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Communication-Driven Localization and Mapping for Millimeter Wave Networks
Get PDFMillimeter wave (mmWave) communications are an essential component of 5G-and-beyond ultra-dense Gbit/s wireless networks, but also pose significant challenges related to the communication environment. Especially beam-training and tracking, device association, and fast handovers for highly directional mmWave links may potentially incur a high overhead. At the same time, such mechanisms would benefit greatly from accurate knowledge about the environment and device locations that can be provided through simultaneous localization and mapping (SLAM) algorithms.
In this paper we tackle the above issues by proposing CLAM, a
distributed mmWave SLAM algorithm that works with no initial
information about the network deployment or the environment,
and achieves low computational complexity thanks to a fundamental reformulation of the angle-differences-of-arrival mmWave anchor location estimation problem. All information required by CLAM is collected by a mmWave device thanks to beam training
and tracking mechanisms inherent to mmWave networks, at no
additional overhead. Our results show that CLAM achieves sub-
meter accuracy in the great majority of cases. These results are
validated via an extensive experimental measurement campaign
carried out with 60-GHz mmWave hardware.TRUEpu
Infrastructureless Pervasive Information Sharing with COTS Devices and Software
Get PDFInformation sharing is becoming a relevant issue for mobile broadband operators, due to the increasing popularity of social networks, to the increasing volumes of shared information, and to the steady increase in the number and capabilities of mobile devices connected to the Internet. Offloading information sharing services from the cellular infrastructure to device-to-device (D2D) communications can offer a welcome reduction of traffic. This paper discusses experiments with a smartphone information sharing application that can be used on commercial-off-the-shelf devices, with no need to root the device's software. In order to avoid unrealistic assumptions on the behavior of D2D communications, this work includes and builds upon the implementation of an Android application that supports infrastructureless distributed content sharing among wireless devices using Wi-Fi Direct. The collected experimental data permit a detailed analysis of the occurring events, and a careful assessment of the performance of pervasive information sharing services. Our experiments reveal that many assumptions commonly used in the literature do not hold in real settings. We conclude that delay-tolerant services can be supported, albeit we also show that high densities of devices can (somewhat counter-intuitively) impair performance.TRUEpu
A Multi-Traffic Inter-Cell Interference Coordination Scheme in Dense Cellular Networks
Get PDFhis paper proposes a novel semi-distributed and practical ICIC scheme based on the Almost Blank SubFrame (ABSF) approach specified by 3GPP. We define two mathematical programming problems for the cases of guaranteed and best-effort traffic, and use game theory to study the properties of the derived ICIC distributed schemes, which are compared in detail against unaffordable centralized schemes. Based on the analysis of the proposed models, we define Distributed Multi-traffic Scheduling (DMS), a unified distributed framework for adaptive interference-aware scheduling of base stations in future cellular networks, which accounts for both guaranteed and best-effort traffic. DMS follows a two-tier approach, consisting of local ABSF schedulers, which perform the resource distribution between the guaranteed and best effort traffic, and a light-weight local supervisor, which coordinates ABSF local decisions. As a result of such a two-tier design, DMS requires very light signaling to drive the local schedulers to globally efficient operating points. As shown by means of numerical results, DMS allows to: (i) maximize radio resources rescue; (ii) provide requested quality for guaranteed traffic; (iii) minimize the time dedicated to guaranteed traffic to leave room for best-effort traffic; and (iv) maximize resource utilization efficiency for the best-effort traffic.TRUEpu
Hybrid Access Femtocells in Overlaid MIMO Cellular Networks with Transmit Selection under Poisson Field Interference
Get PDFThis paper analyzes the performance of hybrid
control-access schemes for small cells (such as femtocells) in the context of two-tier overlaid cellular networks. The proposed hybrid access schemes allow for sharing the same downlink resources between the small-cell network and the original macrocell network, and their mode of operations are characterized considering post-processed signalto-interference-plus-noise ratios (SINRs) or pre-processed interference-aware operation. The work presents a detailed treatment of achieved performance of a desired user that benefits from MIMO arrays configuration through the use of transmit antenna selection (TAS) and maximal ratio combining (MRC) in the presence of Poisson field interference processes on spatial links. Furthermore, based on the interference awareness at the desired user, two TAS approaches are treated, which are the signal-tonoise (SNR)-based selection and SINR-based selection. The analysis is generalized to address the cases of highlycorrelated and un-correlated aggregated interference on different transmit channels. In addition, the effect of delayed TAS due to imperfect feedback and the impact of arbitrary TAS processing are investigated. The analytical results are validated by simulations, to clarify some of the main outcomes herein.pu
Underwater Delay-Tolerant Routing via Probabilistic Spraying
Get PDFWe propose underwater delay-tolerant routing via probabilistic spraying (UDTN-Prob), a routing protocol for underwater delay-tolerant networks based on the store-and-forward paradigm. Our protocol exploits limited statistical knowledge of the time between two subsequent contacts between pairs of network nodes in order to filter the packets injected into the network, so that only those with a sufficiently high chance of being delivered to their intended destination within a given deadline are actually transmitted. In addition, the foreseen duration of a contact is estimated via a preliminary packet exchange, so that the nodes get a fair share of the contact time to exchange their own data. The transmission is protected against channel-induced packet losses via an ARQ scheme modified to adapt itself to typical underwater transmission times and to the variation of round-trip times induced by node mobility. We simulate the protocol using the DESERT Underwater libraries, that make it possible to accurately reproduce the nodes' behavior and mobility patterns. Our results show that the proposed protocol achieves significantly better performance than Spray-and-Wait, which is currently the most typical choice among store-and-forward protocols. Moreover, we show that a 2-hop statistical knowledge of the node contact process yields marginally higher utility with respect to a simpler 1-hop knowledge, which is also much easier to collect or estimate.pu
Closed Form Expressions for the Performance Metrics of Data Services in Cellular Networks
Get PDFIn this paper we study the queuing system that describes the operations of data services in cellular networks, e.g., UMTS, LTE/LTE-A, and most likely the forthcoming 5G standard. The main characteristic of all these systems is that after service access, resources remain allocated to the end user for some time before release, so that if the same user requests access to service again, before a system timeout, the same resources are still available. For the resulting queuing model, we express the blocking probability in closed form, and we also provide recursive expressions in the number of connections that can be handled by the base station. Closed form expressions are also derived for other useful performance metrics, i.e., throughput and network
service time. Analytical results are validated against results of a detailed simulation model, and compared to traditional queueing models results, such as the Erlang B formula iteratively applied to the resources that are not blocked by potentially returning users. Our analysis complements the performance evaluation of the other key mechanism used to access data services in cellular networks, namely the random access, which precedes the resource allocation and utilization phase studied in this paper.TRUEpu
Competitive Analysis of Fundamental Scheduling Algorithms on a Fault-Prone Machine and the Impact of Resource Augmentation
Get PDFReliable task execution in machines that are prone to unpredictable crashes and restarts is both challenging and of high importance, but not much work exists on the analysis of such systems. We consider the online version of the problem, with tasks arriving over time at a single machine under worst-case assumptions. We analyze the fault-tolerant properties of four popular scheduling algorithms: Longest In System (LIS), Shortest In System (SIS), Largest Processing Time (LPT) and Shortest Processing Time (SPT).We use three metrics for the evaluation and comparison of their competitive performance, namely, completed load, pending load and latency. We also investigate the effect of resource augmentation in their performance, by increasing the speed of the machine. Hence, we compare the behavior of the algorithms for different speed intervals and show that there is no clear winner with respect to all the three considered metrics. While SPT is the only algorithm that achieves competitiveness on completed load for small speed, LIS is the only one that achieves competitiveness on latency (for large enough speed).pu
Adaptive Scheduling over a Wireless Channel under Constrained Jamming
No full textWe consider in this talk the problem of packet
scheduling over an unreliable wireless communication
channel. A setting with a single pair of nodes is
considered, a sender and a receiver. The sending
station transmits packets to a receiving station over
the channel that can be jammed, which corrupts the
packet being transmitted. The jamming is controlled by
a constrained adversary. The constrained power of the
adversary is modeled by an Adversarial Queueing Theory
(AQT) approach, defined with two main parameters; ρ,
the error availability rate, and σ, the maximum batch
of errors available to the adversary at any time. In
this problem, the scheduling algorithms must decide on
the length of the packets to be transmitted, with the
objective of maximizing the goodput rate; the rate of
successfully transmitted load. It is seen, that even
for the simplest settings, finding an optimal
algorithm is not trivial, but efficient solutions can
be found.FALSEpu
Profiling Energy Efficiency of Mobile Crowdsensing Data Collection Frameworks for Smart City Applications
Get PDFMobile crowdsensing has emerged in the last years and has become one of the most prominent paradigms for urban sensing. In MCS, citizens actively participate in the sensing process by contributing data with their smartphones, tablets, wearables and other mobile devices to a collector. As citizens sustain costs while contributing data, i.e., the energy spent from the batteries for sensing and reporting, devising energy efficient Data Collection Frameworks (DCF) is essential. In this work, we compare energy efficiency of several DCFs through simulations with the CrowdSenSim simulator, which allows to perform large-scale experiments in realistic urban environments. Specifically, the DCF under analysis differ one with each other by the data reporting mechanism implemented and the signaling between users and the collector needed for sensing and reporting decisions. The results reveal that the key criterion differentiating DCFs' energy consumption is the data reporting mechanism. In principle, continuous reporting to the collector should be more energy consuming than probabilistic reporting. However, DCFs with continuous reporting that implement mechanisms to block sensing and data delivery after a certain amount of contribution are more effective in harvesting data from the crowd.TRUEpu
Design and Large-Scale Evaluation of WiFi Proximity Metrics
Get PDFWe study the problem of deriving proximity metrics based on WiFi fingerprints without the need of external sensors and access to the locations of APs. Applications that benefit from proximity metrics are movement estimation of a single node over time, WiFi fingerprint matching for localization systems and attacks on privacy. Using a large-scale, real-world WiFi fingerprint data set consisting of 200,000 fingerprints resulting from a large deployment of wearable WiFi sensors, we show that metrics from related work perform poorly on real-world data. We analyze the cause for this poor performance, and show that imperfect observations of APs in the neighborhood are the root cause. We then propose improved metrics to provide such proximity estimates, without requiring knowledge of location for the observed AP. Our metrics allow to derive a relative distance estimate based on two observed WiFi fingerprints. We demonstrate that their performance is superior to the related work metrics.TRUEpu