WiMAX OFDM Research Articles

A Review of Physical Layer of Mobile WiMAX System and OFDM

A Review of Physical Layer of Mobile WiMAX System and OFDM

A Review of Physical Layer of Mobile WiMAX System and OFDM

A Review of Physical Layer of Mobile WiMAX System and OFDM

Impact of Distinctive Jamming Signals on WiMAX System

In this recent era wireless communication industries have focused on the uses of broadband system having high quality functions. Because of this issue new advances with high transmission capability technologies are designed. The broadband wireless access turns into the best approach to satisfy the high business interest for expanding the web connection. WiMAX (Worldwide Interoperability for Microwave Access) is a broadband wireless technology is developed to meet the growing demand of increased data rate and accessing the internet at high speeds as well as low cost maintenance. It is based on the IEEE 802.16-2004 standard family. In this system allows using an efficient bandwidth in a wide frequency range, and last mile solution for broadband internet access. The jamming and scrambling are two important threats in WiMAX system. This paper presents the simulation of WiMAX system with and without impact of jamming signals. The performance parameter BER of the system is analyzed in all conditions and the result implies the enormously changes with the utilization of distinctive jamming signals. The aim of this paper is to analyze and simulate WIMAX OFDM system in the presence of interference signals. MATLAB Simulink software is used to simulate and analyze the WIMAX system. The simulation results include the performance analysis based on bit error rate (BER) versus signal to noise rate (Eb/No).

BER ANALYSIS OF WIMAX IN MULTIPATH FADING CHANNELS

In this paper, an effort has been made to inspect the performance of WiMAX OFDM physical layer under the effect of noise. An End-to-end baseband WiMAX OFDM physical layer has been modelled in Multipath fading environment using MATLAB Simulink. BER has been evaluated for the Binary Phase Shift Keying (BPSK), Quadrature Phase Shift Keying (QPSK), 16 Quadrature Amplitude Modulation (16 QAM) and 64 Quadrature Amplitude Modulation (64 QAM) schemes over a range of SNR (dB). The BER of a digital communication system is an important figure of merit for quantifying the integrity of data transmitted through the communication system. Several plots between BER and SNR (dB) for the abovementioned modulation schemes in Rayleigh and Rician fading channels have been investigated for the analysis.

Using a HAP Network to Transfer WiMAX OFDM Signals: Outage Probability Analysis

Transferring wireless broadband services across extremely far distances on Earth is usually implemented nowadays either by ground-based or satellite communications. Terrestrial networks require, however, heavy installation and maintenance costs, whereas satellite networks suffer from excessively high power requirements. An alternative but highly challenging solution is to employ a network consisting of high-altitude platforms (HAPs). In this paper, we propose a way of delivering WiMAX traffic using a serial multi-hop HAP network configuration. HAPs are located at specific locations in the stratosphere, pick up the traffic from the Earth region they cover, and communicate with each other using optical links. In such a configuration, we determine the WiMAX quality of service by evaluating the outage probability for the entire HAP network. The overall performance is examined by using a channel model that takes into account laser path loss and pointing error effects. The findings of the present study indicate that the consideration of specific network and channel model parameters is crucial toward the design and implementation of future multi-hop HAP networks.

Spectrum efficiency of Fixed WiMAX OFDM network in the presence of co-channel interference with diversity combining

WiMAX (Worldwide Interoperability for Microwave Access) is a promising technology which can offer high speed voice, video and data services upto the requirements at the customer's end. The objectives of this paper is the Performance evaluation of a WiMAX system under various diversity schemes (Selection combining, Maximal ratio combining and Equal gain combining), employing different adaptive transmission policies, such as Optimal power and rate adaptation policy, Optimal rate adaptation with constant transmit power policy, Channel inversion with fixed rate policy, and Truncated channel inversion policy, subjected to co-channel interference. The WiMAX system incorporates OFDM with BPSK modulation as the transmission scheme. Simulated results of the estimated spectrum efficiency shows that the implementation of Optimal power and rate adaptation policy is highly effective to combat co-channel interference in the WiMAX communication system, under Selection combining.

A 25 dBm Digitally Modulated CMOS Power Amplifier for WCDMA/EDGE/OFDM With Adaptive Digital Predistortion and Efficient Power Control

A digitally modulated power amplifier (DPA) in 1.2 V 0.13 mum SOI CMOS is presented, to be used as a building block in multi-standard, multi-band polar transmitters. It performs direct amplitude modulation of an input RF carrier by digitally controlling an array of 127 unary-weighted and three binary-weighted elementary gain cells. The DPA is based on a novel two-stage topology, which allows seamless operation from 800 MHz through 2 GHz, with a full-power efficiency larger than 40% and a 25.2 dBm maximum envelope power. Adaptive digital predistortion is exploited for DPA linearization. The circuit is thus able to reconstruct 21.7 dBm WCDMA/EDGE signals at 1.9 GHz with 38% efficiency and a higher than 10 dB margin on all spectral specifications. As a result of the digital modulation technique, a higher than 20.1 % efficiency is guaranteed for WCDMA signals with a peak-to-average power ratio as high as 10.8 dB. Furthermore, a 15.3 dBm, 5 MHz WiMAX OFDM signal is successfully reconstructed with a 22% efficiency and 1.53% rms EVM. A high 10-bit nominal resolution enables a wide-range TX power control strategy to be implemented, which greatly minimizes the quiescent consumption down to 10 mW. A 16.4% CDMA average efficiency is thus obtained across a > 70 dB power control range, while complying with all the spectral specifications.