The objective of this thesis is to model and analyze the energy consumption in heterogeneous cellular systems and develop techniques to minimize it. First, the energy consumption is modeled and analyzed for multi-layered heterogeneous wireless systems. This work encompasses the characterization of all the energy consumed at the base stations. Then, a novel on-off and cell-association scheme is proposed to minimize the overall network energy consumption while satisfying the spatially- and temporally-varying traffic demands. Second, we exploit the use of multi-stream carrier aggregation not only to improve the energy efficiency, but also to balance it with the conflicting objective of capacity maximization. Third, we analyze the performance of discontinuous reception methods for energy savings within the user equipments. Then, for scenarios that support carrier aggregation, we develop a cross-carrier-aware technique that further enhances such savings with minimum impact on the packet delay. Fourth, the use of small cells as an energy-saving tool and its limitations are analyzed and modeled in OPNET, a high-fidelity simulation and development platform. To bypass such limitations, a novel small cell solution is proposed, modeled, and analyzed in OPNET and then compared against its existing alternative.

No description available.

Femtocell is an effective approach to increase system capacity in cellular networks. Since traditional Femtocells use the same frequency band as the cellular network, cross-tier and co-tier interference exist in such Femtocell networks and have a major impact on deteriorating the system throughput. In order to tackle these challenges, interference mitigation has drawn attentions from both academia and industry. TV White Space (TVWS) is a newly opened portion of spectrum, which comes from the spare spectrum created by the transition from analogue TV to digital TV. It can be utilized by using cognitive radio technology according to the policies from telecommunications regulators. This thesis considers using locally available TVWS to reduce the interference in Femtocell networks. The objective of this research is to mitigate the downlink cross-tier and co-tier interference in different Femtocell deployment scenarios, and increase the throughput of the overall system. A Geo-location database model to obtain locally available TVWS information in UK is developed in this research. The database is designed using power control method to calculate available TVWS channels and maximum allowable transmit power based on digital TV transmitter information in UK and regulations on unlicensed use of TVWS. The proposed database model is firstly combined with a grid-based resource allocation scheme and investigated in a simplified Femtocell network to demonstrate the gains of using TVWS in Femtocell networks. Furthermore, two Femtocell deployment scenarios are studied in this research. In the suburban Femtocell deployment scenario, a novel system architecture that consists of the Geo-location database and a resource allocation scheme using TVWS is proposed to mitigate cross-tier interference between Macrocell and Femtocells. In the dense Femtocell deployment scenario, a power efficient resource allocation scheme is proposed to maximize the throughput of Femtocells while limiting the co-tier interference among Femtocells. The optimization problem in the power efficient scheme is solved by using sequential quadratic programming method. The simulation results show that the proposed schemes can effectively mitigate the interference in Femtocell networks in practical deployment scenarios.

The whole-cell behavior arises from the interplay among signaling, metabolic, and regulatory processes, which differ not only in their mechanisms, but also in the time scale of their execution. Proper modeling of the overall function of the cell requires development of a new modeling approach that accurately integrates these three types of processes, using the representation that best captures each one of them, and the interconnections between them. Traditionally, signaling networks have been modeled with ordinary differential equations (ODEs), regulation with Boolean networks, and metabolic pathways with Petri nets – these approaches are widely accepted and extensively used. Nonetheless, each of these methods, while being effective, have had limitations pointed out to them. Particularly, ODEs generally require very thorough parameterization, which is difficult to acquire, Boolean networks have been argued to be not capable of capturing complex systems dynamics, and the effectiveness of Petri nets when comparing to other, steady-state methods, have been debated. The main goal of this dissertation is to devise an integrated model that capture the whole-cell behavior and accurately combines these three components in the interplay between them. I provide a systematic study on using particle swarm optimization (PSO) as an effective approach for parameterizing ODEs. I survey different inference method for Boolean networks on the sets of complex dynamic data and demonstrate that they are, in fact, capable of capturing a variety of different systems. I review the existing use of Petri nets in modeling of biochemical system to show their effectiveness and, particularly, the ease for their integration with other methods. Finally, I propose an integrated hybrid model (IHM) that uses Petri nets to represent metabolic and signaling components, and Boolean networks to model regulation. The interconnections between these models allow to overcome the time scale differences of the processes by adding appropriate delay mechanisms. I validate IHM on two data sets. The significant advantage of IHM over other models is that it is able to capture the dynamics of all three components and can potentially identify novel and important cross-talk within the cell.

Diss. Luleå : Luleå tekniska univ., 2002.

No description available.

Modern cellular networks including LTE (Long Term Evolution) and the evolving LTE- Advanced provide high-speed and high-capacity data services for mobile users. As we become more reliant on wireless connectivity, the security of voice and data transmissions on the network becomes increasingly important. While the LTE network standards provide strict security guidelines, these requirements may not be completely followed when LTE networks are deployed in practice. This project provides a method for improving the security of LTE networks by 1) characterizing a gap between security requirements defined in the standards and practical implementations, 2) designing a language to express the encoding formats of one of LTE’s network-layer protocols, 3) developing a compiler to translate a protocol description in our language into an implementation, and 4) providing recommendations on lessons learned during development of the language and compiler to support development of future protocols that employ formal representations. In this way, our work demonstrates how a formal language can be utilized to represent a cellular network protocol and serves as an example for further research on how adding formalism to network standards can help ensure that the security goals defined in the standards can be upheld in an implementation.

In fifth generation (5G) networks, more base stations (BSs) and antennas have been deployed to meet the high data rate and spectrum efficiency requirements. Heterogeneous and ultra dense networks not only pose substantial challenges to the resource allocation design, but also lead to unprecedented surge in energy consumption. Supplying BSs with renewable energy by utilising energy harvesting technology has became a favourable solution for cellular network operators to reduce the grid energy consumption. However, the harvested renewable energy is fluctuating in both time and space domains. The available energy for a particular BS at a particular time might be insufficient to meet the traffic demand which will lead to renewable energy waste or increased outage probability. To solve this problem, the concept of energy cooperation was introduced by Sennur Ulukus in 2012 as a means for transferring and sharing energy between the transmitter and the receiver. Nevertheless, resource allocation in energy cooperation enabled cellular networks is not fully investigated. This thesis investigates resource allocation schemes and resource allocation optimisation in energy cooperation enabled cellular networks that employed advanced 5G techniques, aiming at maximising the energy efficiency of the cellular network while ensuring the network performance. First, a power control algorithm is proposed for energy cooperation enabled millimetre wave (mmWave) HetNets. The aim is to maximise the time average network data rate while keeping the network stable such that the network backlog is bounded and the required battery capacity is finite. Simulation results show that the proposed power control scheme can reduce the required battery capacity and improve the network throughput. Second, resource allocation in energy cooperation enabled heterogeneous networks (Het- Nets) is investigated. User association and power control schemes are proposed to maximise the energy efficiency of the whole network respectively. The simulation results reveal that the implementation of energy cooperation in HetNets can improve the energy efficiency and the improvement is apparent when the energy transfer efficiency is high. Following on that, a novel resource allocation for energy cooperation enabled nonorthogonal multiple access (NOMA) HetNets is presented. Two user association schemes which have different complexities and performances are proposed and compared. Following on that, a joint user association and power control algorithm is proposed to maximise the energy efficiency of the network. It is confirmed from the simulation results that the proposed resource allocation schemes efficiently coordinate the intra-cell and inter-cell interference in NOMA HetNets with energy cooperation while exploiting the multiuser diversity and BS densification. Last but not least, a joint user association and power control scheme that considers the different content requirements of users is proposed for energy cooperation enabled caching HetNets. It shows that the proposed scheme significantly enhances the energy efficiency performance of caching HetNets.

Heterogeneous cellular networks (HCNs) – comprising traditional macro base stations (BSs) and heterogeneous infrastructure such as microcells, picocells, femtocells and distributed antennas – are fast becoming a cost-effective and essential way of handling explosive wireless data traffic demands. Up until now, little basic research has been done on the fundamentals of managing so much infrastructure – much of it unplanned – together with the carefully planned macro-cellular network. This dissertation addresses the key technical challenges of inter-cell interference management in this new network paradigm. This dissertation first studies uplink femtocell access control in uncoordinated two-tier networks, i.e. where the femtocells cannot coordinate with macrocells. Closed access allows registered home users to monopolize their own femtocell and its backhaul connection, but also results in severe interference between femtocells and nearby unregistered macro users. Open access reduces such interference by handing over such users, at the expense of femtocell resource sharing. In the first analytical work on this topic, we studied the best femtocell access technique from the perspectives of both network operators and femtocell owners, and show that it is strongly contingent on parameters such as multiple access schemes (i.e. orthogonal vs. non- orthogonal) and cellular user density (in TDMA/OFDMA). To study coordinated algorithms whose success depends heavily on the rate and delay (vs. user mobility) of inter-cell overhead sharing, this dissertation develops various models of overhead signaling in general HCNs and derives the overhead quality contour – the achievable set of overhead packet rate and delay – under general assumptions on overhead arrivals and different overhead signaling methods (backhaul and/or wireless). The overhead quality contour is further simplified for two widely used models of overhead arrivals: Poisson and deterministic. Based on the overhead quality contour that is applicable to generic coordinated techniques, this dissertation develops a novel analytical framework to evaluate downlink coordinated multi-point (CoMP) schemes in HCNs. Combined with the signal-to-interference-plus-noise-ratio (SINR) characterization, this framework can be used for a class of CoMP schemes without user data sharing. As an example, we apply it to downlink CoMP inter-cell interference cancellation (ICIC), after deriving SINR results for it using the spatial Poisson Point Process (PPP) to capture the uncertainty in base station locations. / text

Mobile devices like smartphones and tablets are being adopted with unprecedented speed. The growth in demand and system complexity increasingly requires collaboration of multiple parties in order to achieve better functionality, efficiency, performance, etc. This poses unique challenges such as information sharing among different parties, utility sharing among different parties, and dishonest and collusive behaviors. Different mobile services may require different types of collaboration and involve different entities in the system. In this work we take a bottom-up approach by first looking at collaboration at the end user level, then the cross level collaboration and finally at the service provider level. Specifically, we first consider a completely distributed service: friend discovery in mobile social networks, where users of a mobile social network work together with each other to discover potential new friends nearby by computing their social proximity. We develop mathematically sound yet highly efficient approaches that simultaneously achieve privacy and verifiability. We then focus on cellular offloading where a cellular service provider seeks third party resource to offload cellular demand, as an example of cross level collaboration. We propose a reverse auction framework: iDEAL, which efficiently allocates cellular resource and third party resource in a joint optimization, effectively incentivize third party resource owners and mitigates dishonest and collusive behaviors. We validate our findings and approaches with real trace driven analysis and simulation, as well as real implementation. Finally we focus on collaboration at the service provider level and propose a double auction framework - DA². DA² allows cellular service providers to reallocate spectrum resource in a dynamic fashsion. It preserves all the desired economic properties. Compared with existing spectrum double auctions, DA² achieves higher efficiency, revenue, and spectrum resource utilization, due to its ability to more accurately capture the competition among buyers, which is characterized by a complex conflict graph. We evaluate DA² and demonstrate its superior performance via simulations on conflict graphs generated with real cell tower locations. / text