Highly dynamic geographical topology, two-direction mobility, and varying traffic density can lead to fairness issues in Vehicular Ad-hoc Networks (VANETs). The Medium Access Control (MAC) protocol plays a vital role in sharing the common wireless channel efficiently between vehicles in a VANET system. However, ensuring fairness between vehicles can be a challenge in designing MAC protocols for VANET systems. The existing protocol, IEEE 802.11 DCF, ensures that the packet transmission rate for a particular vehicle is directly proportional to the amount of time a vehicle spends within a service area, but it does not guarantee that faster vehicles will be able to send the minimum number of packets. Other existing MAC protocols based on IEEE 802.11 are able to provide a minimum amount of data transmission regardless of velocity, but are unable to provide an amount of data transmission that is more proportionate to the time a vehicle spends in the service area. To address the above limitations, we propose a Speed Aware Fairness Enabled MAC (SAFE-MAC) protocol that calculates the residence time of a vehicle in a service area by using mobility metrics such as position, direction, and speed to synthesize the transmission probability of each individual vehicle with respect to its residence time. This is achieved by dynamically altering the values of parameters such as minimum contention window, maximum backoff stage, and retransmission limit in the MAC protocol. We then develop an analytical model to compare the performance of our proposed protocol with contemporary MAC protocols. Numerical analysis results show that our proposed protocol significantly improves fairness among the speed-varying vehicles in VANET.

This research explains the advancement and characterization of a highly sensitive hexagonal photonic crystal fiber (H-PCF) optical alcohol sensor in the terahertz range, with an emphasis on improving its capabilities using innovative materials and design. In this instance, the PCF’s core is exposed to the analyte’s flow in order to facilitate detection. This newly developed sensor’s sensing capabilities are carefully investigated using perfectly matched layer (PML) boundary conditions and the fully vectoral finite element method (FV-FEM), facilitated by the COMSOL Multiphysics software. According to the results of the FV-FEM numerical analysis, the proposed optical H-PCF sensor exhibited very high relative sensitivities of 90.65 %, 93.20 %, 93.95 %, and 94.42 % for four alcohols at 1.8 terahertz, namely, ethanol (n=1.354), propanol (n=1.387), butanol (n=1.399), and pentanol (n=1.4072) respectively. Moreover, at 1.8 terahertz (THz), the low confinement losses are 2.11×10-9 dB/m, 9.66×10-11 dB/m, 1.044×10-11 dB/m, 2.66×10-11 dB/m and correspondingly, effective material losses are 0.013497 cm-1, 0.01089 cm-1, 0.010087 cm-1, and 0.009588 cm-1 for similar alcohols. Furthermore, this article provides a brief description of the effective area, effective refractive index, and power fraction. Many contemporary technologies can be used to create this suggested sensor. In addition, let’s anticipate that our sensor will work well for applications in the food and medical sectors to determine the amount of alcohol in different kinds of drinks and beverages. It will also be highly effective in biomedical sectors, public health care, industrial settings, material science, nano-optics, and other terahertz waveguide technology communication domains

This work proposes a hollow-core photonic crystal fiber-based edible oil sensor in the terahertz (THz) range (e.g., 1.0THz ≤ f ≤ 3.0THz) and different sensing characteristics are numerically analyzed. The suggested sensor’s performance was assessed by means of COMSOL Multiphysics, a commercial program that uses the finite element approach. The computational results indicate that the relative sensitivity is 85.591%, 84.648%, 82.625%, 82.683%, and 79.161%, respectively, at f = 2.2 THz, for several types of sunflower oil, mustard oil, coconut oil, olive oil and palm oil; and the corresponding effective areas are 7.22×10-8 um2, 7.09×10-8 um2, 6.83×10-8 um2,7.09×10-8 um2, 6.5231 ×10-8 um2. In addition, the effective material loss for sunflower oil, muster oil, coconut oil, olive oil, and palm oil has been found to be 0.02561 cm-1, 0.027054 cm-1, 0.030322 cm-1, 0.028854 cm-1 ,0.035427cm-1 respectively. Moreover, the proposed sensor also has low confinement loss are 1.55×10-8 dB/m, 1.63×10-8 dB/m, 1.31×10-8 dB/m, 1.99×10-8 dB/m, 4.0345×10-8 dB/m.This proposed sensor can be fabricated using extrusion and 3D-printing technologies, and due to its augmented detecting capabilities, it can be a vital part of oil sensing devices implemented in real life such as industry fields.

Minimizing number of forwarding stations is the prime objective of any broadcast protocol of wireless ad-hoc networks. Although existing proactive protocols show better performance than reactive protocols in minimizing number of forwarding stations but these are non-scalable than reactive protocols because proactive protocols use more network overhead (extended neighbor information) and message overhead (appended forward list) which consume more network resources. Timer mechanism based reactive protocols are more scalable than self-pruning and enhance the network performance but these are not more effective due to probabilistic selection of timer value. In this paper, we propose a reactive broadcast protocol named IT-SBA that uses a deterministic selection of timer value and completes the broadcast by less number of forwarding stations in expense of broadcast delay. Simulation results show that IT-SBA outperforms existing reactive protocols viz. flooding, self-pruning, SBA, E-SBA for both sparse and dense networks.