Topological Interference Management through Index Coding

This work studies linear interference networks, both wired and wireless, with no channel state information at the transmitters (CSIT) except a coarse knowledge of the end-to-end one-hop topology of the network that only allows a distinction between weak (zero) and significant (non-zero) channels and no further knowledge of the channel coefficients' realizations. The network capacity (wired) and DoF (wireless) are found to be bounded above by the capacity of an index coding problem for which the antidote graph is the complement of the given interference graph. The problems are shown to be equivalent under linear solutions. An interference alignment perspective is then used to translate the existing index coding solutions into the wired network capacity and wireless network DoF solutions, as well as to find new and unified solutions to different classes of all three problems.Comment: Revised for the IEEE Transactions on Information Theor

Cyclic Interference Alignment and Cancellation in 3-User X-Networks with Minimal Backhaul

We consider the problem of Cyclic Interference Alignment (IA) on the 3-user X-network and show that it is infeasible to exactly achieve the upper bound of $\frac{K^2}{2K-1}=\frac{9}{5}$ degrees of freedom for the lower bound of n=5 signalling dimensions and K=3 user-pairs. This infeasibility goes beyond the problem of common eigenvectors in invariant subspaces within spatial IA. In order to gain non-asymptotic feasibility with minimal intervention, we first investigate an alignment strategy that enables IA by feedforwarding a subset of messages with minimal rate. In a second step, we replace the proposed feedforward strategy by an analogous Cyclic Interference Alignment and Cancellation scheme with a backhaul network on the receiver side and also by a dual Cyclic Interference Neutralization scheme with a backhaul network on the transmitter side.Comment: 8 pages, short version submitted to ISIT 201

Low-Latency Infrastructure-Based Cellular V2V Communications for Multi-Operator Environments With Regional Split

[EN] Mobile network operators are interested in providing Vehicle-to-Vehicle (V2V) communication services using their cellular infrastructure. Regional split of operators is one possible approach to support multi-operator infrastructure-based cellular V2V communication. In this approach, a geographical area is divided into non-overlapping regions, each one served by a unique operator. Its main drawback is the communication interruption motivated by the inter-operator handover in border areas, which prevents the fulfillment of the maximum end-to-end (E2E) latency requirements of fifth generation (5G) V2V services related to autonomous driving. In this work, we enable a fast inter-operator handover based on the pre-registration of the users on multiple operators, which substantially reduces the handover time to guarantee maximum E2E latency values of 100 ms in non-congested scenarios. To further reduce the latency of time-critical services to always less than 70 ms, even with the handover interruption time, while providing a latency around 20 ms in the majority of locations, we propose to complement the former technique with a mobile edge computing approach. Our proposal consists in the localization of application servers and broadcasting entities in all the base stations, to avoid the communication through the core network, together with the use of a new set of nodes in the base stations of cross-border areas called inter-operator relays, to minimize the communication latency between operators. Based on analytic and simulation results, it is demonstrated that the proposed techniques are effective to support low-latency infrastructure-based cellular V2V communications in multi-operator environments with regional split.The work of S. Roger was partially supported by the Spanish Ministry of Science, Innovation and Universities through grant number RYC-2017-22101.Martín-Sacristán, D.; Roger, S.; Garcia-Roger, D.; Monserrat Del Río, JF.; Spapis, P.; Zhou, C.; Kaloxylos, A. (2021). Low-Latency Infrastructure-Based Cellular V2V Communications for Multi-Operator Environments With Regional Split. IEEE Transactions on Intelligent Transportation Systems. 22(2):1052-1067. https://doi.org/10.1109/TITS.2019.29620971052106722

Design and analysis of a 3-dimensional cluster multicomputer architecture using optical interconnection for petaFLOP computing

In this dissertation, the design and analyses of an extremely scalable distributed multicomputer architecture, using optical interconnects, that has the potential to deliver in the order of petaFLOP performance is presented in detail. The design takes advantage of optical technologies, harnessing the features inherent in optics, to produce a 3D stack that implements efficiently a large, fully connected system of nodes forming a true 3D architecture. To adopt optics in large-scale multiprocessor cluster systems, efficient routing and scheduling techniques are needed. To this end, novel self-routing strategies for all-optical packet switched networks and on-line scheduling methods that can result in collision free communication and achieve real time operation in high-speed multiprocessor systems are proposed. The system is designed to allow failed/faulty nodes to stay in place without appreciable performance degradation. The approach is to develop a dynamic communication environment that will be able to effectively adapt and evolve with a high density of missing units or nodes. A joint CPU/bandwidth controller that maximizes the resource allocation in this dynamic computing environment is introduced with an objective to optimize the distributed cluster architecture, preventing performance/system degradation in the presence of failed/faulty nodes. A thorough analysis, feasibility study and description of the characteristics of a 3-Dimensional multicomputer system capable of achieving 100 teraFLOP performance is discussed in detail. Included in this dissertation is throughput analysis of the routing schemes, using methods from discrete-time queuing systems and computer simulation results for the different proposed algorithms. A prototype of the 3D architecture proposed is built and a test bed developed to obtain experimental results to further prove the feasibility of the design, validate initial assumptions, algorithms, simulations and the optimized distributed resource allocation scheme. Finally, as a prelude to further research, an efficient data routing strategy for highly scalable distributed mobile multiprocessor networks is introduced

Heterogeneous Cloud Systems Based on Broadband Embedded Computing

Computing systems continue to evolve from homogeneous systems of commodity-based servers within a single data-center towards modern Cloud systems that consist of numerous data-center clusters virtualized at the infrastructure and application layers to provide scalable, cost-effective and elastic services to devices connected over the Internet. There is an emerging trend towards heterogeneous Cloud systems driven from growth in wired as well as wireless devices that incorporate the potential of millions, and soon billions, of embedded devices enabling new forms of computation and service delivery. Service providers such as broadband cable operators continue to contribute towards this expansion with growing Cloud system infrastructures combined with deployments of increasingly powerful embedded devices across broadband networks. Broadband networks enable access to service provider Cloud data-centers and the Internet from numerous devices. These include home computers, smart-phones, tablets, game-consoles, sensor-networks, and set-top box devices. With these trends in mind, I propose the concept of broadband embedded computing as the utilization of a broadband network of embedded devices for collective computation in conjunction with centralized Cloud infrastructures. I claim that this form of distributed computing results in a new class of heterogeneous Cloud systems, service delivery and application enablement. To support these claims, I present a collection of research contributions in adapting distributed software platforms that include MPI and MapReduce to support simultaneous application execution across centralized data-center blade servers and resource-constrained embedded devices. Leveraging these contributions, I develop two complete prototype system implementations to demonstrate an architecture for heterogeneous Cloud systems based on broadband embedded computing. Each system is validated by executing experiments with applications taken from bioinformatics and image processing as well as communication and computational benchmarks. This vision, however, is not without challenges. The questions on how to adapt standard distributed computing paradigms such as MPI and MapReduce for implementation on potentially resource-constrained embedded devices, and how to adapt cluster computing runtime environments to enable heterogeneous process execution across millions of devices remain open-ended. This dissertation presents methods to begin addressing these open-ended questions through the development and testing of both experimental broadband embedded computing systems and in-depth characterization of broadband network behavior. I present experimental results and comparative analysis that offer potential solutions for optimal scalability and performance for constructing broadband embedded computing systems. I also present a number of contributions enabling practical implementation of both heterogeneous Cloud systems and novel application services based on broadband embedded computing

Ant-based evidence distribution with periodic broadcast in attacked wireless network

In order to establish trust among nodes in large wireless networks, the trust certicates need to be distributed and be readily accessible. However, even so, searching for trust certicates will still become highly cost and delay especially when wireless network is suering CTS jamming attack. We believe the individual solution can lead us to solve this combination problems in the future. Therefore, in this work, we investigate the delay and cost of searching a distributed certicate and the adverse eects of fabiricated control packet attacks on channel throughput and delivery ratio respectively, and propose two techniques that can improve the eciency of searching for such certicates in the network and mitigate the CTS jamming attack's eect. Evidence Distribution based on Periodic Broadcast (EDPB) is the rst solution we presented to help node to quickly locate trust certicates in a large wireless sensor network. In this solution, we not only take advantages from swarm intelligence alogrithm, but also allow nodes that carrying certicates to periodically announce their existence. Such announcements, together with a swarm-intelligence pheromone pdate procedure, will leave traces on the nodes to lead query packets toward the certicate nodes. We then investigate the salient features of this schema and evaluate its performance in both static and mobile networks. This schema can also be used for other essential information dissemination in mobile ad hoc networks. The second technqiue, address inspection schema (AIS) xes vulnerabilities exist in distribution coordinating function (DCF) dened in IEEE 802.11 standard so that each node has the ability to beat the impact of CTS jamming attack and furthermore, benets network throughput. We then perform ns-2 simulations to evaluate the benet of AIS

Enabling Large-Scale Peer-to-Peer Stored Video Streaming Service with QoS Support

This research aims to enable a large-scale, high-volume, peer-to-peer, stored-video streaming service over the Internet, such as on-line DVD rentals. P2P allows a group of dynamically organized users to cooperatively support content discovery and distribution services without needing to employ a central server. P2P has the potential to overcome the scalability issue associated with client-server based video distribution networks; however, it brings a new set of challenges. This research addresses the following five technical challenges associated with the distribution of streaming video over the P2P network: 1) allow users with limited transmit bandwidth capacity to become contributing sources, 2) support the advertisement and discovery of time-changing and time-bounded video frame availability, 3) Minimize the impact of distribution source losses during video playback, 4) incorporate user mobility information in the selection of distribution sources, and 5) design a streaming network architecture that enables above functionalities.To meet the above requirements, we propose a video distribution network model based on a hybrid architecture between client-server and P2P. In this model, a video is divided into a sequence of small segments and each user executes a scheduling algorithm to determine the order, the timing, and the rate of segment retrievals from other users. The model also employs an advertisement and discovery scheme which incorporates parameters of the scheduling algorithm to allow users to share their life-time of video segment availability information in one advertisement and one query. An accompanying QoS scheme allows reduction in the number of video playback interruptions while one or more distribution sources depart from the service prematurely.The simulation study shows that the proposed model and associated schemes greatly alleviate the bandwidth requirement of the video distribution server, especially when the number of participating users grows large. As much as 90% of load reduction was observed in some experiments when compared to a traditional client-server based video distribution service. A significant reduction is also observed in the number of video presentation interruptions when the proposed QoS scheme is incorporated in the distribution process while certain percentages of distribution sources depart from the service unexpectedly