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Search Results: 1 - 10 of 609 matches for " Eitan Altman "
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Flow-level performance of random wireless networks
Richard Combes,Eitan Altman
Computer Science , 2013,
Abstract: We study the flow-level performance of random wireless networks. The locations of base stations (BSs) follow a Poisson point process. The number and positions of active users are dynamic. We associate a queue to each BS. The performance and stability of a BS depend on its load. In some cases, the full distribution of the load can be derived. Otherwise we derive formulas for the first and second moments. Networks on the line and on the plane are considered. Our model is generic enough to include features of recent wireless networks such as 4G (LTE) networks. In dense networks, we show that the inter-cell interference power becomes normally distributed, simplifying many computations. Numerical experiments demonstrate that in cases of practical interest, the loads distribution can be well approximated by a gamma distribution with known mean and variance.
Coordination of autonomic functionalities in communications networks
Richard Combes,Zwi Altman,Eitan Altman
Computer Science , 2012,
Abstract: Future communication networks are expected to feature autonomic (or self-organizing) mechanisms to ease deployment (self-configuration), tune parameters automatically (self-optimization) and repair the network (self-healing). Self-organizing mechanisms have been designed as stand-alone entities, even though multiple mechanisms will run in parallel in operational networks. An efficient coordination mechanism will be the major enabler for large scale deployment of self-organizing networks. We model self-organizing mechanisms as control loops, and study the conditions for stability when running control loops in parallel. Based on control theory and Lyapunov stability, we propose a coordination mechanism to stabilize the system, which can be implemented in a distributed fashion. The mechanism remains valid in the presence of measurement noise via stochastic approximation. Instability and coordination in the context of wireless networks are illustrated with two examples and the influence of network geometry is investigated. We are essentially concerned with linear systems, and the applicability of our results for non-linear systems is discussed.
Virtual sectorization: design and self-optimization
Abdoulaye TALL,Zwi Altman,Eitan Altman
Computer Science , 2015,
Abstract: Virtual Sectorization (ViSn) aims at covering a confined area such as a traffic hot-spot using a narrow beam. The beam is generated by a remote antenna array located at-or close to the Base Station (BS). This paper develops the ViSn model and provides the guidelines for designing the Virtual Sector (ViS) antenna. In order to mitigate interference between the ViS and the traditional macro sector covering the rest of the area, a Dynamic Spectrum Allocation (DSA) algorithm that self-optimizes the frequency bandwidth split between the macro cell and the ViS is also proposed. The Self-Organizing Network (SON) algorithm is constructed to maximize the proportional fair utility of all the users throughputs. Numerical simulations show the interest in deploying ViSn, and the significant capacity gain brought about by the self-optimized bandwidth sharing with respect to a full reuse of the bandwidth by the ViS.
Multilevel beamforming for high data rate communication in 5G networks
Abdoulaye Tall,Zwi Altman,Eitan Altman
Computer Science , 2015,
Abstract: Large antenna arrays can be used to generate highly focused beams that support very high data rates and reduced energy consumption. However, optimal beam focusing requires large amount of feedback from the users in order to choose the best beam, especially in Frequency Division Duplex (FDD) mode. This paper develops a methodology for designing a multilevel codebook of beams in an environment with low number of multipaths. The antenna design supporting the focused beams is formulated as an optimization problem. A multilevel codebook of beams is constructed according to the coverage requirements. An iterative beam scheduling is proposed that searches through the codebook to select the best beam for a given user. The methodology is applied to a mass event and to a rural scenario, both analyzed using an event-based network simulator. Very significant gains are obtained for both scenarios. It is shown that the more dominant the Line of Sight (LoS) component, the higher the gain achieved by the multilevel beamforming.
Self-optimizing load balancing with backhaul-constrained radio access networks
Abdoulaye Tall,Zwi Altman,Eitan Altman
Computer Science , 2015, DOI: 10.1109/LWC.2015.2477499
Abstract: Self-Organizing Network (SON) technology aims at autonomously deploying, optimizing and repairing the Radio Access Networks (RAN). SON algorithms typically use Key Performance Indicators (KPIs) from the RAN. It is shown that in certain cases, it is essential to take into account the impact of the backhaul state in the design of the SON algorithm. We revisit the Base Station (BS) load definition taking into account the backhaul state. We provide an analytical formula for the load along with a simple estimator for both elastic and guaranteed bit-rate (GBR) traffic. We incorporate the proposed load estimator in a self-optimized load balancing algorithm. Simulation results for a backhaul constrained heterogeneous network illustrate how the correct load definition can guarantee a proper operation of the SON algorithm.
Self Organizing strategies for enhanced ICIC (eICIC)
Abdoulaye Tall,Zwi Altman,Eitan Altman
Computer Science , 2014, DOI: 10.1109/WIOPT.2014.6850315
Abstract: Small cells have been identified as an effective solution for coping with the important traffic increase that is expected in the coming years. But this solution is accompanied by additional interference that needs to be mitigated. The enhanced Inter Cell Interference Coordination (eICIC) feature has been introduced to address the interference problem. eICIC involves two parameters which need to be optimized, namely the Cell Range Extension (CRE) of the small cells and the ABS ratio (ABSr) which defines a mute ratio for the macro cell to reduce the interference it produces. In this paper we propose self-optimizing algorithms for the eICIC. The CRE is adjusted by means of load balancing algorithm. The ABSr parameter is optimized by maximizing a proportional fair utility of user throughputs. The convergence of the algorithms is proven using stochastic approximation theorems. Numerical simulations illustrate the important performance gain brought about by the different algorithms.
Forward Correction and Fountain codes in Delay Tolerant Networks
Eitan Altman,Francesco De Pellegrini
Computer Science , 2008,
Abstract: Delay tolerant Ad-hoc Networks make use of mobility of relay nodes to compensate for lack of permanent connectivity and thus enable communication between nodes that are out of range of each other. To decrease delivery delay, the information that needs to be delivered is replicated in the network. Our objective in this paper is to study replication mechanisms that include coding in order to improve the probability of successful delivery within a given time limit. We propose an analytical approach that allows to quantify tradeoffs between resources and performance measures (energy and delay). We study the effect of coding on the performance of the network while optimizing parameters that govern routing. Our results, based on fluid approximations, are compared to simulations which validate the model
Network Non-Neutrality through Preferential Signaling
Manjesh Kumar Hanawal,Eitan Altman
Computer Science , 2013,
Abstract: One of the central issues in the debate on network neutrality has been whether one should allow or prevent preferential treatment by an internet service provider (ISP) of traffic according to its origin. This raised the question of whether to allow an ISP to have exclusive agreement with a content provider (CP). In this paper we consider discrimination in the opposite direction. We study the impact that a CP can have on the benefits of several competing ISPs by sharing private information concerning the demand for its content. More precisely, we consider ISPs that compete over access to one common CP. Each ISP selects the price that it charges its subscribers for accessing the content. The CP is assumed to have private information about demand for its content, and in particular, about the inverse demand function corresponding to the content. The competing ISPs are assumed to have knowledge on only the statistical distribution of these functions. We derive in this paper models for studying the impact that the CP can have on the utilities of the ISPs by favoring one of them by exclusively revealing its private information. We also consider the case where CP can charge ISPs for providing such information. We propose two mechanisms based on {\em weighted proportional fairness} for payment between ISPs and CP. Finally, we compare the social utility resulting from these mechanisms with the optimal social utility by introducing a performance metric termed as {\em price of partial bargaining}
A hybrid decision approach for the association problem in heterogeneous networks
Salah Eddine Elayoubi,Eitan Altman,Majed Haddad,Zwi Altman
Computer Science , 2010,
Abstract: The area of networking games has had a growing impact on wireless networks. This reflects the recognition in the important scaling advantages that the service providers can benefit from by increasing the autonomy of mobiles in decision making. This may however result in inefficiencies that are inherent to equilibria in non-cooperative games. Due to the concern for efficiency, centralized protocols keep being considered and compared to decentralized ones. From the point of view of the network architecture, this implies the co-existence of network-centric and terminal centric radio resource management schemes. Instead of taking part within the debate among the supporters of each solution, we propose in this paper hybrid schemes where the wireless users are assisted in their decisions by the network that broadcasts aggregated load information. We derive the utilities related to the Quality of Service (QoS) perceived by the users and develop a Bayesian framework to obtain the equilibria. Numerical results illustrate the advantages of using our hybrid game framework in an association problem in a network composed of HSDPA and 3G LTE systems.
Distributed coordination of self-organizing mechanisms in communication networks
Abdoulaye Tall,Richard Combes,Zwi Altman,Eitan Altman
Computer Science , 2013,
Abstract: The fast development of the Self-Organizing Network (SON) technology in mobile networks renders the problem of coordinating SON functionalities operating simultaneously critical. SON functionalities can be viewed as control loops that may need to be coordinated to guarantee conflict free operation, to enforce stability of the network and to achieve performance gain. This paper proposes a distributed solution for coordinating SON functionalities. It uses Rosen's concave games framework in conjunction with convex optimization. The SON functionalities are modeled as linear Ordinary Differential Equation (ODE)s. The stability of the system is first evaluated using a basic control theory approach. The coordination solution consists in finding a linear map (called coordination matrix) that stabilizes the system of SON functionalities. It is proven that the solution remains valid in a noisy environment using Stochastic Approximation. A practical example involving three different SON functionalities deployed in Base Stations (BSs) of a Long Term Evolution (LTE) network demonstrates the usefulness of the proposed method.
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