pinecone/core-2020-05-10-deduplication huggingface dataset:
Common Problems in Delay-Based Congestion Control Algorithms: A Gallery
  of Solutions

Although delay-based congestion control protocols such as FAST promise to
deliver better performance than traditional TCP Reno, they have not yet been
widely incorporated to the Internet. Several factors have contributed to their
lack of deployment. Probably, the main contributing factor is that they are not
able to compete fairly against loss-based congestion control protocols. In
fact, the transmission rate in equilibrium of delay-based approaches is always
less than their fair share when they share the network with traditional
TCP-Reno derivatives, that employ packet losses as their congestion signal.
There are also other performance impairments caused by the sensitivity to
errors in the measurement of the congestion signal (queuing delay) that reduce
the efficiency and the intra-protocol fairness of the algorithms. In this paper
we report, analyze and discuss some recent proposals in the literature to
improve the dynamic behavior of delay-based congestion control algorithms, and
FAST in particular. Coexistence of sources reacting differently to congestion,
identifying congestion appearance in the reverse path and the persistent
congestion problem are the issues specifically addressed
Study of the potential energy savings in Ethernet by combining Energy Efficient Ethernet and Adaptive Link Rate

The Energy Efficient Ethernet (EEE) standard (IEEE 802.3az) has introduced some modifications to existing Ethernet standards with the aim of improving energy efficiency in the transmission of data frames. The adopted mechanism is to use different power modes of operation such that a device can be put into a low-power mode when there is no data to transmit and awake it very quickly upon frame arrival. This is expected to reduce energy consumption significantly, especially on low-loaded links. An alternative to EEE, known as Adaptive Link Rate (ALR), was also proposed to improve energy efficiency in Ethernet by dynamically changing the link speed at different traffic loads. ALR reduces the energy consumption because the lower the link speed, the less energy is consumed. However, this option is no longer considered in the EEE standard process. In this work, the potential energy savings of combining both EEE and ALR are explored. The results show that such a combination can further improve the already efficient EEE standard given the different power overheads associated with transitions between the active and idle power modes at different link speeds. This conclusion provides a clear motivation to investigate the combination of EEE and ALR more in detail in further developments.The project T2C2 (under code TIN2008-06739-C04-01) and
the Medianet research grant (under code S2009/TIC-1468)
for the development of this work.Publicad
Comparison of multiple-input single-output single-user ultra-wideband systems with pre-distortion

This paper presents a performance analysis of a baseband multiple-input single-output ultra-wideband system over scenarios CM1 and CM3 of the IEEE 802.15.3a channel model, incorporating four different schemes of pre-distortion: time reversal, zero-forcing pre-equaliser, constrained least squares pre-equaliser, and minimum mean square error pre-equaliser. For the third case, a simple solution based on the steepest-descent (gradient) algorithm is adopted and compared with theoretical results. The channel estimations at the transmitter are assumed to be truncated and noisy. Results show that the constrained least squares algorithm has a good trade-off between intersymbol interference reduction and signal-to-noise ratio preservation, providing a performance comparable to the minimum mean square error method but with lower computational complexity. Copyright (C) 2011 John Wiley & Sons, Ltd.Brazilian agency National Council for Scientific Technological Development (CNPq)Brazilian agency National Council for Scientific Technological Development (CNPq) [303426/2009-8
A utility minimization approach for energy-aware cooperative content distribution with fairness constraints

Cooperation between mobile terminals (MTs) with the objective of energy minimization is studied. The purpose is to distribute a content of common interest to collaborating MTs while ensuring a reduced energy consumption. To reach this goal, the content is sent to selected MTs on a long-range link. Then, it is forwarded to other MTs on short-range mobile-to-mobile links. The problem is formulated as an optimization problem, and the optimal solution is shown to consist of sending the content to a single MT on the long-range link and of having that MT distribute it on the short-range links. This leads to an unfair energy consumption for the selected MT. Thus, to ensure fairness in energy consumption, a low complexity utility minimization algorithm is proposed. Using the appropriate utilities, the algorithm can be used to implement the optimal greedy energy minimization solution or to ensure different degrees of fairness in energy consumption. Practical constraints concerning the centralised and distributed implementations of the proposed algorithm are also discussed. Simulation results show that significant energy savings can be achieved with the proposed approach compared with the non-collaborative case. In addition, a tradeoff between fairness and energy savings is achieved depending on the utility selectedPublishedN/
Reduced feedback load using user selection algorithms for the multiuser multi-input single-output systems

Locate full-text(opens in a new window)|Full Text(opens in a new window)|View at Publisher| 
Export
 | Download  | Add to List  | More...
Transactions on emerging telecommunications technologies
Volume 24, Issue 7-8, November-December 2013, Pages 809-819
Reduced feedback load using user selection algorithms for the multiuser multi-input single-output systems  (Article)
Khanfir, H.a ,  Le Ruyet, D.a,  Özbek, B.b  
a  Electronics and Communications Laboratory, CNAM, 292 Rue Saint Martin, 75141, Paris, France 
b  Electrical and Electronics Engineering Department, Izmir Institute of Technology, Urla, 35430, Izmir, Turkey 
View references (27)
Abstract
For wireless multiuser multi-input single-output communication systems with adaptive scheduling and precoding, the users have to feed back their channel state information. However, the amount of feedback data increases with the number of users and the number of transmit antennas. In this paper, we propose a criterion based on the orthogonality between the users' channels to reduce this uplink load. Without cooperation between the users, we only allow users that are semi-orthogonal to feed back their quantized channel information to the base station. We propose a lower bound on the sum rate for the proposed criterion. We show that the performance is almost independent of the number of quantized channel quality information and only channel direction information is important at the transmitter. Then, we consider a noisy feedback channel and propose an algorithm to reduce the noise effect on the analogue feedbac
Bound-based spectrum allocation for cooperative positioning

This paper discusses the performance of distributed and centralised cooperative positioning system for multiple mobile terminals. A cooperative positioning system uses ranging between base stations and mobile terminals, and in addition exploits the links between the mobile terminals as well. However, the number of links in an all-to-all connected setup increases quadratically with the number of nodes. Our goal is to schedule the access for the available resources (used bandwidth) to track the nodes of a dynamic system. Therefore, it is essential to reason if the different links between the mobile terminals are useful. The reasoning assists in allocating resources properly. We investigate distributed algorithms that act based on the Cramér–Rao Lower Bound. We use as benchmark a centralised and much more complex algorithm that requires all link information and we ignore any latency aspects. The results show that our distributed algorithm using limited information performs well
Correlation between traffic granularity and defragmentation periodicity in elastic optical networks

While elastic optical network technologies have emerged as promising solutions for future ultra-high-speed optical transmission, the unavoidable spectral fragmentation problem that appears in such networks significantly degrades their performance. In light of this, spectral defragmentation technologies have been introduced in elastic optical networks, aiming to increase the spectrum utilisation. During the defragmentation operation, the available fragmented spectrum bands are consolidated by reallocating existing connections, either re-routing them along alternative routes and/or re-tuning them onto different spectrum portions. Obviously, spectral defragmentation increases network complexity and cost. Therefore, it is highly desirable to limit its application as much as possible, while keeping network performance within acceptable margins. In this paper, we focus on analyzing the correlation between the optimal (i.e. minimum) spectrum defragmentation periodicity in the network with the granularity of the supported traffic. For this purpose, we initially introduce a novel algorithm for efficient spectrum defragmentation. The proposed algorithm aims to consolidate the available fibre spectrum as much as possible, while limiting the number of reallocated active connections. Then, supported on extensive simulation results, we show how spectral defragmentation periodicity can be effectively configured by having knowledge of the offered traffic granularity.Peer ReviewedPostprint (author's final draft
Self Organising Cloud cells: A Resource Efficient Network Densification Strategy

Network densification is envisioned as the key enabler for 2020 vision that requires cellular systems to grow in capacity by hundreds of times to cope with unprecedented traffic growth trends being witnessed since advent of broadband on the move. However, increased energy consumption and complex mobility management associated with network densifications remain as the two main challenges to be addressed before further network densification can be exploited on a wide scale. In the wake of these challenges, this paper proposes and evaluates a novel dense network deployment strategy for increasing the capacity of future cellular systems without sacrificing energy efficiency and compromising mobility performance. Our deployment architecture consists of smart small cells, called cloud nodes, which provide data coverage to individual users on a demand bases while taking into account the spatial and temporal dynamics of user mobility and traffic. The decision to activate the cloud nodes, such that certain performance objectives at system level are targeted, is carried out by the overlaying macrocell based on a fuzzy-logic framework. We also compare the proposed architecture with conventional macrocell only deployment and pure microcell-based dense deployment in terms of blocking probability, handover probability and energy efficiency and discuss and quantify the trade-offs therei
Interference management in LTE-based HetNets: a practical approach

This is the peer reviewed version of the following article: [Font-Bach, O., Bartzoudis N., Pascual-Iserte, A., Payaró M., Blanco L., López Bueno D., and Molina M. (2015) Interference management in LTE-based HetNets: a practical approach, Trans. Emerging Tel. Tech., 26, 195–215, doi: 10.1002/ett.2833.], which has been published in final form at [http://onlinelibrary.wiley.com/doi/10.1002/ett.2833/epdf]. This article may be used for non-commercial purposes in accordance with Wiley Terms and Conditions for Self-Archiving.Interference is a major obstacle in radio communications, especially when opportunistic frequency reuse is an inherent\ud
requirement for maximising spectral ef¿ciency in heterogeneous networks. A typical example is encountered in cellular\ud
communications where macrocell-edge users receive interference from small cell transmissions that use the same radio\ud
frequency band. Innovating interference management algorithms are employed towards this end, which because of their\ud
interdependencies with numerous parameters of the target operating scenario and various low-level implementation\ud
aspects, need to be prototyped in real-time signal processing platforms in order to be credibly veri¿ed. In this paper, we\ud
present the development and experimental validation of a macrocell/femtocell coexistence scenario in close to real-life\ud
conditions. The inclusion of an agile interference management scheme increased the signal processing complexity at\ud
the physical layer. This overhead was appropriately addressed by engaging advanced parallel processing techniques,\ud
optimisations of the arithmetic operations and intelligent reuse of logic and memory resources in the ¿eld programmable\ud
gate array (FPGA)-based baseband processing architecturePeer ReviewedPostprint (author's final draft
Dynamic frame aggregation scheduler for multimedia applications in IEEE 802.11n networks

International audienceProviding Quality of Service (QoS) to real time applications over Wireless Local Area Networks (WLANs) is becoming a very challenging task due to the diversity of multimedia applications. Concurrently, there are numerous WLANs devices that are rising recently. Mainly, we focus on IEEE 802.11n since it was designed to support a high data transmission rate (toward 600 Mbps) based on frame aggregation schemes. The aggregation mechanism accumulates many frames before transmitting them into a single larger frame, thus reducing overhead and increasing efficiency and throughput. Yet, this scheme cannot provide QoS satisfaction for delay sensitive application even if it supports higher throughputs. Indeed, aggregation headers cause supplementary delays particularly when aggregating unfrequent packets with small sizes. To overcome this limitation, we propose in this paper a new Dynamic Frame Aggregation (DFA) scheduler to provide QoS satisfaction to real time services. To achieve this goal, we defined new scheduling parameters such as QoS delays to avoid accumulation of non-scheduled packets. Hence, the DFA scheduler serves packets and dynamically adjusts the aggregated frame size based on these QoS delays. Conducted simulations illustrate the performance of our proposed DFA scheduler in term of satisfying QoS, throughput, loss and delay requirements of voice and video traffics
Cubic spline extrapolation for uplink channel quality prediction in LTE-A with carrier aggregation

This is the peer reviewed version of the following article: Lema, M. A., García-Lozano, M., and Ruiz, S. (2015), Cubic spline extrapolation for uplink channel quality prediction in LTE-A with carrier aggregation. Trans. Emerging Tel. Tech., doi: 10.1002/ett.2950., which has been published in final form at http://onlinelibrary.wiley.com/doi/10.1002/ett.2950/epdf. This article may be used for non-commercial purposes in accordance with Wiley Terms and Conditions for Self-Archiving.In the context of wireless communications, an accurate channel state information is the key to a correct radio resource management. In the uplink of long-term evolution advanced, obtaining up-to-date channel state information relies on user equipments that send sounding signals throughout the available bandwidth. This procedure is quite challenging when considering the ever increasing bandwidth demands and the introduction of carrier aggregation. Information from many radio resource blocks becomes outdated and unreliable for scheduling operations. Besides, interference values are much more variant than in the downlink due to changes in the position of interferers and their transmission power. This work proposes the introduction of a cubic spline extrapolation method to obtain a prediction horizon that allows extending the reliability of the channel quality evaluation along time. Although very high interference levels and variations thereof imply no gains, the mechanism succeeds with moderate interference, situation that can be provided by interference cancellation strategies.Peer ReviewedPostprint (author's final draft
Maximum Likelihood TOA and OTDOA Estimation with First Arriving Path Detection for 3GPP LTE System

The US Federal Communications Commission (FCC) has mandated wireless network operators and mobile devices to provide accurate location information for E-911. Requirements for time of arrival (TOA) and time difference of arrival (TDOA) measurements have been specified in 3GPP LTE Rel. 9 to ensure accurate user equipment (UE) positioning even under bad conditions (e.g. with channel quickly varying and SNR being as low as −13 dB). To fulfil these requirements, it is vital to accurately estimate the first signal arriving path. In this work, we first derive - without any approximation - the Cramér–Rao lower bound (CRLB) of the LTE TOA and TDOA measurements based on the different pilots, which is shown to be as low as a few metres for SNR = −13 dB. The achievable performance of the LTE system is compared with the FCC and 3GPP requirements, and the impact of mobile multipath channels on the measurements is analysed. Then, we describe practical low-complexity methods for LTE TOA and TDOA measurements with enhanced first arriving path detection. The maximum likelihood based correlation profile is used as detection metric. After grossly determining the signal region by a moving window, three methods, namely, peak detection, SNR-based threshold and adaptive threshold based on noise floor and metric peak value are employed to estimate the first arriving path. Simulation results show that the proposed adaptive threshold-based method can meet all 3GPP requirements under various realistic mobile channels, and can in some cases achieve a performance close to the CRLB
Scalability study of backhaul capacity sensitive network selection scheme in LTE-wifi HetNet

Wireless Heterogeneous Network (HetNet) with small cells presents a new backhauling challenge which differs from those of experienced by conventional macro-cells. In practice, the choice of backhaul technology for these small cells whether fiber, xDSL, point–to-point and point-to-multipoint wireless, or multi-hop/mesh networks, is often governed by availability and cost, and not by required capacity. Therefore, the resulting backhaul capacity of the small cells in HetNet is likely to be non-uniform due to the mixture of backhaul technologies adopted. In such an environment, a question then arises whether a network selection strategy that considers the small cells’ backhaul capacity will improve the end users’ usage experience. In this paper, a novel Dynamic Backhaul Capacity Sensitive (DyBaCS) network selection schemes (NSS) is proposed and compared with two commonly used network NSSs, namely WiFi First (WF) and Physical Data Rate (PDR) in an LTE-WiFi HetNet environment. The proposed scheme is evaluated in terms of average connection or user throughput1and fairness among users. The effects of varying WiFi backhaul capacity (uniform and non-uniform distribution), WiFi-LTE coverage ratio, user density and WiFi access points (APs) density within the HetNet form the focus of this paper. Results show that the DyBaCS scheme generally provides superior fairness and user throughput performance across the range of backhaul capacity considered. Besides, DyBaCS is able to scale much better than WF and PDR across different user and WiFi densities
Inter-Layer Per-Mobile Optimization of Cloud Mobile Computing: A
  Message-Passing Approach

Cloud mobile computing enables the offloading of computation-intensive
applications from a mobile device to a cloud processor via a wireless
interface. In light of the strong interplay between offloading decisions at the
application layer and physical-layer parameters, which determine the energy and
latency associated with the mobile-cloud communication, this paper investigates
the inter-layer optimization of fine-grained task offloading across both
layers. In prior art, this problem was formulated, under a serial
implementation of processing and communication, as a mixed integer program,
entailing a complexity that is exponential in the number of tasks. In this
work, instead, algorithmic solutions are proposed that leverage the structure
of the call graphs of typical applications by means of message passing on the
call graph, under both serial and parallel implementations of processing and
communication. For call trees, the proposed solutions have a linear complexity
in the number of tasks, and efficient extensions are presented for more general
call graphs that include "map" and "reduce"-type tasks. Moreover, the proposed
schemes are optimal for the serial implementation, and provide principled
heuristics for the parallel implementation. Extensive numerical results yield
insights into the impact of inter-layer optimization and on the comparison of
the two implementations.Comment: submitte
Optimal energy allocation policies for a high altitude flying wireless access point

Inspired by recent industrial efforts towards high altitude flying wireless access points powered by renewable energy, an online resource allocation problem for a mobile access point travelling at high altitude is formulated. The access point allocates its resources (available energy) to maximise the total utility (reward) provided to a sequentially observed set of users demanding service. The problem is formulated as a 0/1 dynamic knapsack problem with incremental capacity over a finite time horizon, and the solution of which is quite open in the literature. We address the problem through deterministic and stochastic formulations followed by a model where the statistics of the underlying processes are not known and learned through rule-based and neural network approaches. For the deterministic problem, several online approximations including optimisation via genetic algorithm and rule-based approach are proposed based on an instantaneous threshold that can adapt to short-time-scale dynamics. For the stochastic model, after showing the optimality of a threshold-based solution on a dynamic programming formulation, an approximate threshold-based policy is obtained. The performances of proposed policies are compared with that of the optimal solution obtained through dynamic programming
Quality of service provision and capacity expansion through extended-DSA for 5G

5G systems are expected to advance on a number of aspects compared with current systems, for example, providing a 1000 times higher capacity, a much lower latency and improved quality of user experience. This paper presents the vision and approach followed by the H2020 project SPEED-5G. The approach is based on densification of small cells, exploitation of Multi-RAT, development of new resource management techniques and a more efficient use of spectrum. A novel 5G system architecture is proposed based on the Network Slicing paradigm, which enables a highly flexible, scalable and backwards compatible architecture. A core aspect is the definition of a new MAC layer that facilitates Multi-RAT access and allows prioritising and allocating traffic across heterogeneous access technologies