A cross-layer jitter-based TCP for wireless networks

The Transmission Control Protocol (TCP) is one of the main communication protocols in the Internet, and it has been designed to provide an efficient reaction to packet loss events which are due to network congestion. Congestion is the main cause of losses in wired networks, but in today heterogeneous networks, loss events can also be introduced due to higher error rates on wireless channels, host mobility, and frequent handovers. Unfortunately, all packet losses are interpreted by TCP as a sign of congestion, triggering an inappropriate reaction which reduces its transmission rate and leads to performance degradation. In order to avoid this problem, it is important for TCP to correctly understand whether the reason of a packet loss is due to congestion or to a problem in the wireless link. This paper presents an innovative jitter-based cross-layer TCP algorithm, named XJTCP. It adopts the jitter ratio as loss predictor, joined with a layer two notification, in order to correctly infer the nature of a loss event. Performance evaluation and comparison with other common TCP implementations shows how XJTCP can be an interesting solution in the presence of wireless environments

A wireless sensor network framework for real-time monitoring of height and volume variations on sandy beaches and dunes

In this paper, the authors describe the realization and testing of a Wireless Sensor Network (WSN) framework aiming at measuring, remotely and in real time, the level variations of the sand layer of sandy beaches or dunes. The proposed framework is based on an innovative low cost sensing structure, able to measure the level variations with a 5-cm degree of precision and to locally transfer the acquired data through the ZigBee protocol. The described sensor is integrated in a wider ZigBee wireless sensor network architecture composed of an array of sensors that, arranged according to a grid layout, can acquire the same data at different points, allowing the definition of a dynamic map of the area under study. The WSN is connected to a local Global System for Mobile Communications (GSM) gateway that is in charge of data processing and transmission to a cloud infrastructure through a General Packet Radio Service (GPRS) connection. Data are then stored in a MySQL database and made available any time and anywhere through the Internet. The proposed architecture has been tested in a laboratory, to analyze data acquisition, processing timing and power consumption and then in situ to prove the effectiveness of the system. The described infrastructure is expected to be integrated in a wider IoT architecture including different typologies of sensors, in order to create a multi-purpose tool for the study of coastal erosive processes

An IoT Smart Environment in Support of Disease Diagnosis Decentralization

The percentage of seniors in the global population is constantly growing and solutions in the field of fall detection and early detection of neuro-degenerative pathologies have a crucial role in order to increase life expectancy and quality of life. This study aims to extend fall detection and effective recognition of early signs of diseases to new smart environments, conceiving the decentralization of diagnostic monitoring in everyday life activities in a more pervasive paradigm. Inspiring to research outcomes, in this work an architecture is designed to detect falls in crowded indoor environments during events/exhibitions, for favoring a timely and effective intervention. It also foresees a continue monitoring of the gait for seniors during the visit, thus extracting key features which are stored on a dedicated database. The proposed solution allows third party researchers to perform analysis on the obtained gait datasets, through the adoption of advanced data-mining techniques for the detection of early signs of neuro-degenerative diseases and other pathologies. The architecture designed here aims to provide a step forward concerning the extension of smart monitoring environments for the detection of falls and early signs of pathologies in everyday life, in a more pervasive and decentralized paradigm

Watermill principle applied to energy harvesting for sensor nodes in underground environments

This paper describes an energy harvesting solution for a wireless sensor node based on the watermill principle. This solution has been conceived to be employed for the realization of monitoring infrastructures to be deployed in underground water lines like aqueducts or drainage systems. In particular, this solution has been developed to be employed in a Wireless Sensor Network for the monitoring of the 'Bottini' (the ancient medieval aqueduct) running under the streets of the Historic Centre of Siena, Italy. Through the proposed harvesting system the sensor nodes are able to operate autonomously for long spans of time, allowing the real time remote monitoring of critical environmental parameters that are crucial for the preservation of this cultural site. The power generation system includes a waterwheel exploiting the water flow of the aqueduct to drive an electric motor, and a power control system, in order to manage the power accumulation and the energy consumption of the sensor node. The operation of the whole architecture has been tested in laboratory in order to prove the effectiveness of the solution and its possible use in the real scenario

Wireless Application Protocol (WAP)

The explosive growth of the Internet has fuelled the creation of new and exciting information services. Most of the original technology developed for Internet services has been designed for large computers with medium-to-high bit-rate transmission capabilities, large displays, a keyboard and a mouse as input devices. Whereas, mobile devices have small displays and are constrained in terms of CPU processing capacity, available memory, energy consumption, displays size and input methods (i.e., there is not a mouse). An interesting approach for allowing the mobile access to the Internet is provided by Wireless Application Protocol (WAP), a comprehensive and scalable protocol stack designed for use with diverse mobile phones, several network bearers, many mobile network standards and different operating systems. This chapter focuses on WAP key aspects, capabilities and limitations. The whole protocol stack of WAP is introduced and its service architecture is described

QoS enhancement with dynamic TXOP allocation in IEEE 802.11e

The transmission opportunity (TXOP) mechanism defined in the IEEE 802.11 e Hybrid Coordination Function (HCF) is not optimized to meet the QoS requirements of heterogeneous applications, since it is usually allocated by default according to the different Access Categories (AC). In this paper we propose a new algorithm, named DTXOP, for the dynamic assignment of the TXOP maximum duration at the Access Point (AP) of an IEEE 802.lie WLAN. DTXOP is periodically updated according to the current traffic conditions of each specific AC. Simulation experiments show that DTXOP allows to enhance delay and throughput performance and to maintain fairness between upstream and downstream channel access times

A new NS2 tool to investigate QoS management over mobile WiMAX

WiMAX is one of the most interesting solutions for broadband wireless access, supporting multimedia traffics and applications through an appropriate QoS flow management both for fixed and mobile devices. To study its performance and to test new functionalities, simulation tools play a central role. In this paper we propose a new simulation module compliant to IEEE 802.16. Our key contribution is to offer the research community a useful tool for the investigation of QoS management on mobility in the WiMAX scenario. The developed tool includes the implementation of five QoS classes and of handover procedures. This module is validated and tested through exhaustive simulations, showing its conformance with the defined specifications

A WiMAX simulation module for investigating QoS during horizontal handovers

WiMAX is one of the most interesting solutions for broadband wireless access, supporting multimedia traffic and applications through an appropriate QoS management for fixed and mobile devices. Simulation tools play a central role to study network performance and to test new functionalities. In this paper we propose a new simulation module, compliant to IEEE 802.16e, which implements the five WiMAX QoS classes and handover procedures as well, so as to support investigations on QoS management during mobility in WiMAX scenarios. The developed tool has been validated and tested through exhaustive simulations, showing its conformance with the defined specifications

Low-Power IoT for Monitoring Unconnected Remote Areas

This paper deals with IoT devices deployed in remote areas without terrestrial Internet connectivity. We consider connecting IoT devices on the ground to the Internet through an aerial system based on an Unmanned Aerial Vehicle (UAV) for smart agriculture and environmental monitoring. The UAV flying over the remote area receives data from distributed IoT devices. The transmissions between the ground sensors and the UAV are carried out via LoRa. We have proposed a synchronization protocol for the opportunistic communication of LoRa IoT devices with a gateway onboard the UAV to save node battery life. Class A LoRa nodes on the ground transmit only when the UAV is expected to pass close to them; otherwise, they stay in the sleeping state most of the time. This paper provides a detailed description of the formulation of the synchronization protocol. The UAV’s flying dynamics have been considered for characterizing its speed and the time of visibility of each IoT sensor. Our model has allowed an analytical approach that can help to determine the best settings for LoRa transmissions. Finally, experiments have been carried out to assess the path loss attenuation, and a laboratory setup of the synchronization protocol has been implemented for the preliminary validation of our scheme