Let the Tree Bloom: Scalable Opportunistic Routing with ORPL

Routing in battery-operated wireless networks is challenging, posing a tradeoff between energy and latency. Previous work has shown that opportunistic routing can achieve low-latency data collection in duty-cycled networks. However, applications are now considered where nodes are not only periodic data sources, but rather addressable end points generating traffic with arbitrary patterns. We present ORPL, an opportunistic routing protocol that supports any-to-any, on-demand traffic. ORPL builds upon RPL, the standard protocol for low-power IPv6 networks. By combining RPL's tree-like topology with opportunistic routing, ORPL forwards data to any destination based on the mere knowledge of the nodes' sub-tree. We use bitmaps and Bloom filters to represent and propagate this information in a space-efficient way, making ORPL scale to large networks of addressable nodes. Our results in a 135-node testbed show that ORPL outperforms a number of state-of-the-art solutions including RPL and CTP, conciliating a sub-second latency and a sub-percent duty cycle. ORPL also increases robustness and scalability, addressing the whole network reliably through a 64-byte Bloom filter, where RPL needs kilobytes of routing tables for the same task

Design and analysis of energy-efficient media access control protocols in wireless sensor networks. Design and analysis of MAC layer protocols using low duty cycle technique to improve energy efficient and enhance communication performance in wireless sensor networks.

Wireless sensor network (WSN) technology has gained significant importance due to its potential support for a wide range of applications. Most of the WSN applications consist of a large numbers of distributed nodes that work together to achieve common objects. Running a large number of nodes requires an efficient mechanism to bring them all together in order to form a multi-hop wireless network that can accomplish some specific tasks. Even with recent developments made in WSN technology, numbers of important challenges still stand as vulnerabilities for WSNs, including energy waste sources, synchronisation leaks, low network capacity and self-configuration difficulties. However, energy efficiency remains the priority challenging problem due to the scarce energy resources available in sensor nodes. These concerns are managed by medium access control (MAC) layer protocols. MAC protocols designed specifically for WSN have an additional responsibility of managing radio activity to conserve energy in addition to the traditional functions. This thesis presents advanced research work carried out in the context of saving energy whilst achieving the desired network performance. Firstly the thesis contributes by proposing Overlapped Schedules for MAC layer, in which the schedules of the neighbour clusters are overlapped by introducing a small shift time between them, aiming to compensate the synchronisation errors. Secondly, this thesis proposed a modified architecture derived from S-MAC protocol which significantly supports higher traffic levels whilst achieving better energy efficiency. This is achieved by applying a parallel transmission concept on the communicating nodes. As a result, the overall efficiency of the channel contention mechanism increases and leads to higher throughput with lower energy consumption. Finally, this thesis proposed the use of the Adaptive scheme on Border Nodes to increase the power efficiency of the system under light traffic load conditions. The scheme focuses on saving energy by forcing the network border nodes to go off when not needed. These three contributions minimise the contention window period whilst maximising the capacity of the available channel, which as a result increase network performance in terms of energy efficiency, throughput and latency. The proposed system is shown to be backwards compatible and able to satisfy both traditional and advanced applications. The new MAC protocol has been implemented and evaluated using NS-2 simulator, under different traffic loads and varying duty cycle values. Results have shown that the proposed solutions are able to significantly enhance the performance of WSNs by improving the energy efficiency, increasing the system throughput and reducing the communication delay

Optimal power control in green wireless sensor networks with wireless energy harvesting, wake-up radio and transmission control

Wireless sensor networks (WSNs) are autonomous networks of spatially distributed sensor nodes which are capable of wirelessly communicating with each other in a multi-hop fashion. Among different metrics, network lifetime and utility and energy consumption in terms of carbon footprint are key parameters that determine the performance of such a network and entail a sophisticated design at different abstraction levels. In this paper, wireless energy harvesting (WEH), wake-up radio (WUR) scheme and error control coding (ECC) are investigated as enabling solutions to enhance the performance of WSNs while reducing its carbon footprint. Specifically, a utility-lifetime maximization problem incorporating WEH, WUR and ECC, is formulated and solved using distributed dual subgradient algorithm based on Lagrange multiplier method. It is discussed and verified through simulation results to show how the proposed solutions improve network utility, prolong the lifetime and pave the way for a greener WSN by reducing its carbon footprint

A novel cooperative opportunistic routing scheme for underwater sensor networks

Increasing attention has recently been devoted to underwater sensor networks (UWSNs) because of their capabilities in the ocean monitoring and resource discovery. UWSNs are faced with different challenges, the most notable of which is perhaps how to efficiently deliver packets taking into account all of the constraints of the available acoustic communication channel. The opportunistic routing provides a reliable solution with the aid of intermediate nodes’ collaboration to relay a packet toward the destination. In this paper, we propose a new routing protocol, called opportunistic void avoidance routing (OVAR), to address the void problem and also the energy-reliability trade-off in the forwarding set selection. OVAR takes advantage of distributed beaconing, constructs the adjacency graph at each hop and selects a forwarding set that holds the best trade-off between reliability and energy efficiency. The unique features of OVAR in selecting the candidate nodes in the vicinity of each other leads to the resolution of the hidden node problem. OVAR is also able to select the forwarding set in any direction from the sender, which increases its flexibility to bypass any kind of void area with the minimum deviation from the optimal path. The results of our extensive simulation study show that OVAR outperforms other protocols in terms of the packet delivery ratio, energy consumption, end-to-end delay, hop count and traversed distance

Performance evaluation of wake-up radio based wireless body area network

Abstract. The last decade has been really ambitious in new research and development techniques to reduce energy consumption especially in wireless sensor networks (WSNs). Sensor nodes are usually battery-powered and thus have very limited lifetime. Energy efficiency has been the most important aspect to discuss when talking about wireless body area network (WBAN) in particular, since it is the bottleneck of these networks. Medium access control (MAC) protocols hold the vital position to determine the energy efficiency of a WBAN, which is a key design issue for battery operated sensor nodes. The wake-up radio (WUR) based MAC and physical layer (PHY) have been evaluated in this research work in order to contribute to the energy efficient solutions development. WUR is an on-demand approach in which the node is woken up by the wake-up signal (WUS). A WUS switches a node from sleep mode to wake up mode to start signal transmission and reception. The WUS is transmitted or received by a secondary radio transceiver, which operates on very low power. The energy benefit of using WUR is compared with conventional duty-cycling approach. As the protocol defines the nodes in WUR based network do not waste energy on idle listening and are only awakened when there is a request for communication, therefore, energy consumption is extremely low. The performance of WUR based MAC protocol has been evaluated for both physical layer (PHY) and MAC for transmission of WUS and data. The probabilities of miss detection, false alarm and detection error rates are calculated for PHY and the probabilities of collision and successful data transmission for channel access method Aloha is evaluated. The results are obtained to compute and compare the total energy consumption of WUR based network with duty cycling. The results prove that the WUR based networks have significant potential to improve energy efficiency, in comparison to conventional duty cycling approach especially, in the case of low data-reporting rate applications. The duty cycle approach is better than WUR approach when sufficiently low duty cycle is combined with highly frequent communication between the network nodes

MAC protokol adaptivnog faktora ispune zasnovan na predviđanju u bežičnim senzorskim mrežama sa prikupljanjem solarne energije

Harvesting ambient energy has enabled the development of energy-harvesting wireless sensor networks (EH-WSNs). However, in these networks, the uncertainty in harvesting rate due to dynamic weather conditions raises new challenges. Therefore, this drives the development of energy harvesting-aware solutions. Formerly, many MAC protocols have been developed for EH-WSNs, which offer various features based on available harvested energy to support different applications. Nevertheless, optimizing MAC performance by incorporating predicted future energy intake is relatively new in EH-WSNs. Therefore, this thesis presents a machine learning prediction based adaptive duty cycle medium access control (MAC) protocol for solar energy harvesting wireless sensor networks WSNs. The developed protocol incorporates information about the current and future harvested energy using mathematical formulations to improve network performance. By doing so, the proposed MAC protocol effectively addresses the primary goals of solar energy harvesting WSNs: ensuring long-term network sustainability and efficient utilization of harvested energy to enhance the application performance under dynamically changing energy harvesting conditions.Сакупљање амбијенталне енергије омогућило је развој бежичних сензорских мрежа (EH-WSN) за прикупљање енергије. Међутим, у овим мрежама, неизвесност у стопи жетве услед динамичних временских услова поставља нове изазове. Стога, ово покреће развој решења која су свесна прикупљања енергије. Раније су развијени многи MAC протоколи за EH-WSN, који нуде различите карактеристике засноване на доступној прикупљеној енергији за подршку различитим апликацијама. Ипак, оптимизација перформанси MAC-а укључивањем предвиђеног будућег уноса енергије је релативно нова у EH-WSN-овима. Стога, ова теза представља протокол адаптивног радног циклуса за контролу приступа медијуму (MAC) заснован на предвиђању заснованом на машинском учењу за бежичне WSN мреже за прикупљање соларне енергије. Развијени протокол укључује информације о тренутној и будућој прикупљеној енергији користећи математичке формулације за побољшање перформанси мреже. На тај начин, предложени MAC протокол ефикасно се бави примарним циљевима WSN-а за прикупљање соларне енергије: обезбеђивање дугорочне одрживости мреже и ефикасно коришћење прикупљене енергије за побољшање перформанси апликације под динамички променљивим условима прикупљања енергије.Sakupljanje ambijentalne energije omogućilo je razvoj bežičnih senzorskih mreža (EH-WSN) za prikupljanje energije. Međutim, u ovim mrežama, neizvesnost u stopi žetve usled dinamičnih vremenskih uslova postavlja nove izazove. Stoga, ovo pokreće razvoj rešenja koja su svesna prikupljanja energije. Ranije su razvijeni mnogi MAC protokoli za EH-WSN, koji nude različite karakteristike zasnovane na dostupnoj prikupljenoj energiji za podršku različitim aplikacijama. Ipak, optimizacija performansi MAC-a uključivanjem predviđenog budućeg unosa energije je relativno nova u EH-WSN-ovima. Stoga, ova teza predstavlja protokol adaptivnog radnog ciklusa za kontrolu pristupa medijumu (MAC) zasnovan na predviđanju zasnovanom na mašinskom učenju za bežične WSN mreže za prikupljanje solarne energije. Razvijeni protokol uključuje informacije o trenutnoj i budućoj prikupljenoj energiji koristeći matematičke formulacije za poboljšanje performansi mreže. Na taj način, predloženi MAC protokol efikasno se bavi primarnim ciljevima WSN-a za prikupljanje solarne energije: obezbeđivanje dugoročne održivosti mreže i efikasno korišćenje prikupljene energije za poboljšanje performansi aplikacije pod dinamički promenljivim uslovima prikupljanja energije

INTERMITTENTLY CONNECTED DELAY-TOLERANT WIRELESS SENSOR NETWORKS

Intermittently Connected Delay-Tolerant Wireless Sensor Networks (ICDT-WSNs), a branch of Wireless Sensor Networks (WSNs), have features of WSNs and the intermittent connectivity of Opportunistic Networks. The applications of ICDT-WSNs are increasing in recent years; however, the communication protocols suitable for this category of networks often fall short. Most of the existing communication protocols are designed for either WSNs or Opportunistic Networks with sufficient resources and tend to be inadequate for direct use in ICDT-WSNs. In this dissertation, we study ICDT-WSNs from the perspective of the characteristics, chal- lenges and possible solutions. A high-level overview of ICDT-WSNs is given, followed by a study of existing work and our solutions to address the problems of routing, flow control, error control, and storage management. The proposed solutions utilize the utility level of nodes and the connectedness of a network. In addition to the protocols for information transmissions to specific destinations, we also propose efficient mechanisms for information dissemination to arbitrary destinations. The study shows that our proposed solutions can achieve better performance than other state of the art communication protocols without sacrificing energy efficiency