IMDEA Networks Institute Digital Repository
Not a member yet
1915 research outputs found
Sort by
Analysis and Modeling of Mobile Traffic Using Real Traces
Get PDFThe analysis of real mobile traffic traces is helpful to understand usage patterns of cellular networks. In particular, mobile data may be used for network optimization and management in terms of radio resources, network planning, energy saving, for instance. However, real network data from the operators is often difficult to be accessed, due to legal and privacy issues. In this paper, we overcome the lack of network information using a LTE sniffer capable of decoding the unencrypted LTE control channel and we present a temporal and spatial analysis of the recorded traces. Moreover, we present a methodology to derive a stochastic characterization for the daily variation of the LTE traffic. The proposed model is based on a discrete-time Markov chain and is compared with the real traces. Results show that, with a limited number of states, our model presents a high level of accuracy in terms of first and second order statistics.TRUEpu
Performance Modeling of Vehicular Floating Content in Urban Settings
Get PDFBest Student Paper AwardAmong the proposed opportunistic content sharing
services, Floating Content (FC) is of special interest for the vehicular environment, not only for cellular traffic offloading, but also as a natural communication paradigm for location-based context-aware vehicular applications. Existing results on the performance of vehicular FC have focused on content persistence, without addressing the key issues of the effectiveness with which content is replicated and made available, and of what are the conditions which enable acceptable FC performance in the vehicular environment. This work presents a first analytical
model of FC performance in vehicular ad-hoc networks in urban settings. It is based on a variation of the random waypoint (RWP) mobility model, and it does not require a model of road grid geometry for its parametrization. We validate our model extensively, through numerical simulations on real-world traces, showing its accuracy on a variety of mobility patterns and traffic conditions. Through analysis and simulations, we show the feasibility of the FC paradigm in realistic urban settings over a wide range of traffic conditions.TRUEpu
Throughput vs. Latency: QoS-centric Resource Allocation for Multi-User Millimeter Wave Systems
Get PDFMillimeter wave (mm-wave) communication is a topic of intensive recent study, as it allows to significantly boost data rates of future 5G networks. In this paper, we focus on a mm-wave system consisting of a single Access Point (AP) and two User Equipments (UEs), where one UE requires high throughput, while the other is characterized by a low latency demand. Given that setup, we aim at optimally allocating the available AP hardware resources for the beam training phase and data communication, in order to efficiently serve both UEs via hybrid analog-digital beamforming. We evaluate an optimization framework with the objective to maximize the expected rate of one UE, for a given latency constraint set by the other UE. The optimal data rates are illustrated for different latency constraints and for different strategies of exploiting the full RF chain set at the AP side. We observe that our proposed access schemes outperform the basic TDMA approach by up to 22%.TRUEpu
PoC of SCMA-Based Uplink Grant-Free Transmission in UCNC for 5G
Get PDFA 5G mobile network has evolved from a cell centric radio access network to a user centric one. A user-centric no-cell (UCNC) framework has been proposed, which enables physical layer coordination over a large number of transmission and reception points for each mobile user to always experience cell-center-like communications. This paper presents some key technologies in the UCNC framework. The focus is on proof of concept of UL grant-free transmissions in the UCNC architecture. Massive connectivity supporting a huge number of devices is one of the three important scenarios in 5G networks. The challenges to support massive connectivity lie in the cost of signaling overhead and transmission latency. An uplink grant-free transmission based on sparse code multiple access (SCMA) design is proposed. The proposed scheme can provide different levels of overloading to efficiently meet the massive connectivity requirements. Grant-free transmission conducted in RRC connected state can reduce signaling overhead, while in energy conserved operation (ECO) state, it can significantly reduce the user plane transmission latency. Extensive laboratory testing has been conducted in a collaborative project of Huawei and Telefonica to verify the performance matrices. Taking LTE as a baseline for comparison purposes, it is shown that the signaling overhead by using uplink grant-free transmission can be reduced by around 80% and the user plane transmission latency in ECO state can be reduced by around 93%. Moreover, massive connectivity is efficiently supported with the SCMA scheme that yields around 230% gain over OFDMA in terms of supported active users.pu
Planning in Compute-Aggregate Problems as Optimization Problems on Graphs
Get PDFEfficient representation of data aggregations is a fundamental problem in modern big data applications. We present a formalization of compute-aggregate planning parameterized by the aggregation function.TRUEpu
Not All Apps Are Created Equal: Analysis of Spatiotemporal Heterogeneity in Nationwide Mobile Service Usage
Get PDFWe investigate how individual mobile services are consumed at a national scale, by studying data collected in a 3G/4G mobile network deployed over a major European country. rough correlation and clustering analyses, our study unveils a strong heterogeneity in the demand for di erent mobile services, both in time and space. In particular, we show that: (i) somehow surprisingly, almost all considered services exhibit quite di erent temporal usage pa erns; (ii) in contrast to such temporal behavior, spatial pa erns are fairly uniform across all services; (iii) when looking at usage pa erns at di erent locations, the average tra c volume per user is dependent on the urbanization level, yet its temporal dynamics are not. Our ndings do not only have sociological implications, but are also relevant to the orchestration of network resources.TRUEpu
SEMPER: A Stateless Traffic Engineering Solution based on MP-TCP for WAN networks
Get PDFCurrent Enterprise Networks deployments must accomplish a strong set of requirements in terms of resiliency, reliability and resources usage. As current approaches are based on monolithic and expensive infrastructures built on dedicated overlay links, vendors are trying to move to economical hybrid solutions that encompasses private dedicated links with public/regular Internet connections. However, these usually rely on complex Traffic Engineering solutions hardware dependent or proprietary that are costly in terms of computational time and memory usage in the forwarding nodes. In this paper, we propose SEMPER: a lightweight traffic engineering (TE) solution based on MP-TCP which, in contrast to other TE solutions, moves the complexity to the endpoints of the connection, and relieves the forwarding elements from complex operations or maintaining state. As our evaluation shows, SEMPER efficiently makes use of all available paths between the endpoints while maintaining fairness, and properly adapts to variations on the available capacity.Telematics EngineeringUniversidad Carlos III de Madrid, Spainpu
Network Slicing Games: Enabling Customization in Multi-Tenant Mobile Networks
Get PDFNetwork slicing to enable resource sharing among
multiple tenants –network operators and/or services– is considered a key functionality for next generation mobile networks. This paper provides an analysis of a well-known model for resource sharing, the ‘share-constrained proportional allocation’ mechanism, to realize network slicing. This mechanism enables tenants to reap the performance benefits of sharing, while
retaining the ability to customize their own users’ allocation. This results in a network slicing game
in which each tenant reacts to the user allocations of the other tenants so as to maximize its own utility. We show that, under appropriate conditions, the
game associated with such strategic behavior converges to a Nash equilibrium. At the Nash equilibrium, a tenant always achieves the same, or better, performance than under a static partitioning of resources, hence providing the same level of protection as such static partitioning. We further analyze the efficiency and fairness of the resulting allocations, providing tight bounds for the price of
anarchy and envy-freeness. Our analysis and extensive simulation results confirm that the mechanism provides a comprehensive practical solution to realize network slicing. Our theoretical results also fill a gap in the literature regarding the analysis of this resource allocation model under strategic players.TRUEpu
Filtering Noisy 802.11 Time-of-Flight Ranging Measurements From Commoditized WiFi Radios
Get PDFTime-of-flight (ToF) echo techniques have been recently suggested for ranging mobile devices over WiFi radios.
However, these techniques have yielded only moderate accuracy in indoor environments because WiFi ToF measurements suffer from extensive device-related noise which makes it challenging to differentiate between direct path from non-direct path signal components when estimating the ranges. Existing multipath mitigation techniques tend to fail at identifying the direct path when the device-related Gaussian noise is in the same order of magnitude, or larger than the multipath noise. In order to address this challenge, we propose a new method for filtering ranging measurements that is better suited for the inherent large noise as found in WiFi radios. Our technique combines statistical learning and robust statistics in a single filter. The filter is lightweight in the sense that it does not require specialized hardware, the intervention of the user, or cumbersome on-site manual calibration. This makes our method particularly suitable for indoor localization in large-scale deployments using existing legacy WiFi infrastructures. We evaluate our technique for indoor mobile tracking scenarios in multipath environments and, through extensive evaluations across four different testbeds covering areas up to 1000 m2, the filter is able to achieve a median 2-D positioning error between 2 and 3.4 m.pu