Bit-error-rate Optimization for CDMA Ultra-wideband System Using Generalized Gaussian Approach

Ultra-wideband is a wireless technology arisen for future high speed multimedia applications. It can provide data rate in excess of Gigabits per second by transmitting impulse signal through the free space. However, the ultra-wideband indoor channel models proposed by the IEEE P802.15.3a suffer long multipath propagation. Due to this multipath effect, several studies have been done to improve the bit-error-rate performance of the ultra-wideband system in the existence of severe interference. Yet, most of the proposed algorithms were formulated based on the Gaussian distribution, which is not true in ultra-wideband. In this paper, we first analyze the statistical behavior of the CDMA-UWB signal by applying the Kullback-Leibler divergence index. Based on the analysis, a non-Gaussian equalizer is developed by deriving an enhanced bit-error-rate optimization algorithm using the Generalized Gaussian approach. The proposed equalizer has been shown to achieve a performance gain of at least 1.5dB to 2dB over the other equalizers simulated under IEEE P802.15.3a channel models

Multimode HMSIW-based bandpass filter with improved selectivity for fifth-generation (5G) RF front-ends

This article presents the detailed theoretical, simulation, and experimental analysis of a half-mode substrate integrated waveguide (HMSIW)-based multimode wideband filter. A third-order, semicircular HMSIW filter is developed in this paper. A semicircular HMSIW cavity resonator is adopted to achieve wide band characteristics. A U-shaped slot (acts as a lambda/4 stub) in the center of a semicircular HMSIW cavity resonator and L-shaped open-circuited stubs are used to improve the out-of-band response by generating multiple transmission zeros (TZs) in the stop-band region of the filter. The TZs on either side of the passband can be controlled by adjusting dimensions of a U-shaped slot and L-shaped open-circuited stubs. The proposed filter covers a wide fractional bandwidth, has a lower insertion loss value, and has multiple TZs (which improves the selectivity). The simulated response of filter agrees well with the measured data. The proposed HMSIW bandpass filter can be integrated with any planar wideband communication system circuit, thanks to its planar structure.This work is partially supported by RTI2018-095499-B-C31, funded by Ministerio de Ciencia, Innovacion y Universidades, Gobierno de Espana (MCIU/AEI/FEDER, UE)

Design and performance evaluation of a novel broadband THz modulator based on graphene metamaterial for emerging applications

Introduction: Metamaterials consist of periodic arrangements of artificial subwavelength units that possess electromagnetic properties not present in natural media. It has attracted more interest due to its ability to alter electromagnetic radiation in a flexible manner, which has resulted in the development of multiple radio frequency devices based on metamaterials. Metamaterials with the required frequency band for electric or magnetic resonance can be made using unit cell structure. The incident electromagnetic wave will enter the metamaterials and be kept there in the absence of reflection.Methods: This paper proposes a novel broadband THz absorber filter based on graphene for emerging applications. The proposed structure comprised of three parts. The top layer consists of graphene, the middle layer consists of dielectric and the bottom layer is made up of gold.Results: The proposed structure is experimentally designed and validated using the COMSOL simulator.Discussion: Simulation results show that the proposed absorber has better performance as compared with existing methods

Near field UHF RFID tag antenna backed by a conducting loop reflector

A novel UHF printed loop antenna backed by a conducting loop reflector is proposed for near field RFID tag antenna application. The backed conducting loop reflector is adopted to achieve stronger magnetic field distribution along the loop tag antenna in order to work properly in proximity to the water and metallic object. The proposed antenna is constructed on FR4 substrate with the dimension of 30 mm × 30 mm × 3.2 mm. The simulated results exhibit constant current and uniform magnetic distribution to operate frequency at 915 MHz. The near field performance of the proposed antenna is practically verified by the read range measurement and compared with the commercially-available near field tag antenna to offer a promising solution of above-mentioned problems

A Survey of Handover Management in Mobile HetNets: Current Challenges and Future Directions

: With the rapid growth of data traffic and mobile devices, it is imperative to provide reliable and stable services during mobility. Heterogeneous Networks (HetNets) and dense networks have been identified as potential solutions to address the upcoming capacity crunch, but they also pose significant challenges related to handover optimization. This paper presents a comprehensive review of recent handover decision algorithms in HetNets, categorizing them based on their decision techniques and summarizing their input parameters, techniques, and performance evaluations. Our study highlights the technical challenges and opportunities related to handovers in HetNets and dense cellular networks and provides key findings from recent studies. The significance of this survey is to provide a comprehensive overview of handover decision algorithms in HetNets and dense cellular networks, which can aid in the development of more advanced handover optimization approaches

Wideband Half Mode Substrate Integrated Waveguide (HMSIW) Bandpass Filter

A higher-order wideband multimode filter is proposed in this paper. The proposed filter is designed using a half-mode substrate integrated waveguide (HMSIW) technology. A wideband frequency response is achieved by exciting multiple modes in the same cavity resonator. A U-shaped slot and hook-shaped open circuited stubs are added to the HMSIW resonator to generate the transmission zeros (TZs) and hence increase the selectivity. The filters with high-selectivity a realways desirable in highly-sensitive radio frequency (RF) circuits. The proposed filter shows wide passband (FBW = 69.31%), lower insertion loss (IL <; 0.9 dB) and good selectivity

Design of an Efficient Hybrid RF Solar Energy Harvesting System for Wireless Power Communication

This project proposes a hybrid RF solar energy harvesting system to scavenge ambient RF signals at GSM 900 and solar energy from sunlight to supply energy for low power devices. This solution aims to overcome the limited lifetime of battery operated devices such as WSN nodes and IoT microconcontrollers by providing an environmental friendly and sustainable hybrid RF solar energy harvesting system. The system proposed brings about the complementary benefits of the RF energy harvester and the solar energy harvester. The hybrid RF energy harvester is made up of a RF energy harvester and a solar energy harvester. A two element microstrip patch antenna was designed and simulated using CST whereas the RF energy harvesting circuit was designed and simulated using PathWave ADS before fabrication and experimental testing. It consists of a voltage doubler rectifier, a single stub impedance matching network, and a low pass filter. Besides, the solar energy harvester was designed using EasyEDA software before fabrication and testing. The solar energy harvester encompasses a 3 W monocrystalline solar panel, a solar charger module with Maximum Power Point Tracking (MPPT) a Lithium rechargeable battery, a battery protection Integrated Circuit (IC) and a DC-DC converter. The hybrid energy harvester in this project achieved a peak power conversion efficiency of 81 39 with a total of 2 3604 W output power

A Survey on 5G Coverage Improvement Techniques: Issues and Future Challenges

Fifth generation (5G) is a recent wireless communication technology in mobile networks. The key parameters of 5G are enhanced coverage, ultra reliable low latency, high data rates, massive connectivity and better support to mobility. Enhanced coverage is one of the major issues in the 5G and beyond 5G networks, which will be affecting the overall system performance and end user experience. The increasing number of base stations may increase the coverage but it leads to interference between the cell edge users, which in turn impacts the coverage. Therefore, enhanced coverage is one of the future challenging issues in cellular networks. In this survey, coverage enhancement techniques are explored to improve the overall system performance, throughput, coverage capacity, spectral efficiency, outage probability, data rates, and latency. The main aim of this article is to highlight the recent developments and deployments made towards the enhanced network coverage and to discuss its future research challenges

A novel microstrip antenna loaded with EBG and ELC for bandwidth enhancement

This paper proposes the design of three compact antennas for WiMAX, WLAN and ISM band applications. Antenna 1 consists of a monopole radiating element with an electromagnetic band gap (EBG) structured ground. By employing the EBG structure, an ultra-wide band frequency of 2.4-4.8 GHz (66.66%) is achieved. Antenna 2 is configured with an electric-LC (ELC) element, which achieved an ultra-wide band (UWB) frequency of 2.38-4.91 GHz (69.41%). Antenna 3 is integrated with ELC and EBG together, in which a UWB frequency of 2.3-5.3 GHz (78.94%) is obtained with improved impedance matching. The three antennas have omnidirectional radiation patterns which cover the ISM band at 2.4 GHz and WiMAX at 2.5/3.5 GHz over the operating bands. The radiation efficiency is > 75% throughout the operating bands of all the antennas. In addition to the WiMAX and ISM bands, antenna 3 covers WLAN in the 5.2 GHz band. The proposed design can be applied to wireless mobile communication systems, which have the advantage of ease of fabrication and compactness

Wideband L-probe circular patch antenna for dual-frequency RFID application

In this article, a new high-gain wideband L-probe proximity-fed circular patch antenna using electrically thick substrate is proposed. By employing a dual-patch microstrip antenna excited by two L-probes, the bandwidths requirement for the ultrahigh frequency (UHF) and microwave radio frequency identification (RFID) application are met. The antennas integrated with slot-loading techniques are extensively studied. It is demonstrated that the proposed antenna achieves widebands of UHF and microwave for RFID application. A good agreement is obtained between the computed and measured results. (c) 2014 Wiley Periodicals, Inc. Microwave Opt Technol Lett 56:1421-1424, 201