State-of-Art and Open Issues of Cross-Layer Design and QOS Routing in Internet of Vehicles

VANET (Vehicular Ad Hoc Network) is a significant term in ITS (intelligent transportation systems). VANETs are also mentioned as ITN (intelligent transportation Networks), which are used to enhance road safety in growing technology. The connectivity of nodes is a challenging one because of its high mobility and the sparse network connectivity must be handled properly during its initial deployment of a VANET for avoiding accidents. Quality of service (QoS) in VANET becomes a significant term because of its increasing dare about unique features, like poor link quality, high mobility, and inadequate transporting distance. Routing is the foremost issue in the wireless ad hoc network, which is used to transmit data packets significantly. This paper provides a crucial review of the classification of existing QoS routing protocols, cross-layer design approach and classification, and various performance parameters used in QoS routing protocols. The corresponding cross-layer protocols are overviewed, followed by the major techniques in cross-layer protocol design. Moreover, VANET is presented with many exclusive networking research challenges in precise areas such as security, QoS, mobility, effective channel utilization, and scalability. Finally, the paper concluded by various comparison discussion, issues, and challenges of several routing protocols for VANET. No. of publications over the period from 2010 to 2019 in various scientific sources also showed in this review. This survey provided the technical direction for researchers on routing protocols for VANET using QoS.

     

Structural and Magnetic Studies of Cu-Substituted Nanocrystalline Ni–Zn Ferrites Obtained Via Hexamine–Nitrate Combustion Route

Ni\({}_{0.6 -_x}\)Cu _x Zn_0.4Fe₂ O ₄ ferrite compositions with x = 0.1, 0.2, 0.3, 0.5, and 0.6 were synthesized by a hexamine–nitrate combustion route. The phase purity and nanocrystalline nature was confirmed from XRD studies. The structural parameters such as lattice constant, X-ray density, bulk density, and porosity were calculated and compared for the effect of Cu inclusion in Ni–Zn ferrites. The lattice constant, X-ray density, and bulk density increase while the porosity exhibits a decreasing trend with increasing copper content. The FTIR spectra display two characteristic bands in the region 574–548 and 421–395 cm^?1 assigned to M–O stretching vibrations in tetrahedral and octahedral sites, respectively. The AC susceptibility studies indicate the presence of superparamagnetic as well as single-domain particles and the decrease in Curie temperature with Cu substitution. The saturation magnetization, remanence, and coercivity were found to decrease with increasing Cu concentration and attributed to the lower magnetic moment of Cu ions than Ni ions.     

Characterization of Nano-Particle Co<Subscript>1−<Emphasis Type="Italic">x</Emphasis></Subscript>Zn<Subscript><Emphasis Type="Italic">x</Emphasis></Subscript>Fe<Subscript>2</Subscript>O<Subscript>4</Subscript> Synthesized Using Alove Vera Gel

Nano-particle Co_1?x Zn _x Fe₂O₄ (x = 0.0, 0.3, 0.5, 0.7, and 1.0) samples were prepared via combustion route using Alove Vera Gel. XRD, IR, and SAED analysis represents single-phase formation of ferrite samples, and nano-sizes of the particles in the range of 6 to 13 nm were confirmed using XRD data and TEM images. Decrease in lattice constant with increasing Zn content reflects formation of compositionally homogeneous samples. Dielectric constant and dielectric loss study showed promising results. The room temperature Mossbauer spectrum showed mixed superparamagnetic and ordered ferromagnetic behavior. The possible modification in the cation distributions was seen in the nano-particle ZnFe₂O₄ sample obtained in the present work compared to conventional bulk samples.     

Size variation and magnetic dilution effects on the structure and magnetic properties of cobalt zinc ferrite

Nanocrystalline cobalt zinc ferrites Co_1?xZn_xFe₂O₄ (x?=?0.0, 0.2, 0.4, 0.5, 0.6, 0.8, 1.0), have been prepared by employing a precursor combustion method via decomposition of the metal carboxylato hydrazinate precursors. This synthesis technique yields nanoparticles with particle size between 12 and 15 nm as determined from transmission electron microscopy (TEM) studies. The nanoferrites were then sintered at 1000 °C for 15 h to obtain micrometer size ‘bulk’ ferrites in the range of 0.3–0.8 μm. X-ray diffraction (XRD) and Fourier transform infrared (FTIR) Spectroscopy confirmed the formation of the mixed ferrites without any impurities. Addition of non-magnetic ion like Zn²⁺ into the crystal structure of cobalt ferrite leads to a prominent change in the size, structure and properties. The saturation magnetization values (M_S) increases upto x?=?0.4 and then decreases with further increase in Zn concentration. A maximum M_S value of 90.85 emu/g and 79.59 emu/g for x?=?0.4 was obtained for the sintered and nanoferrite sample, respectively. The lower M_S and higher coercivity (H_C) values for nanoferrites than the sintered ferrites exhibited a strong dependence on the particle size due to the cation distribution and surface effects. The Curie temperature (T_C) was found to decrease appreciably with the reduction in particle size and with increasing concentration of Zn. The room temperature Mössbauer spectra showed a transition from ferrimagnetic to a paramagnetic state with increasing zinc concentration along with superparamagnetic features which was in corroboration with VSM studies.