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Reliable and efficient transmission of emergency calls during a massive network failure is both an indispensable and challenging task. In this paper, we propose a novel fully 3GPP and 5G compatible emergency call protocol named 5G StandalOne Service (5G-SOS). A 5G-SOS-enabled emergency service provides potential out-of-coverage victims' devices with a way to contact the 4G/5G core network through D2D multi-hop relaying protocol. The objective of 5G-SOS is to maintain this connection even when a large fraction of the network infrastructure is destroyed. 5G-SOS is a fully distributed protocol designed to generate zero additional control traffic and to adapt its parameters based on the local emergency call congestion. Therefore, devices behave as an ad-hoc network with the common purpose to ensure the best chances for emergency call transfer within a reasonable delay. A densely populated Traverse city of Michigan, USA, with a 15,000 population, is used to evaluate 5G-SOS under extreme emergency scenarios. The performance of 5G-SOS is shown to be significant when compared with existing protocols, namely, M-HELP and FINDER, in terms of transmission success rate, end-to-end latency, network traffic control, and energy management. 5G-SOS provides satisfactory performance (success rate of 50%) even when the number of simultaneous emergency calls is very high (5000 calls over 10 min). On average, 5G-SOS performs 24.9% better than M-HELP and 73.9% than FINDER in terms of success rate. Additionally, 5G-SOS reduces the average end-end latency of the emergency calls transfer by 20.8% compared to M-HELP and 61.7% compared to FINDER. [ABSTRACT FROM AUTHOR]

To design a cellular radio network (GSM, UMTS, WiFi ...) it is indispensable today to use a radio planning software. In current commercialized tools, radio network planning is based on a numerical evaluation of a set of radio metrics, directly linked to quality of service notion, such as interference, throughput, coverage, capacity ... The network configurations produced by such tools are generally faced with the human expert judgment who attaches great importance to the organizational aspects such as cells size and the topology. In other words, all those concepts related to the visual cells shape and geometry. In this article we emphasize the simplicity and the strength by which the geometrical concepts helps to bring out good network properties which are not taken into account by conventional radio criteria. On one hand, well-formed cells lead to reduce the number of handover calls, and to form transition zones between cells allowing proper completion of the handover procedure. On the other hand, cell geometry optimization produce performing network schemes in which the frequencies reuse (frequencies planning in GSM, WiFi) is simplified. We describe in this paper an original and practical modeling of the cellular geometry criteria granting the integration of this concept into the automatic planning process of mobile radio networks. The relevance of this criterion is assessed on three different levels. On a local level, we first establish the correlation between the geometric criteria and the improvement of point-by-point radio quality indicators. We secondly show geometry impact on radio frequency planning and the improving of the handover zones. Finally we analyze the impact of geometric criterion on improving indoor positioning systems. [ABSTRACT FROM AUTHOR]

Self-reconfiguration for mobile microrobots currently needs a positioning system and a map of the target shape. Traditional positioning solutions, such as GPS or multilateration are not applicable in the micro-world, and maps sharing does not scale. In the literature, if we want a self-reconfiguration of microrobots to a target shape that consists of millions of positions, each microrobot should have a memory capacity of at least million positions. Therefore, this is not scalable. In this paper, nodes do not record any position. We present self-reconfiguration methods where nodes are unaware of their positions and where they do not have the final coordinates of each microrobot. In other words, nodes do not store the coordinates that build the target shape. Therefore, memory usage for each node is hugely reduced to $$O(1)$$ and communications are limited to neighboring nodes. These algorithms aim to improve the logical topology of a set of microrobots by restructuring their physical topology. To that end, we consider here the case of restructuring a set of microrobots from a chain to a square and we study two algorithms: the first algorithm ensures the connectivity of the network at the end of the algorithm, where the second guarantees the connectivity of the network through the execution time. The paper presents both analytical and experimental assessments of the algorithms performances using the declarative language $$Meld$$ and executed under the Dynamic Physical Rendering Simulator (DPRSim). [ABSTRACT FROM AUTHOR]

The contribution of this work is twofold. Firstly, we introduce a new channel assignment model for GSM radio networks. In this model both spatial and temporal variations of traffic are taken into account in order to improve network capacity and robustness. Secondly, using this model, we develop an original and effective hybrid algorithm to get high quality frequency plans. This algorithm combines a problem specific crossover and a Tabu search procedure. The proposed model and hybrid algorithm are evaluated using both artificial and real data. Computational results allow us to confirm the effectiveness of the proposed approach. [ABSTRACT FROM AUTHOR]

Standard tabu search methods are based on the complete exploration of current solution neighborhood. However, for some problems due to the neighborhood size or to the fitness evaluation complexity, the total exploration of the neighborhood is impractical. The main purpose of this paper is to propose a local search method with no enumeration procedure. In other words, a single solution is examined at each iteration and retained for the future iterations. The idea is to randomly select one solution among a sub-set of the neighborhood of the current one. An adaptive exploration of neighborhood, using extension and restriction mechanisms represented by loop detection and tabu list structure, determines this sub-set. This approach is applied to the K-coloring problem and evaluated on standard benchmarks like DIMACS. The objective is to show how a generic method, without full neighborhood exploration, degradation control and problem-oriented operators, provides a very competitive results comparing to the best dedicated algorithms for graph coloring problems published in the literature. [ABSTRACT FROM AUTHOR]

Under a dense and large IoT network, a star topology where each device is directly connected to the Internet gateway may cause serious waste of energy and congestion issues. Grouping network devices into clusters provides a suitable architecture to reduce the energy consumption and allows an effective management of communication channels. Although several clustering approaches were proposed in the literature, most of them use the single-hop intra-clustering model. In a large network, the number of clusters increases and the energy draining remains almost the same as in un-clustered architecture. To solve the problem, several approaches use the k-hop intra-clustering to generate a reduced number of large clusters. However, k-hop proposed schemes are, generally, centralized and only assume the node direct neighbors information which lack of robustness. In this regard, the present work proposes a distributed approach for the k-hop intra-clustering called Distributed Clustering based 2-Hop Connectivity (DC2HC). The algorithm uses the two-hop neighbors connectivity to elect the appropriate set of cluster heads and strengthen the clusters connectivity. The objective is to optimize the set of representative cluster heads to minimize the number of long range communication channels and expand the network lifetime. The paper provides the convergence proof of the proposed solution. Simulation results show that our proposed protocol outperforms similar approaches available in the literature by reducing the number of generated cluster heads and achieving longer network lifetime. [ABSTRACT FROM AUTHOR]

Energy efficiency is a major concern in the emerging mobile cellular wireless networks since massive connectivity is to be expected with high energy requirements from the network operators. Non-orthogonal multiple access (NOMA) being the frontier multiple access scheme for 5G, there exists numerous research attempts on enhancing the energy efficiency of NOMA enabled wireless networks while maintaining its outstanding performance metrics such as high throughput, data rates and capacity maximized optimally.The concept of green NOMA is introduced in a generalized manner to identify the energy efficient NOMA schemes. These schemes will result in an optimal scenario in which the energy generated for communication is managed sustainably. Hence, the effect on the environment, economy, living beings, etc is minimized. The recent research developments are classified for a better understanding of areas which are lacking attention and needs further improvement. Also, the performance comparison of energy efficient, NOMA schemes against conventional NOMA is presented. Finally, challenges and emerging research trends, for energy efficient NOMA are discussed. [ABSTRACT FROM AUTHOR]