110 research outputs found
Multipath streaming: fundamental limits and efficient algorithms
We investigate streaming over multiple links. A file is split into small
units called chunks that may be requested on the various links according to
some policy, and received after some random delay. After a start-up time called
pre-buffering time, received chunks are played at a fixed speed. There is
starvation if the chunk to be played has not yet arrived. We provide lower
bounds (fundamental limits) on the starvation probability of any policy. We
further propose simple, order-optimal policies that require no feedback. For
general delay distributions, we provide tractable upper bounds for the
starvation probability of the proposed policies, allowing to select the
pre-buffering time appropriately. We specialize our results to: (i) links that
employ CSMA or opportunistic scheduling at the packet level, (ii) links shared
with a primary user (iii) links that use fair rate sharing at the flow level.
We consider a generic model so that our results give insight into the design
and performance of media streaming over (a) wired networks with several paths
between the source and destination, (b) wireless networks featuring spectrum
aggregation and (c) multi-homed wireless networks.Comment: 24 page
Risk-hedging using options for an upgrading investment in a data network
In this paper, we illustrate how a mobile data network operator can plan an upgrading investment to anticipate explosions of the demand, taking into account the expected generated profit and the customers satisfaction. The former parameter grows with the demand, whereas the latter sinks if the demand is too high as throughput may collapse. As the equipment price decreases with time, it may be interesting to wait rather than to invest at once. We then propose a real option strategy to hedge against the risk that the investment has to take place earlier than expected. At last, we price this option with a backward dynamic programming approach, using recent improvements based on least-squares estimations.
Optimizing the date of an upgrading investment in a data network
Due to the introduction of new services, the volume of data transferred in mobile networks is rapidly growing and operators periodically face the necessity to upgrade their network. Such upgrades allow them to increase the capacity and provide adequate Quality of Service (QoS). In this paper we propose a general framework for deriving the optimal date for a network upgrade. We show that this date is the result of a compromise between the decrease of upgrade investment cost with time and the loss of profit generated by insufficient capacity. The upgrade should hence be performed when the loss of profit, derived using analytical capacity expressions, exceeds the expected discount. The model presented herein accounts for the randomness of the demand and upgrading cost functions, and results are given for a HSDPA network.data flows, brownian motion, quality of service, customer satisfaction
A hybrid decision approach for the association problem in heterogeneous networks
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.Comment: 5 pages, 4 figures, IEEE Infocom, San Diego, USA, March 2010
Impact of Mobility on MIMO Green Wireless Systems
This paper studies the impact of mobility on the power consumption of
wireless networks. With increasing mobility, we show that the network should
dedicate a non negligible fraction of the useful rate to estimate the different
degrees of freedom. In order to keep the rate constant, we quantify the
increase of power required for several cases of interest. In the case of a
point to point MIMO link, we calculate the minimum transmit power required for
a target rate and outage probability as a function of the coherence time and
the number of antennas. Interestingly, the results show that there is an
optimal number of antennas to be used for a given coherence time and power
consumption. This provides a lower bound limit on the minimum power required
for maintaining a green network.Comment: Accepted for EUSIPCO conference. 5 page
An Interaction-Based Mobility Model for Dynamic Hot Spot Analysis
International audienceIn this paper, we analyze phenomena related to user clumps and hot spots occuring in mobile networks at the occasion of large urban mass gatherings in large cities. Our analysis is based on observations made on mobility traces of GSM users in several large cities. Classical mobility models, such as the random waypoint, do not allow one to represent the observed dynamics of clumps in a proper manner. This motivates the introduction and the mathematical analysis of a new interaction-based mobility model, which is the main contribution of the present paper. This model is shown to allow one to describe the dynamics of clumps and in particular to predict key phenomena such as the building of hot spots and the scattering between hot spots, which play a key role in the engineering of wireless networks during such events. We show how to obtain the main parameters of this model from simple communication activity measurements and we illustrate this calibration process on real cases
Performance evaluation of intra-site coordination schemes in cellular networks
International audienceIn this work, we develop performance evaluation models for some intra-site coordination schemes in cellular networks, with a focus on Multi-flow transmission in HSPA+. We first focus on a static scheme where coordination is always performed for all users in the overlapping region of two cells. Through the analysis of a flow-level model, we show that this scheme indeed improves the cell-edge throughput at low loads but may make the system unstable at high loads, due to the suboptimal allocation of radio resources. We notice also that these results are very sensitive to the coordination threshold. We thus investigate a dynamic scheme which performs coordination according to resource availability in the site and show that this scheme outperforms the static one at all traffic loads independently of the coordination threshold. Additional results demonstrate an efficient load balancing ability across cells. We finally analyze how our models extend to the case of opportunis-tic scheduling schemes, like Proportional Fair, and show the impact of these schemes on the coordination gains
An Interaction-Based Mobility Model for Dynamic Hot Spot Analysis
In this paper, we analyze phenomena related to user clumps and hot spots occurring in mobile networks at the occasion of large urban mass gatherings in large cities. Our analysis is based on observations made on mobility traces of GSM users in several large cities. Classical mobility models, such as the random waypoint, do not allow one to represent the observed dynamics of clumps in a proper manner. This motivates the introduction and the mathematical analysis of a new interaction based mobility model, which is the main contribution of the present paper. This model is shown to allow one to describe the dynamics of clumps and in particular to predict key phenomena such as the building of hot spots and the scattering between hot spots, which play a key role in the engineering of wireless networks during such events. We show how to obtain the main parameters of this model from simple communication activity measurements and we illustrate this calibration process on real cases
Impatience in mobile networks and its application to data pricing
We consider in this paper an import Quality of Experience (QoE) indicator in
mobile networks that is reneging of users due to impatience. We specifically
consider a cell under heavy load conditions and compute the reneging
probability by using a fluid limit analysis. By solving the fixed point
equation, we obtain a new QoE perturbation metric quantifying the impact of
reneging on the performance of the system. This metric is then used to devise a
new pricing scheme accounting of reneging. We specifically propose several
flavors of this pricing around the idea of having a flat rate for accessing the
network and an elastic price related to the level of QoE perturbation induced
by communications
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