IMDEA Networks Institute Digital Repository
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Challenges and solutions for networking in the millimeter-wave band
No full textOne of the most promising options to significantly increase data rates in future wireless networks is to vastly increase the communication bandwidth. Such 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, for example IEEE 802.11ad, are already starting to exploit this part of the radio spectrum to achieve data rates of several GBit/s. mm-wave communication is also discussed as key technology for 5G mobile networks. However, communication at such high frequencies also suffers from high attenuation and signal absorption, often restricting communication to line-of-sight 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. It is essential to take these characteristics into account to design efficient wireless architectures. The talk will highlight main challenges and possible solutions for networking in the mm-wave band.TRUEpu
Lightweight Capacity Measurements For Mobile Networks
Get PDFMobile data traffic is increasing rapidly and wireless spectrum is becoming a more and more scarce resource. This makes it highly important to operate mobile networks efficiently. In this paper we are proposing a novel lightweight measurement technique that can be used as a basis for advanced resource optimization algorithms to be run on mobile phones. Our main idea leverages an original packet dispersion based technique to estimate per user capacity. This allows passive measurements by just sampling the existing mobile traffic. Our technique is able to efficiently filter outliers introduced by mobile network schedulers and phone hardware. In order to asses and verify our measurement technique, we apply it to a diverse dataset generated by both extensive simulations and a week-long measurement campaign spanning two cities in two countries, different radio technologies, and covering all times of the day. The results demonstrate that our technique is effective even if it is provided only with a small fraction of the exchanged packets of a flow. The only requirement for the input data is that it should consist of a few consecutive packets that are gathered periodically. This makes the measurement algorithm a good candidate for inclusion in OS libraries to allow for advanced resource optimization and application-level traffic scheduling, based on current and predicted future user capacity.pu
Adopting Software-Defined Networking: Challenges and Recent Developments
Get PDFTraditional network management only allows to deploy a predefined set of management policies whose parameters can be adapted to specific network conditions. The incorporation of new management policies requires complex control/data plane code changes. Objectives beyond fairness and the consideration of additional traffic properties lead to new challenges in the implementation and performance for traditional network element. This calls for novel abstractions that enable the definition of management policies. Designing such abstractions however is non-trivial, as they must satisfy a number of possibly conflicting requirements as expressiveness, simplicity, and performance. Initially, SDN has been promoted as a simpler and more flexible way of managing networks than traditional approaches. In this talk we critically look over current developments in SDN and identify interesting research directions.TRUEpu
Implementation and Evaluation of a WLAN IEEE 802.11ad Model in ns-3
Get PDFThe IEEE 802.11ad amendment to the 802.11 standard for multi-gigabit communication at 60 GHz was published several years ago, but to date, no precise simulation model for networking in this band is available. In this paper, we present a model for IEEE 802.11ad implemented in the network simulator ns-3. We model new techniques that are essential for IEEE 802.11ad operation such as beamforming training and steering, relay support, and fast session transfer. We then evaluate by simulation the performance of IEEE 802.11ad as well as the gains obtained through the aforementioned techniques. The code for our simulation model is publicly available.Telematics EngineeringUniversidad Carlos III de Madrid, Spainpu
Mobile network architecture evolution toward 5G
Get PDFAs a chain is as strong as its weakest element, so are the efficiency, flexibility, and robustness of a mobile network, which relies on a range of different functional elements and mechanisms. Indeed, the mobile network architecture needs particular attention when discussing the evolution of 3GPP EPS because it is the architecture that integrates the many different future technologies into one mobile network. This article discusses 3GPP EPS mobile network evolution as a whole, analyzing specific architecture properties that are critical in future 3GPP EPS releases. In particular, this article discusses the evolution toward a "network of functions," network slicing, and software-defined mobile network control, management, and orchestration. Furthermore, the roadmap for the future evolution of 3GPP EPS and its technology components is detailed and relevant standards defining organizations are listed.pu
Hybrid Analog-Digital Beam Training for mmWave Systems with Low-Resolution RF Phase Shifters
Get PDFMillimeter wave (mmWave) wireless technologies are expected to exploit large-scale multiple-input multiple-output and adaptive antenna arrays at both the transmitter and receiver to deal with unfavorable radio propagation and realize sufficient link margin. However, the high cost and power consumption of mmWave radio components prohibit the use of fully-digital precoding/combining architectures, which incurs one dedicated RF chain per antenna element. This paper proposes a practical design of multi-beamwidth codebook exploiting hybrid analogdigital architectures with a number of RF chains much lower than the number of antenna elements and 2-bit RF phase shifters. The proposed solution relies on the orthogonal matching pursuit algorithm enhanced by a dynamic dictionary learning mechanism. Simulation results show that the designed hybrid codebooks are able to shape beam patterns very close to those attained by a fully-digital beamforming architecture. Furthermore, when leveraged in the framework of an adaptive, multiresolution beam training protocol, our hybrid codebooks are able to estimate the most promising angle-of-departure and angle-ofarrival directions with extreme accuracy, yet requiring lower complexity hardware compared to the state of art.Signal Theory and CommunicationsUniversidad Carlos III de Madrid, Spainpu
Saving Energy by Powering Down Links
No full textIn this talk I will be presenting two related papers that have to do with energy savings in wired networks. In the first paper I present a model that allows to estimate the energy savings of links that implement the new standards IEEE
802.3az Energy Efficient Ethernet, as a function of simple traffic parameters. Under this standard, the link can go to a low power mode when there is not traffic over the link. Then, in a network of (idealized) EEE links, I present algorithms to schedule and route packets in order to reduce energy consumption while maintaining the latency low.TRUEpu
Thwarting Selfish Behavior in 802.11 WLANs
Get PDFThe 802.11e standard enables user configuration of several MAC parameters, making WLANs vulnerable to users that selfishly configure these parameters to gain throughput. In this paper, we propose a novel distributed algorithm to thwart such selfish behavior. The key idea of the algorithm is for stations to react, upon detecting a misbehavior, by using a more aggressive configuration that penalizes the misbehaving station. We show that the proposed algorithm guarantees global stability while providing good response times. By conducting an analysis of the effectiveness of the algorithm against selfish behaviors, we also show that a misbehaving station cannot obtain any gain by deviating from the algorithm. Simulation results confirm that the proposed algorithm optimizes throughput performance while discouraging selfish behavior. We also present an experimental prototype of the proposed algorithm demonstrating that it can be implemented on commodity hardware.pu
A Demonstration of ANALYSE: A Learning Analytics Tool for Open edX
Get PDFhttp://dx.doi.org/10.1145/2876034.2893402.Education is being powered by technology in many ways. One of the main advantages is making use of data to improve the learning process. The massive open online course (MOOC) phenomenon became viral some years ago, and with it many different platforms emerged. However most of them are proprietary solutions (i.e. Coursera, Udacity) and cannot be used by interested stakeholders. At the moment Open edX is placed as the primary open source application to support MOOCs. The community using Open edX is growing at a fast pace with many interested institutions. Nevertheless, the learning analytics support of Open edX is still in its first steps. In this paper we present an overview and demonstration of ANALYSE, an open source learning analytics tool for Open edX. ANALYSE includes currently 12 new
visualizations that can be used by both instructors and
students.TRUEpu
Design and Evaluation of a Low-Cost Acoustic Chamber for Underwater Networking Experiments
Get PDFTesting acoustic equipment before sea experiments is a necessary step, which usually requires large and expensive facilities. In this paper, we present the design guidelines, structure and details of a small-scale, low-cost acoustic chamber for in-lab testing of underwater acoustic networks. The chamber has been assembled with the objective to be of low cost and limited size: therefore, its installation fits small university laboratories that cannot afford large testing pools. The chamber was designed to mitigate the extreme multipath which, in a small chamber, makes communications unreliable. Considering this challenge, our chamber includes a phono-absorbing coating on the walls and floor, to be optionally complemented by a panel of the same coating material, to be installed at the water surface level. After providing the details of several phono-absorbing materials to motivate our specific choice, we carry out a number of transmission experiment with EvoLogics modems, proving that our design substantially reduces the severe multipath and thereby improves the communications quality.TRUEpu