Traffic-aware techniques to reduce 3G/LTE wireless energy consumption

The 3G/LTE wireless interface is a significant contributor to battery drain on mobile devices. A large portion of the energy is consumed by unnecessarily keeping the mobile device's radio in its "Active" mode even when there is no traffic. This paper describes the design of methods to reduce this portion of energy consumption by learning the traffic patterns and predicting when a burst of traffic will start or end. We develop a technique to determine when to change the radio's state from Active to Idle, and another to change the radio's state from Idle to Active. In evaluating the methods on real usage data from 9 users over 28 total days on four different carriers, we find that the energy savings range between 51% and 66% across the carriers for 3G, and is 67% on the Verizon LTE network. When allowing for delays of a few seconds (acceptable for background applications), the energy savings increase to between 62% and 75% for 3G, and 71% for LTE. The increased delays reduce the number of state switches to be the same as in current networks with existing inactivity timers.National Science Foundation (U.S.) (Grant CNS-0931550

Storms in mobile networks

Mobile networks are vulnerable to signalling attacks and storms caused by traffic that overloads the control plane through excessive signalling, which can be introduced via malware and mobile botnets. With the advent of machine-to-machine (M2M) communications over mobile networks, the potential for signalling storms increases due to the normally periodic nature of M2M traffic and the sheer number of communicating nodes. Several mobile network operators have also experienced signalling storms due to poorly designed applications that result in service outage. The radio resource control (RRC) protocol is particularly susceptible to such attacks, motivating this work within the EU FP7 NEMESYS project which presents simulations that clarify the temporal dynamics of user behavior and signalling, allowing us to suggest how such attacks can be detected and mitigated

Signalling Storms in 3G Mobile Networks

We review the characteristics of signalling storms that have been caused by certain common apps and recently observed in cellular networks, leading to system outages. We then develop a mathematical model of a mobile user's signalling behaviour which focuses on the potential of causing such storms, and represent it by a large Markov chain. The analysis of this model allows us to determine the key parameters of mobile user device behaviour that can lead to signalling storms. We then identify the parameter values that will lead to worst case load for the network itself in the presence of such storms. This leads to explicit results regarding the manner in which individual mobile behaviour can cause overload conditions on the network and its signalling servers, and provides insight into how this may be avoided.Comment: IEEE ICC 2014 - Communications and Information Systems Security Symposiu

Architecture d'interopérabilité et mécanismes de relève pour les réseaux sans fil de prochaine génération

Intégration, interopéribilité et mobilité -- An analytical framework for performance evaluation of IPV6-Based mobility management protocols -- An architecture for seamless mobility support in Ip-Based next generation wireless networks -- Adaptive handoff scheme for heterogeneous ip wireless networks -- Enhanced fast handoff scheme for heterogeneous wireless networks

Técnicas de gestão de feixe de onda para sistemas Massive MIMO nas redes 5G NR

The use of Millimeter wave (mmWave) spectrum frequencies is seen as a key enabler technology for the future wireless communication systems to overcome the bandwidth shortage of the sub 6GHz microwave spectrum band, enabling high speed data transmissions in the 5G/6G systems. Nevertheless, mmWave propagation characteristics are associated to significant free-path losses and many more attenuations that become even more harsher as the frequency increases, rendering the communication challenging at this frequencies. To overcome these distinct disadvantages, multiple antenna arrays are employed to allow beamforming techniques for the transmission of narrower concentrated beams in more precise directions and less interference levels between them, consequently improving the link budget. Thus, to constantly assure that the communication with each device is done using the beam pair that allows the best possible connectivity, a set of Beam Management control procedures is necessary to assure an efficient beamformed connection establishment and its continuous maintenance between the device and the network. This dissertation will address the description of the Initial Beam Establishment (IBE) BM procedure, focusing the selection of the most suitable transmit-receive beam pair available after completed beam sweeping techniques to measure the different power levels of the received signal. The main goal is to design a new 3GPP-standard compliant beam pair selection algorithm based on SSS angle estimation (BSAE), that makes use of multiple Synchronization Signal Blocks (SSBs) to maximize the Reference Signal Received Power (RSRP) value at the receiver, through the selected beam pair. This optimization is done using the Secondary Synchronization Signals (SSSs) present in each SSB to perform channel estimation in the digital domain (comprising the effects of the analog processing). Afterwards, the combination of those estimations were used to perform the equivalent channel propagation matrix estimation without the analog processing effects. Finally, through the channel propagation matrix, the angle that maximizes the RSRP was determined to compute the most suitable beam through the aggregated response vector. The obtained results show that the proposed algorithm achieves better performance levels compared to a conventional beam pair selection algorithm. Furthermore, a comparison with an optimal case is also done, i.e., the situation where the channel is known, and the optimal beam pair angle can be determined. Therefore, the similar performance results compared to the optimal case indicates that the proposed algorithm is interesting for practical 5G mmWave mMIMO implementations, according to 3GPP-compliant standards.O uso de frequências na banda das ondas milimétricas é visto como uma tecnologia chave para os futuros sistemas de comunicação móveis, tendo em vista a ultrapassar o problema da escassez de banda a sub-6 GHz, e por permitir as elevadas taxas de dados requeridas para sistemas 5G/6G. Contudo, a propagação deste tipo de ondas está associado a perdas acentuadas em espaço livre e várias atenuações que se tornam cada vez mais significativas com o aumento do valor da frequência, impondo obstáculos à comunicação. Para ultrapassar estas adversidades, agregados constituídos por múltiplos elementos de antena são implementados por forma a permitir técnicas de formação de feixe e possibilitar a transmissão de feixes mais estreitos e altamente direcionais, diminuindo os níveis de interferência e melhorando consequentemente o link budget. Deste modo, para assegurar constantemente que a comunicação efetuada em cada dispositivo ocorre utilizando o conjunto de feixes que proporciona o melhor nível de conectividade, é então necessário um conjunto de procedimentos de controlo de gestão de feixe, assegurando um estabelecimento eficiente da comunicação e a sua contínua manutenção entre um dispositivo e a rede. Esta dissertação descreve o procedimento de gestão de feixe conhecido como estabelecimento inicial de feixe, focando o processo de seleção do melhor par de feixe de transmissão-receção disponível após o uso de técnicas de varrimento de feixe por fim a efetuar medições dos diferentes níveis de potência do sinal recebido. O principal objetivo passa pela conceção de um novo algoritmo de estabelecimento de par de feixes baseado em estimações de ângulo (BSAE), que explora o uso de múltiplos SSBs definidos pelo 3GPP, por forma a maximizar o RSRP no recetor, através do feixe selecionado. Esta otimização é feita usando os sinais de sincronização secundários (SSSs) presentes em cada SSB para efetuar uma estimação de canal no domínio digital (que contém o efeito do processamento analógico). Depois, combinando essas estimações, foi feita uma estimação da matriz do canal de propagação, sem o efeito desse processamento analógico. Finalmente, através da matriz do canal de propagação, foi determinado o ângulo que maximiza o RSRP, e calculado o feixe através do vetor de resposta do agregado. Os resultados obtidos demonstram que o algoritmo proposto atinge melhor desempenho quando comparado com o algoritmo convencional de seleção de par de feixes. Foi feita ainda uma comparação com o caso ótimo, isto é, com o caso em que se conhece completamente o canal e se obtém um ângulo ótimo. Os resultados obtidos pelo algoritmo proposto foram muito próximos do caso ótimo, pelo que é bastante interessante para sistemas práticos 5G mmWave mMIMO, que estejam de acordo com o padrão 3GPP.Mestrado em Engenharia Eletrónica e Telecomunicaçõe

IP Mobility in Wireless Operator Networks

Wireless network access is gaining increased heterogeneity in terms of the types of IP capable access technologies. The access network heterogeneity is an outcome of incremental and evolutionary approach of building new infrastructure. The recent success of multi-radio terminals drives both building a new infrastructure and implicit deployment of heterogeneous access networks. Typically there is no economical reason to replace the existing infrastructure when building a new one. The gradual migration phase usually takes several years. IP-based mobility across different access networks may involve both horizontal and vertical handovers. Depending on the networking environment, the mobile terminal may be attached to the network through multiple access technologies. Consequently, the terminal may send and receive packets through multiple networks simultaneously. This dissertation addresses the introduction of IP Mobility paradigm into the existing mobile operator network infrastructure that have not originally been designed for multi-access and IP Mobility. We propose a model for the future wireless networking and roaming architecture that does not require revolutionary technology changes and can be deployed without unnecessary complexity. The model proposes a clear separation of operator roles: (i) access operator, (ii) service operator, and (iii) inter-connection and roaming provider. The separation allows each type of an operator to have their own development path and business models without artificial bindings with each other. We also propose minimum requirements for the new model. We present the state of the art of IP Mobility. We also present results of standardization efforts in IP-based wireless architectures. Finally, we present experimentation results of IP-level mobility in various wireless operator deployments.Erilaiset langattomat verkkoyhteydet lisääntyvät Internet-kykyisten teknologioiden muodossa. Lukuisten eri teknologioiden päällekkäinen käyttö johtuu vähitellen ja tarpeen mukaan rakennetusta verkkoinfrastruktuurista. Useita radioteknologioita (kuten WLAN, GSM ja UMTS) sisältävien päätelaitteiden (kuten älypuhelimet ja kannettavat tietokoneet) viimeaikainen kaupallinen menestys edesauttaa uuden verkkoinfrastruktuurin rakentamista, sekä mahdollisesti johtaa verkkoteknologioiden kirjon lisääntymiseen. Olemassa olevaa verkkoinfrastruktuuria ei kaupallisista syistä kannata korvata uudella teknologialla yhdellä kertaa, vaan vaiheittainen siirtymävaihe kestää tyypillisesti useita vuosia. Internet-kykyiset päätelaitteet voivat liikkua joko saman verkkoteknologian sisällä tai eri verkkoteknologioiden välillä. Verkkoympäristöstä riippuen liikkuvat päätelaitteet voivat liittyä verkkoon useiden verkkoyhteyksien kautta. Näin ollen päätelaite voi lähettää ja vastaanottaa tietoliikennepaketteja yhtäaikaisesti lukuisia verkkoja pitkin. Tämä väitöskirja käsittelee Internet-teknologioiden liikkuvuutta ja näiden teknologioiden tuomista olemassa oleviin langattomien verkko-operaattorien verkkoinfrastruktuureihin. Käsiteltäviä verkkoinfrastruktuureita ei alun perin ole suunniteltu Internet-teknologian liikkuvuuden ja monien yhtäaikaisten yhteyksien ehdoilla. Tässä työssä ehdotetaan tulevaisuuden langattomien verkkojen arkkitehtuurimallia ja ratkaisuja verkkovierailujen toteuttamiseksi. Ehdotettu arkkitehtuuri voidaan toteuttaa ilman mittavia teknologisia mullistuksia. Mallin mukaisessa ehdotuksessa verkko-operaattorin roolit jaetaan selkeästi (i) verkko-operaattoriin, (ii) palveluoperaattoriin ja (iii) yhteys- sekä verkkovierailuoperaattoriin. Roolijako mahdollistaa sen, että kukin operaattorityyppi voi kehittyä itsenäisesti, ja että teennäiset verkkoteknologiasidonnaisuudet poistuvat palveluiden tuottamisessa. Työssä esitetään myös alustava vaatimuslista ehdotetulle mallille, esimerkiksi yhteysoperaattorien laatuvaatimukset. Väitöskirja esittelee myös liikkuvien Internet-teknologioiden viimeisimmän kehityksen. Työssä näytetään lisäksi standardointituloksia Internet-kykyisissä langattomissa arkkitehtuureissa

Interference mitigation in cognitive femtocell networks

“A thesis submitted to the University of Bedfordshire, in partial fulfilment of the requirements for the degree of Doctor of Philosophy”.Femtocells have been introduced as a solution to poor indoor coverage in cellular communication which has hugely attracted network operators and stakeholders. However, femtocells are designed to co-exist alongside macrocells providing improved spatial frequency reuse and higher spectrum efficiency to name a few. Therefore, when deployed in the two-tier architecture with macrocells, it is necessary to mitigate the inherent co-tier and cross-tier interference. The integration of cognitive radio (CR) in femtocells introduces the ability of femtocells to dynamically adapt to varying network conditions through learning and reasoning. This research work focuses on the exploitation of cognitive radio in femtocells to mitigate the mutual interference caused in the two-tier architecture. The research work presents original contributions in mitigating interference in femtocells by introducing practical approaches which comprises a power control scheme where femtocells adaptively controls its transmit power levels to reduce the interference it causes in a network. This is especially useful since femtocells are user deployed as this seeks to mitigate interference based on their blind placement in an indoor environment. Hybrid interference mitigation schemes which combine power control and resource/scheduling are also implemented. In a joint threshold power based admittance and contention free resource allocation scheme, the mutual interference between a Femtocell Access Point (FAP) and close-by User Equipments (UE) is mitigated based on admittance. Also, a hybrid scheme where FAPs opportunistically use Resource Blocks (RB) of Macrocell User Equipments (MUE) based on its traffic load use is also employed. Simulation analysis present improvements when these schemes are applied with emphasis in Long Term Evolution (LTE) networks especially in terms of Signal to Interference plus Noise Ratio (SINR)