Wireless networks are growing exponentially by the steady improvement of its speed and quality. IEEE 802.11-based Wireless Local Area Networking (WLAN) has been developed for mobile computing devices in LANs, in a short and limited range. IEEE 802.16 Wireless Metropolitan Area Network (WMAN) is designed for a line-of-sight (LOS) distance with QoS capability. The IEEE 802.11 standard has a totally different MAC layer compared to the IEEE 802.16 standard, normally they will communicate at the Network Layer by switches or routers. This thesis investigates the major design requirements for SoftMAC design, and will demonstrate a prototype that can meet the design requirements. It proves the possibility and flexibility of using SoftMAC to connect and control Heterogeneous Wireless Network, in order to fulfill seamless handover among multiple heterogeneous wireless interfaces. We will show that by adding the proposed SoftMAC on top of the traditional MAC layer, the mobile station cannot only perform handover between access points, but also essentially open a door to a wider range of application and services.

This paper presents a reconfigurable FFT architecture for variable length andmultistreaming WiMax wireless standard. The architecture processes 1 streamof 2048-pt FFT, up to 2 streams of 1024-pt FFT or up to 4 streams of 512-ptFFT. The architecture consists of 11 SDF pipelined stages and radix-2 butterflyis calculated in each stage. The sampling frequency of the system is varied inaccordance with FFT length. The wordlength and buffer length in each stage isconfigurable depending on the FFT length. Latch-free clock gating technique isused to reduce power consumption.The architecture is synthesized for Virtex-6 XCVLX760 FPGA. Experimentalresults show that the architecture achieves the throughput as required by theWiMax standard and the design has additional features compared to the previousapproaches. The design used 1% of the total available FPGA resources andmaximum clock frequency of 313.67 MHz was achieved.

Wireless networks are growing exponentially by the steady improvement of its speed and quality. IEEE 802.11-based Wireless Local Area Networking (WLAN) has been developed for mobile computing devices in LANs, in a short and limited range. IEEE 802.16 Wireless Metropolitan Area Network (WMAN) is designed for a line-of-sight (LOS) distance with QoS capability. The IEEE 802.11 standard has a totally different MAC layer compared to the IEEE 802.16 standard, normally they will communicate at the Network Layer by switches or routers. This thesis investigates the major design requirements for SoftMAC design, and will demonstrate a prototype that can meet the design requirements. It proves the possibility and flexibility of using SoftMAC to connect and control Heterogeneous Wireless Network, in order to fulfill seamless handover among multiple heterogeneous wireless interfaces. We will show that by adding the proposed SoftMAC on top of the traditional MAC layer, the mobile station cannot only perform handover between access points, but also essentially open a door to a wider range of application and services.

The new generation wireless broadband access technology-WiMAX¡]Worldwide Interoperability for Microwave Access¡^, possessing advanced features, such as higher transmission rates, longer transmission distances and wider coverage, is considered as one of the key technologies that can affect the future development of wireless telecommunications industry. Taiwan has ranked it a priority developing industry and has integrated the strengths of industries, government agencies, academia and research institutes to aggressively promote it in order to establish a more complete miniature of WiMAX industry chain. For the purposes of attracting information industry to enter this field, encouraging new applied services and development and achieving the goal of bringing services to push forward industry, the National Communication Commission¡]NCC¡^has issued 3 wireless broadband access business licenses in both north and south areas on July 2007. The bid-winners all adopts WiMAX technology to set up broadband mobile network, and provides services. Thus, at present, the wireless broadband access business is equal to WiMAX business. Therefore, the development of WiMAX industry plays a decisive role in Taiwan¡¦s economic development, its effecting level to the whole economic impact deserves analyzing and researching carefully. Based mainly on the Input-Output model, this study uses ex post facto comparison group and domestic concepts to combine the viewpoints of industrial analysis with the categories of 2004 Input-Output Table published by National Statistics, Executive Yuan, R.O.C., and then, adjusts Input-Output Table into 40 departments according to the policy of developing WiMAX that aggressively pushes forward the equipment and applied service fields. After that, defines related industries of network setup area and proceeds industry categorizing. Furthermore, this research does the analysis of Input-Output related effects and of multiplier effect so as to determine the role what it can play in the whole economic system. In the meanwhile, this study predicts the economic benefits of future development in setting up WiMAX and the operating period and the spurring effect of other related industries. The following are the research results¡G 1. In the next 3 years period and 5 years period of developing WiMAX network, the estimated total amount of investments will 21,549 million NT dollars and 37,291 million NT dollars each . It is predicted that there will be a whole output of domestic economic system of 34,489 million NT dollars and 59,685 million NT dollars; the created income effect will be 7,675 million NT dollars and 13,282 million NT dollars; the employment will be 7,588 jobs and 13,131 jobs each. 2. In the next 3 years period and 5 years period of operation, the estimated final demand variation amount will be 18,006 million NT dollars and 101,961 million NT dollars each by WiMAX services to customer. It is predicted that there will be a whole output of economic system of 27,063 million NT dollars and 153,249 million NT dollars; the created income effect will be 11,760 million NT dollars and 66,595 million NT dollars; the employment will be 4,766 jobs, 26,987 jobs. In sum, the promotion of WiMAX network construction will have positive influencing effect on the domestic economic growth and the development of every kind of industry.

Wimax (Worldwide Interoperability for Microwave Access) is a standard of wireless metropolitan area networks (WMAN), designed by IEEE 802.16 standards group. The coverage of Wimax is wide, so it is suited for developing in large networks and provides more steady, high-speed, and secure data transmission for fixed and mobile subscribers. As the result, Wimax is designed for solving last mile problem because of the bandwidth is limit and the expensive building cost in the traditional networks. IEEE 802.16 (Wimax) defines two modes of data communication topology: PMP (Point-to-multipoint) mode and Mesh mode. In Mesh mode, the data can route through another subscriber station (SS), so it not only improves coverage range but also raises the throughput. Although IEEE 802.16 defined a secure sub layer in the MAC (Media Access Control) layer to provide privacy by encrypting connections between base station (BS) and subscriber station (SS), but it still face many security problems. In the mesh mode, it is not like PMP mode that the traffic is only between BS and SS, the traffic sometime will pass through another SS, for this reason, it is prone to bring many problems, such as shared secret key exposing, man-in-the-middle attack, eavesdropping threat¡Ketc. On the relay node (we termed sponsor node here), it also involved more unnecessary loads of encryption and decryption. In this thesis, we focus on the MAC layer , and we propose some schemes to modify the present of PKM and the traffic encryption key used for transmitting data, and we will show that these schemes can achieve better security than previous ones, also achieve efficient in data transmission.

Σκοπός της παρούσης διπλωματικής εργασίας είναι η προσομοίωση των λειτουργικών χαρακτηριστικών του ασύρματου δικτύου ΙΕΕΕ 802.16. Στο 1ο κεφάλαιο επιχειρείται μια εισαγωγή στην ασύρματη πρόσβαση ευρείας ζώνης. Στο 2ο κεφάλαιο γίνεται περιληπτική αναφορά στην εξέλιξη του WiFi, τον τρόπο λειτουργίας του και τη σημασία του ως πρόγονος του WiMAX. Στο 3ο κεφάλαιο γίνεται εισαγωγή στο WiMAX, τα διάφορα υποπρότυπα που κυκλοφορούν, τις τεχνολογίες που χρησιμοποιούν και σύγκριση με άλλες υπάρχουσες ασύρματες τεχνολογίες. Στο 4ο κεφάλαιο γίνεται σε βάθος εξερεύνηση του φυσικού στρώματος του WiMAX. Στο 5ο κεφάλαιο μελετούμε το στρώμα πρόσβασης μέσου του προτύπου. Στο 6ο κεφάλαιο αναλύουμε την αρχιτεκτονική του δικτύου WiMAX. Για το πρακτικό μέρος της διπλωματικής στο 7ο κεφάλαιο έγινε προσομοίωση του φυσικού στρώματος ενός ασύρματου ευρυζωνικού πομποδέκτη του υποπροτύπου IEEE 802.16-2004, με χρήση κεραιών ΜΙΜΟ, για σταθερή (fixed) πρόσβαση. Στο 8ο κεφάλαιο βρίσκονται τα συμπεράσματα από τις προσομοιώσεις. / --

Αντικείμενο της εργασίας είναι η μελέτη και η ανάλυση επίδοσης πρωτοκόλλων πρόσβασης μέσου που μπορούν να χρησιμοποιηθούν για ασύρματα μητροπολιτικά δίκτυα. Στην εργασία γίνεται εκτενής μελέτη του πρωτοκόλλου 802.16 της IEEE, αναφορές στην εμπορική υλοποίηση αυτού, WiMAΧ. Επίσης γίνεται η χρήση του εξομοιωτή OPNET modeller για εκτίμηση κάποιων QoS παραμέτρων του MAC επιπέδου του 802.16. / The subject of this thesis is the study and evaluation analysis of MAC layer in broadband wireless networks and especially in 802.16. Opnet Modeller is used to test some of 802.16 and WiMAX QoS features.

Applications such as video and audio streaming, online gaming, video conferencing, Voice over IP (VoIP) and File Transfer Protocol (FTP) demand a wide range of QoS requirements such as bandwidth and delay. Existing wireless technologies that can satisfy the requirements of heterogeneous traffic are very costly to deploy in rural areas and “last mile” access. Worldwide Interoperability for Microwave Access (WiMAX) provides an affordable alternative for wireless broadband access supporting a multiplicity of applications. The IEEE 802.16 standard provides specification for the Medium Access Control (MAC) and Physical (PHY) layers for WiMAX. A critical part of the MAC layer specification is scheduling, which resolves contention for bandwidth and determines the transmission order of users. It is imperative for a scheduling algorithm to have a multi-dimensional objective of satisfying QoS requirements of the users, maximizing system utilization and ensuring fairness among the users. In this thesis, we categorize and study various scheduling algorithms for the uplink traffic in WiMAX in view of these objectives. The algorithms are studied under different mixes of traffic and for various characteristics of the IEEE 802.16 MAC layer such as uplink burst preamble, frame length, bandwidth request mechanisms etc. Simulation results indicate that legacy algorithms are not suitable for the multi-class traffic in WiMAX as they do not explicitly incorporate the WiMAX QoS parameters. We provide recommendations for enhancing existing scheduling schemes in WiMAX, and shed light on some of the open issues that need to be addressed. / Thesis (Master, Computing) -- Queen's University, 2007-12-29 18:21:21.521

A major consideration for mobile WiMAX is seamless handoff. The British English term for transferring a cellular call is handover whereas the Americans prefer to call it handoff. Cellular-based standards have the advantage of many years experience in handover for voice calls, while for broadband mobility in itself is no mean feat, and handover is still a challenge. Mobile IP, with "slow" handover, will be fine for web-browsing but not good enough for decent voice quality. Many services require the appearance of seamless connections (VoIP, VPNs, etc). Much of the complexity (and latency) in the cellular network is from maintaining these connections across cell boundaries. Handovers in wireless technologies have always been a challenging topic of discussion. According to the mobility framework of IEEE 802.16e, a Mobile Station (MSS) should scan the neighbouring Base Stations (BSs) for selecting the best BS for a potential handover. However, the standard does not specify the number of BSs to be scanned leaving room for unnecessary scanning. Moreover, prolonged scanning also interrupts data transmissions thus degrading the QoS of an ongoing connection. Reducing unnecessary scanning is an important issue. This thesis proposes a scheme to reduce the number of BSs to scan, thus improving the overall handover performance. Simulation results show that the proposed hybrid predictive BS selection scheme for potential scanning activities is more effective than the conventional IEEE 802.16e handover scheme in terms of handover delay and resource wastage. Before the actual handover process, there is scope of reducing the total number of iterations of message exchanges occurring between the mobile MSS, the SBS and the neighbouring BSs which are potential targets for handover. Simulations prove that it takes upto 700 ms to decide the target BS before initiating the handover process with it. There are multiple message exchanges to choose a set of potential target BSs from all the neighbouring BSs. A few more messages flow between the MSS, SBS and potential target BSs to choose the best candidate BS for handover. The many stages and messages waste time and could be reduced. This thesis discusses some ways to reduce them and backs it up with simulation results.

The Worldwide Interoperability for Microwave Access, or WiMax, is a wireless communication technique based on IEEE 802.16 standards. Its advantage of sending high data rates over long distances, while using a single base station to cover a large area, has made this technique a flexible and reliable solution for public wireless networks. WiMax has two main types of networks: Fixed and Mobile. The most popular transceiver used in WiMax applications is the “Direct-Conversion Architecture” due to its high level of integration and less component requirements, which leads to reduced power dissipation. In Direct Conversion Architecture, the mixer is a key block in the transceiver chain. Depending on design specifications and constraints, different types of mixers may be considered. However, the most appropriate down converter mixer for WiMax applications is the Gilbert-cell mixer. This thesis will then explore the design of a down converter Gilbert-Cell Mixer within the realm of Fixed WiMax technology. This design was achieved in the commercial circuit simulator Advanced Design System (ADS) using the 0.15mm InGaAs pHEMT technology process provided by Win Semiconductor Crop.