Open Topics

Vol. 70, n° 7-8, July-August 2015
Content available on Springerlink

Congestion dispersion in device-to-device discovery for proximity-based services

Sueng Jae Bae, Jaheon Gu, Syed Faraz Hasan, Min Young Chung
Sungkyunkwan University, Korea

Abstract Proximity service (ProSe) enables the development of various applications that exploit proximity of the mobile devices. In ProSe, devices are expected to communicate with each other on device-to-device (D2D) links and make use of proximity information for the provision of a variety of services. An essential functionality in ProSe is the ability of a device to identify its neighbors. This process is referred to as D2D discovery. This paper investigates distributed D2D discovery based on greedy resource selection. In order to facilitate rapid and efficient distributed D2D discovery, we propose group-based peer discovery resource selection range restriction (GPSRR) scheme. GPSRR scheme disperses the devices concentrated at a certain discovery resource over multiple resources. This is done by limiting the resource selection of a device to a specified group of resources. We also propose group reselection (GR) scheme to resolve the unbalance of congestion among different groups of resources. Simulation results show that the proposed schemes can improve the speed of discovery and the number of discovered devices, especially in densely populated environments.

Keywords Device-to-device (D2D) communication – Discovery – Proximity service

Elasticity in cloud computing: a survey

Emanuel Ferreira Coutinho, Flávio Rubens de Carvalho Sousa, Paulo Antonio Leal Rego, Danielo Gonçalves Gomes, José Neuman de Souza
Federal University of Ceara (UFC), Fortaleza, Brazil

Abstract Cloud computing is now a well-consolidated paradigm for on-demand services provisioning on a pay-as-you-go model. Elasticity, one of the major benefits required for this computing model, is the ability to add and remove resources “on the fly” to handle the load variation. Although many works in literature have surveyed cloud computing and its features, there is a lack of a detailed analysis about elasticity for the cloud. As an attempt to fill this gap, we propose this survey on cloud computing elasticity based on an adaptation of a classic systematic review. We address different aspects of elasticity, such as definitions, metrics and tools for measuring, evaluation of the elasticity, and existing solutions. Finally, we present some open issues and future directions. To the best of our knowledge, this is the first study on cloud computing elasticity using a systematic review approach.

Keywords Cloud computingElasticitySystematic reviewMetrics Strategies

Uplink spectrum resource allocation in heterogeneous networks (small cell/macrocell)

Mncedisi Bembe1,2, Jeongchan Kim1, Martin Mhlanga2, Jae Jeung Rho3, Youngnam Han1
1 KAIST University, Daejeon, Korea
2 CSIR-Meraka, Pretoria, South Africa

Abstract Small cells are expected to increase network capacity, extend the macrocell coverage and to add edge-based intelligence. These advantages are achieved by overlaying macrocell networks with the small cells, resulting in a two-tier network. However, the average capacity of the network is reduced due to interference generated by the two-tier configuration. Conventional small cells are configured to have either an open or closed access scheme. Small cells with a hybrid access scheme or partially open access scheme are known for their flexibility and improved performance achieved through their interference-mitigating ability and adaptive resource allocation capabilities. In a hybrid access scheme, resource allocation is a vital issue in the design of small cells networks. In this paper, we propose an uplink resource allocation technique to enhance hybrid small cell capacity in orthogonal frequency division multiple access (OFDMA) two-tier cellular networks. In particular, we investigate a new possibility available for developing an optimal scheme for OFDMA hybrid access small cells. We formalize the problem as an optimization problem for an uplink resource allocation that partitions the bandwidth for both subscribed or unsubscribed users. Moreover, we propose a convex optimization model for the gradient of the capacity difference between closed access and hybrid access capacity. We present two schemes, firstly an optimal scheme and secondly a scheme that is the simple version of the optimal scheme. Numerical results show the effectiveness of the proposed bandwidth resource allocation, where the simple solution shows inferior performance than the optimal solution with a small margin while the optimal solution has a more mathematical complexity disadvantage due to the mathematical functions it employs. Numerical results also show the convergence and effectiveness of the proposed uplink bandwidth resource allocation scheme.

Keywords Small cellsHybrid femtocellsResource allocation

Multimedia content delivery trigger in a mobile network to reduce the peak load

Eduardo Andrès Celis Muñoz1, Fabrice Le Denmat2, Arnaud Morin2, Xavier Lagrange1
1 Télécom Bretagne, IRISA, Rennes, France
2 Orange Labs, Lannion, France

Abstract Nowadays, smartphones are used to download files such as movies, music, etc. These files present some flexibility in delivery time; we exploit this feature to reduce network overload peaks. If the network is overloaded, downloads are postponed, thus reducing the traffic load during rush hours. We propose an architecture that enables the network to determine the best time to trigger a download that is queued. This architecture is based on a specific server in the network and a mobile application. This contribution describes the proposed architecture, presents the developments that have been made, and analyzes the performance of this novel concept.

Keywords Cellular networksDelay-tolerant usersDelay-tolerant servicesAdmission-controlImplementationPerformance analysis

Internet capacity: optimizing autonomous system inbound traffic using specialist knowledge as support for decision-making

Márcio A. de Deus, Paulo H. P. Carvalho, João Paulo Leite
University of Brasilia, Brazil

Abstract Autonomous systems provide network control without external monitoring. This can be a problem when the traffic is asymmetric with a higher portion being inbound, as networks are generally designed for symmetrical loads. This problem occurs frequently in networks within South American countries as the inbound and outbound portions of traffic are unbalanced by a factor greater than 5:1. Furthermore, national content is usually hosted in the USA, exacerbating the problem. In this study, networks in Brazil, Colombia, and Venezuela are analyzed and characterized. Decision-making techniques are proposed as a tentative external control method or, in some cases, as a proactive attempt to interfere in an internal decision. Our new adaptive algorithm outperformed manual human intervention, which has potential utility to assist long-term capacity planning of the interconnection between autonomous systems.

Keywords Internet trafficPlanning CapacityBGP policiesBGP Traffic engineeringCharacterization – ForecastingDecision-making

Interference and SINR coverage in spatial non-slotted Aloha networks

Barłomiej Błaszczyszyn1, Paul Mühlethaler2
1 Inria/ENS, Paris, France
2 Inria Rocquencourt, Le Chesnay, France

Abstract In this paper, we propose two analytically tractable stochastic-geometric models of interference in ad hoc networks using pure (non-slotted) Aloha as the medium access. In contrast to the slotted model, the interference in pure Aloha may vary during the transmission of a tagged packet. We develop closed-form expressions for the Laplace transform of the empirical average of the interference experienced during the transmission of a typical packet. Both models assume a power-law path-loss function with arbitrarily distributed fading and feature configurations of transmitters randomly located in the Euclidean plane according to a Poisson point process. Depending on the model, these configurations vary over time or are static. We apply our analysis of the interference to study the signal-to-interference-and-noise ratio (SINR) outage probability for a typical transmission in pure Aloha. The results are used to compare the performance of non-slotted Aloha to slotted Aloha, which has almost exclusively been previously studied in the context of wired networks.

Keywords Pure (non-slotted) Aloha – Slotted Aloha – SINR – Shot noise – MAC layer optimization – Throughput – Stochastic geometry – Poisson point process

Priority levels based multi-hop broadcasting method for vehicular ad hoc networks

Wahabou Abdou, Benoît Darties, Nader Mbarek
Université de Bourgogne, Dijon, France

Abstract This paper deals with broadcasting problem in vehicular ad hoc networks (VANETs). This communication mode is commonly used for sending safety messages and traffic information. However, designing an efficient broadcasting protocol is hard to achieve since it has to take into account some parameters related to the network environment, for example, the network density, in order to avoid causing radio interferences. In this paper, we propose a novel Autonomic Dissemination Method (ADM) which delivers messages in accordance with given priority and density levels. The proposed approach is based on two steps: an offline optimization process and an adaptation to the network characteristics. The first step uses a genetic algorithm to find solutions that fit the network context. The second one relies on the Autonomic Computing paradigm. ADM allows each vehicle to dynamically adapt its broadcasting strategy not only with respect to the network density, but also in accordance to the priority level of the message to send. The experimental results show that ADM effectively uses the radio resources even when there are globally many messages to send simultaneously. Moreover, ADM allows to increase the message delivery ratio and to reduce the latency and radio interferences.

Keywords VANETBroadcastAutonomic computingMessage priority levelDensity evaluationQuality of ServiceOptimization