The telecommunications sector is increasingly connected to the Internet, resulting in an expanded attack surface accessible from the public Internet. This has increased the availability of information such as IP addresses, open ports, and other network details that anyone from the Internet can access. As a result, potential entry points for attackers have increased, making it essential to map the attack surface of telecommunication networks from the public Internet. While previous research has explored various tools and techniques for mapping the attack surface of the Internet of Things (IoT) and Industrial Control Systems (ICS), such techniques have not yet been extended to the telecommunications domain. This thesis aims to comprehensively map the attack surface of telecommunications operators from the public Internet. To achieve this, we conducted a thorough literature review and proposed a methodology for mapping the attack surface explicitly designed for the telecommunications sector. First, we devised a research workflow that outlines the steps involved in the methodology. Second, we developed a Python-based tool to automate the workflow. We used the tool for a particular mobile network operator. It successfully gathered DNS records, IP addresses, exposed ports, services, Autonomous System Numbers (ASN), server versions, and potential vulnerabilities. The collected data provides valuable insights into the network infrastructure of the operator, aiding in the understanding of potential security risks. / Telekommunikationssektorn blir allt mer kopplad till Internet, detta resulterar i en större attackyta som är tillgänglig från det offentliga Internet. Detta har gett en ökad tillgänglighet av information som till exempel IP adresser, öppna portar, och annan nätverksinformation som vem som helst kan få åtkomst till via Internet. På grund av detta, har potentiella ingångar för attacker ökat, detta gör det avgörande att kartlägga attackytan för telekommunikationsnätverk från det offentliga Internet. Medan tidigare forskning har undersökt olika verktyg och tekniker för att kartlägga attackytor för the Internet of Things (IoT) och Industrial Control Systems (ICS), så har sådana tekniker ännu inte sträckt sig till telekommunikationsdomänen. Denna avhandling har som mål att utförligt kartlägga attackytan för telekommunikationsoperatörer från det offentliga Internet. För att uppnå detta, har vi utfört en grundlig litteraturgranskning och föreslagit en metodologi för kartläggning av attackytor specifikt designat för telekommunikationssektorn. Först konstruerade vi ett forskningsarbetsflöde som beskriver stegen involverade i metodologin. Sedan konstruerade vi ett Python-baserat verktyg för att automatisera arbetsflödet. Vi använde verktyget för en särskild mobilnätverksoperatör. Den samlade framgångsrikt in DNS uppgifter, IP adresser, exponerade portar, tjänster, Autonomous System Numbers (ASN), versioner av servrar, och potentiella sårbarheter. Den insamlade informationen ger värdefulla insikter i nätverksinfrastrukturen hos operatören, vilket hjälper till att förstå potentiella säkerhetsrisker

With the development of 5G technology and edge computing, more and more network application services have been migrated to the cloud network in order to improve the performance, availability and ensure Quality of Service. Edge computing has essentially changed the service deployment model and reduce the latency further for better customer experience, which is realized by deploying network service replicas in geographically distributed edge sites. However, how to discover edge application servers and select a proper instance to serve the edge users becomes an important research topic. This master thesis project addresses the problem by leveraging DNS based service selection mechanism, designing and implementing stable match based service selection algorithms with the aim of minimizing latency between edge users and services and balance the load among edge sites, and integrating the solutions by RESTful APIs. To evaluate the performance of the service selection algorithms, a set of experiments are carried on different simulated topologies with different traffic pattern. The experimental results show that the stable match algorithm and its variants can significantly reduce the average latency by up to 50% compared to traditional approaches, while the enhanced stable match based algorithms are able to have the same load balancing effect with the widely used Round Robin algorithm. / Med utvecklingen av 5G-teknik och edge computing har fler nätverkstjänster migrerats till molnätet för att förbättra prestanda, tillgänglighet och säkerställa servicekvalitet. Edge computing har i huvudsak förändrat tjänster distribution modellen och minskat latensen ytterligare för bättre kundupplevelse, vilket realiseras genom att distribuera nätverkstjänstreplikat på geografiskt distribuerade kantsajter. Hur man upptäcker kantappservrar och väljer en rätt instans för att betjäna kantanvändarna blir dock ett viktigt forskningsämne. Detta projekt löser problemet genom att utnyttja DNS-baserad mekanism för tjänstval, designa och implementera stabila matchbaserade algoritmer för tjänsteval i syfte att minimera latens mellan kantanvändare och tjänster och balansera belastningen mellan kantsajter och integrera lösningarna med RESTful API:er. För att utvärdera prestandan för algoritmerna för val av tjänster utförs en uppsättning experiment på olika simulerade topologier med olika trafikmönster. De experimentella resultaten visar att den stabila matchningsalgoritmen och dess varianter avsevärt kan minska den genomsnittliga latensen med upp till 50% jämfört med traditionella metoder, medan de förbättrade stabila matchbaserade algoritmerna kan ha samma belastningsbalanseringseffekt med den mycket använda Round Robin algoritm.

Net Neutrality implicates that all data being transmitted online is treated equal by Internet Service Providers. In 2016, the public debate regarding Net Neutrality in Sweden started growing as two major Mobile Network Operators were investigated by the Swedish Post and Telecom Authority for violation of European Union Net Neutrality regulations. Several studies have been conducted regarding Net Neutrality, most of them written in a legal, financial or technological perspective. This study takes another direction, aimed at understanding the consumer’s point of view regarding Net Neutrality. This study investigates whether or not consumers are aware of the subject and if so, how they value it. To measure this, an online survey was constructed, containing a total of 12 questions and statements. 77 people participated in the survey and out of these, 10 people participated in qualitative follow-up interviews. The interviews were semi-structured and individually designed according to each participant’s answers in the survey. This was done in order to gain a deeper understanding of the consumer’s reasoning while answering the survey. The results show that consumers lack knowledge regarding Net Neutrality. A major part of the consumers had not heard of the term or did not know the meaning of it, making it hard to determine whether or not the consumers value NN. However, when given a more concrete example of the implications of Internet Traffic Management from ISPs, the participants had a better understanding of what kind of implications NN could have on their Internet usage. They valued the implications of Net Neutrality, even though they did not know the theory of the term itself. The study also revealed that consumers have a big confidence in National Regulatory Authorities when it comes to looking after the openness of the Internet. Therefore, it is likely that National Regulatory Authorities must inform and educate consumers in the matter of Net Neutrality for them to value it and see its long-term implications. / Nätneutralitet innebär kortfattat att all data som skickas över Internet ska behandlas likvärdigt utav Internetleverantörer (ISP). Under 2016 växte debatten kring nätneutralitet i Sverige då två stycken mobiloperatörer utreddes utav Post- och Telestyrelsen. Båda dessa mobiloperatörer lanserade kampanjer till sina kunder som ansågs strida mot EU:s förordning 2015/2120 rörande nätneutralitet. Ett antal studier har redan gjorts på ämnet nätneutralitet, dock har de flesta haft en infallsvinkel där man tittat på juridiska, finansiella eller tekniska perspektiv. Den här studien har en annan infallsvinkel och riktar sig istället mot konsumenters syn på nätneutralitet. Den ämnar undersöka huruvida konsumenter känner till begreppet nätneutralitet och om de gör det, hur värderar de konceptet? För att undersöka detta konstruerades en online-enkät, innehållandes 12 frågor. 77 personer deltog i enkäten och utav dessa så deltog 10 personer i uppföljande, kvalitativa intervjuer. Intervjuerna var semi-strukturerade och individuella med frågor baserade på individens svar i enkäten. Dessa intervjuer var till för att ge en fördjupad förståelse av konsumenternas syn på nätneutralitet och deras resonemang kring svaren under enkäten. Resultaten visar att konsumenter, deltagande i den här studien, har låg kunskap kring nätneutralitet. Majoriteten utav deltagarna hade inte hört termen eller kände inte till dess mening, vilket gjorde det svårt att dra några slutsatser kring huruvida konsumenterna värderar konceptet. Men när konsumenterna fick ett mer konkret exempel på hur Internetleverantörers datahantering påverkar kundernas Internetanvändande så tycktes konsumenterna förstå vilka implikationer nätneutralitet kan ha på deras eget Internetanvändande. De tycktes således värdera innebörden av nätneutralitet, även om de inte förstod teorin kring konceptet. Studien påvisade också att konsumenter har en stor tilltro till vederbörande myndighet, Post- och Telestyrelsen här i Sverige, när det gäller att se efter Internets öppenhet och mångfald. Det är därför troligt att Post- och Telestyrelsen kommer att behöva informera och utbilda konsumenter rörande nätneutralitet för att få konsumenter att se värdet av och de långsiktiga implikationerna utav det.

Les réseaux ad hoc mobiles sont des réseaux qui se forment spontanément grâce à la présence de terminaux mobiles. Ces réseaux sans fil sont de faible capacité. Les nœuds se déplacent librement et de manière imprévisible et ils se déchargent très rapidement. En conséquence, un réseau MANET est très enclin à subir des partitionnements fréquents. Les applications déployées sur de tels réseaux, souffrent de problèmes de disponibilité des données induits par ces partitionnements. La réplication des données constitue un mécanisme prometteur pour pallier ce problème. Cependant, la mise en œuvre d’un tel mécanisme dans un environnement aussi contraint en ressources constitue un réel défi. L’objectif principal est donc de réaliser un mécanisme peu consommateur en ressources. Le second objectif de la réplication est de permettre le rééquilibrage de la charge induite par les requêtes de données. Le choix des données à répliquer ainsi que celui des nœuds optimaux pour le placement des futurs réplicas est donc crucial, spécialement dans le contexte du MANET. Dans cette thèse, nous proposons CReaM (Community-Centric and Resource-Aware Replication Model”) un modèle de réplication adapté à un réseau MANET. CReaM fonctionne en mode autonomique : les prises de décisions se basent sur des informations collectées dans le voisinage du nœud plutôt que sur des données globalement impliquant tous les nœuds, ce qui permet de réduire le trafic réseau lié à la réplication. Pour réduire l’usage des ressources induit par la réplication sur un nœud, les niveaux de consommation des ressources sont contrôlés par un moniteur. Toute consommation excédant un seuil prédéfini lié à cette ressource déclenche le processus de réplication. Pour permettre le choix de la donnée à répliquer, une classification multi critères a été proposée (rareté de la donnée, sémantique, niveau de demande); et un moteur d’inférence qui prend en compte l’état de consommation des ressources du nœud pour désigner la catégorie la plus adaptée pour choisir la donnée à répliquer. Pour permettre de placer les réplicas au plus près des nœuds intéressés, CReaM propose un mécanisme pour l’identification et le maintien à jour des centres d’intérêt des nœuds. Les utilisateurs intéressés par un même sujet constituent une communauté. Par ailleurs, chaque donnée à répliquer est estampillée par le ou les sujets au(x)quel(s) elle s’apparente. Un nœud désirant placer un réplica apparenté à un sujet choisira le nœud ayant la plus grande communauté sur ce sujet. Les résultats d’expérimentations confirment la capacité de CReaM à améliorer la disponibilité des données au même niveau que les solutions concurrentes, tout en réduisant la charge liée à la réplication. D’autre part, CReaM permet de respecter l’état de consommation des ressources sur les nœuds. / A Mobile Ad-hoc Network is a self-configured infrastructure-less network. It consists of autonomous mobile nodes that communicate over bandwidth-constrained wireless links. Nodes in a MANET are free to move randomly and organize themselves arbitrarily. They can join/quit the network in an unpredictable way; such rapid and untimely disconnections may cause network partitioning. In such cases, the network faces multiple difficulties. One major problem is data availability. Data replication is a possible solution to increase data availability. However, implementing replication in MANET is not a trivial task due to two major issues: the resource-constrained environment and the dynamicity of the environment makes making replication decisions a very tough problem. In this thesis, we propose a fully decentralized replication model for MANETs. This model is called CReaM: “Community-Centric and Resource-Aware Replication Model”. It is designed to cause as little additional network traffic as possible. To preserve device resources, a monitoring mechanism are proposed. When the consumption of one resource exceeds a predefined threshold, replication is initiated with the goal of balancing the load caused by requests over other nodes. The data item to replicate is selected depending on the type of resource that triggered the replication process. The best data item to replicate in case of high CPU consumption is the one that can better alleviate the load of the node, i.e. a highly requested data item. Oppositely, in case of low battery, rare data items are to be replicated (a data item is considered as rare when it is tagged as a hot topic (a topic with a large community of interested users) but has not been disseminated yet to other nodes). To this end, we introduce a data item classification based on multiple criteria e.g., data rarity, level of demand, semantics of the content. To select the replica holder, we propose a lightweight solution to collect information about the interests of participating users. Users interested in the same topic form a so-called “community of interest”. Through a tags analysis, a data item is assigned to one or more communities of interest. Based on this framework of analysis of the social usage of the data, replicas are placed close to the centers of the communities of interest, i.e. on the nodes with the highest connectivity with the members of the community. The results of evaluating CReaM show that CReaM has positive effects on its main objectives. In particular, it imposes a dramatically lower overhead than that of traditional periodical replication systems (less than 50% on average), while it maintains the data availability at a level comparable to those of its adversaries.

There has been a steady growth in the traffic generated by Mobile Network Operators (MNOs), and by 2020 it is expected to overload the existing licensed spectrum capacity and lead to the problem of scarce resources. One method to deal with this traffic overload is to access unlicensed and shared spectrum bands using an opportunistic approach. The use of Licensed Shared Access (LSA) is a novel approach for spectrum sharing between the incumbent user (i.e., the current owner of the shared spectrum) and the LSA licensee (i.e., the temporary user of frequencies, such as an MNO). The LSA system allows the incumbent users to temporarily provide the LSA licensee with access to its spectrum resources. However, licensees must adopt vertical handover and traffic steering procedures to vacate their customers from the LSA band without causing interference, whenever this is required by the incumbent. These procedures should be carried out, de facto, before the base station is turned off as a part of a rapid release of unscheduled LSA band facing evacuation scenarios. Thus, in this dissertation, a cognitive mechanism is proposed to make decisions in advance to find the best target network(s) for evacuated customers in connected mode and with active traffic per class of service. On the basis of these decisions, the vertical handover and traffic steering procedures are carried out for the best target network(s), which are selected in advance and undertaken immediately to avoid interference between the licensee and incumbent services. Furthermore, this guarantees the seamless connectivity and QoS of evacuated customers and their traffic respectively, during and after the unscheduled evacuation scenarios. A performance evaluation conducted in a simulating scenario consisting of one LTE-LSA and three Wi-Fi networks, demonstrated that the proposed solution could be completed within the time required for the unscheduled evacuation, as well as, being able to ensure the QoS and seamless connectivity of the evacuees. The total execution time obtained during the performance evaluation of the proposed solution was around 46% faster than of two related works and could thus avoid interference between the licensee and incumbent services.

澳門電信管理局在2012年1月推出「全城3G」計劃，規定2012年7月8日停用所有GSM服務，16萬2G用戶要在半年內轉移到3G服務，但是外地遊客仍可繼續在澳門使用2G漫遊服務，政府希望透計劃推動3G服務的發展，讓無線電資源更具效率地利用，然而在計劃推行期間澳門出現多宗電信故障，加上澳門廉政公署就「全城3G」計劃所發表的調查報告指有關計劃過份介入市場運作，使得本地用戶失去選擇權，損害用戶及業者的權益，而且不符合公共利益，最終「全城3G」計劃無法如期實行，各業者的2G執照與其3G執照一同延長有效期至2023年6月4日。 　　本研究利用文獻分析法，透過蒐集澳門「全城3G」計劃的相關資料，分析澳門「全城3G」計劃的得失，與此同時借鏡與澳門政治體制相似的香港政府的頻譜政策，檢視兩地政府在回收2G頻譜的成效。本研究綜合分析下發現澳門與香港回收2G頻譜最大的差異在於香港回收的是兩個閒置的CDMA及TDMA系統，對業者有一定的影響，但是影響民眾的範圍卻很小，而且給予3年緩衝的時間讓業者轉移用戶，而澳門則是停用一個在世界上仍算主流的GSM服務，而且要在半年內轉移十多萬用戶到3G，加上在過渡期間出現5宗電信故障，讓民眾質疑計劃的可行性，最終把技術問題變成社會問題。因此本研究建議政府未來要避免直接介入市場，以間接的方式例如徵收階梯式的頻譜使用費來推動行動通訊業發展，回收頻譜時要以平穩適度的方式進行，以及提高電信故障的罰款。 / In January 2012, the Telecommunications Regulation Bureau of Macau (DSRT) announced its decision to scrap the city’s 2G network and rely solely on 3G capabilities. Effective on July 8, 2012, the policy change left about 160,000 local users without 2G service, primarily affecting local tourists still on the 2G roaming network. DSRT stated that the objectives of its decision were to create more investment opportunities and to facilitate the adequate diversification of economic development. However, during this time, two mobile operators failed to provide stable and adequate network services and the Commission Against Corruption (CCAC) of Macau stated that DSRT’s decision deprived consumers of their right to choose their own cellular network and their right to fair treatment. This prompted the 2G service cancellation to be further postponed until June 4, 2023. This study used literature analysis to review the termination of the 2G mobile network in Macau, and to examine the 2G spectrum reallocation in Hong Kong. This study found that Hong Kong terminated two unused mobile network services (CDMA and TDMA), while Macau is planning to scrap a GSM service which will affect about 150,000 users in Macau. Therefore, opposition to network terminations are greater in Macau than in Hong Kong. At the same time, the failure to provide adequate mobile services by two network operators in Macau led to public mistrust of the government. This study suggests that 1) the DSRT should not have used administrative means to force consumers into using a specific mobile system, and 2) the DSRT should have amended the penalties for mobile operators to closer reflect the current social situation.

With mobile phones almost being ubiquitous in most communities, the electronic payment industry has realised the potential of using mobile phones as devices that can be used to conduct electronic payments. This realisation has led to an increase in the number of mobile payment solutions, which are being deployed for use by the public. However, these mobile payment solutions have not been widely adopted, especially by the citizens who are residing in the townships. Thus, this study investigates the factors that inhibit township residents from adopting mobile payments. The study was done at the Soshanguve township on the outskirts of Pretoria in Gauteng, South Africa. The study adopted a mixed method approach to collect data. Phase 1 relied on the interviews from a few selected individuals to collect the initial data, once this process was complete; a questionnaire (Phase 2) was developed and distributed to the general community of Soshanguve for data collection, which was qualitatively and quantitatively analysed.the diffusion and use of mobile payments in the townships. Some of the factors are as follows: mobile payments are not easy to use; lack of products to purchase using mobile payments; high costs associated with using mobile payment solutions; lack of trialability of mobile payment solutions; and lack of awareness of mobile payment providers in the townships. The study proposes several guidelines that could help developers and operators of mobile payment solutions to design and deploy their solutions in such a way that they are suitable for consumption by the users in township communities. Proposed guidelines are as follows: (1) when a mobile payment solution is launched, effort should be made to market it to the target market; (2) potential adopters of mobile payments should be able to try it without incurring any financial penalties; (3) mobile payments should be easier to use; (4) mobile payment security features should be apparent to the potential adopters in order to alleviate their fears; (5) mobile payment solutions should be designed according to the needs of the target market as one size fits all does not work; (6) mobile payment solutions should fulfill a need which is not met by the current alternatives or it should offer more value than the existing alternatives; (7) the cost of conducting mobile payments should be affordable; and (8) the regulator should develop legislation that stimulates innovation and competition while ensuring the security of mobile payments. / Computing / M. Sc. (Computing)

There has been a steady growth in the traffic generated by Mobile Network Operators (MNOs), and by 2020 it is expected to overload the existing licensed spectrum capacity and lead to the problem of scarce resources. One method to deal with this traffic overload is to access unlicensed and shared spectrum bands using an opportunistic approach. The use of Licensed Shared Access (LSA) is a novel approach for spectrum sharing between the incumbent user (i.e., the current owner of the shared spectrum) and the LSA licensee (i.e., the temporary user of frequencies, such as an MNO). The LSA system allows the incumbent users to temporarily provide the LSA licensee with access to its spectrum resources. However, licensees must adopt vertical handover and traffic steering procedures to vacate their customers from the LSA band without causing interference, whenever this is required by the incumbent. These procedures should be carried out, de facto, before the base station is turned off as a part of a rapid release of unscheduled LSA band facing evacuation scenarios. Thus, in this dissertation, a cognitive mechanism is proposed to make decisions in advance to find the best target network(s) for evacuated customers in connected mode and with active traffic per class of service. On the basis of these decisions, the vertical handover and traffic steering procedures are carried out for the best target network(s), which are selected in advance and undertaken immediately to avoid interference between the licensee and incumbent services. Furthermore, this guarantees the seamless connectivity and QoS of evacuated customers and their traffic respectively, during and after the unscheduled evacuation scenarios. A performance evaluation conducted in a simulating scenario consisting of one LTE-LSA and three Wi-Fi networks, demonstrated that the proposed solution could be completed within the time required for the unscheduled evacuation, as well as, being able to ensure the QoS and seamless connectivity of the evacuees. The total execution time obtained during the performance evaluation of the proposed solution was around 46% faster than of two related works and could thus avoid interference between the licensee and incumbent services.

There has been a steady growth in the traffic generated by Mobile Network Operators (MNOs), and by 2020 it is expected to overload the existing licensed spectrum capacity and lead to the problem of scarce resources. One method to deal with this traffic overload is to access unlicensed and shared spectrum bands using an opportunistic approach. The use of Licensed Shared Access (LSA) is a novel approach for spectrum sharing between the incumbent user (i.e., the current owner of the shared spectrum) and the LSA licensee (i.e., the temporary user of frequencies, such as an MNO). The LSA system allows the incumbent users to temporarily provide the LSA licensee with access to its spectrum resources. However, licensees must adopt vertical handover and traffic steering procedures to vacate their customers from the LSA band without causing interference, whenever this is required by the incumbent. These procedures should be carried out, de facto, before the base station is turned off as a part of a rapid release of unscheduled LSA band facing evacuation scenarios. Thus, in this dissertation, a cognitive mechanism is proposed to make decisions in advance to find the best target network(s) for evacuated customers in connected mode and with active traffic per class of service. On the basis of these decisions, the vertical handover and traffic steering procedures are carried out for the best target network(s), which are selected in advance and undertaken immediately to avoid interference between the licensee and incumbent services. Furthermore, this guarantees the seamless connectivity and QoS of evacuated customers and their traffic respectively, during and after the unscheduled evacuation scenarios. A performance evaluation conducted in a simulating scenario consisting of one LTE-LSA and three Wi-Fi networks, demonstrated that the proposed solution could be completed within the time required for the unscheduled evacuation, as well as, being able to ensure the QoS and seamless connectivity of the evacuees. The total execution time obtained during the performance evaluation of the proposed solution was around 46% faster than of two related works and could thus avoid interference between the licensee and incumbent services.

L'efficacité énergétique constitue l'objectif clef pour la conception des protocoles de communication pour des réseaux de capteurs radio multi-sauts. Beaucoup d'efforts ont été réalisés à différents niveaux de la pile protocolaire à travers des algorithmes d'agrégation spatiale et temporelle des données, des protocoles de routage efficaces en énergie, et des couches d'accès au médium avec des mécanismes d'ordonnancement permettant de mettre la radio en état d'endormissement afin d'économiser l'énergie. Pour autant, ces protocoles utilisent de façon importante des paquets de contrôle et de découverte du voisinage qui sont coûteux en énergie. En outre, cela se fait très souvent sans aucune interaction entre les différentes couches de la pile. Ces travaux de thèse s'intéressent donc particulièrement à la problématique de l'énergie des réseaux de capteurs à travers des protocoles de routage et d'accès au médium. Les contributions de cette thèse se résument de la manière suivante : Nous nous sommes tout d'abord intéressés à la problématique de l'énergie au niveau routage. Dans cette partie, les contributions se subdivisent en deux parties. Dans un premier temps, nous avons proposé une analyse théorique de la consommation d'énergie des protocoles de routage des réseaux radio multi-sauts d'appréhender au mieux les avantages et les inconvénients des uns et des autres en présence des modèles de trafic variables, un diamètre du réseau variable également et un modèle radio qui permet de modéliser les erreurs de réception des paquets. À l'issue de cette première étude, nous sommes parvenus à la conclusion que pour être économe en énergie, un protocole de routage doit avoir des approches similaires à celle des protocoles de routage géographique sans message hello. Puis, dans un second temps, nous introduisons une étude de l'influence des stratégies de relayage dans un voisinage à 1 saut sur les métriques de performance comme le taux de livraison, le nombre de messages dupliqués et la consommation d'énergie. Cette étude est suivie par une première proposition de protocole de routage géographique sans message hello (Pizza-Forwarding (PF)) exploitant des zones de relayage optimisées et sans aucune hypothèse sur les propriétés du canal radio. Dans le but de réduire considérablement la consommation de PF, nous proposons de le combiner avec une adaptation d'un protocole MAC asynchrone efficace en énergie à travers une approche transversale. La combinaison de ces deux approches montre un gain significatif en terme d'économie d'énergie avec des très bon taux de livraison et cela quels que soient les scénarios et la nature de la topologique. / Energy-efficient communication protocol is a primary design goal for Wireless Sensor Networks (WSNs). Many efforts have been done to save energy anywhere in the protocol stack through temporal and spatial data aggregation schemes, energy-aware routing protocols, activity scheduling and energy-efficient MAC protocols with duty cycle. However both control packets and beacons remain which induces a huge waste energy. Moreover, their design follows the classical layered approach with the principle of modularity in system development, which can lead to a poor performance in WSNs. This thesis focuses on the issues of energy in WSNs through energy-efficient routing and medium access control protocols. The constributions of this thesis can be summarized as follows: First, we are interested on the energy issues at the routing layer for multihop wireless sensor networks (WSNs). We propose a mathematical framework to model and analyze the energy consumption of routing protocols in multihop WSNs by taking into account the protocol parameters, the traffic pattern and the network characteristics defined by the medium channel properties, the dynamic topology behavior, the network diameter and the node density. In this study, we show that Beacon-less routing protocol should be a best candidate to save energy in WSNs. We investigate the performance of some existing relay selection schemes which are used by Beacon-less routing protocols. Extensive simulations are proposed to evaluate their performance locally in terms of packet delivery ratio, duplicated packet and delay. Then, we extend the work in multihop wiriless networks and develop an optimal solution, Enhanced Nearest Forwarding within Radius, which tries to minimize the per-hop expected number of retranmissions in order to save energy. We present a new beaconless routing protocol called Pizza-Forwarding (PF) without any assumption on the radio environment: neither the radio range nor symmetric radio links nor radio properties (shadowing, etc.) are assumed or restricted. A classical greedy mode is proposed. To overcome the hole problem, packets are forwarded to an optimal node in the two hop neighbor following a reactive and optimized neighborhood discovery. In order to save energy due to idle listening and overhearing, we propose to combine PF's main concepts with an energy-efficient MAC protocol to provide a joint MAC/routing protocol suitable for a real radio environment. Performance results lead to conclude to the powerful behavior of PFMAC.