Medium access control, error control and routing in underwater acoustic networks: a discussion on protocol design and implementation

The journey of underwater communication which began from Leonardo’s era took four and a half centuries to find practical applications for military purposes during World War II. However, over the last three decades, underwater acoustic communications witnessed a massive development due to the advancements in the design of underwater communicating peripherals and their supporting protocols. Successively, doors are opened for a wide range of applications to employ in the underwater environment, such as oceanography, pollution monitoring, offshore exploration, disaster prevention, navigation assistance, monitoring, coastal patrol and surveillance. Different applications may have different characteristics and hence, may require different network architectures. For instance, routing protocols designed for unpartitioned multi-hop networks are not suitable for Delay-Tolerant Networks. Furthermore, single-hop networks do not need routing protocols at all. Therefore, before developing a protocol one must study the network architecture properly and design it accordingly. There are several other factors which should also be considered with the network architecture while designing an efficient protocol for underwater networks, such as long propagation delay, limited bandwidth, limited battery power, high bit error rate of the channel and several other adverse properties of the channel, such as, multi-path, fading and refractive behaviors. Moreover, the environment also has an impact on the performance of the protocols designed for underwater networks. Even temperature changes in a single day have an impact on the performance of the protocols. A good protocol designed for any network should consider some or all of these characteristics to achieve better performance. In this thesis, we first discuss the impact of the environment on the performance of MAC and routing protocols. From our investigation, we discover that even temperature changes within a day may affect the sound speed profile and hence, the channel changes and the protocol performance vary. After that we discuss several protocols which are specifically designed for underwater acoustic networks to serve different purposes and for different network architectures. Underwater Selective Repeat (USR) is an error control protocol designed to assure reliable data transmission in the MAC layer. One may suspect that employing an error control technique over a channel which already suffers from long propagation delays is a burden. However, USR utilizes long propagation by transmitting multiple packets in a single RTT using an interlacing technique. After USR, a routing protocol for surveillance networks is discussed where some sensors are laid down at the bottom of the sea and some sinks are placed outside the area. If a sensor detects an asset within its detection range, it announces the presence of intruders by transmitting packets to the sinks. It may happen that the discovered asset is an enemy ship or an enemy submarine which creates noise to jam the network. Therefore, in surveillance networks, it is necessary that the protocols have jamming resistance capabilities. Moreover, since the network supports multiple sinks with similar anycast address, we propose a Jamming Resistance multi-path Multi-Sink Routing Protocol (MSRP) using a source routing technique. However, the problem of source routing is that it suffers from large overhead (every packet includes the whole path information) with respect to other routing techniques, and also suffers from the unidirectional link problem. Therefore, another routing protocol based on a distance vector technique, called Multi-path Routing with Limited Cross-Path Interference (L-CROP) protocol is proposed, which employs a neighbor-aware multi-path discovery algorithm to support low interference multiple paths between each source-destination pair. Following that, another routing protocol is discussed for next generation coastal patrol and surveillance network, called Underwater Delay-Tolerant Network (UDTN) routing where some AUVs carry out the patrolling work of a given area and report to a shore based control-center. Since the area to be patrolled is large, AUVs experience intermittent connectivity. In our proposed protocol, two nodes that understand to be in contact with each other calculate and divide their contact duration equally so that every node gets a fair share of the contact duration to exchange data. Moreover, a probabilistic spray technique is employed to restrict the number of packet transmissions and for error correction a modified version of USR is employed. In the appendix, we discuss a framework which was designed by our research group to realize underwater communication through simulation which is used in most of the simulations in this thesis, called DESERT Underwater (short for DEsign, Simulate, Emulate and Realize Test-beds for Underwater network protocols). It is an underwater extension of the NS-Miracle simulator to support the design and implementation of underwater network protocols. Its creation assists the researchers in to utilizing the same codes designed for the simulator to employ in actual hardware devices and test in the real underwater scenario

Performance analysis of on-demand routing protocols in wireless mesh networks

Wireless Mesh Networks (WMNs) have recently gained a lot of popularity due to their rapid deployment and instant communication capabilities. WMNs are dynamically self-organizing, self-configuring and self-healing with the nodes in the network automatically establishing an adiej hoc network and preserving the mesh connectivity. Designing a routing protocol for WMNs requires several aspects to consider, such as wireless networks, fixed applications, mobile applications, scalability, better performance metrics, efficient routing within infrastructure, load balancing, throughput enhancement, interference, robustness etc. To support communication, various routing protocols are designed for various networks (e.g. ad hoc, sensor, wired etc.). However, all these protocols are not suitable for WMNs, because of the architectural differences among the networks. In this paper, a detailed simulation based performance study and analysis is performed on the reactive routing protocols to verify the suitability of these protocols over such kind of networks. Ad Hoc On-Demand Distance Vector (AODV), Dynamic Source Routing (DSR) and Dynamic MANET On-demand (DYMO) routing protocol are considered as the representative of reactive routing protocols. The performance differentials are investigated using varying traffic load and number of source. Based on the simulation results, how the performance of each protocol can be improved is also recommended

On mitigating hop-to-hop congestion problem in IoT enabled Intra-Vehicular communication

Internet of Things enabled Intra-Vehicular Network (IVN) refers to the network where large number of sensors are connected with each other for sharing the vehicle's status information in order to develop a smart vehicular system. The number of sensor nodes in the vehicle has increased significantly due to the increasing vehicular applications. The phenomenon of congestion poses a problem in the IVN where the traffic load and number of sensors are increased. This problem can be resolved by mitigating the limitation of the existing Media Access Control (MAC) protocols. In this paper, we address this issue and proposed a MAC strategy for solving this problem in this network. Furthermore, we discuss the design of IVN scenario and the performance is evaluated in terms of end-to-end delay. The simulation results reveal the effectiveness of our proposal

Collab-SAR:A Collaborative Avalanche Search-and-Rescue Missions Exploiting Hostile Alpine Networks

Every year, Alpine experiences a considerable number of avalanches causing danger to visitor and saviors, where most of the existing techniques to mitigate the number of fatalities in such hostile environments are based on a non-collaborative approach and is time- and effort-inefficient. A recently completed European project on Smart collaboration between Humans and ground-aErial Robots for imProving rescuing activities in Alpine environments (SHERPA) has proposed a novel collaborative approach to improve the rescuing activities. To be an integral part of the SHERPA framework, this paper considers deployment of an air-ground collaborative wireless network (AGCWN) to support search and rescue (SAR) missions in hostile alpine environments. We propose a network infrastructure for such challenging environments by considering the available network components, hostility of the environments, scenarios, and requirements. The proposed infrastructure also considers two degrees of quality of service, in terms of high throughput and long coverage range, to enable timely delivery of videos and images of the long patrolled area, which is the key in any searching and rescuing mission. We also incorporate a probabilistic search technique, which is suitable for collaborative search assuming AGCWN infrastructure for sharing information. The effectiveness of the proposed infrastructure and collaborative search technique, referred to as Collab-SAR, is demonstrated via a series of computer simulations. The results confirm the effectiveness of the proposal

A performance comparison of proactive and reactive routing protocols of Mobile Ad-hoc Network (MANET)

Mobile Ad-hoc NETwork (MANET) is a collection of wireless mobile nodes dynamically forming a temporary network without the use of any existing network infrastructure or centralized administration. To support MANET, many routing protocols are already designed, such as DSDV, DSR, AODV, TORA, OLSR, WRP, ZRP and many more. This study analyzes these three routing protocols using Network Simulator version no 2 (ns-2). The performance of these protocols are compared in terms of their packet delivery fraction, average end-to-end delay, normalized routing load and routing overhead (packets) for 50 nodes and 100 nodes model with various numbers of sources. However performance comparison and comparative analysis of these protocols for above mention metrics has not yet been performed. This study does that comparison and pointed out the relative strengths and weakness of those proactive and reactive routing protocols

A Comparative Study of Analgesic, Antidiarrhoeal and Antimicrobial Activities of Methanol and Acetone Extracts of Fruits Peels of Limonia acidissima L. (Rutaceae)

Objectives: Present study was designed to evaluate Analgesic, Antidiarrhoeal and Antimicrobial activities of methanol and acetone extracts of fruit peels of Limonia acidissima L. by different methods. Method: The analgesic activity of the samples was studied using acetic acid- induced writhing model in mice. Castor oil-induced antidiarrheal activity was observed by Thomas method and antimicrobial activity was monitored by disc diffusion method. Results: Limonia acidissima L. inhibited 60.53 % and 59.65 % writhing of methanol as well as acetone fruit peels extracts, respectively, compared to standard drug Diclofenac Na inhibited 78.07 % writhing. At higher dose (500 mg/kg) of the methanol and acetone fruit peels extracts, significant inhibition 47.13 and 44.83 % of characteristic diarrhoeal feces was observed, respectively, as well as at lower dose (250 mg/kg) of the both extracts, inhibition 34.45 and35.63 %. Mention able on average 12mm zone of inhibition was observed of both extract at 250µg/disc and 500µg/disc compare to zone of inhibition 36mm of ciprofloxacin at 50µg/disc. Conclusion: From the above results, it will be very much possible source for an isolating lead compound for curing the numerous disorders. Keywords: Limonia acidissima L. Fruit peels, Diclofenac sodium, Loperamide, Ciprofloxacin

Exploiting Privacy-Policy and -Management Features on Social Networks: A User's Perspective

A social network is a type of media that allows users to engage social interaction in the cyber world. Nowadays, this network becomes a backbone of the digital communication world as it transformed the way of information being shared across the different communities. Exploiting this network, people can easily share huge volume of information (e.g., text, audio and video) without paying any charge that runs to gain overwhelming popularity of it. Nevertheless, it is an important issue for the users to select the privacy options for their information, resulting in the decision making on who can access the information and how the information should be used. This decision can be made via privacy management features within the social networks' applications. However, the lack of study to explain the perceived use of privacy policies and management features, among social networks' users, has conjured up the significant concerns about how social network users felt about the use of these features in social networks. To address this issue, in this paper, an empirical study has been conducted to seek for users' feedbacks on the use of existing privacy policies and management features of social networks. These feedback assist in improving further the social network users' privacy features

Region-Based Distance Analysis of Keyphrases: A New Unsupervised Method for Extracting Keyphrases Feature from Articles

Due to the exponential growth of information’s and web sources, Automatic keyphrase extraction is still a challenging issue in the current research area. Keyphrases are very helpful for several tasks in natural language processing (NLP) and information retrieval (IR) systems. Feature extractions for those keyphrases execute a vital role in extracting the top-quality keyphrases and summarising the documents at a superior level. This paper proposes a new region-based distance analysis of keyphrases (RDAK) unsupervised technique for feature extraction of keyphrases from articles. The proposed method comprises six phases: data acquisition and preprocessing, data processing, distance calculation, average distance, curve plotting, and curve fitting. At first, the system inputs the collected different datasets to the preprocessing step by employing some text preprocessing techniques. Afterwards, the preprocessed data is applied to the data processing phase, and then after distance calculation, it is passed to the region-based average calculation process, then curve plotting analysis, and afterwards, the curve fitting technique is utilized. Finally, the proposed system has tested and evaluated the performance through implementing them on benchmark datasets. The proposed system will significantly improve the performance of existing keyphrase extraction techniques

Keyphrases Concentrated Area Identification from Academic Articles as Feature of Keyphrase Extraction: A New Unsupervised Approach

The extraction of high-quality keywords and sum-marising documents at a high level has become more difficult in current research due to technological advancements and the expo-nential expansion of textual data and digital sources. Extracting high-quality keywords and summarising the documents at a high-level need to use features for the keyphrase extraction, becoming more popular. A new unsupervised keyphrase concentrated area (KCA) identification approach is proposed in this study as a feature of keyphrase extraction: corpus, domain and language independent; document length-free; utilized by both supervised and unsupervised techniques. In the proposed system, there are three phases: data pre-processing, data processing, and KCA identification. The system employs various text pre-processing methods before transferring the acquired datasets to the data processing step. The pre-processed data is subsequently used during the data processing step. The statistical approaches, curve plotting, and curve fitting technique are applied in the KCA identification step. The proposed system is then tested and evaluated using benchmark datasets collected from various sources. To demonstrate our proposed approach’s effectiveness, merits, and significance, we compared it with other proposed techniques. The experimental results on eleven (11) datasets show that the proposed approach effectively recognizes the KCA from articles as well as significantly enhances the current keyphrase extraction methods based on various text sizes, languages, and domains