IMDEA Networks Institute Digital Repository
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Essential Traffic Parameters for Shared Memory Switch Performance
Get PDFCloud applications bring new challenges to the design of network elements, in particular accommodating for the burstiness of traffic workloads. Shared memory switches represent the best candidate architecture to exploit buffer
capacity; we analyze the performance of this architecture. Our goal is to explore the impact of additional traffic characteristics such as varying processing requirements and packet values on objective functions. The outcome of this work is a better understanding of the relevant parameters for buffer management to achieve better performance in dynamic environments of data centers. We consider a model that captures more of the properties of the target architecture than previous work and consider several scheduling and buffer management algorithms that are specifically designed to optimize its performance. In particular, we provide analytic guarantees for the throughput performance of our algorithms that
are independent from specific distributions of packet arrivals. We furthermore report on a comprehensive simulation study which validates our analytic results.TRUEpu
RMSC: A Cell Slicing Controller for Multi-tenant Mobile Networks
No full textThe traditional model of single ownership of the mobile network infrastructure is being challenged by the forecasted mobile data tsunami and the resulting CAPEX and OPEX costs. In this context, the sharing of network infrastructure among operators has emerged as a way to ensure operators' future cost competitiveness. While the elementary concepts related to passive network sharing are already being exploited today, active network sharing is raising in importance to enable further reduction of network expenses in a substantial and sustainable way. The work presented in this paper addresses this challenge by designing a RAN Multi- tenant cell Slicing Controller (RMSC) that allows to flexibly share the RAN resources among multiple virtual operators (tenants). Three different possible designs for the RMSC controller are proposed, ranging from a fully distributed system with no inter-base station communication to a fully centralized solution with all information available. The proposed solutions are benchmarked against a distributed static slicing solution and a centralized load balancing solution, considering realistic scenarios of uneven user location distribution per tenant. The performance results obtained indicate that the proposed RMSC schemes can significantly outperform traditional solutions for multi-tenant mobile networks.TRUEpu
CSMA/CA in Time and Frequency Domains
Get PDFIt has recently been shown that flexible channelization, whereby wireless stations adapt their spectrum bands on a per-frame basis, is feasible in practice. In this paper, we propose TF-CSMA/CA, an algorithm for flexible channelization that schedules packets in time and frequency domains. TF-CSMA/CA is a simple extension of the CSMA/CA protocol used by IEEE 802.11. Contrary to existing channelization schemes, it is entirely distributed and it reacts only to packet collisions, successful transmissions and carrier sensing. With TF-CSMA/CA, when a station is involved in a collision, it performs backoff in both time and frequency domains. Backing off also in the frequency domain allows the transmitters to be much more efficient and aggressive in the time domain, which significantly reduces the severe overheads present with recent 802.11 PHY layers. The main challenge, however, is that the stations need some level of self-organization in order to find spectrum bands of variable widths that minimize interference, while still efficiently using the available spectrum. Using analysis and simulations, we show that such an extension of CSMA/CA to the frequency domain drastically improves both throughput and fairness. Notably, it enables the stations to find interference-free spectrum bands of appropriate size using no communication – relying only on collisions and successes as implicit signals.TRUEpu
Simonstrator: Simulation and Prototyping Platform for Distributed Mobile Applications
Get PDFThe increasing market penetration of mobile devices, such
as smartphones and tablets, poses additional challenges on
the design of distributed systems. Due to the heterogeneous
environment consisting of both, mobile and fixed devices, a
multitude of effects on different scales need to be considered. Microscopic effects, such as an individual user's interaction with the device, as well as macroscopic effects, such as scalability with the number of users have an impact on the system's performance. The combined evaluation of micro- and macroscopic effects requires both, simulations and prototypical deployments. Furthermore, insights obtained through prototypes during user studies can lead to refined protocols and algorithms, thereby contributing to the overall design process. To enable parallel assessment of micro- and macroscopic effects, we propose the Simonstrator platform, consisting of a lightweight framework for the development and instrumentation of distributed systems as well as runtime environments for (i) the interaction with common simulators,
(ii) the deployment on testbeds, and (iii) Android devices.
The platform is speciffically targeted towards distributed systems for heterogeneous scenarios, considering mobile and
fixed networks. We show sample simulations and prototypical
deployments of two exemplary use cases: a live video streaming system and a middleware for augmented reality
games, highlighting different evaluation goals and environments supported by the proposed Simonstrator platform.TRUEpu
Efficient Networking in Millimeter Wave Bands
No full textState-of-the-art wireless communication already operates close to Shannon capacity and one of the most promising options to further increase data rates is to increase the communication bandwidth. Very high bandwidth channels are only available in the extremely high frequency part of the radio spectrum, the millimeter wave band (mm-wave). Upcoming communication technologies, such as IEEE 802.11ad, are already starting to exploit this part of the radio spectrum to achieve data rates of several GBit/s. However, communication at such high frequencies also suffers from high attenuation and signal absorption, often restricting communication to line-of-sight (LOS) scenarios and requiring the use of highly directional antennas. This in turn requires a radical rethinking of wireless network design. On the one hand side, such channels experience little interference, allowing for a high degree of spatial reuse and potentially simpler MAC and interference management mechanisms. On the other hand, such an environment is extremely dynamic and channels may appear and disappear over very short time intervals, in particular for mobile devices. This talk will highlight some of the challenges of and possible approaches for networking in the mm-wave band.TRUEpu
Internet of People - An Approach to People-Centric Internet of Things
No full textTechnology now offers the possibility of delivering a vast range of low-cost people-centric services to citizens. Internet of Things (IoT) supporting technologies are becoming robust, viable and cheaper. Mobile phones are increasingly more powerful and disseminated. On the other hand, social networks and virtual worlds are experiencing an exploding popularity and have millions of users. These low-cost technologies can now be used to create an Internet of People (IoP), a dynamically configurable integration platform of connected smart objects that allows enhanced, people-centric applications. As opposed to things-centric ones, IoP combines the real, sensory world with the virtual world for the benefit of people while it also enables the development of sensing applications in contexts such as e-health, sustainable mobility, social networks enhancement or fulfilling people’s special needs. This talk identifies the main challenges, a possible approach, and key enabling technologies for a people-centric society based on the Internet of Things.TRUEpu
Jamming Mitigation by Randomized Bandwidth Hopping
Get PDFWe present bandwidth hopping spread spectrum (BHSS), a novel technique to improve the jamming resistance of wireless communications. In BHSS, the bandwidth of a signal is hopped rapidly in a manner that is unpredictable to the jammer. We show in this work that by combining bandwidth hopping at the transmitter with adaptive filtering at the receiver, BHSS is able to improve the jamming resistance of the communication beyond the processing gain of conventional spread spectrum techniques such as DSSS and FHSS without an increase in RF spectrum requirements. We have designed and implemented a BHSS transmitter and receiver system on off-the-shelf software-defined radios. Our experimental results with different hopping patterns show that BHSS is able to boost the power advantage of spread spectrum communication by 8 to \,dB for jammers of fixed bandwidth. When both transmitter and jammer hop randomly, the average power advantage we achieve with our system is 11.4 dB.TRUEpu
Simulation of a Multimodal Wireless Remote Control System for Underwater Vehicles
Get PDFWhile the design of reliable and enduring remotely operated vehicles for underwater operations is currently a hot research area, there are not many options to control these systems in real time using wireless telemetry. In particular, a reliable, fully wireless control method that exploits state-of-the-art underwater wireless communication technologies is still lacking. In this paper, we consider the design and engineering of one such multimodal control system comprising optical and acoustic underwater communications, and characterize its performance under different configurations of the communication protocol stack. Compared to previous work, we introduce a proactive mechanism to switch among the components of the multimodal system by means of a signaling mechanism that requires negligible overhead. Our results suggest that a multimodal wireless control system can provide satisfactory control performance by supplying different levels of interaction with the vehicle, depending on the technology in use, and by reliably and timely switching between the available communication technologies.TRUEpu
Resource Allocation for elastic traffic in mobile networks shared by multiple operators
Get PDFThe traditional model of single ownership of the mobile network infrastructure is being challenged by the forecasted mobile data tsunami. In this context, the sharing of network infrastructure among operators has emerged as a way to ensure operators’ future cost competitiveness. While the elementary concepts related to passive sharing are already exploited,active sharing is raising in importance. The work presented in this thesis presents a solution for active RAN sharing in new generation cellular networks that takes into account inter and intra operator fairness and has desirable properties from base station and user association perspectives. An offline centralized approximation algorithm that provides theoretical performance guarantees is proposed. Making use of the available real-time neighbour information we designed an approximated distributed algorithm with a log(e) additive ratio. Finally, we confirm the theoretical results by a set of performance evaluations in a LTE-Advanced system-level simulator.Telematics EngineeringUniversidad Carlos III de Madrid, Spainpu
