Apart from the the increasing demand of smartphones in human-to-human (H2H) communications, the introduction of machine-to-machine (M2M) devices poses significant challenges to wireless cellular networks. In order to offer the ability to connect billion of devices to propel the society into a new era of connectivity in our homes, officies and smart cities, we design novel radio resource sharing algorithms in a H2H/M2M coexistence case to accommodate M2M communications while not severely degrading existing H2H services. We propose group-based M2M communications that share the same spectrum with H2H communications through device-to-device (D2D) communication, as one of the technology components of 5G architecture. First, we formulate radio resource sharing problem as a sum-rate maximization, problem for which the optimal solution is non-deterministic polynomial-time hard (NP-hard). To overcome the computational complexity of the optimal solution, we model the resource sharing problem as a bipartite graph, then propose a novel interference-aware graph-based resource sharing scheme using a fixed M2M transmit power. To further enhance the protection of H2H services, we introduce an adaptive power control mechanism into the interference-aware graph-based resource sharing scheme. M2M transmit power is efficiently adjusted using one among the two following alternative controllers, namely, either the proportional integral derivative (PID) or the fuzzy logic. The latter is proposed within the aim to assure the desired quality-of-service (QoS) of H2H users and increase the efficiency of M2M spectrum usage. In both cases (fixed and adaptive), a centralized and a semi-distributed instantiations are given. Simulation results show that adaptive M2M radio resource sharing scheme using fuzzy logic is the one that achieves the best compromise. In fact, it guarantees H2H performance in terms of throughput and fairness while maximizing the efficiency of M2M spectrum usage. Simulation results also show that in spite of its quite good performance, semi-distributed M2M resource sharing instantiation achieves them with a decline of up to 10% in terms of H2H throughput compared to the centralized instantiation. This is achieved through a markedly lower communication overhead.
Evaluation of the parameters affecting the shear strength and ductility of steel–concrete composite beam is the goal of this study. This study focuses on predicting the future output of beam’s strength and ductility based on relative inputs using a soft computing scheme, extreme learning machine (ELM). Estimation and prediction results of the ELM models were compared with genetic programming (GP) and artificial neural networks (ANNs) models. Referring to the experimental results, as opposed to the GP and ANN methods, the ELM approach enhanced generalization ability and predictive accuracy. Moreover, achieved results indicated that the developed ELM models can be used with confidence for further work on formulating novel model predictive strategy in shear strength and ductility of steel concrete composite. Furthermore, the experimental results indicate that on the whole, the newflanged algorithm creates good generalization presentation. In comparison to the other widely used conventional learning algorithms, the ELM has a much faster learning ability. 相似文献
In orthogonal frequency division multiplexing (OFDM) system, high value of peak-to-average power ratio (PAPR) is an operational problem that may cause non-linear distortion resulting in high bit error rate. Selected mapping (SLM) is a well known technique that shows good PAPR reduction capability but inflicts added computational overhead. In this paper, using Riemann sequence based SLM method, we applied reverse searching technique to find out low PAPR yielding phase sequences with significant reduction in computational complexity. Additionally, we explored side-information free transmission that achieves higher throughput but sacrifices PAPR reduction. Finally, to overcome this loss in PAPR reduction, we proposed application of Square-rooting companding technique over the output OFDM transmitted signal. Simulation results show that the proposed method is able to compensate the sacrifice in PAPR and achieved PAPR reduction of 8.9 dB with very low computational overhead. 相似文献
We have investigated the structural, magnetic, and electrical transport properties of a series of ABO3-type perovskite compounds, La0.67Sr0.33Mn1?xVxO3 (0≤x≤0.15). The samples were characterized by X-ray diffraction and data were analyzed using Rietveld refinement technique, it has been concluded that these materials have the rhombohedral structure with $\mathrm{R}\overline{3}\mathrm{C}$ space group. The magnetization and resistivity measurements versus temperature proved that all our samples exhibit a ferromagnetic to paramagnetic transition and a metallic to semiconductor one when the temperature increases. Both the Curie temperature TC and the resistivity transition temperature TP of the composites decrease, while the resistance increases as the V content increases. It has been concluded that the electrical conduction mechanism in the metallic regime at low temperatures (T<TP) can be explained on the basis of grain boundary effects and the single electron-magnon scattering process. Resistivity data were well fitted with the relation ρ=ρ0+ρ2T2+ρ4.5T4.5, whereas the adiabatic Small Polaron Hopping (SPH) and Variable Range Hopping (VRH) models are found to fit well in the paramagnetic semiconducting regime at the high temperature (T>TP). 相似文献
A new nano-flower lead(II) azido coordination polymer from the ligand, orthophenanthroline (o-phen), [Pb(o-phen)(μ1,1-N3)(μ1,3-N3)]n (1), was synthesized by a sonochemical method. Compound 1 was characterized by scanning electron microscopy (SEM), X-ray diffraction (XRD), elemental analyses and IR spectroscopy. Single crystalline material was obtained using a heat gradient applied to a solution of the reagents. The structure of 1 is a coordination polymer of lead(II) containing the Pb-(μ1,1-N3)(μ1,3-N3) motif, formed of one-dimensional chains. The structure of the 1 was optimized by density functional theory. Structural parameters and IR spectra for 1 are consistent with the crystal structure. Pure phase PbO nanoparticles were obtained by thermolysis of 1 with oleic acid as a surfactant at 180 and 200 °C an air. PbO nanoparticles were characterized by XRD and SEM. 相似文献
Routing protocols are the binding force in mobile ad hoc network (MANETs) since they facilitate communication beyond the wireless
transmission range of the nodes. However, the infrastructure-less, pervasive, and distributed nature of MANETs renders them
vulnerable to security threats. In this paper, we propose a novel cluster-based trust-aware routing protocol (CBTRP) for MANETs
to protect forwarded packets from intermediary malicious nodes. The proposed protocol organizes the network into one-hop disjoint
clusters then elects the most qualified and trustworthy nodes to play the role of cluster-heads that are responsible for handling
all the routing activities. The proposed CBTRP continuously ensures the trustworthiness of cluster-heads by replacing them
as soon as they become malicious and can dynamically update the packet path to avoid malicious routes. We have implemented
and simulated the proposed protocol then evaluated its performance compared to the clustered based routing protocol (CBRP)
as well as the 2ACK approach. Comparisons and analysis have shown the effectiveness of our proposed scheme. 相似文献