WiMAX System and its QoS Mechanism

The popular application of optical fiber technology increases the bearing capacity of backbone network greatly and makes the access network the bottleneck for services. The WiMAX is characterized by large bandwidth, wide covering range, and mobility supporting. Though WiMAX system has brought many new features to the access network, it brought new problems such as security guarantee under wireless environment, dynamic resource management, and mobility management. Especially the QoS mechanism is important in providing reliable end-to-end services under complicated communication environment. All those problems need to be solved in practice gradually.

Pilot and Channel Estimation for WiMAX System

Orthogonal Frequency Division Multiplexing(OFDM)is very suitable for high data rate transmission in wide band wireless channel for the excellent capability to mitigate the frequency selective fading and Inter-Symbol Interference(ISI).In WiMAX system,Orthogonal Frequency Division Multiple Access(OFDMA)is adopted as the basic multiple access scheme,and different pilot patterns has been defined for both uplink and downlink channels.Pilot pattern should be changed,especially when Multiple Input Multiple Output(MIMO)technique is combined with OFDMA,in order to support multiple antennas.There are five pilot patterns in the WiMAX-MIMO-OFDMA system,namely:Downlink-Partially Used Sub-Channel(DL-PUSC),Downlink-Fully Used Sub-Channel(DL-FUSC),Downlink-Optional Fully Used Sub-Channel(DL-OFUSC),Uplink-Partially Used Sub-Channel(UL-PUSC)and Uplink-Optional Partially Used Sub-Channel(UL-OPUSC).Moreover,by analyzing the simulation results of time domain Least Square(LS),frequency domain LS,and Fast Fourier Transform(FFT)-based channel estimation algorithms,the best pilot pattern can be found.Based on the simulation comparison of several channel estimation methods in the WiMAX-MIMO-OFDMA system presented in this article,the best channel estimation for each pilot pattern is concluded.

Multiple Antenna Technology and Its Application in WiMAX System

Worldwide Interoperability for Microwave Access (WiMAX) technology has rapidly developed in recent years. It is becoming one of the hotspots among broadband wireless access technologies. A WiMAX system can provide bandwidth efficiency higher than 2 bps/Hz. In order to improve coverage and reliability of the WiMAX system,the IEEE 802.16 standard supports multiple antenna techniques such as Alamouti Space-Time Coding (STC),Adaptive Antenna System (AAS) and Multiple Input Multiple Output (MIMO). The applications of the multiple antenna techniques improve system capacity and bandwidth efficiency significantly,and enhance the competence of the WiMAX technology greatly.

New Preamble Sequence for WiMAX System with Improved Synchronization Accuracy

Worldwide Interoperability for Microwave Access(WiMAX)trusts Multiple Input Multiple Output-Orthogonal Frequency Division Multiplexing(MIMO-OFDM)combination for the deployment of physical layer functions and for connecting the medium access control to the wireless media.Even though Orthogonal Frequency Division Multiplexing(OFDM)facilitates reliable digital broadband transmission in the fading wireless channels,the presence of synchro-nization errors in the form of Carrier Frequency Offset(CFO)and Time Offset(TO)adversely affect the performance of OFDM based physical layers.The objective of this work is to improve the accuracy of the frequency and the time offset estimation in the WiMAX physical layer.A method to enhance the synchro-nization accuracy byfine-tuning the merit factor of the preamble sequence is sug-gested in this paper.Also,a new preamble with improved synchronization accuracy is proposed for the WiMAX system.The performance of the proposed preamble is evaluated in a Rayleigh fading channel and the results of simulations show that the Mean Square Error(MSE)in offset estimation is significantly reduced and it outperforms the standard WiMAX preamble.

On the Performance of Mobile WiMAX System: Measurement and Propagation Studies

In this paper, we present drive test results for mobile WiMAX system for desert and cosmopolitan terrains where there are few studies reported in the literature. The extensive measurement is performed in the framework of the physical performance of the WiMAX technology which is often considered as a 4G system. Path loss model is fitted for the collected data. The work is unique in the sense that most empirical channel models are produced in regions where the environments (weather, buildings, vegetation, among others) are quite different from the desert terrains that are considered in this study. We also show that shadowing is truly lognormal in dB and the standard deviation values are calculated for the desert terrain from the measurement data. The measurements are collected using WiMAX BS station, with greenpacket dongle, and NEMO versatile outdoor drive test equipment to evaluate and characterize the performance of the system. The received signal strength indicators measured, are analyzed to complement network design and network optimization for regions where the popular models may not be accurate.

WiMAX System Simulation and Performance Analysis under the Influence of Jamming

This paper presents simulation of WiMAX based system under jamming. The performance of the system was found out to greatly differ with the use of different jamming signals, allowing central areas to be identified, where system devel-opment should be focused on. In addition, from the basic theory point of view, rather surprising results were also found. This work should give a clear picture of how the studied WiMAX system performs under jamming as well as without jamming. The results show that some forms of interference degrade the performance of the system rapidly, thus the form of incoming jamming should be known and considered before deploying the system. Single carrier jamming and multi–carrier jamming are discussed here. The issues related to jamming and jamming reduction techniques are also covered. Jamming can destroy communication in the targeted area. Multi–carrier jamming is challenge in WiMAX because WiMAX is having OFDM based physical layer. Simulation is the main approach in this paper. OPNET MODELER 14.5 is the software used for the simulation purpose.

Design and Realization of a Dual Wide Band Printed Monopole Antenna for WiFi and WiMAX Systems

A Printed monopole antenna was designed and manufactured with the wideband performances in two frequency bands. The antenna is compatible with WiMAX and WiFi standards. After reviewing a couple of literatures, the antenna was designed, analyzed and proven for two central frequencies, 2.5 GHz and 5.6 GHz, with much improved bandwidths. Finally, the antenna was manufactured with the overall size of 4 cm × 4.4 cm on Rogers (RO4003) substrate. The antenna is made into three L-shaped radiators. A 50 Ω microstrip feed line connects the port to the two L-shaped radiators of different lengths, thus providing two frequency bands. An inverted L-shaped radiator is printed on the less radiation upped side, to tune the antenna for wide band performances. The raised problem was solved with the integral equation solver of the Ansoft high frequency simulator structure (HFSS-IE). Optimal results are presented in this article: the simulation results in comparison with measured results. This antenna prototype’s overall dimensions would be readjusted according to any industrial and manufacturing requests.

A WiMAX-ZigBee Energy Management System for Green Education

A WiMAX-ZigBee energy management system for green education has been developed. The system helps to resolve the disgusting environmental problems. This paper explores the concept of energy management and introduces an Energy Management System located at campus areas. Analysis shows that 30% energy can be saved from the total energy consumption which translates to a saving of 72 thousand million kWh of energy annually. Such saving reduces 48 million tons of CO2 emission for the environment.

Dual Wideband Antenna for WLAN/WiMAX and Satellite System Applications Based on a Metamaterial Transmission Line

A dual band planar antenna based on metamaterial transmission lines is presented for WLAN,WiMAX,and satellite system communication applications.This antenna is composed of an interdigital capacitor and a ground plane with triangular shaped slots on its top edges to broaden the impedance bandwidth.The measured bandwidth for 10 dB return loss is from 3.29 to 4.27 GHz and 5.04 to 9.8 GHz,covering the 5.2/5.8 GHz WLAN,3.5/5.5 GHz WiMAX bands,and the X-band satellite communication systems at 7.4 GHz.The proposed antenna exhibits stable monopole-like radiation patterns and enough gains across the dual operating bands.

Modeling and analysis of multiservice queuing system for WiMAX network

An analytical queuing model is proposed for the classified services of WiMAX network. Simulation model is also developed that corresponds to the Markovian analytical model using Java modeling tool （JMT）. This is a new and efficient discrete event tool for queuing network modeling and workload analysis. QoS metrics have been evaluated for the multi-rate traffic in multiple scenari- os. Results obtained from simulation are compared for validation and analysis. Outcomes show that the proposed model is more efficient than the conventional method by improving residence time, re- sponse time, increasing system throughput and efficiency at queuing level with a slight degradation in call acceptance factor.

A New Remote and Automated Control System for the Vineyard Hail Protection Based on ZigBee Sensors, Raspberry-Pi Electronic Card and WiMAX

A new inexpensive vineyard protection against hailstorm has been realized and tested. The system has been designed and organized in such a way to perform autonomously local activities to physically control the protection of the vineyard but also to transmit information toward a remote control. Each row has an ＂umbrella＂ designed by the authors which, unlike other commercial solutions, protects the product without hindering all the mechanical activities typical of a modem vineyard. Locally the single umbrella uses an electronic card for the management and a ZigBee mesh telecommunication network to transmit data to a central control unit which manages the protection. Because of its efficiency, a Raspberry-Pi control card has been chosen as central unit. Finally, a WiMAX connection was chosen to remotely control the system, thus allowing the authors to overcome distance limitations of commercial Wi-Fi networks. The system has been realized and tested for some months in field also during a hailstorm. The results of these tests proved how the system is easy to use and effectively protects against hail; moreover the authors proved the high reliability of the mechanical components which allow the authors to lower the maintenance costs.

MIMO-WiMAX system incorporated with diverse transformation for 5G applications

Wireless systems and standards are now progressing toward the implementation of fifth generation (5G) to combat with an expected and explosive growth of demands of wireless services in future. Consequently, wireless interoperability for microwave access (WiMAX) with orthogonal frequency division multiplexing (OFDM) technology at its physical layer is being utilized for the uplink and downlink transmission to afford the high spectral efficiency in fading environments. However, the 5G implementation requires additional improvements to meet the futuristic stress. This work proposes an innovative solution that combines WiMAX system with multiple input multiple output (MIMO) technology to meet the required elevated data rates as desired by the growing application needs of 5G. MIMO is capable to fulfil the vision of 5G to realize a huge number of base stations equipped with a large number of terminals to be served in the same time-frequency resource without severe inter-user interference. Furthermore, the proposed system is demon- strated incorporation with discrete wavelet transform (DWT), and fractional Fourier transforms (FrFTs) in the physical layer of the WiMAX system. The evaluated outcomes exemplify a considerable improvement in bit error rate (BER) performance in contrast with the earlier reported work.

‘Fading is Our Friend!’: A Performance Comparison of WiMAX-MIMO/MISO/SISO Communication Systems

Research work for some time now has shown that fading wireless channels present enormous advantages if properly exploited through a Multiple-Input Multiple-Output (MIMO) communication model. In this paper, we demonstrate the advantages of implementing the MIMO communication model by investigating three communication techniques, namely, Single-Input Single-Output (SISO), Multiple-Input Single-Output (MISO) and MIMO for WiMAX communication systems. The performances of these communication techniques are analyzed and compared for three scenarios - rural environment, TGV (high-speed train) environment and urban environment by using the models to investigate several communication parameters.

WIMAX Implementation of Smart Grid Wide Area Power System Load Protection Model in MATLAB/SIMULINK

As the revolutionary change in electric power industry begins with the latest communication infrastructure, it is on the verge of a revolutionary transformation to develop a smart grid to meet the requirements of our digital society. Wide Area Power System is made up of plentiful automated transmission and distribution systems with strong communication infrastructure, all operating in a coordinated, proficient and reliable mode. This paper is fretful with the wide area power system load protection scheme and ensuing design requirement that enhances stability as well as control. It discusses the architecture that upgrades the existing scheme by controlling all the control signals traffic between generating units, server, connected loads, and protection devices using WIMAX. The main theme of the paper is on the use of information technology to obtain more flexibility and smartness in the Wide Area Power System Load Protection by designing the Communication channel using WIMAX. Faults detected in Local area networks and Information regarding the faults of Local Areas is communicated to Load Area Manager (LAM) which takes required control action to handle it. Finally the paper shows islanding operation through WAM for the areas that becomes intensive faulty. Results have been verified in MATLAB/ SIMULIMK.

Strix Systems在美Akron市启动Wi-Fi／WiMAX无线城市网络计划

无线mesh网络设备的领先厂商Strix Systems公司和无线运营商MobilePro公司近日宣布，与俄亥俄州的Akron市合作建设其62平方英里的无线城市网络。Akron市将随之开始推出无线服务，并具备支持未来WiMAX技术标准以及其他新无线技术的能力。在近日的媒体采访中，Akron市的首席技术官Rick Leu先生表示：“最初的推出将被视为首期开创，而整个计划将着重远期升级的考虑。这样可以不必要放弃已有投入或是禁锢自身。”

德州仪器与Mercury Computer Systems为新一代移动宽带市场联袂推出WiMAX AMC

日前，德州仪器（TI）与Mercuty Computer Systems公司联合宣布合作开发针对WiAMX无线局端数字基带应用的Mercury MTI-203 AMC。

以WIMAX技术为主导视频监控系统设计

随着信息技术的飞速发展,视频监控系统在各个领域中扮演着越来越重要的角色。传统的视频监控系统往往依赖于有线网络进行数据传输,但在某些场景下,如偏远地区或不易布线的地方,有线网络的建设和维护成本较高。因此,基于WIMAX技术的无线视频监控系统成为了一个可行的解决方案。本文提出了一种基于WIMAX技术的视频监控系统设计方案,保证视频质量、传输效率以及安全性等方面的优良性能。

移动WiMAX系统的关键技术及未来演进

本文首先介绍了移动WiMAX为支持高速移动数据业务所采用的关键技术,主要包括多天线技术和分组调度算法,然后阐述了移动WiMAX为符合国际电联IMT-Advanced要求而提出的IEEE802.16m增强标准,就其主要内容和标准化进程进行了详细介绍,给出了未来演进思路和协议标准化计划。

基于WiMAX技术的实时视频监控系统设计

分析了WiMAX的技术特点和安全性,探讨了其在实时视频监控系统中应用。提出了基于Inter WiMAX Connection 2250技术的实时视频监控系统设计方案。