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Experimenting with Commodity 802.11 Hardware: Overview and Future Directions
Get PDFThe huge adoption of 802.11 technologies has triggered a vast amount of experimentally-driven research works. These works range from performance analysis to protocol enhancements, including the proposal of novel applications and services. Due to the affordability of the technology, this experimental research is typically based on commercial off-the-shelf (COTS) devices, and given the rate at which 802.11 releases new standards (which are adopted into new, affordable devices), the field is likely to continue to produce results. In this paper, we review and categorise the most prevalent works carried out with 802.11 COTS devices over the past fifteen years, to present a timely snapshot of the areas that have attracted to most attention so far, though a taxonomy that distinguishes between performance studies, enhancements, services and methodology. In this way, we provide a quick overview of the results achieved by the research community that enables prospective authors to identify potential areas of new research, some of which are discussed after the presentation of the survey.pu
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
Route Bazaar: Automatic Interdomain Contract Negotiation
Get PDFWhile it is widely acknowledged that the Border Gateway
Protocol (BGP) has many flaws, most of the proposed
fixes focus solely on improving the stability and security
of its path computation. However, because interdomain
routing involves contracts between Autonomous Systems
(ASes), this paper argues that contractual and routing issues should be tackled jointly. We propose Route Bazaar,
a backward-compatible system for flexible Internet connectivity. Inspired by the decentralized construction of
trust in cryptocurrencies, Route Bazaar uses a decentralized
public ledger and cryptography to provide ASes with
automatic means to form, establish, and verify end-to-end
connectivity agreements.TRUEpu
An Analytical Approach to Performance Analysis of Coupled Processor Systems.
Get PDFWe consider a queuing system with coupled processors
(CPS), in which the service rate at each queue varies
over time in function of the set of active queues in the system.
Performance analysis of CPS has so far been based on simulations or on complex Markov chains under restricting assumptions on input traffic statistics. In contrast, we propose a fully analytical approach to CPS, based on a worst case analysis of system dynamics, and applicable to a large family of traffic characterizations.
We derive sufficient conditions for stability for traffic
characterized stochastically as well as for traffic constrained by arrival curves, and we show how to compute bounds on backlog and delay. We illustrate our approach and assess our results by means of an example of coupling of wireless transmissions.TRUEpu
Staying Alive: System Design for Self-Sufficient Sensor Networks
Get PDFSelf-sustainability is a crucial step for modern sensor networks. Here, we offer an original and comprehensive framework for autonomous sensor networks powered by renewable energy sources. We decompose our design into two nested optimization steps: the inner step characterizes the optimal network operating point subject to an average energy consumption constraint, while the outer step provides online energy management policies that make the system energetically self-sufficient in the presence of unpredictable and intermittent energy sources. Our framework sheds new light into the design of pragmatic schemes for the control of energy-harvesting sensor networks and permits to gauge the impact of key sensor network parameters, such as the battery capacity, the harvester size, the information transmission rate, and the radio duty cycle. We analyze the robustness of the obtained energy management policies in the cases where the nodes have differing energy inflow statistics and where topology changes may occur, devising effective heuristics. Our energy management policies are finally evaluated considering real solar radiation traces, validating them against state-of-the-art solutions, and describing the impact of relevant design choices in terms of achievable network throughput and battery-level dynamics.pu
An Open-Source Research Platform for Embedded Visible Light Networking
Get PDFDespite the growing interest in Visible Light Communication (VLC), a reference networking platform based on commercial off-the-shelf components is not available yet. An open-source platform would lower the barriers to entry to VLC network research and help the VLC community gain momentum. We introduce OpenVLC, an open-source VLC research platform based on software-defined implementation. Built around a credit-card-sized embedded Linux platform with a simple opto-electronic transceiver front-end, OpenVLC offers a basic physical layer, a set of essential medium access primitives, as well as interoperability with Internet protocols. We investigate the performance of OpenVLC and show examples of how it can be used along with standard network diagnostics tools. Our software-defined implementation can currently reach throughput in the order of the basic rate of IEEE 802.15.7 standard. We discuss several techniques that researchers and engineers could introduce to improve the performance of OpenVLC and envision several directions that can benefit from OpenVLC by adopting it as a reference platform.pu
Two-level Opportunistic Spectrum Management for Green 5G Radio Access Networks
Get PDFIn this paper, we pioneer a novel mechanism that jointly enforces intra-cell and inter-cell resource allocation for future green 5G networks. Our proposal, namely TOMRAN, efficiently coordinates the activity of base stations in small dense cell deployments by means of the ABSF standard tool for intercell interference coordination. Additionally, TOMRAN applies intra-cell offloading of the cellular traffic through resource- limited outband D2D relay communications, using, e.g., 802.11-based connectivity. We take advantage of this tailwind to show that our approach offers significant performance gain while imposing minor network protocol modifications. Indeed, through an exhaustive simulation campaign, we prove that outband D2D relay communications not only reduce the complexity of interference coordination operations, but also greatly boost the energy efficiency of future green 5G networks.TRUEpu
Packet Scheduling over a Wireless Channel: AQT-based Constrained Jamming
Get PDFIn this paper we consider a two-node setting with a sender transmitting packets to a receiver over a wireless channel. Unfortunately, the channel can be jammed, thus corrupting the packet that is being transmitted at the time. The sender has a specific amount of data that needs to be sent to the receiver and its objective is to complete the transmission of the data as quickly as possible in the presence of jamming.
We assume that the jamming is controlled by a constrained adversary. In particular, the adversary’s power is constrained by two parameters, and . Intuitively, represents the rate at which the adversary can jam the channel, and the length of the largest bursts of jams it can cause. This definition corresponds to the translation of the Adversarial Queuing Theory (AQT) constrains, typically defined for packet injections in similar settings, to channel jamming.
We propose deterministic scheduling algorithms that decide the lengths of the packets to be sent by the sender in order to minimize the transmission time. We first assume all packets being of the same length (uniform) and characterize the corresponding optimal packet length. Then, we show that if the packet length can be adapted, for specific values of and the transmission time can be improved.TRUEpu
Brief Announcement: A Hierarchy of Congested Clique Models: From Broadcast to Unicast
Get PDFThe CONGEST model is a synchronous, message-passing
model of distributed computation in which each node can
send (possibly different) messages of O(log n) bits along each of its incident communication links in each round, where n is the number of computing nodes in the system. In the particular case where the communication network is a complete graph, we have the unicast congested clique model. On the other end is the broadcast version of the congested clique model, in which each node can only broadcast a single message over all its links in each round. In this paper we explore the space, in terms of round complexity, that lies between these two congested clique models. Hence, we parametrize the congested clique model with the range r, the maximum number of different messages a node can send over its incident links in one round. Additionally, we study the effect of the bandwidth b, the maximum size in bits of these messages.
We show that the space between the unicast and broadcast congested clique models is very rich and interesting. For instance, we show that a problem (especially designed for this work) takes(n= log n) rounds in the broadcast model
(r = 1), while it can be solved in two rounds if two messages can be sent (r = 2). Other gaps are found in other parts of the spectrum of values of r. We do this by providing techniques to simulate protocols with different parameters. Therefore, we conclude that, with respect to their power to solve certain problems, there is a strict hierarchy of congested clique models.TRUEpu
Opportunistic Finite Horizon Multicasting of Erasure-coded Data
Get PDFWe propose an algorithm for opportunistic multicasting in wireless networks. Whereas prior multicast rate adaptation schemes primarily optimize long-term throughput, we investigate the finite horizon problem where a fixed number of packets has to be transmitted to a set of wireless receivers in the shortest amount of time – a common problem, e.g., for software updates or video multicast. In the finite horizon problem, the optimum rate critically depends on the recent reception history of the receivers and requires a fine balance between maximizing overall throughput and equalizing individual receiver throughput. We formulate a dynamic programming algorithm that optimally solves this problem. We then develop two low complexity heuristics that perform close to the optimal solution and are suitable for practical online scheduling. We further analyze the performance of our algorithms by means of simulation. They substantially outperform existing solutions based on throughput maximization or favoring the user with the worst channel, and we obtain a 30% performance improvement over the former and a 120% improvement over the latter in scenarios with Rayleigh fading. We further analyze the performance of the schemes under imperfect state information and observe an even higher improvement over the benchmark schemes.pu