based Ad-Hoc on Demand Distance Vector (IA-AODV) ultra wideband system routing protocol
No full textUltra wideband (UWB) systems are communication systems based on a baseband impulsive transmission that has recently excited interest both in the commercial and academic fields. Physical layer aspects and MAC protocols have been intensively investigated in the recent years leading, in some cases, to important and definitive results. However, many questions relating to the UWB network layer are still open. The aim of this paper is to investigate the network layer of the UWB system: for this purpose a new routing protocol called Interference Aware-based Ad-Hoc On Demand Distance Vector (IA-AODV) and based on the interference concept has been proposed. In particular, two distinct metrics are explained in detail: the first one is based on the concept of global interference perceived by each node; the second one is based on the concept of link interference perceived by a node on a wireless path to a generic neighbor. Finally, a comparative analysis between our protocol and Ad-Hoc On Demand Distance Vector (AODV) protocol are carried out in order to show the soundness of our proposal. © 2011 Elsevier B.V. All rights reserved
Mobility independent and dependent predictive services management in wireless/mobile multimedia network
No full textIn this paper the attention is focused on the management of services independent and dependent from mobility in the adaptive multimedia networking, where the bandwidth of an ongoing multimedia flow can be dynamically adjusted. Two classes of services have been considered: MIP and MDP classes defined in Integrated Services for mobile wireless environment. In order to offer an adaptive QoS (soft QoS) increasing the total wireless system utilization, a rate adaptation algorithm has been considered. The valued algorithm is based on user utility function and its target is to maximize this function. The mobility of host can impact on number of handoff and on channel states (fading), so the rate adaptation accounts the degradation channel state conditions. An algorithm of admission control has been considered too in order to regulate the access to wireless multimedia network. The admission control can use the pre-reservation phase among potentially visited cells from mobile hosts for MIP services and consider only the bandwidth availability on current cells for MDP services. The performance evaluations of the wireless system have been evaluated in terms of total bandwidth utilization for MIP and MDP services, average user utility perceived by mobile users and system outage probability. © 2004 IEEE
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