Laura Galluccio

Software Defined Wireless Networks: Unbridling SDNs

The software defined networking (SDN) paradigm promises to dramatically simplify network configuration and resource management. Such features are extremely valuable to network operators and therefore, the industrial (besides the academic) research and development community is paying increasing attention to SDN. Although wireless equipment manufacturers are increasing their involvement in SDN-related activities, to date there is not a clear and comprehensive understanding of what are the opportunities offered by SDN in most common networking scenarios involving wireless infrastructureless communications and how SDN concepts should be adapted to suit the characteristics of wireless and mobile communications. This paper is a first attempt to fill this gap as it aims at analyzing how SDN can be beneficial in wireless infrastructureless networking environments with special emphasis on wireless personal area networks (WPAN). Furthermore, a possible approach (called SDWN) for such environments is presented and some design guidelines are provided.

SDN-WISE: Design, prototyping and experimentation of a stateful SDN solution for WIreless SEnsor networks

In this paper SDN-WISE, a software defined networking (SDN) solution for wireless sensor networks, is introduced. Differently from the existing SDN solutions for wireless sensor networks, SDN-WISE is stateful and pursues two objectives: (i) to reduce the amount of information exchanged between sensor nodes and the SDN network controller, and (ii) to make sensor nodes programmable as finite state machines so enabling them to run operations that cannot be supported by stateless solutions. A detailed description of SDN-WISE is provided in this paper. SDN-WISE offers APIs that allow software developers to implement the SDN Controller using the programming language they prefer. This represents a major advantage of SDN-WISE as compared to existing solutions because it increases flexibility and simplicity in network programming. A prototype of SDN-WISE has been implemented and is described in this paper. Such implementation contains the modules that allow a real SDN Controller to manage an OMNeT++ simulated network. Finally, the paper illustrates the results obtained through an experimental testbed which has been developed to evaluate the performance of SDN-WISE in several operating conditions.

MACRO: an integrated MAC/routing protocol for geographic forwarding in wireless sensor networks

Sensor networks are characterized by limited battery supplies. Due to this feature, communication protocols specifically designed for these networks should be aimed at minimizing energy consumption. To this purpose, the sensors capability of transmitting with different power levels can be exploited. With this in mind, in this paper an integrated MAC/routing protocol, called MACRO, which exploits the capability of sensor devices to tune their transmission power is introduced. The proposed protocol requires that each node only knows its own coordinates and the coordinates of the destination, but does not require any exchange of location information. In order to select the next relay node, a competition is triggered at each hop, so that the most energy efficient relay node is chosen. This is achieved through maximization of a newly introduced parameter, called weighted progress factor, which represents the progress towards the destination per unit of transmitted power. To this aim, an analytical framework which guarantees that MACRO performs the best choice is derived. MACRO performance is evaluated through ns-2 simulation and compared to other relevant routing schemes. Performance results show that the proposed protocol outperforms other solutions in terms of energy efficiency and boosts data aggregation.

Challenges and implications of using ultrasonic communications in intra-body area networks

Body area networks (BANs) promise to enable revolutionary biomedical applications by wirelessly interconnecting devices implanted or worn by humans. However, BAN wireless communications based on radio-frequency (RF) electromagnetic waves suffer from poor propagation of signals in body tissues, which leads to high levels of attenuation. In addition, in-body transmissions are constrained to be low-power to prevent overheating of tissues and consequent death of cells. To address the limitations of RF propagation in the human body, we propose a paradigm shift by exploring the use of ultrasonic waves as the physical medium to wirelessly interconnect in-body implanted devices. Acoustic waves are the transmission technology of choice for underwater communications, since they are known to propagate better than their RF counterpart in media composed mainly of water. Similarly, we envision that ultrasound (e.g., acoustic waves at non-audible frequencies) will provide support for communications in the human body, which is composed for 65% of water. In this paper, we first assess the feasibility of using ultrasonic communications in intra-body BANs, i.e., in-body networks where the devices are biomedical sensors that communicate with an actuator/gateway device located inside the body. We discuss the fundamentals of ultrasonic propagation in tissues, and explore important tradeoffs, including the choice of a transmission frequency, transmission power, bandwidth, and transducer size. Then, we discuss future research challenges for ultrasonic networking of intra-body devices at the physical, medium access and network layers of the protocol stack.

Transmission of VoIP traffic in multihop ad hoc IEEE 802.11b networks: experimental results

In the last decade numerous studies have been carried out into the transmission of VoIP traffic over wireless networks. However, only a few works have addressed the topic of supporting real-time audio applications on multi-hop IEEE 802.11 ad hoc networks from the perspective of simulations and testbeds. This paper presents the results of the implementation of a VoIP testbed on a multihop IEEE 802.11b ad hoc network with stationary hosts. The real-time audio transmission is evaluated using two different multihop routing protocols, AODV and OLSR. The quality of the voice transmission, using different codecs, is measured through different performance metrics such as end-to-end delay, delay jitter and sequence number error.

A MAC/Routing cross-layer approach to geographic forwarding in wireless sensor networks

Geographic forwarding is an emerging paradigm for communications between nodes in sensor networks. No exchange of location information is required, and nodes only have to know their own coordinates and those of the destination. Due to the devices limited processing and storage capabilities, a simplified protocol architecture should be designed so as to make communications in these networks efficient and simple at the same time. Moreover, sensor nodes are battery supplied and, thus, protocol design should be aimed at reducing energy consumption in order to increase network lifetime. In this perspective, one sensor feature recently regarded as of key importance, is the ability to tune the transmission power. This allows the communication range to be varied according to node density and connectivity constraints. In this paper we propose an integrated cross-layer protocol, called MACRO, which integrates MAC and routing layer functionalities in order to support geographic forwarding in wireless sensor networks. In MACRO, a competition is triggered to select the best next relay node while forwarding information to the destination. The competition is based on the evaluation of a weighted progress factor representing the progress towards the destination per unit of transmission power. An analytical paradigm facilitating the most appropriate choice of the next relay is proposed. The proposed solution is assessed through both analysis and ns-2 simulations. Performance results show the advantages of the proposed solution when compared to other geographic forwarding protocols which do not exploit cross-layer features.

Networked Labs-on-a-Chip (NLoC): Introducing networking technologies in microfluidic systems

Abstract Microfluidics is a science and a technology which deals with manipulation and control of small volumes of fluids flowing in channels of micro-scale size. It is currently used for Labs-On-a-Chip (LoCs) applications mainly. In this context, recently fluids have been used in the discrete form of droplets or bubbles dispersed into another immiscible fluid. In this case, droplets or bubbles can be exploited as a means to transport digital information between microfluidic components, with sequences of particles (i.e. droplets or bubbles) representing sequences of binary values. LoCs are today realized through monolithic devices in which samples are processed by passing them through a predetermined sequence of elements connected by fixed and preconfigured microfluidic channels. To increase the reusability of LoCs, effectiveness and flexibility, networking functionalities can be introduced so that the sequence of elements involved in the processing can be dynamically selected. Accordingly, in this paper we introduce the Networked LoC (NLoC) paradigm that brings networking concepts and solutions into microfluidic systems such as LoCs. More specifically, in this paper the need for the introduction of the NLoC paradigm is motivated, its required functions are identified, a system architecture is proposed, and the related physical level design aspects, such as channel characterization, information representation and information capacity are investigated.

Analytical evaluation of a tradeoff between energy efficiency and responsiveness of neighbor discovery in self-organizing ad hoc networks

Ad hoc networking enables novel communication paradigms which require the definition of new quality-of-service (QoS) parameters and frameworks for QoS support. The relevant QoS requirements are frequently antagonist and, consequently, an appropriate tradeoff has to be determined and achieved to fit all of them. As an example, the spontaneous networking featured by self-organizing ad hoc networks is possible only if neighboring communication nodes discover each other within a short period of time; however, velocity of discovery is paid in terms of energy consumption. In this paper, an analytical framework is derived which allows an evaluation of the tradeoff between energy efficiency and responsiveness in the discovery process. More specifically, the analytical framework allows either to achieve the highest velocity in the discovery process, given that the energy consumption is lower than a certain threshold, or to minimize the energy consumption given that specific requirements in terms of the discovery velocity are satisfied. The analytical framework is applied to significant case studies to derive design implications on neighbor discovery algorithms.

Medium access control and rate adaptation for ultrasonic intrabody sensor networks

The use of wirelessly internetworked miniaturized biomedical devices is promising a significant leap forward in medical treatment of many pervasive diseases. Recognizing the limitations of traditional radio-frequency wireless communications in interconnecting devices within the human body, in this paper, we propose for the first time to develop network protocols for implantable devices based on ultrasonic transmissions. We start off by assessing the theoretical feasibility of using ultrasonic waves in human tissues and by deriving an accurate channel model for ultrasonic intrabody communications. Then, we propose a new ultrasonic transmission and multiple access technique, which we refer to as Ultrasonic WideBand (UsWB). UsWB is based on the idea of transmitting information bits spread over very short pulses following a time-hopping pattern. The short impulse duration results in limited reflection and scattering effects, and the low duty cycle reduces the impact of thermal and mechanical effects, which may be detrimental for human health. We then develop a multiple access technique with distributed control to enable efficient simultaneous access by mutually interfering devices based on minimal and localized information exchange and on measurements at the receiver only. Finally, we demonstrate the performance of UsWB through a multiscale simulator that models the proposed communication system at the acoustic wave level, at the physical (bit) level, and at the network (packet) level. We also validate the simulation results by comparing them to experimental results obtained with a software-defined testbed.

Ultrasonic networking for E-health applications

Wirelessly networked systems of intra-body sensors and actuators could enable revolutionary applications at the intersection between biomedical science, networking, and control with a strong potential to advance medical treatment of major diseases of our times. Yet, most research to date has focused on communications along the body surface among devices interconnected through traditional electromagnetic radio-frequency (RF) carrier waves; while the underlying root challenge of enabling networked intra-body miniaturized sensors and actuators that communicate through body tissues is substantially unaddressed. The main obstacle to enabling this vision of networked implantable devices is posed by the physical nature of propagation in the human body. The human body is composed primarily (65 percent) of water, a medium through which RF electromagnetic waves do not easily propagate, even at relatively low frequencies. Therefore, in this article we take a different perspective and propose to investigate and study the use of ultrasonic waves to wirelessly internetwork intra-body devices. We discuss the fundamentals of ultrasonic propagation in tissues, and explore important tradeoffs, including the choice of a transmission frequency, transmission power, and transducer size. Then, we discuss future research challenges for ultrasonic networking of intra-body devices at the physical, medium access and network layers of the protocol stack.