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Internet blackouts are challenging environments for anonymity and censorship resistance. Existing popular anonymity networks (e.g., Freenet, I2P, Tor) rely on Internet connectivity to function, making them impracticable during such blackouts. In such a setting, mobile ad-hoc networks can provide connectivity, but prior communication protocols for ad-hoc networks are not designed for anonymity and attack resilience. We address this need by designing, implementing, and evaluating Moby, a blackout-resistant anonymity network for mobile devices. Moby provides end-to-end encryption, forward secrecy and sender-receiver anonymity. It features a bi-modal design of operation, using Internet connectivity when available and ad-hoc networks during blackouts. During periods of Internet connectivity, Moby functions as a regular messaging application and bootstraps information that is later used in the absence of Internet connectivity to achieve secure anonymous communications. Moby incorporates a model of trust based on users’ contact lists, and a trust establishment protocol that mitigates flooding attacks. We perform an empirically informed simulation-based study based on cellphone traces of 268,596 users over the span of a week for a large cellular provider to determine Moby’s feasibility and present our findings. Last, we implement and evaluate the Moby client as an Android app.

The paper is devoted to the analysis of the effectiveness of the DTN (delay tolerant network) system in a communication network on a railway line. Trains act as moving objects that are sending and receiving messages to/from an external network. Trains may also transmit telemetry collected during movement. The article presents data on the effectiveness of the DTN network with various protocols in terms of reducing the delay in the message and telemetry delivery and in increasing the total number of delivered messages in the railway scenario. An analysis of railway lines with various loads and different coverage of mobile networks was made. These models are based on real railway maps and train schedules. The effectiveness of DTN during migration to networks of a higher data rate (5G) and networks with satellite connection of trains is discussed.

Vehicular delay tolerant network (VDTN) technology uses vehicles on the road as moving nodes to deliver data from source to destination using several intermediate nodes. Efficient data dissemination in VDTN is a difficult problem due to existing trade-offs between several metric variables such as delivery ratio, delay, and overhead ratio. Inclusion of important social network parameters (like community, social strength, trust, friendship, and selfishness) in computation of forwarding probability may help to improve the performance of a routing algorithm. However, different tuning of these parameters results in different outcomes for the metric variables. A proper balancing of these parameters may result in an optimized outcome solving the trade-off between the metric variables. Nonetheless, dependency of the variables on a number of social network parameters and their mutual trade-offs makes this a non-trivial optimization problem. In this paper, we propose a novel approach to optimize these trade-offs using multi-objective particle swarm optimization (MOPSO). The proposed approach provides a set of pareto-optimal solutions also known as non-dominating solutions. Further, based on the requirements of a target application scenario, a specific optimal solution out of the pareto-optimal solution set is delivered using artificial intelligence (AI) technique. The proposed methodology is simulated in a VDTN scenario using the opportunistic network environment (ONE) simulator and Matlab. Furthermore, based on the experimental results, an exhaustive analysis is provided about how the metric variables are affected by the involvement of the social-based parameters. The capabilities of the proposed approach are validated using a statistical comparative analysis of the results. In future, the outcome of the study may play a helpful role to decide the priorities of the network parameters while designing new data dissemination algorithms for VDTN.

Wireless communication remains to be the most efficient way of providing access to information to users in developing economies. We are interested in Delay-Tolerant Networks (DTNs) for distributing multimedia content to micro-entrepreneurs in under-served rural areas of South Africa. In our project, public commuter buses carrying WLAN-enabled devices (mobile infostations) that provide DTN connectivity are used to ferry data between urban and rural areas. Before the actual deployment in the field, rigorous lab experiments have been performed to study the performance of the proposed network design. Such an activity is time consuming and requires arduous preparation. Simulators, while convenient, do not provide the most realistic results. Given the complexity of DTN testing, we try to find a middle ground approach by building a mobility emulator testbed, which we use to emulate the network scenario. In this paper, we outline the design and implementation details of the network emulator. We then describe the experiments that were performed to study the impact of different network dynamics on content delivery, and their results. The results from the experiments are used to improve our current network design.

Recently, Delay Tolerant Network (DTN) is used to cope with disaster response environment where infrastructure is unavailable for a long run. In such situation, cooperation among nodes is very essential to forward urgent situational information from different disaster affected corners. However, due to existence of some selfish and non-cooperative nodes could cause catastrophic damage to cooperative communication and can jeopardize whole network. Researchers have devoted their work to address this problem by assigning reputation of nodes based on interaction pattern. The major drawback of these schemes is nodes with bad reputation are discarded which results less number of available nodes for delivering messages. To alleviate this problem, literatures suggest incentive based mechanism to stimulate nodal collaboration. Many incentive based schemes are proposed to motivate nodes to cooperate in data dissemination. Due to intermittent connectivity, DTN nodes can acquire correct information about the local transactions occurring in their neighbourhood but they have limited knowledge about the transactions occurring in other parts of the network. Therefore, possibility of double spending poses a serious threat in crypto currency based transactions occurring in post disaster communication network. A user may spend same single token more than once due to malevolence and ask for reimbursement multiple times. Here, credit based incentive scheme, iCredit is proposed that uses credits in terms of signed crypto_coin to motivate nodes to cooperate and to prevent double spending without involving trusted third party. Detailed analysis and extensive simulation results demonstrate the efficiency and efficacy of the proposed scheme.

In vehicular ad-hoc network, vehicles are move very speedy thus their topology is changing frequently and intermittent connectivity occur often. The intermittent connectivity network (delay and disruption-tolerant network) resulting is end to end path is absent. In this intermittent network connectivity areas, during emergency event occurs, emergency rescue message (Example: Fire, Accident, etc.,) are sent to a rescue team is most necessary. Due to these constraints, general ad hoc protocol approaches is not suitable and, as a result, alternative protocol must be deliberated. This leads to the make a specific protocol mechanisms able to deliver both fast and trustworthiness in-order delivery emergency message needed. Thus we introduce the DFEMDR protocol, it follow the vehicular delay tolerant network (VDTN) common technique store carry-forward method and message replicas. This paper describes an efficient Delay tolerant Fast Emergency Message Dissemination Routing Protocol, called DFEMD routing protocol. This protocol enables in VDTN, the source node broadcast an emergency message to all available node in its communication range. The source node allocates a message replicas and message time to live to the neighbour nodes (forwarded node) based on that node has credence value. Credence value is calculated to all nodes based on two values; the first value is visited level estimation, it is calculated based on the number of nodes previously visited by the node. The second value is Destination Reaches Level Estimation (DLE); it is calculated based on the number of times the node successfully delivered the message to the destination. Finally, each node credence value is calculated, from this visited level and destination reaches level estimation values. Finally, the trust authority received emergency messages and evaluate the trustworthiness of message based on message reputation value or message confidence value.

The maritime communication network is assembled by emergent network technologies. However, the adverse maritime environment impedes the efficiency of resources allocation in maritime communication network. Here we show a joint sleeping scheduling and opportunistic transmission scheme in delay-tolerant maritime wireless communication networks based on software defined networking (SDN) to find a better tradeoff between the energy consumption and the delay. Specifically, an energy-limited delay tolerant networking (DTN) node deployed in the ocean receives/transmits data from/to vessels within its communication range. To further save the energy, a long-term energy minimization problem is formulated with sleeping scheduling and opportunistic transmission. After that, a multi-objective minimization problem of energy and delay is first modeled by Lyapunov optimization (LO), which then is solved by convex optimization. Both mathematical analyses and simulation results demonstrate how the maritime communication network allocates satisfactorily with the proposed allocation scheme.

Electric vehicles (EVs) are being introduced by different manufacturers, thanks to their environment-friendly perspective to alleviate CO2 pollution. In this paper, the proposed EV charging management scheme enables pre-empted charging service for heterogeneous EVs ( depends on different charging capabilities, brands, etc. ). Particularly, the anticipated EVs’ charging reservations information, including their arrival time and expected charging time at charging stations (CSs), are brought for planning CS-selection (where to charge). Along with applying ubiquitous cellular network communication to deliver ( delay tolerant ) EVs’ charging reservations, we further study the feasibility of applying opportunistic vehicle-to-vehicle (V2V) communication with delay/disruption tolerant networking (DTN) nature, due primarily to its flexibility and cost-efficiency in vehicular ad hoc networks (VANETs). Evaluation results under the realistic Helsinki city scenario show that applying the V2V-based charging reservation is promisingly cost-efficient in terms of communication overhead, while achieving a comparable charging performance to apply cellular network communication.

Information-Centric Networking (ICN) emerges as a promising architecture for the future Internet to keep up with the tremendous growth of Internet users and the explosive increase of mobile data traffic. ICN can be coupled with Disruption Tolerant Networking (DTN) to overcome the limitations of the current Internet architecture in some challenging environments where we cannot establish a network connection, and also lighten the load on the Internet backhaul. Unfortunately, resources constraints, such as energy and buffer space, are among the most serious issues in Mobile Information-Centric Disruption Tolerant Networking (MICDTN). In this paper, we introduce an opportunistic DTN-based forwarding mechanism of Interest and Data for ICN, named Fast-MICDTN. The propagation of the content have been modeled using Markov-Decision Process (MDP). Hence, we characterize the living period in transit of the content to reach the maximum possible number of mobiles. Through extensive simulations based on synthetic mobility model and real-world traces, we prove the efficiency of the new approach in sharing content within a large number of users under a low cost.

The current blockchain deployment solutions rely on a continuous connectivity network. Unfortunately, the delay tolerant network does not meet this condition. Therefore, we construct a novel blockchain transaction framework with discrete token negotiation called DTNB, which can be deployed on the delay tolerant network to provide transaction services. Specifically, we present the structure of add-chains by modifying the existing block structure. Then, we design a mining qualification determining scheme to achieve fair transactions, including discrete token generation algorithm and mining qualification attribution algorithm, and this scheme avoids the problem that nodes with more stakes in the PoS and DPoS algorithms can obtain mining qualifications with a higher probability. Furthermore, we present two mining schemes and also design a fork processing algorithm, which ensures that blocks on the add-chain generated by the local network can be appended to the main chain with the equal probability. Finally, we design the second consensus algorithm to avoid the problem of false and repeated transactions of the blocks on the add-chains in the local network. Theoretical analysis shows three properties of DTNB, including safety, reliability and activeness, and the experimental simulations demonstrate DTNB has advantages in throughput, block generation time and fork rate.

Context. The main purpose of Correlation Extremal Navigation system is finding coordinates in case of absence of Global Positioning System signal and as a result high-accuracy maps as the main source of information for finding coordinates are very important. Magnetic field map as the main source of information can include errors values, as an example: not good enough equipment or human factor can cause error value of measurements. Objective. In order to create high-accuracy maps given work proposes to improve the process of creating magnetic field maps. The given work represents delay tolerant networking as an additional approach for data transmission between magnetic observatory and magnetic station and its improvement. Method. Improved Dijkstra’s algorithm together with Ford-Fulkerson’s algorithm for finding path with minimum capacity losses, earliest delivery time and maximum bit rate in case of overlapping contacts should be represented in the given work because nowadays, delay tolerant networking routing protocols do not take into account the overlap factor and resulting capacity losses and it leads to big problems Results. For the first time will be presented algorithm that chooses the route that guarantees the minimum of capacity losses, earliest delivery time and maximum bit rate in the delay tolerant networking with overlapping contacts and increases the probability of successful data transmission between magnetic stations and magnetic observatories. Conclusions. In order to perform high-accuracy measurement of magnetic field group of people allocate their equipment for magnetic field measurement in remote areas in order to avoid the influence of environment on measurements of magnetometer. Since magnitude of magnetic field can vary dependent on temperature, proximity to the ocean, latitude (diurnal variation of magnetic field) and magnetic storms magnetic station from time to time adjusts its measurements with a help of reference values of magnetic field (magnetic station sends request for reference values to magnetic observatory). The problem of the given approach is that remote areas usually are not covered by network (no Internet) and as a result the adjustment of measurements is impossible. In order to make adjustment of measurements possible and as a result improve accuracy of magnetic maps given work proposed the usage of Delay Tolerant Networking that delivers internet access to different areas around the world and represented its improvement to make its approach even better.The results are published for the first time.

Delay tolerant networks (DTNs) offer a set of standardized protocols to enable Internet-like connectivity across the solar system. Unlike other protocols such as the Transmission Control Protocol (...

In tactical environments, mobility has a significant impact on the performance such as handover delay. In this paper, we design and implement an integrated tactical mobility testbed that consists of (1) host identify protocol module for secure initial registration, (2) Proxy Mobile IPv6-based distributed mobility management module for infrastructure-based mobility cases, and (3) delay/disruption tolerant networking module for opportunistic mobility cases. The implementation and experimental results demonstrate that the integrated testbed can be used to consider diverse tactical mobility scenarios and to evaluate the handover performance.

A Delay Tolerant Network (DTN) is a network capable of handling long delays and data loss efficiently in various challenged scenarios and environments. Owing to the mentioned challenges, it becomes crucial to study how the routing protocols are designed to adapt in such networks. Currently, the research in this domain is focused on the improving the data delivery ratio and minimizing delays in the routing protocols. This paper reviews state-of-the-art routing protocols for Delay Tolerant Networks (DTNs) as well as performs their comparative analysis. DTN routing protocols are grouped into four categories viz encounter based, time based, infrastructure based and hybrid & others. This categorization depends on the information they use for relay selection routing. We have also discussed some of the inherent drawbacks such as energy consumption, delivery rates and buffer constraints of the existing routing algorithms. We have also conducted an empirical analysis and observed the performance of the most popular existing algorithms of encounter and time based category. This paper offers a widespread study of the routing protocols with their pros and cons.

This paper introduces a trust-based multipath routing protocol for exploiting different paths between source as well as destination to mitigate energy constraints. The key idea is to determine optimal path from the entire paths available among source and target node. To improve the security in routing protocol, the factors, like trust factors, and distance are considered as major components. Based on these parameters, the multipath routing is carried out based on HH-Jaya Algorithm. The HH-Jaya is designed newly by integrating Harris Hawks Optimization (HHO) and Jaya Algorithm. After that, the reputation and trust-based context aware routing (RCAR) protocol is utilized to select the optimal path with more trust factor. Here, the trust is modelled by considering trust factors, like direct, indirect, history, forwarding rate, and availability factors, in addition to the utility function. The proposed HH-Jaya outperformed other methods with minimal delay of 0.007 sec, maximal throughput of 0.913 for 10 user and maximal packet deliver rate (PDR) of 0.991 for 20 users respectively.

PurposeIn this study, we discuss three DTN routing protocols, these are epidemic, PRoPHET and spray and wait routing protocols. A special simulator will be used; that is opportunistic network environment (ONE) to create a network environment. Spray and wait has highest delivery rate and low latency in most of the cases. Hence, spray and wait have better performance than others. This analysis of the performance of DTN protocols helps the researcher to learn better of these protocols in the different environment.Design/methodology/approachDelay-Tolerant Network (DTN) is a network designed to operate effectively over extreme distances, such as those encountered in space communications or on an interplanetary scale. In such an environment, nodes are occasional communication and are available among hubs, and determinations of the next node communications are not confirmed. In such network environment, the packet can be transferred by searching current efficient route available for a particular node. Due to the uncertainty of packet transfer route, DTN is affected by a variety of factors such as packet size, communication cost, node activity, etc.FindingsSpray and wait have highest delivery rate and low latency in most of the cases. Hence, spray and wait have better performance than others.Originality/valueThe primary goal of the paper is to extend these works in an attempt to offer a better understanding of the behavior of different DTN routing protocols with delivery probability, latency and overhead ratio that depend on various amounts of network parameters such as buffer size, number of nodes, movement ratio, time to live, movement range, transmission range and message generation rate. In this study, we discuss three DTN routing protocols: these are epidemic, PRoPHET and spray and wait routing protocols. A special simulator will be used; that is opportunistic network environment (ONE) to create a network environment. Spray and wait have highest delivery rate and low latency in most of the cases. Hence, spray and wait have better performance than others. This analysis of the performance of DTN protocols helps the researcher to learn better of these protocols in the different environment.

In the aftermath of a large-scale disaster, such as an earthquake, existing telecommunication (e.g., cellular towers) and other public infrastructures (e.g., power lines, roads, etc.) are often severely damaged. This prevents the seamless exchange of situational awareness and rescue/relief based information between the volunteers, shelter points, and the coordination center. A temporary communication infrastructure utilizing smartphones, communication towers, drones, smart badges, etc., commonly referred to as network resources, can be formed, which promises to bridge the communication gap between various stakeholders in the disaster area and enable timely information exchange between them. However, the efficacy of such networks is often challenged by the limited availability of network resources in the disaster area. To address this issue, in this paper, we propose to design, develop, and test a novel strategy that intelligently deploys the limited network resources in the disaster area, and thus, creates an efficient temporary communication infrastructure in such resource-constrained post-disaster situations. We formulate the network resource deployment (ResDep) problem as an integer linear programming optimization problem and show that it is NP-Hard. Next, we propose a near-optimal polynomial-time heuristic solution for solving it. Our extensive simulation study on top of ONE simulator and proof-of-concept pilot deployment study, both based on our university, National Institute of Technology — Durgapur, India, reveal that the proposed heuristic performs nearly as well as that of the optimal solution (computed using Gurobi optimizer), and outperforms its variant and baseline approaches when compared in terms of end-to-end network latency and message delivery.

Delay Tolerant Network (DTN) can be characterized as a heterogeneous network of nodes in which nodes mobility is high and resources are limited to transmit messages. In DTN, nodes use store, carry, and forward principle for delivering messages to the destination node. To forward messages through intermediate nodes may cause security issues in the network since there may exist a few selfish nodes. These nodes can affect the network's performance as they may drop messages due to their limited resources such as energy and storage capacity. To handle this kind of hazard, it is necessary to propose a mechanism that may decrease the degree of the selfishness of nodes and improve the network's delivery ratio by fully distributing credits to nodes. In this article, a credit-based mechanism has been proposed based on Combined Trust Value (CTV) of nodes in DTN. In the proposed mechanism, an agent is used to compute each node's trust value grounded of the number of messages relayed by sensor nodes. This trust value is used to distribute credits to the nodes in a distributed manner without any partiality with nodes. Backtracking approach is used to distribute credits to boundary nodes deserving credits but didn’t get credits by agent node. The proposed mechanism is implemented using ONE simulator, and the performance of the projected scheme is analyzed in comparison to existing techniques Dynamic Trust, SMART (Secure Multilayer credit based incentive Technique) and Credit-based. The results exhibit that the suggested mechanism is superior than existing techniques with reference to various performance metrics like 25% higher delivery ratio, 41% less overhead, 21% less average message delay, and 28% less packets dropped. The proposed mechanism might be helpful in scenarios where the degree of selfishness is high, and the distribution of credit follows a fully distributed approach rather than an existing partial distribution used in existing techniques.

Due to the unguaranteed connectivity, wireless sensor networks based on delay tolerant network (DTN) are typically characterized by the opportunistic forwarding mechanism in transmission. Such a mechanism requires nodes to participate in forwarding messages actively. However, when the mechanism is used in the real world, selfish nodes will exhibit some non-cooperation behaviors. Therefore, some incentive mechanism may be designed to encourage selfish nodes. In order to solve the selfishness problem, we propose a fair credit-based incentive mechanism for routing in DTN-based sensor networks. In this mechanism, when a source node sends messages to its destination, each relay node will be rewarded with some credits. The accumulated credits are then used to evaluate the level of cooperation in the network. The selfish nodes with few credits are not able to get enough service from other nodes. With the fair incentive, all participating relays will get equal rewards by the trusted third party. In order to evaluate the proposed mechanism, we also perform some simulation, and the results demonstrate that the method can be used to support efficient routing for DTN-based sensor networks.

The Interplanetary Network (IPN) or the Interplanetary Internet is a network composed of interconnected space objects, which are in turn connected to mission control stations on the surface of Earth. The IPN is our only portal to the deep space, and yet it has been relatively sparse, until recently. With the ongoing and the planned missions to the outer space, the Delay Tolerant Networking (DTN) based network infrastructure will require more scalable routing and scheduling algorithms. In this paper, we propose the first Mixed Integer Linear Programming (MILP) model for message routing and scheduling in the IPN using Multi-Attribute Decision Making (MADM) principles. Based on this model, we propose a novel MADM-based algorithm called Multi-Attribute Routing and Scheduling (MARS) algorithm. This algorithm uses a sliding window of size $n$ to schedule the first $n$ messages in the buffer based on multiple attributes. After finding the optimal schedule for these messages (in terms of delivery rate), they are routed using our proposed Dijkstra-based routing algorithm. We use an existing MADM technique, PROMETHEE II, and consider the four main attributes of a message: size, priority, time to live (TTL), and time in buffer (TiB). Finally, we run multiple simulation experiments in order to test the performance of the proposed MARS and show that MADM coupled with scheduling and routing in IPN delivers at least three times more messages than a previously proposed technique, the Contact Graph Routing (CGR), while significantly reducing the average end-to-end delay and overhead.

The vehicular delay-tolerant network is the real-life application based area of Delay tolerant network where communication takes place using vehicular nodes and roadside units. The topology used in vehicular networks is highly dynamic by architecture due to the use of moving vehicular nodes. It operates in such a scenario where a direct path between source and destination remains absent on the most piece of the time. In case of non-existence of connected path vehicular delay-tolerant network works opportunistically and uses the same store, carry, and forward paradigm as Delay Tolerant Network. However, the routing protocols designed for vehicular delay-tolerant network faces crucial challenges like inadequate relay node, incomplete data transfer, a large number of packet drop, and uncertain delivery time. In this research paper, we propose a novel routing strategy for the vehicular delay-tolerant network. The proposed routing strategy selects efficient vehicular relay node for complete packet transfer and intelligently reduces the packet drop for timely packet delivery. We implement the proposed routing strategy in the ONE simulator; the ONE simulator provides an opportunistic environment for nodes. We analyze the performance of the proposed strategy under various simulations results using different parameters. The results show that the proposed strategy outperforms standard routing protocols in terms of considered parameters and provide an efficient solution for the problem of disconnection.

Opportunistic network is emerging as a research domain nowadays with the introduction of Internet of things phenomena. In recent years, storage level congestion issue due to handheld devices is considered as a key challenge to be handled in the opportunistic networks. The prime objective of conducting this research is to develop artificial intelligence rule-based fire engine model to be tested using artificial intelligence latest classification algorithms further implemented using ONE simulator tool over MaxProp protocol. The achieved results show 98% accuracy in terms of classification using k-fold validation technique over six algorithms. The achieved results have been compared with MaxProp protocol over evaluation parameters such as delivery ratio, throughput, routing load, and overhead; whereas delivery ratio increase about 20% for node level and 5% for buffer level and throughput tends to increase 500 and 150 kbps for network and buffer levels, respectively.

As the percentage of Vehicles are increasing on roads, Vehicular Ad-hoc network have reached to a significant interest of the researcher in recent times. V2V network and V2I are prominent as an orga...

Delay tolerant networks(DTN) belong to a category of SHIP (Sparse,Hybrid, Intermittent,Partitioned) networks where aim is to deliver a message with acceptable delay. In the literature of DTN, many ...

The delay tolerant network multi-copy protocols create and transmit multiple copies of each message that overload the buffer size, energy and bandwidth. The resource consumption is controlled by transmitting the messages to nodes having high encountering ability to meet their destinations. Hence, nodes loss energy only in transmitting and receiving messages and went to dead state. However, message transmission continues even though the destination is dead. This wastes the network resources because messages destining to dead node will not be able to find their destinations. The existing routing protocols focus on message transmissions and do not have any mechanism to detect inactive nodes or to stop massage replications destining to inactive nodes. In this paper we have proposed a routing protocol called as Energy Efficient Inactive Node Detecting Based Routing Protocol for Delay Tolerant Network (InD). The proposed protocol has employed the node mobility to detect inactive nodes. Moreover, an intelligent buffer management policy has been designed that detect and drop those messages which are destining to dead nodes. The real time mobility scenarios have been used to evaluate the performance of existing and proposed routing protocols under the metrics of message transmissions, message drop, and message delivery and hop count average.

This article is the third of a three-part series in which we present the results of a study exploring concepts for improving communications and tracking capabilities of deep space SmallSats. In Part I, we discussed SmallSat direct-to-Earth links as well as SmallSat communications equipment, and provided recommendations for future work. In Part II, we focused on SmallSat navigation options, disruption tolerant networking, proximity links, and the use of the communication link for science observations. In Part III, we focus on ground support of deep space SmallSats. We present a brief overview of NASA's deep space network (DSN) along with concepts for adapting the DSN to improve support for SmallSats. We discuss approaches for increasing the DSN's efficiency in handling the anticipated increase in SmallSat communications, such as reducing setup and teardown times for a communications pass, and reducing DSN time allocated to Doppler and range measurements. A new demand access operational paradigm is proposed, which is more consistent with SmallSat communications requirements and will facilitate the DSN handling of larger numbers of spacecraft. Finally, we present the conclusion of the study as a list of recommendations to improve SmallSat communications and tracking.

Two of the most dominant challenges in post disaster emergency resource allocation are: 1) understanding the exact utility, i.e., exigency, of emergency resources and 2) collecting and transmitting the need for these resources to the control station from where resources are allocated. Measuring the utility of resources with precision becomes tricky in a dynamic post disaster scenario, where demands are constantly evolving and supplies trickle in at an uncertain rate. Moreover, collection and transmission of resource needs of far-flung areas are easier said than done owing to the post disaster disruption of communication infrastructure. These result in the ad-hoc allocation of emergency resources to the shelters. In this paper, we first derive a utility function for dynamically enumerating the shelter specific utility of each emergency resource. Subsequently, we propose an opportunistic knowledge sharing scheme for gathering and disseminating resource needs to the control station using a smartphone-based delay tolerant network. Finally, based on these opportunistically transmitted needs, we formulate a utility driven optimal resource allocation model which minimizes overall resource deficit and total resource deployment time. The proposed system optimally assigns constrained emergency resources to different shelters, so that high-utility resources are deployed fast. The effectiveness of the proposed system is evaluated using ONE simulator and LINGO optimization modeling tool. Exhaustive simulation is done to evaluate the comparative performance of our system with a number of competing schemes. Results show that our system outperforms all these schemes in a fully connected scenario. It is also observed that even in an intermittently connected environment, the performance of our system is almost at par with the competing schemes.

This article is the second of a three-part series in which we present the results of a study exploring concepts for improving communications and tracking capabilities of deep space SmallSats. In Part I, we discussed SmallSat direct-to-earth links and SmallSat communications equipment, and provided recommendations for future work. In Part II, we focus on SmallSat navigation options, Disruption Tolerant Networking (DTN), proximity links, and the use of the communication link for science observations, and we provide recommendations for future work. We have examined both radio and optical navigation options, and considered autonomous and semiautonomous navigation to reduce operational costs for planetary SmallSats. We note that communication link resilience to delay and disruption enhances spacecraft autonomy; therefore, we have provided a discussion of DTN to indicate that using DTN allows for automated data transmission and recovery, therefore, reducing manual operations. SmallSats in deep space may utilize a relay spacecraft for communications with earth or function as a relay for landed and in-orbit assets. We present a detailed examination of relay proximity links and networks where we address both proximity hardware and networking scenarios. The proximity link features that we examine include the network architecture and its relationship to DTN, proximity radios and antennas, communications link performance, and proximity navigation. The use of the communication link for science has been practiced by primary missions in deep space scenarios. (Two examples of past planetary radio science experiments can be found in the following: https://solarsystem.nasa.gov/missions/cassini/mission/spacecraft/cassini-orbiter/radio-science-subsystem/ and https://www.boulder.swri.edu/pkb/ssr/ssr-rex.pdf) Likewise, SmallSats can offer their radio links for radio science investigations. This article provides a brief introduction to radio science and presents the prerequisite features necessary for radio science observations by SmallSats. We conclude with nine recommendations based on the findings of the study. These recommendations are guidelines on the design, implementation, and operation of deep space SmallSat communication links. The adoption of some or all of the guidelines should result in an enhanced communication and tracking capability for the deep space SmallSat missions.

According to the Smart City Council, an adequate telecommunications infrastructure is vital for the success of businesses, industries as well as residents of Smart cities. However, currently available standard and cellular technologies, such as 3/4G, GSM (Global System for Mobile Communications) and LTE (Long-Term Evolution), are rapidly reaching their limit mainly due to increased traffic demand. Such limitations are only going to worsen in the next years, due to the advent of Internet of Things technologies that are expected to interconnect billions of devices to the Internet. In this paper, we propose a novel network architecture that supports several delay-tolerant (non-real-time) Smart city applications and services (e.g., gathering air pollution information), and therefore, a promising approach to address the burdening of increased traffic demand to Smart city’s legacy standard and cellular communication infrastructure. The proposed architecture is based on an innovative diverse band-aware Dynamic Spectrum Access ( d-DSA ) paradigm, that allows a certain wireless device to opportunistically access idle channels in multiple licensed/unlicensed spectrum bands. d-DSA radio devices are mounted on Smart city’s urban vehicles (e.g., taxis) that act as mobile routers to gather, carry, and forward various types of data traffic. This results in a time-varying and unpredictable delay-tolerant network (DTN) where each node can access whitespace channels and transmit in multiple spectrum bands. Given lack of research in efficient routing schemes for such d-DSA DTN networks, we propose a distributed and lightweight d-DSA aware Geographical Routing (dDSA-GR) protocol, that utilizes a weighted linear metric for selecting a suitable spectrum band, and classic georouting principle for choosing next hop node in the path route between any node pair in d-DSA DTNs. Results on realistic traces based on the map of Lexington, KY, USA, show that our dDSA-GR routing protocol outperforms baseline approaches in terms of network delay, message delivery ratio, and energy efficiency, under all considered scenarios.