Cross-layer energy optimisation of routing protocols in wireless sensor networks

Recent technological developments in embedded systems have led to the emergence of a new class of networks, known asWireless Sensor Networks (WSNs), where individual nodes cooperate wirelessly with each other with the goal of sensing and interacting with the environment.Many routing protocols have been developed tomeet the unique and challenging characteristics of WSNs (notably very limited power resources to sustain an expected lifetime of perhaps years, and the restricted computation, storage and communication capabilities of nodes that are nonetheless required to support large networks and diverse applications). No standards for routing have been developed yet for WSNs, nor has any protocol gained a dominant position among the research community. Routing has a significant influence on the overall WSN lifetime, and providing an energy efficient routing protocol remains an open problem. This thesis addresses the issue of designing WSN routing methods that feature energy efficiency. A common time reference across nodes is required in mostWSN applications. It is needed, for example, to time-stamp sensor samples and for duty cycling of nodes. Alsomany routing protocols require that nodes communicate according to some predefined schedule. However, independent distribution of the time information, without considering the routing algorithm schedule or network topology may lead to a failure of the synchronisation protocol. This was confirmed empirically, and was shown to result in loss of connectivity. This can be avoided by integrating the synchronisation service into the network layer with a so-called cross-layer approach. This approach introduces interactions between the layers of a conventional layered network stack, so that the routing layer may share information with other layers. I explore whether energy efficiency can be enhanced through the use of cross-layer optimisations and present three novel cross-layer routing algorithms. The first protocol, designed for hierarchical, cluster based networks and called CLEAR (Cross Layer Efficient Architecture for Routing), uses the routing algorithm to distribute time information which can be used for efficient duty cycling of nodes. The second method - called RISS (Routing Integrated Synchronization Service) - integrates time synchronization into the network layer and is designed to work well in flat, non-hierarchical network topologies. The third method - called SCALE (Smart Clustering Adapted LEACH) - addresses the influence of the intra-cluster topology on the energy dissipation of nodes. I also investigate the impact of the hop distance on network lifetime and propose a method of determining the optimal location of the relay node (the node through which data is routed in a two-hop network). I also address the problem of predicting the transition region (the zone separating the region where all packets can be received and that where no data can be received) and I describe a way of preventing the forwarding of packets through relays belonging in this transition region. I implemented and tested the performance of these solutions in simulations and also deployed these routing techniques on sensor nodes using TinyOS. I compared the average power consumption of the nodes and the precision of time synchronization with the corresponding parameters of a number of existing algorithms. All proposed schemes extend the network lifetime and due to their lightweight architecture they are very efficient on WSN nodes with constrained resources. Hence it is recommended that a cross-layer approach should be a feature of any routing algorithm for WSNs

5G NR sidelink on UE protocol stack

Abstract. The idea of effcient communication outside of coverage of base stations have been discussed for a long time. The most suitable solution for this idea has been the ability to extend the communication through devices. In theory, it would be necessary for just one device to be in the coverage of the base station, and the communication could be further extended by hopping from device to device. These communications are called device-to-device communications. Multiple different technologies could be used to solve this task, such as Wi-Fi, Bluetooth and sidelink. Especially when it comes to high mobility and reliability dependent use cases, technologies such as Wi-Fi are simply not capable. This is where the sidelink technology comes in. The sidelink is a communication technology that allows devices to communicate with each other directly, without the need for a cellular network. This technology utilizes the frequency spectrum and enables high-speed, low-latency communication between devices. It has numerous potential applications, including vehicle-to-vehicle communication, machine-type communication, and local area networking. In this thesis, technical characteristics of 5G NR sidelink and its potential applications and challenges are considered. The overview of the ongoing standardization efforts and the deployment status of this technology are discussed. The effciency of the sidelink technology is evaluated and compared to the existing technologies. The sidelink related future updates are discussed and their effect on the current specifcation is evaluated.5G NR sidelink -käyttäjäpäätteen protokollapino. Tiivistelmä. Tukiasemien kantavuuden ulkopuolelle yltävistä verkkoyhteyksistä on keskusteltu jo pitkään. Potentiaalisesti toimivin ratkaisu olisi kasvattaa kantavuutta kannettavien laitteiden kautta. Teoriassa tukiaseman kantaman sisällä tarvitaan vain yksi laite, jonka avulla yhteys voitaisiin kuljettaa laitteelta toiselle tukiaseman kantaman ulkopuolella. Tämänlaisia yhteyksiä kutsutaan suoriksi laitteelta laitteelle yhteyksiksi. Kyseiset yhteydet voitaisiin toteuttaa useilla eri teknologioilla, kuten Wi-Fi:llä, Bluetooth:lla tai sidelink:llä. Erityisesti suurta liikkuvuutta ja luotettavuutta vaativiin käyttökohteisiin Wi-Fi ei ole riittävän tehokas. Tämänlaisissa käyttökohteissa sidelink voisi toimia sopivana Wi-Fi:n korvaajana. Sidelink-teknologia antaa laitteille mahdollisuuden kommunikoida suoraan toistensa kanssa. Nämä yhteydet eivät vaadi matkapuhelinverkkoa toimiakseen. Sidelink-teknologialla mahdollistetaan nopeat, luotettavat ja matalan latenssin yhteydet laitteiden välillä. Sidelink mahdollistaa useita moderneja käyttökohteita, kuten ajoneuvojen väliset yhteydet. Tässä diplomityössä sidelinkin ominaisuuksia käydään läpi. Potentiaalisia sovellutuksista ja teknologiaan liittyvistä haasteista keskustellaan. Käynnissä olevat standardisoinnit käydään tärkeimmiltä osiltaan läpi. Sidelink-teknologian toimivuutta verrataan olemassa oleviin vastaaviin teknologioihin. Myös LTE ja NR versioiden eroja käydään läpi. Myös tulevia muutoksia ja standardisointeja tarkastellaan

Energy-Efficient Communication in Wireless Networks

This chapter describes the evolution of, and state of the art in, energy‐efficient techniques for wirelessly communicating networks of embedded computers, such as those found in wireless sensor network (WSN), Internet of Things (IoT) and cyberphysical systems (CPS) applications. Specifically, emphasis is placed on energy efficiency as critical to ensuring the feasibility of long lifetime, low‐maintenance and increasingly autonomous monitoring and control scenarios. A comprehensive summary of link layer and routing protocols for a variety of traffic patterns is discussed, in addition to their combination and evaluation as full protocol stacks

Smart PIN: performance and cost-oriented context-aware personal information network

The next generation of networks will involve interconnection of heterogeneous individual networks such as WPAN, WLAN, WMAN and Cellular network, adopting the IP as common infrastructural protocol and providing virtually always-connected network. Furthermore, there are many devices which enable easy acquisition and storage of information as pictures, movies, emails, etc. Therefore, the information overload and divergent content’s characteristics make it difficult for users to handle their data in manual way. Consequently, there is a need for personalised automatic services which would enable data exchange across heterogeneous network and devices. To support these personalised services, user centric approaches for data delivery across the heterogeneous network are also required. In this context, this thesis proposes Smart PIN - a novel performance and cost-oriented context-aware Personal Information Network. Smart PIN's architecture is detailed including its network, service and management components. Within the service component, two novel schemes for efficient delivery of context and content data are proposed: Multimedia Data Replication Scheme (MDRS) and Quality-oriented Algorithm for Multiple-source Multimedia Delivery (QAMMD). MDRS supports efficient data accessibility among distributed devices using data replication which is based on a utility function and a minimum data set. QAMMD employs a buffer underflow avoidance scheme for streaming, which achieves high multimedia quality without content adaptation to network conditions. Simulation models for MDRS and QAMMD were built which are based on various heterogeneous network scenarios. Additionally a multiple-source streaming based on QAMMS was implemented as a prototype and tested in an emulated network environment. Comparative tests show that MDRS and QAMMD perform significantly better than other approaches

The Design of a System Architecture for Mobile Multimedia Computers

This chapter discusses the system architecture of a portable computer, called Mobile Digital Companion, which provides support for handling multimedia applications energy efficiently. Because battery life is limited and battery weight is an important factor for the size and the weight of the Mobile Digital Companion, energy management plays a crucial role in the architecture. As the Companion must remain usable in a variety of environments, it has to be flexible and adaptable to various operating conditions. The Mobile Digital Companion has an unconventional architecture that saves energy by using system decomposition at different levels of the architecture and exploits locality of reference with dedicated, optimised modules. The approach is based on dedicated functionality and the extensive use of energy reduction techniques at all levels of system design. The system has an architecture with a general-purpose processor accompanied by a set of heterogeneous autonomous programmable modules, each providing an energy efficient implementation of dedicated tasks. A reconfigurable internal communication network switch exploits locality of reference and eliminates wasteful data copies