WiMAX System Research Articles

Design a Folded Mixer with High Conversion Gain for 2-11GHz WiMAX System

Design a Folded Mixer with High Conversion Gain for 2-11GHz WiMAX System

Enabling Optical Network Test Bed for 5G Tests

ABSTRACTIn this work, we show some experimental approaches concerning optical network design dedicated to 5G infrastructures. In particular, we show some implementations of network slicing based on Carrier Ethernet forwarding, which will be very suitable in the context of 5G heterogeneous networks, especially looking at services for vertical enterprises. We also show how to adopt a central unit (orchestrator) to automatically manage such logical paths according to quality-of-service requirements, which can be monitored at the user location. We also illustrate how novel all-optical processes, such as the ones based on all-optical wavelength conversion, can be used for multicasting, enabling development of TV broadcasting based on 4G–5G terminals. These managing and forwarding techniques, operating on optical links, are tested in a wireless environment on Wi-Fi cells and emulating LTE and WiMAX systems by means of the NS-3 code.

Physical layer design for image transmission between WiMAX/DSRC system

In order to enhance and meet the demands of vehicular communication several authors have proposed the possibility of convergence between two different technologies. In context to this, authors of this paper proposed a novel combined hybrid infrastructure for efficient vehicular communication. The novelty of this approach is the vehicular standard, i.e. dedicated short range communication (DSRC) can be converged with the existing wireless mobile communication network, i.e. Worldwide Interoperability for Microwave Access (WiMAX) technology. Authors critically explored the two different systems in terms of their physical layer, frame structure and packet format. As these technologies are based on the Institute of Electrical and Electronics Engineers therefore we do not intend to change the standards, instead we are attempting to change only a few possible parameters which can be configured to create a bridge between the physical layers of the mentioned technologies. By using this bridge we are able to establish the image transmission between WiMAX and DSRC system. The MATLAB simulation result shows that the hybrid system can be implemented to establish communication in vehicular network.

Performance Evaluation of Dynamic Burst Mapping in a WiMAX System

Allocating resources to WiMAX (Worldwide Interoperability for Microwave Access) users in a rectangular region is often known as burst mapping. The WiMAX standard only specifies a horizontal-strip-based mapping for uplink transmission; the downlink (DL) mapping is not specified. Previous studies have proposed various solutions for DLs, and yet, only a few consider the power of the subchannel (i.e., a group of subcarriers). This paper examines a Dynamic Power Burst Mapping (DyPBM) technique whereby the subchannel qualities and the DL rectangular mapping are considered. This research is then extended to the fragmentation of Medium Access Protocol (MAC) Packet Data Units (PDUs) during burst mapping, which has yet to be highlighted in the literature. The simulation results show that the use of DyPBM results in few unused slots (carrying no data) within the data regions in the unfragmented PDU case. Nevertheless, numerous unallocated slots (free slots) within the frames are found, resulting in achievable goodput that is similar to that of other non-dynamic techniques. When the PDUs are variably fragmented subject to the area of free spaces within the frames, the numerical results show a goodput increment up to 0.7 Mbps. These results indicate that DyPBM significantly relies on the MAC PDU fragmentation to achieve high performance. The trade-off is increased system complexity compared with other techniques.

Performance Assessment of WiMAX using Diverse FEC Schemes over Fading Channels

Diverse modern wireless broadband communication systems are based on what is called Orthogonal Frequency Division Multiplexing (OFDM), which is a basic part of WiMAX. By making use of OFDM, we deal with frequency and time selectivity which are the major concerns when mobile or wireless communication is established between base and subscriber stations. WiMAX cuts the cost because it’s a wireless technology and hence there is little maintenance. Also, it provides higher data rates and has large coverage area compared to its counters parts. In this paper, we make a comparison of various channel coding techniques like convolutional codes, BCH codes, LDPC codes and RS codes over two fading channels namely Rayleigh channel and Rician channel and four modulation orders of PSK. The simulation results show that RS codes and BCH codes perform very well in all conditions whereas convolutional codes lag somewhat in their performance. In addition to this, Rician channel has a better response compared to Rayleigh channel in any modulation order or FEC codes being used in a WiMAX system.

Single- and Dual-Band Bandpass Filters Using Coupled Stepped-Impedance Resonators With Embedded Coupled-Lines

A pair of coupled stepped-impedance resonators and its use to build single- and dual-band bandpass filter (BPF) is presented. To that end, two symmetrical stepped-impedance resonators with two embedded coupled-line sections are used. The adopted resonators are coupled at the two open-ended edges. The first even-mode resonant mode can be suppressed or excited based on whether it is required to realize a single- or dual-band response. Sharp passband selectivity and stopband harmonic suppression are achieved due to the existence of multiple transmission zeros. For verification, single- and dual-band filters using the proposed resonator are designed, fabricated and tested. The experimental results show a passband of 2.34-2.62 GHz (centered at 2.45 GHz for WLAN system), less than 1.5 dB insertion loss for the single-band filter; the dual-band design has two passbands ranged from 2.28-2.67 GHz and 3.35-3.63 GHz with less than 1.2 dB insertion loss for WLAN and WiMAX systems.

BER Analysis of WiMAX using Diverse Channel Coding Schemes

WiMAX is the most popular wireless technology these days for it has high data rates and better performance than other wireless and wired broadband technologies. The performance of WiMAX is severely affected by the multipath fading environment. The efficiency of the WiMAX system can be improved using efficient forward error coding schemes. In this paper a comparison of various FEC schemes such as BCH, RS, LDPC and convolution encoding has been done on two different channels namely-Rayleigh and AWGN. The BER performance of the WiMAX system is further analyzed by utilizing diverse modulation levels over both Rayleigh and AWGN channel. The simulation results show that the best performance is achieved by RS codes and BCH codes followed by LDPC codes and then the convolutional codes. Also, as we vary the code rate of the convolution encoder the BER further degrades. The graphical representations show that the improvement can go as high as 4 dB in some cases in terms of SNR required achieving a particular BER value. The use of RS and BCH encoding schemes will result in better performance in existing WiMAX systems.

A Comparative Analysis of WiMax System with Partial Transmit Sequence (PTS) and Low Complexity PTS

A Comparative Analysis of WiMax System with Partial Transmit Sequence (PTS) and Low Complexity PTS

Joint scheduling and mapping in support of downlink fairness and spectral efficiency in ieee 802.16e OFDMA system

SummaryThe next generation broadband wireless networks deploy orthogonal frequency division multiple access (OFDMA) as the enabling technologies for broadband data transmission with QoS capabilities. In such broadband wireless systems, one major issue is how to utilize radio resource efficiently while maintaining fairness between sessions as well as providing adequate QoS. In this work, we propose an approach for OFDMA/time division duplex (TDD) downlink suitable for IEEE802.16e WiMAX systems that combines scheduling and burst mapping algorithms for a trade‐off between session fairness, QoS, and spectral efficiency. While optimizing radio resources under QoS and fairness constraints is an NP‐hard problem, we follow a heuristic approach that simplifies the complexity of the algorithm. Performance results show that while the new scheme outperforms the Proportional Fair algorithm in terms of fairness, it also improves the overall system spectral efficiency. Copyright © 2016 John Wiley & Sons, Ltd.

A Compact Multiband BPF Using Step-impedance Resonators with Interdigital Capacitors

A compact multiband band-pass filter design for applications of GSM, Wi-MAX and WLAN systems is pre- sented. The design is based on the resonant characteristics of step-impedance and interdigital capacitor resonators with overlap cross coupling structure. The fabricated filter has been operated at the fundamental, first and second harmonic resonant frequencies of 1.8 GHz, 3.7 GHz, and 5.2 GHz, respectively. The experimental results of the fab- ricated filter agree very well with the simulation expecta- tions using IE3D package. The proposed filter has good performances, while the resonator size can be reduced from λ/2 �to λ/8, resulting in the most compact multiband band-pass filter compared with the others using transmis- sion line resonators .

Design & Analysis of Microstrip Patch Antenna Using Different Dielectric Materials for WiMAX Communication System

This Paper presents Microstrip patch antenna for WiMAX communication system which operate at 5.8 GHz frequency band. The main objective of this paper is to design and observe the performance of the designed microstrip patch antenna for different dielectric materials. The size of the designed antenna has been also miniaturized. Better performance is observed for FR4 and dupont-951 dielectric material. For FR4 radiation efficiency is-2.776 dB and total efficiency is -3.026 dB at 5.8 GHz, this indicates better performance. And for dupont-951 the return loss is much lower comparing to the other dielectric materials used in this research, which is -16.609 dB. Also for dupont-951 and FR4, VSWR is found 1.35 and 1.7 respectively which is desirable. Also the size of the antenna has been reduced. In this paper we also observed and analyzed the radiation pattern of far field region, gain, radiation efficiency and total efficiency for different dielectric materials.

Preference‐based zone selection in 802.16 networks

AbstractWe examine a new problem called the Zone Selection Problem (ZSP) in wireless Orthogonal Frequency‐Division Multiple Access (OFDMA)‐based systems. We consider the case where the mobile station (MS) informs the base station of its preferences regarding possible working modes supported by the system. In Worldwide Interoperability for Microwave Access (WiMAX) systems, which are used as a practical reference system for constraints and specific modes of operations, each working mode must be assigned at a different time interval called a Zone. Such zone may, in the downlink subframe, define a specific transmission scheme, which can be either single‐input single‐output or one of the multiple‐in multiple‐out (MIMO) modes supported by the system. We define ZSP as a problem where the base station assigns MSs to zones in a way that optimizes the system utilization (in terms of resource usage) while trying to satisfy the preferences of the users as much as possible. This makes ZSP a bi‐objective optimization problem. We derive assignment costs from physical channel models that integrate specific MIMO schemes and channel conditions. We provide an exact solution to ZSP by using a combinatorial optimization abstraction. We propose a simplified and practical mode ranking approach that enables the MS to define its preferences regarding operation in the optional MIMO modes in the system. We prove that ZSP is NP‐hard and describe two heuristic solutions: a greedy approach and a local search approach. Simulation results show the performance of the exact algorithms on a realistic WiMAX system assumptions and present the trade‐off between the user preferences and system preferences. Copyright © 2016 John Wiley & Sons, Ltd.

Performance Analysis of RSCC Based WiMax System for Different SUI Channel Conditions Using QPSK and QAM-16

In recent times, new advanced wireless systems are growing at fast rate to meet high speed applications. To meet these demands, 4G technologies are being used nowadays. Broadband wireless access (BWA) is the outcome in this direction which promises to cater these high speed and high quality applications. WiMax is an IEEE 802.16 standard-based BWA technology which employs Coded orthogonal frequency division multiplexing access (COFDM). This paper analyses bit error rate for WiMax based COFDM system under Standard University Interim channel conditions.

Performance Review of MIMO-WiMAX

Orthogonal Frequency Division Multiplexing (OFDM) is mostly considered because of its highly efficient bandwidth capability, its high data rate and ability to prevent multipath fading. It is much suitable technique for parallel transmission and use Wireless interoperability for Microwave Access (WiMAX) on its physical layer. Higher the speed of communication better will be the veracity in it. This broadband is trying its best to get available to every place where they are lagging behind and should be accessible to all as soon as possible. On the other hand, Multiple Input Multiple Output (MIMO) techniques are important part of IEEE 802.16e 2005 specifications in adaptable WiMAX systems. From WiMAX technology, we can conquer the current problems of mobile communication systems like precise coverage of area, flat data rate and dearth of security. In this paper, the focus is on WiMAX model along with MIMO techniques. Moreover, ideas regarding MIMO-WiMAX are also highlighted.

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 Compact Triple-Band Printed Monopole Antenna for WLAN/WiMAX Applications

A novel multifrequency printed monopole antenna applied to both WLAN and WiMAX systems is proposed in this letter. The antenna structure is simple, and the size is 34×18 mm <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sup> . The proposed microstrip-fed antenna mainly comprises a fork-shaped strip that is etched on a modified rectangular ring and a rectangular-defected ground plane. To experimentally analyze the characteristics of this antenna, the design, fabrication, and measurement have been completed. Good antenna performances have been obtained.

Design of Low Power and High Speed Correlators for IEEE 802.16 WiMAX Systems

The advanced communication system uses wireless broadband access technologies which provide high speed data connectivity to the subscribers. One of the most popular wireless access technology is Worldwide Interoperability for Microwave Access (WiMAX) and it is based on IEEE 802.16 standard. WiMAX used Orthogonal Frequency Division Multiplexing (OFDM) is an effective modulation technique to improve the timing synchronization. The performance of channel is affected due to the synchronization mismatching between the transmitter and receiver ends. To achieve the timing synchronization in IEEE 802.16 systems, the cross correlator is used to synchronize the received signal with the known signal. In this paper, two high speed correlators are proposed based on Q1.15 format, which is used to validate the timing synchronization problem. The proposed work has been mapped on XC6VCX75T FPGA and simulations are carried out on the Xilinx-ISIM platform. The implementation result shows that the power delay product reduction is 40.81%, and delay reduction is 39.59% over the conventional multiplier less correlators.

A Novel Design of Dual-Band Coupler with Stepped-Impedance Open Stubs

This paper presents a novel dual band coupler design that can operate at two frequency bands. It is accomplished by modifying the length and impedance of the branch lines in the conventional structure. Open stubs are used to achieve dual band branch line coupler with compact size and improve the performances. The dimensions of a conventional BLC “Branch Line coupler” occupy large area, according to the length of the transmission line which is always (g/4 of the operating frequency, ( is so long at low frequencies. When we use open ended stubs the dimensions of the new BLC is reduced compared to the conventional design. The proposed model was shown to reduce the size of the dual-band BLC around 61% based on the proposed topology. It was designed and simulated using EM solver tools for both DCS and WIMAX systems. The final optimized microstrip coupler was fabricated and measured. The simulation and measurement results are in good agreements.

Design Analysis of Channel Filter for Digital Down Converter in WiMAX Application

filter has been designed for Digital Down converter (DDC),that meets the standard of WiMAX in wireless communication. WiMAX is a technology emerging in the wireless communication system, in order to enhance the broadband wireless internet access. Digital Up Converter (DUC) and Digital Down Converter (DDC) are integral part of WiMAX system, that results in efficient low cost WiMAX system. In order to fulfill the spectral requirement of bandwidth reduction, effective spectral leakage and eliminating interference from adjacent channels, in WiMAX system, DDC and DUC utilizes a channel filter for pulse shaping. Channel Filter in DDC applies pulse shaping to attenuate any out of band energy in the baseband data after decimation. The raised cosine filter and Gaussian filters are the most common pulse-shaping filters in communications systems. In present paper raised cosine filter technique and Gaussian filter is utilizes and compared for designing and analysis of channel filter using MATLAB.

A symmetric key-based pre-authentication protocol for secure handover in mobile WiMAX networks

Providing secured and seamless service is one of the most important aspects of mobile networks, particularly for mobile WiMAX systems. However, the long delay handover schemes brought by the time-consuming EAP-based authentication may cause service disruption when a mobile WiMAX user moves between the coverage areas of different base stations. In this paper, we propose a handover scheme using symmetric key cryptography and pre-authentication approach to shorten the delay while ensuring high security level for Mobile WiMAX handover. The scheme is proven by BAN logic to achieve the security goals of an authentication scheme. A performance analysis is also carried out to show the effectiveness of this scheme in reducing handover delay and saving computational resources.