Search results for " Allocation"

Wireless sensor network for Spectrum Cartography based on Kriging interpolation

2012

Dynamic spectrum access with Cognitive Radio (CR) network is a promising approach to increase the efficiency of spectrum usage. To allow the optimization of resource allocation and transmission adaptation techniques, each CR terminal needs to acquire awareness of the state of the time-frequency-location varying radio spectrum. In this paper we present a Spectrum Cartography (SC) approach where CR terminals are supported by a fixed wireless sensor network (WSN) to estimate and update the Power Spectral Density (PSD) over the area of interest. The wireless sensors collaborate to estimate the spatial distribution of the received power at a given frequency using either a centralized or a distri…

MDP-based Resource Allocation for Uplink Grant-free Transmissions in 5G New Radio

2020

The diversity of application scenarios in 5G mobile communication networks calls for innovative initial access schemes beyond traditional grant-based approaches. As a novel concept for facilitating small packet transmission and achieving ultra-low latency, grant-free communication is attracting lots of interests in the research community and standardization bodies. However, when a network consists of both grant based and grant-free based end devices, how to allocate slot resources properly between these two categories of devices remains as an unanswered question. In this paper, we propose a Markov decision process based scheme which dynamically allocates grant-free resources based on a spec…

Analysis of interference avoidance with load balancing in heterogeneous cellular networks

2016

In heterogeneous cellular networks (HCNets) smallcells are overlaid with macro-cells to handle heavy cellular data traffic in an efficient way. To achieve fast and reliable access to data with a better coverage it is necessary to offload users to the underutilized small-cells from the congested macro-cells. Sharing of the same licensed frequency spectrum by smallcells and macro-cells results in heavy cross-tier interference which significantly affects the downlink SINR. In this paper, we investigate and analyze a joint frequency-division duplex based cross-tier complementary spectrum sharing technique which is also regarded as reverse frequency allocation (RFA) scheme with load balancing. T…

Kalman filter estimation of the contention dynamics in error-prone IEEE 802.11 networks

2008

In the last years, several strategies for maximizing the throughput performance of IEEE 802.11 networks have been proposed in literature. Specifically, it has been shown that optimizations are possible both at the medium access control (MAC) layer, and at the physical (PHY) layer. In fact, at the MAC layer, it is possible to minimize the channel wastes due to collisions and backoff expiration times, by tuning the minimum contention window as a function of the number n of competing stations. At the PHY layer, it is possible to improve the transmission robustness, by selecting a suitable modulation/coding scheme as a function of the channel quality perceived by the stations. However, the feas…

Energy-Efficient M2M Communications in for Industrial Automation

2020

M2M communication with autonomous data acquisition and exchange plays a key role in realizing the “control”-oriented tactile Internet (TI) applications such as industrial automation. In this chapter, we develop a two-stage access control and resource allocation algorithm. In the first stage, we introduce a contract-based incentive mechanism to motivate some delay-tolerant machine-type communication (MTC) devices to postpone their access demands in exchange for higher access opportunities. In the second stage, a long-term cross-layer online resource allocation approach is based on Lyapunov optimization, which jointly optimizes rate control, power allocation, and channel selection without pri…

Accuracy and the role of experience in dynamic computer guided dental implant surgery: an in-vitro study

2019

Background To compare the accuracy of implant placement using the conventional freehand method and a dynamic navigation system; to assess the role of the surgeon’s experience in implant placement using these two methods. Material and Methods A randomized in-vitrostudy was conducted. Six resin mandible models and 36 implants were used. Two researchers with differing clinical experience (novice and experienced) placed implants using either the Navident dynamic navigation system (navigation group) or the conventional freehand method (freehand group). Accuracy was measured by overlaying the real position in the postoperative CBCT on the virtual presurgical placement of the implant in a CBCT ima…

Sensor networks for cognitive radio : theory and system design

2008

Further Investigation of Harmonic Priming in Long Contexts Using Musical Timbre as Surface Marker to Control for Temporal Effects

2004

Harmonic priming studies have reported facilitated processing for chords that are harmonically related to the prime context. Responses to the target (the last chord of an 8-chord sequence) were faster and more accurate when the target was strongly related, i.e., a tonic chord, to the preceding prime context than when it was less related, i.e., a subdominant chord. Results have been interpreted in terms of musical expectations and processing speed: the prime allows listeners to develop expectations for future events which lead to facilitated processing of the most strongly expected event. The present experiment investigated an alternative hypothesis suggesting that the harmonic structure of…

Optimal growth and land preservation

1997

A model of optimal economic growth with a constant population subject to a constraint on the availability of land is presented. It takes account of the dual character of land as a production factor and as a consumption good (environmental amenities) by determining the optimal intertemporal allocation of land between productive and recreational uses. An extension of the analysis for the case of a growing population with endogenous growth based on human capital accumulation shows that if the rate of discount is not very low then there exists a set of balanced growth paths compatible with a constant allocation of land. En este trabajo se presenta un modelo de crecimiento económico óptimo con u…

“The Limits” of Economic Growth in Romania

2014

Abstract A sustainable economic growth of GDP of 3-4% annually in Romania for the reduction of gaps in development was considered impossible by most institutions of various skill and opinion leaders, as well as of international financial bodies. The reasons cited were delayed public reforms, low growth potential as a result of the crisis, the overview status of the states in the Eurozone dependent on inside community trade and also the prospects for a lasting economic stagnation, the balance sheet effect, as a result of over indebtedness of firms and individuals that substantially reduced inclination towards investment and consumption. Contradicting these forecasts, in 2013, Romania's econo…