Goby-Acomms version 2: extensible marshalling, queuing, and link layer interfacing for acoustic telemetry

We present the Goby-Acomms project version 2 (Goby2) which provides software for communication amongst autonomous marine vehicles over extremely bandwidth-constrained links. Goby2's modular design provides four discrete yet interoperable components: 1) physics- oriented marshalling via the Dynamic Compact Control Language (DCCL); 2) dynamic priority queuing; 3) time division multiple access (TDMA) medium access control (MAC); 4) and an extensible link-layer interface (ModemDriver). Keywords: Communication protocols; autonomous vehicles; marine systems; telemetry; source codin

Time-Constrained Communication in Multiple Access Networks

The characteristics of time-constrained communication applications,' such as packetized voice, differ significantly from those of standard data communication applications. First, messages not received within a fixed amount of time after their generation at a sending station are considered lost. Secondly, a certain amount of message loss is tolerable. In this thesis we address the problem of supporting time constrained communication applications in a multiple access network. The principal contributions of this thesis fall into two categories. The first contribution is the development and analysis of a new class of protocols for supporting multi-access time-constrained communication. These protocols are based on a generalization of the time window mechanism and provide a family of network-wide message transmission scheduling disciplines based on message generation times. The problem of determining the optimal elements of the protocol's window selection policy is addressed. A semi-markov decision model is formulated for protocol operation and the optimal elements of the windowing policy are found to be both simple and intuitive. The extension of the protocol for transmitting both time-constrained and non-time-constrained messages is considered. In our scheme, time-constrained traffic, when transmitted, receives preemptive priority over other classes of traffic. Several novel analytic performance models are developed and validated through simulation. The protocol's time-constrained performance is found to critically depend on its imposed scheduling function and is significantly better under the optimal windowing policy elements than under other policy elements. For multiple classes of traffic, our results indicate that trading time-constrained message loss against the average delay of non-time-constrained traffic is not usually a viable option. The second major contribution of this thesis is the development of a systematic, formal approach towards distributed optimization via a fictitious resource sharing paradigm and a decentralized "microeconomics" solution to the resource sharing problem. This approach, which draws on previous work In mathematical economics, is successfully used to compute the optimum transmission probabilities for both the time window and Slotted Aloha protocols. Interestingly, several network mechanisms, such as flow control and priorities, are found to emerge naturally from this approach

Combining distributed queuing with energy harvesting to enable perpetual distributed data collection applications

This is the peer reviewed version of the following article: Vazquez-Gallego F, Tuset-Peiró P, Alonso L, Alonso-Zarate J. Combining distributed queuing with energy harvesting to enable perpetual distributed data collection applications. Trans Emerging Tel Tech. 2017;e3195 , which has been published in final form at https://doi.org/10.1002/ett.3195. This article may be used for non-commercial purposes in accordance with Wiley Terms and Conditions for Self-Archiving.This paper presents, models, and evaluates energy harvesting–aware distributed queuing (EH-DQ), a novel medium access control protocol that combines distributed queuing with energy harvesting (EH) to address data collection applications in industrial scenarios using long-range and low-power wireless communication technologies. We model the medium access control protocol operation using a Markov chain and evaluate its ability to successfully transmit data without depleting the energy stored at the end devices. In particular, we compare the performance and energy consumption of EH-DQ with that of time-division multiple access (TDMA), which provides an upper limit in data delivery, and EH-aware reservation dynamic frame slotted ALOHA, which is an improved variation of frame slotted ALOHA. To evaluate the performance of these protocols, we use 2 performance metrics: delivery ratio and time efficiency. Delivery ratio measures the ability to successfully transmit data without depleting the energy reserves, whereas time efficiency measures the amount of data that can be transmitted in a certain amount of time. Results show that EH-DQ and TDMA perform close to the optimum in data delivery and outperform EH-aware reservation dynamic frame slotted ALOHA in data delivery and time efficiency. Compared to TDMA, the time efficiency of EH-DQ is insensitive to the amount of harvested energy, making it more suitable for energy-constrained applications. Moreover, compared to TDMA, EH-DQ does not require updated network information to maintain a collision-free schedule, making it suitable for very dynamic networks.Peer ReviewedPostprint (author's final draft

A-Stack : a TDMA framework for reliable, real-time and high data-rate wireless sensor networks

The reduced size, power consumption and cost of wireless sensors make them an excitingtechnology for many monitoring and control applications. However, developing reliable, realtimeand high data-rate applications is challenging due to time-variations and interference inwireless channels and the medium access delays. For high data-rate and real-time applications,time division multiple access (TDMA) based medium access approach performs better ascompared to carrier sense multiple access (CSMA) based approach. On the other hand,implementation of TDMA in resource constrained wireless nodes requires difficult designdecisions. This document presents A-Stack, a real-time protocol stack for time synchronized, multichanneland slotted communication in multi-hop wireless networks. The stack is developed tomeet the reliability and accuracy requirements of real-time applications such as wirelessautomation and wireless structural health monitoring. A-Stack provides a flexible developmentenvironment for such applications by ensuring deterministic reliability and latency. It includesMAC, routing and time-synchronization protocols as well as a node-joining algorithm. Thestack is further supplemented with PC tools for optimizing the network as per the targetapplication for easy prototyping. This document explains the design and operational aspects ofA-Stack. Various deployment scenarios as well as long term system and communicationreliability tests are presented in the document

A survey of communication protocols for internet of things and related challenges of fog and cloud computing integration

The fast increment in the number of IoT (Internet of Things) devices is accelerating the research on new solutions to make cloud services scalable. In this context, the novel concept of fog computing as well as the combined fog-to-cloud computing paradigm is becoming essential to decentralize the cloud, while bringing the services closer to the end-system. This article surveys e application layer communication protocols to fulfill the IoT communication requirements, and their potential for implementation in fog- and cloud-based IoT systems. To this end, the article first briefly presents potential protocol candidates, including request-reply and publish-subscribe protocols. After that, the article surveys these protocols based on their main characteristics, as well as the main performance issues, including latency, energy consumption, and network throughput. These findings are thereafter used to place the protocols in each segment of the system (IoT, fog, cloud), and thus opens up the discussion on their choice, interoperability, and wider system integration. The survey is expected to be useful to system architects and protocol designers when choosing the communication protocols in an integrated IoT-to-fog-to-cloud system architecture.Peer ReviewedPostprint (author's final draft

Integration of heterogeneous devices and communication models via the cloud in the constrained internet of things

As the Internet of Things continues to expand in the coming years, the need for services that span multiple IoT application domains will continue to increase in order to realize the efficiency gains promised by the IoT. Today, however, service developers looking to add value on top of existing IoT systems are faced with very heterogeneous devices and systems. These systems implement a wide variety of network connectivity options, protocols (proprietary or standards-based), and communication methods all of which are unknown to a service developer that is new to the IoT. Even within one IoT standard, a device typically has multiple options for communicating with others. In order to alleviate service developers from these concerns, this paper presents a cloud-based platform for integrating heterogeneous constrained IoT devices and communication models into services. Our evaluation shows that the impact of our approach on the operation of constrained devices is minimal while providing a tangible benefit in service integration of low-resource IoT devices. A proof of concept demonstrates the latter by means of a control and management dashboard for constrained devices that was implemented on top of the presented platform. The results of our work enable service developers to more easily implement and deploy services that span a wide variety of IoT application domains

Service Virtualisation of Internet-of-Things Devices: Techniques and Challenges

Service virtualization is an approach that uses virtualized environments to automatically test enterprise services in production-like conditions. Many techniques have been proposed to provide such a realistic environment for enterprise services. The Internet-of-Things (IoT) is an emerging field which connects a diverse set of devices over different transport layers, using a variety of protocols. Provisioning a virtual testbed of IoT devices can accelerate IoT application development by enabling automated testing without requiring a continuous connection to the physical devices. One solution is to expand existing enterprise service virtualization to IoT environments. There are various structural differences between the two environments that should be considered to implement appropriate service virtualization for IoT. This paper examines the structural differences between various IoT protocols and enterprise protocols and identifies key technical challenges that need to be addressed to implement service virtualization in IoT environments.Comment: 4 page