WiMAX System Research Articles

A novel miniaturized antenna with multiple band-notched characteristics for UWB communication applications

ABSTRACTA novel miniaturization planar ultra-wideband antenna with triple-notched bands is proposed. The antenna mainly consists of an elliptical patch, a rectangular split-ring patch with a π-shaped slit and a T-shaped slit, and two small additional patches. Two different type slits are adopted to realize multiple-notched bands and reduce the antenna size. The designed antenna has a small dimension of 17 × 16 × 1.6 mm3. The simulated and measured results show the antenna has a very wide impedance bandwidth of 2.96–19.0 GHz with Return Loss less than −10 dB, except triple notched bands of 3.30–3.72, 5.13–5.82 and 7.04–7.92 GHz, respectively, covering the WiMAX, WLAN and X-band systems. Furthermore, surface current distributions, gain, efficiency, radiation patterns and group delay characteristics of the antenna are also discussed. The results show that the antenna has high radiation efficiency, stable radiation pattern and lower group delay time.

Bin Packing Problems (Promising Models and Examples)

The paper is devoted to the promising bin packing problems and some applications. A system view on the formulation of problems based on a set of elements (objects), a set of containers, and binary relations over the specified sets (precedence, dominance, and correspondence of elements to containers) is suggested. Special versions of packing problems with estimations of elements (objects) based on multisets are described. Examples in communication networks, such as the choice of information messages and two-dimensional packaging of messages in WiMAX systems are also briefly considered.

A new inset-fed UWB printed antenna with triple 3.5/5.5/7.5-GHz band-notched characteristics

A novel low-profile inset-fed ultrawideband printed antenna with triple band-notched characteristics is proposed. Wide inverted U-shaped and crescent-shaped slots are used to achieve first and second notched bands in the 3.3--3.7 GHz and 5.1--5.9 GHz ranges for WiMAX and WLAN systems, respectively. Additionally, an altered ground plane with an open-ended L-shaped slot generated a third notched band in the 7.25--7.85 GHz range for downlink of X-band satellite communication systems. The center frequencies of the stop bands are adjusted by altering the parameters of corresponding slots. The antenna prototype is built on a 28 mm $\times $ 24 mm Rogers RT/duroid 5880 ($\varepsilon_{r}$ = 2.2) substrate over a partial ground plane. Two concave circular curves were deployed on the patch with an inset feeding in order to obtain wideband performance in the 2.5--12 GHz (VSWR $

Optimize Transmission of Image over Integrated Mobile WiMAX and WiLAN Network

The problem of multiuser downlink resource allocation in Mobile WiMAX system was studied. Three different network scenarios considered for the transmission of image data. Resource allocation is done using Active Set Optimization and Genetic Algorithm, for all the three network scenarios. Simulation results show that information fed back and association among subcarriers play vital role to improve system performance. As compared to reduced complexity, resource allocation using Active Set Optimization and Genetic Algorithm seems especially attractive as the number of users increases for Image Data. It is observed through simulation that the System using Genetic Algorithm performs better than Active Set. Linear Resource Allocation in terms of significantly decreasing the computational complexity and achieve higher capacities, while being applicable to a more general class of systems. As Genetic Algorithm follows constraints of Stochastic processes it didn’t give results highest in all Experiment Conducted. It is also observed that for Integer-Binary Objective function Performance of Genetic Algorithm is not that much satisfied because of its stochastic processing. Also processing time required to reach final optimize variables values is too much.

Design of Cyclic Prefix Characteristic-Based OFDM System for WiMAX Technology

Worldwide interoperability for microwave access (WiMAX) offers the wireless connectivity using orthogonal frequency division multiplexing (OFDM) modulation is a proficient wireless technology that capacities high-speed data transmission facilities. The existing WiMAX techniques have the problem of increase in inter-symbol interference (ISI) and bit error rate (BER) at reduced power spectrum that degrades the performance of WiMAX system due to high data rate transmission. The utilization of different adaptive modulation techniques seen as a potential solution to reduce the ISI and BER for high data rate transmission. In this paper, OFDM is adapted using advanced modulation technique for WiMAX system. The technique proposes the cyclic prefix (CP) is utilized that include supplementary bits at the stage of the transmitter. The proposed technique offers minimization of ISI and improvement in BER. It is defined that performance of the existing CP system is equated with the designed single cyclic prefix (SCP) and double cyclic prefix (DCP) and non-cyclic prefix (NCP). BER, probability of error, and power spectral density are utilized to analyse the performance of the designed system. The OFDM based SCP and DCP and NCP for WiMAX are demonstrated for modulation techniques such as; QPSK, BPSK, and QAM. It is determined that BPSK has the smallest BER when compared to QPSK, 16-QAM, and 64-QAM modulations. It is also demonstrated that QPSK is also very competent, however, it has a higher BER as compared to BPSK modulation. It is also observed that 16-QAM and 64-QAM are less efficient in terms of BER compared to QPSK and BPKS modulations. 64-QAM offers the high data rates, and due to high SNR ratio. The designed system is tested for under AWGN and Rayleigh fading channel, and effect power spectral density of signal to noise ratio on OFDM for rayleigh fading channel are demonstrated for SCP and DCP and NCP. It is determined that the OFDM transmitter with proposed DCP for random signals is efficiently reducing the BER and ISI for WiMAX system.

A Compact Antenna with WiMAX and WLAN bands notched for UWB applications

A Compact antenna with WiMAX and WLAN bands notched for ultra wide band (UWB) applications is proposed. The proposed antenna is designed for the planar ultra wide band (UWB) antenna and ultra wide band (UWB) antenna having two band rejections. The proposed antenna overall size is 30mm x 40mm x 1.6mm. The antenna consists of a rectangular patch on the top of FR4 substrate with 50ohm feed with defected ground structure. This patch consists of one round cut at each corner having radius 1.575mm. The simulated band width with return loss (RL) >=10db is 3.1 to 11.2 GHz with VSWR<2. It works for the applications of WiMAX system at 3.5GHz (3.3 – 3.7 GHz), C-band satellite communication (3.7 - 4.2 GHz), wireless local area network (WLAN) system at 5GHz (5.15 – 5.825 GHz), X-band satellite communication system (7.25 - 7.75 GHz). The ultra wide band frequency range for these wireless systems causes interference. To diminish obstruction, the band rejection is made. WiMAX and WLAN groups are dismissed by designing slots on the patch. This antenna has an incredible pick up in the Gain while a sharp drop in the rejected groups.

Tri-band MIMO Antenna for WLAN, WiMAX and Defence System & Radio Astronomy Applications

In this paper, an efficacious and impermeable undeviating MIMO consist of 70 x 50 x 0.4 mm3 is used for WLAN, defence system & radio astronomy and WiMAX applications. To keep in order abandoning the reactive connection between the antennas, a neutralizing line is connected between the two symmetrical radiating elements. Another technique to reducing isolation (mutual coupling) between the antennas, four small slits of small size are etched onto to the ground plane. This has resulted in the proposed antenna giving a good bandwidth at the three resonant frequencies of (3.2–3.7 GHz) for Wireless LAN, (5.1–5.6 GHz) WiMAX and (6.7–7.5 GHz) defence system & radio astronomy applications with |S11|< -10 dB and mutual coupling |S12|< -20 dB for the entire operating band. The simulation results and measured results demonstrate that tri-band MIMO antenna is more acceptable for the design in portable device applications.

Miniaturized Dual-Band Bandpass Filter Using Multilayered Dual-Mode Resonator

This paper presents a miniaturized dual-band bandpass filter using two coupled dual-moderesonators (DMRs). The dual-mode resonator is a short-circuited stub loaded square loop resonator. The concept of miniaturization achieved using multilayered technology. Therefore, the filter circuits are achieved in three layers. On the first layer, two coupled dual-mode resonators are designed and shorted to a ground layer to specify the required passbands. Next, a second layer employs two shorted quarter wavelength stubs coupled through one via hole are capacitively coupled to the first layer circuit to achieve the filtering response. For our demonstration, a multi-band bandpass filter is designed to serve a multifunctional wireless system has centre frequencies of 1.9 GHz GSM and 3.5 GHz WiMax systems. The filter is implemented and simulated using the momentum simulator of the Advanced Design System (ADS) software package. The filter response has two second-order passbands with four transmission zeros leads to a high skirt selectivity. The filter circuit area is very small, less than 37 mm2 terminating the feeding ports.

The Capacity of Mesh Cell based on Fixed WiMAX System

The Capacity of Mesh Cell based on Fixed WiMAX System

Evaluation of Circular Pin Fed Linearly Polarized Patch Antenna Using Different Substrates

In this paper, a circular pin fed linearly polarized patch antenna is designed, which can be used in radio & Television, Wimax, GSM, Bluetooth, and WLAN communication systems. The main focus of this paper is to optimize the performance of micro strip patch antenna. In recent times, Wimax based communication applications are widely using circular pin fed linearly polarized patch antenna and it is very familiarized. The proposed antenna design uses 0.5 GHZ frequency band and it is working at narrowband within this band. RT/DUROID 606 material is used for creating the substrate of the micro strip antenna. This new design of the micro strip patch antenna gives high performance in terms of gain and gain bandwidth product.

Design and Analysis of a Compact Band Notch UWB Antenna for Body Area Network

This paper presents the design of a small printed ultra wideband antenna with Band Notched characteristics. Both the free space and on-body performances of this antenna were investigated through simulation. The newly designed UWB antenna is more revised small form factor sized, with the ability to avoid interference caused by WLAN (5.15 - 5.825 GHz) and WiMAX (5.25 - 5.85 GHz) systems with a band notch. The return loss response, gain, radiation pattern on free space of the antenna were investigated. After that, the on-body performances were tested on 3-layer human body model with radiation pattern, gain, return loss, and efficiency at 3.5, 5.7, 8, 10 GHz and all the results were compared with free space results. As the on-body performance was very good, the proposed antenna will be suitable to be used for multi-purpose medical applications and sports performance monitoring.

A dual-band CP dual-orthogonal arms monopole antenna with slanting edge DGS for C-band wireless applications

This communication describes a novel design of circularly-polarized (CP) monopole antenna for dual-band performance. The proposed design offers an impedance bandwidth (IBW) of 3.7 GHz in the frequency range 2.9–6.6 GHz in the lower band and 1 GHz (7.7–8.7 GHz) in the upper band. Proposed antenna has a wide CP (3 dB axial-ratio) bandwidth of 2.42 GHz (46.6%) in lower band (4.08–6.5 GHz) and 300 MHz in upper frequency band (8.1–8.4 GHz). The CP bandwidth is achieved through dual orthogonal arms and slanting edge defected ground structure (DGS). Proposed antenna is suitable for the C-Band wireless applications including WLAN, Wi-MAX communication systems.

A Review of Physical Layer of Mobile WiMAX System and OFDM

A Review of Physical Layer of Mobile WiMAX System and OFDM

Multilayered stepped impedance loaded-resonator for compact dual-band rejection filter design

ABSTRACTA new compact dual-band rejection filter using multilayered stepped impedance loaded-resonator (SILR) is proposed in this article. The stepped impedance loaded-resonator is a dual-mode resonator. The filter structure is compose of two circuits patterned on three layers using two substrates. On the bottom double layer substrate, two SILRs are designed and coupled to generate and control the bandwidths of the first and second bandstops. To achieve the frequency response of the desired filter, a signal path transmission line is realized on a top single layer substrate and vertically coupled to the bottom substrate circuit. To validate the developed approach, a dual-band rejection filter is designed and fabricated to reject the frequencies of 2.4 GHz WLAN and 3.5 GHz WiMax systems. The simulated and measured responses are in good agreement. The resulted filter offers small size, good isolation passband and high selectivity performance with favourite transmission poles around the desired rejection bands.

A novel dual‐band tunable band‐notched antenna

AbstractThis letter presents a novel dual‐band tunable band‐notched antenna. The antenna consists of a monopole ultrawideband (UWB) antenna and two kinds of novel notched structures. A tunable notched wave is obtained by adjusting the capacitance on the notched structure. Monopole antenna works well on 3.1‐10.6 GHz. The low frequency notched wave can be adjusted on the 3–4 GHz, and the high frequency band notched wave can be adjusted on the 5–6 GHz, which can avoid the influence of the WiMax and WLAN narrowband communication system on the UWB communication system, and improve the performance of the antenna system. At the same time, through the analysis of the surface current distribution of the notched antenna, the principle of the notched wave is studied. At last, a prototype of the band‐notched antenna is fabricated and measured whose simulation is consistent with the measurement.

Implementation of a Regional Spectrum Sensing Based Cognitive Radio System for Digital TV White Space

ABSTRACTIt is well-known that cognitive radio (CR) is a fundamental solution to mitigate the spectrum scarcity of today's wireless communication systems. For the realization of CR, there are many obstacles to resolve, including technical and policy perspectives. Since CR is a very sensitive technology, it is particularly important to test the scheme with appropriate operation in a real environment. In this regard, we have developed a testbed of a regional spectrum sensing based CR system for digital TV (DTV) white space. The developed system has a centralized spectrum sensor, and according to the sensing results, mobile WiMAX system provides high quality multimedia service through the spectrum hole in DTV band. There is also a fast frequency hopping capability depending on the sensing results to minimize interference to the actual licensee, the primary DTV system. The performance analysis shows that the developed CR system has excellent performance satisfying the IEEE 802.22 requirements, and is suitable for use in the real environment.

CPW-Fed UWB antenna with sharp and high rejection multiple notched bands using stub loaded meander line resonator

This paper presents a CPW-fed UWB filter-antenna with sharp and high rejection multiple band notches for band-notched UWB communication applications. The band notch operation is achieved by employing a sharp bandstop filter (BSF) with multiple reject bands using only one element meander line resonator at the bottom layer through theoretical calculations and parametric studies. The adjustment of the notched bands is successfully accomplished by loading the meander line with open ended stubs to modify the harmonic frequencies to the desired bands. The structure of the proposed BSF is simple and compact so that the proposed filter-antenna is achieved with the same size of the reference UWB antenna without an extra area. Measurement results show that the proposed filter-antenna has two notches at the WiMAX systems operating in the 5.8GHz (5.725–5.85GHz) and at the international telecommunication union (ITU) operating in the 8.2GHz (8.025–8.4GHz). Also, it has sharp rejection characteristics at the edges of the federal communication commission (FCC) band for UWB communications. The experimental measurements are in good agreement with theoretical and simulation results for the BSF and the filter-antenna. Moreover, the filter-antenna exhibits stable omnidirectional radiation patterns except at the notched bands.

A Review of Physical Layer of Mobile WiMAX System and OFDM

A Review of Physical Layer of Mobile WiMAX System and OFDM

Multi notch-band CPW-fed circular-disk UWB antenna using underground filter

ABSTRACTThis article presents empirical results of multi notch-band coplanar waveguide (CPW) fed circular-disk monopole antennas for ultra-wideband (UWB) applications where the notch-bands are embodied into the antenna using undergrounded filter implemented on U-shape or L-shape stub structures etched on the antenna’s backside. With these stub, the notch characteristics are controllable and so with L-shape, here narrowband antenna designed for 2–6 GHz. The antennas’ performance was validated practically. Both antennas have VSWR < 2. The antenna with undergrounded filter implemented on U-shape stub structure exhibits notch-bands across 2.8–9 GHz necessary to reject interference from WiMAX signals. The antenna with just the L-shape stub structure results in multiple notch-bands necessary to reject 3G, 4G and WiMAX systems. Both antennas radiate omni-directionally in the E-plane and bi-directionally in the H-plane, and have a gain that varies between 0.9–6.7 dBi between 2–11 GHz, with an average gain of 4.2 dBi. The both antennas are fabricated on low cost substrate (FR-4) and simulation results are compared with experimental and the experimental confirmed the simulation.

Reconfigurable microstrip slot antenna with DGS for UWB applications

In this paper, a frequency reconfigurable microstrip slot antenna for ultra-wideband applications with switchable band-notch functions is designed and manufactured. To generate a wide usable fractional bandwidth of 3 to over 13.6 GHz, square patch transforms to a fork-shaped patch, also two triangular-shaped strips have been added at above sections of rectangular slot on the ground plane. Band rejections are obtained by adding two inverted L-shaped strips in the fork-shaped patch and one L-shaped defected ground structure. Moreover, by implementation of two PIN diodes within the antenna structure, four switchable frequency responses are achieved. The designed antenna has simple structure and a small size of 20 × 20 × 0.8 mm3 while providing band rejection characteristics at WiMAX (Worldwide Interoperability for Microwave Access) and WLAN (Wireless Local Area Networks) systems.