Subcarrier and Power Allocation in WiMAX

Worldwide Interoperability for Microwave Access (WiMAX) is one of the latest technologies for providing Broadband Wireless Access (BWA) in a metropolitan area. The use of orthogonal frequency division multiplexing (OFDM) transmissions has been proposed in WiMAX to mitigate the complications which are associated with frequency selective channels. In addition, the multiple access is achieved by using orthogonal frequency division multiple access (OFDMA) scheme which has several advantages such as flexible resource allocation, relatively simple transceivers, and high spectrum efficient. In OFDMA the controllable resources are the subcarriers and the allocated power per subband. Moreover, adaptive subcarrier and power allocation techniques have been selected to exploit the natural multiuser diversity. This leads to an improvement of the performance by assigning the proper subcarriers to the user according to their channel quality and the power is allocated based on water-filling algorithm. One simple method is to allocate subcarriers and powers equally likely between all users. It is well known that this method reduces the spectral efficiency of the system, hence, it is not preferred unless in some applications. In order to handle the spectral efficiency problem, in this thesis we discuss three novel resources allocation algorithms for the downlink of a multiuser OFDM system and analyze the algorithm performances based on capacity and fairness measurement. Our intensive simulations validate the algorithm performances.fi=Opinnäytetyö kokotekstinä PDF-muodossa.|en=Thesis fulltext in PDF format.|sv=Lärdomsprov tillgängligt som fulltext i PDF-format

Antenna and frequency diversity improvement in mimo wimax technology.

Kepelbagaian ialah teknik komunikasi berpengaruh yang mengatasi kekaburan dengan memanfaatkan sifat rawak saluran tanpa wayar dan mengesan laluan isyarat bebas antara pemancar dengan penerima. Dalam lapisan fizikal WiMAX (PHY) teknik kepelbagaian seperti kepelbagaian masa, kepelbagaian frekuensi dan kepelbagaian antena digunakan untuk meningkatkan prestasi. Tujuan utama tesis ini ialah meningkatkan prestasi kepelbagaian WiMAX PHY. Diversity is an influential communication technique that combats fading by exploiting the random nature of the wireless channel and finding independent signal paths between the transmitter and the receiver. In WiMAX PHY, diversity techniques such as time diversity, frequency diversity and antenna diversity are used to improve performance. The main objectives of this thesis are to improve diversity performance in WiMAX PHY

WIMAX LINK PERFORMANCE ANALYSIS FOR WIRELESS AUTOMATION APPLICATIONS

Wireless broadband access technologies are rapidly growing and a corresponding growth in the demand of its applicability transcends faster internet access, high speed file download and different multimedia applications such as voice calls, video streaming, teleconferencing etc, to industrial operations and automation. Industrial and automation systems perform operations that requires the transmission of real time information from one end to another through high-performance wireless broadband communication links. WiMAX, based on IEEE 802.16 standard is one of the wireless broadband access technologies that has overcome location, speed, and access limitations of the traditional Digital Subscriber Line and Wireless Fidelity, and offers high efficient data rates. This thesis presents detailed analysis of operational WiMAX link performance parameters such as throughput, latency, jitter, and packet loss for suitable applicability in wireless automation applications. The theoretical background of components and functionalities of WiMAX physical and MAC layers as well as the network performance features are presented. The equipment deployed for this field experiment are Alvarion BreeZeMAX 3000 fixed WiMAX equipment operating in the 3.5 GHz licensed band with channel bandwidth of 3.5 MHz. The deployed equipment consisting of MBSE and CPE are installed and commissioned prior to field tests. Several measurements are made in three link quality scenarios (sufficient, good and excellent) in the University of Vaasa campus. Observations and results obtained are discussed and analyzed.fi=Opinnäytetyö kokotekstinä PDF-muodossa.|en=Thesis fulltext in PDF format.|sv=Lärdomsprov tillgängligt som fulltext i PDF-format

Performance evaluation of fixed WiMax physical layer under high fading channels

This thesis was submitted for the degree of Master of Philosophy and awarded by Brunel University.A radio channel characteristic modelling is essential in every network planning. This project deals with the performance of WiMax networks in an outdoor environment while using fading channel models. The radio channels characteristics are analyzed by simulations have been done using Matlab programming. Stanford University Interim(SUI) Channels set was proposed to simulate the fixed broadband wireless access channel environments where IEEE 802.16d is to be deployed. It has six channel models that are grouped into three categories according to three typical different outdoor Terrains, in order to give a comprehensive study of fading channels on the overall performance of the system, WiMax system has been tested under SUI channels that modified into account for 30o directional antennas, with 90% cell coverage and with 99.9% reliability in its geographical covered area. Furthermore, in order to combat the fading which occurs in urban areas and improve the capacity and the throughput of the system, multiples antennas at both ends of communication link are used, the transmission gain obtained when using multiple antennas instead of only a single antenna. Space-time coding and maximum ratio combining for more than one transmit and receive antenna is implemented to allow performance investigations in various MIMO scenarios. It has been concluded that uses multiple antennas at the receiver offers a significant improvement of 3 dB of gain in the channel SNR. This thesis also contain implementation of all compulsory features of the WiMax OFDM physical layer specified in IEEE 802.16-2004 using Matlab coding. In order to combat the temporal variations in quality on a multipath fading channel, an adaptive modulation technique is used. This technique employs multiple modulation schemes to instantaneously adapt to the variations in the channel SNR, thus maximizing the system throughput and improving BER performance. WiMax transceiver has been tested with and without encoding and studied the effect of encoding on multipath channel. Testing the system with flexible channel bandwidth has been part of this thesis. Finally it has been explained in this thesis the affect of increasing the size of cyclic prefix on overall performance of WiMax system

Wireless Standards and Mesh Networks.

On March 13th 1980, the Computer Society of the Institute of Electronics and Electrical Engineering (IEEE) approved project 802. IEEE 802 is led by the LAN/MAN Standards Committee(LMSC). Until today, 22 Working Groups (WGs) mainly define standards for the lowest two layers of the ISO/OSI reference model in the 802. For wireless communication, 802.11 WG defines the Wireless Local Area Network (WLAN), 802.15 WG defines the Wireless Personal Area Network (WPAN), and 802.16 WG defines the Wireless Metropolitan Area Network (WMAN) standard. With Multiple Input/Multiple Output (MIMO), Ultrawideband (UWB) and sensitive Modulation and Coding Schemes (MCSs), the latest developments in the IEEE 802 standards enable data rates beyond 500Mbps for new applications of wireless communication. Similar to preceding wireless technologies, data rate slows down by increase in distance of the communication entities. However, demands for new applications emerge that need high data rates regardless of distance. To overcome the link speed limitation, dense deployment of wireless networks is needed1. Wireless Mesh Networks (WMNs) help to overcome current dependencies of wireless communication systems on wired backbones by enabling cost-effective and rapid deployment for a new generation of wireless services

A REVIEW ON OVERVIEW OF WORLDWIDE INTEROPERABILITY FOR MICROWAVE ACCESS (WIMAX) INNOVATION AND ITS FUTURE UTILIZATIONS

This paper introduces the elements of the Worldwide Interoperability for Microwave Access (WiMAX) innovation and future utilizations of WiMAX. It is a connection oriented wireless network that assures Quality of Service (QoS) for all users in the network. By comparing WiMAX with the popular Wi-Fi, 3G and LTE in the market, it analyzes the current situation and future development trend of WiMAX in terms of the difference in technology and applications. WiMAX will become the most prominent technology for Broadband Wireless Access (BWA). The next generation WMAN networks, using the WiMAX as the core technology is evolving as a 4G technology for providing ubiquitous computing solutions. In not a similar way like wireless LANs, WiMAX networks integrate various QoS mechanism at the Media Access Control (MAC) level for secured service for voice, data and video. The unique architecture of the WiMAX MAC and PHY layer that uses OFDMA to allocate multiple channels with different modulation schemes. A few references have been incorporated towards the completion of this paper for those eager to know in brief about certain points

A Technical and Market study for WiMAX

Worldwide Interoperability for Microwave Access (WiMAX) is a broadband wireless technology based on IEEE 802.16-2004 and IEEE 802.16e-2005. This thesis is a study of WiMAX technology and market. The background of WiMAX development is introduced and opportunities and challenges for WiMAX are analyzed in the beginning. Then the thesis focuses on an overview of WiMAX technology, which addresses the physical layer, MAC layer and WiMAX network architecture. The deployment status is investigated in the fourth chapter. Both product development situation and market status are discussed in this section. In the last chapter, the future development trend of WiMAX is addressed

Key Technology in Physical Layer of WiMAX System

随着无线通信中语音业务、数据业务和多媒体业务日益增加，在传输速率、服务质量和系统业务容量等方面的要求与日俱增，因而需要先进的无线通信技术以提高频谱利用效率和链路可靠性。宽带化、无线化已成为接入网的发展方向。 宽带接入方式可分为无线接入和有线接入两种，近年来摆脱了有线束缚，满足人们自由接入的宽带无线接入（BWA）技术越来越引人注目，已成为新技术的热点，有着广阔的发展前景。由IEEE802.16工作组制定的WiMAX无线宽带接入技术更是为众多运营商、设备厂商所青睐。WiMAX物理层采用的是正交频分复用（0FDM）技术。 OFDM是一种多载波数字通信调制技术，它具有频谱利用率高和可对抗多径时延扩...With the growing requirement of voice services, data services and multimedia services in the wireless communication, high data rate, QoS and channel capacity are increasingly necessary, which promote people to improve the spectrum efficiency and stability of the link. So the development of broadband access network focuses on two trends as broadband and wireless. Broadband access technology is divi...学位：理学硕士院系专业：信息科学与技术学院电子工程系_无线电物理学号：20043000

Implementation of WiMAX physical layer baseband processing blocks in FPGA

This project thesis elaborates on designing a baseband processing blocks for Worldwide Interoperability for Microwave Access (WiMAX) physical layer using an FPGA. WiMAX provides broadband wireless access and uses OFDM as the essential modulation technique. The channel performance is badly affected due to synchronization mismatches between the transmitter and receiver ends so the transmitted signal received is not reliable as the OFDM deals with high data rate. This thesis includes the theory and concepts behind OFDM, WiMAX IEEE 802.16d standard and other blocks algorithms, its architectures used for designing as well as a presentation of how they are implemented. Here Altera’s FPGA has been used for targeting to the EP4SGX70HF35C2 device of the Stratix IV family. WiMAX use sophisticated digital signal processing techniques, which typically require a large number of mathematical computations. Here Stratix IV devices are ideally suited for these kinds of complex tasks because the DSP blocks have a combination of dedicated elements that perform multiplication, addition, subtraction, accumulation, summation, and dynamic shift operations. The WiMAX physical layer baseband processing architecture consists of various major modules which were simulated block wise in order to check its giving the correct output as required. The coding style used here is VHDL. The sub-blocks have been synthesized using Altera Quartus II v11. 0 and simulated using ModelSim Altera Edition 6.6d