This thesis describes the design and implementation of the baseband receiver for the IEEE 802.16-2004 Worldwide Interoperability for Microwave Access (WiMAX) wireless communications systems. Firstly, a Matlab floating-point simulation platform is built for system design. In addition to the transmitted signals and the channel models, the signal processing algorithms for the baseband receiver are verified to meet the system performance required by the standard. Then the receiver functional blocks, which include packet detection, timing synchronization, frequency synchronization, channel estimation, and the 256-point fast Fourier transform (FFT), are designed and integrated. Fixed point simulation is also conducted by using Matlab. The hardware implementation is realized by using the Verilog Hardware Description Language (HDL). Behavioral level and gate level simulations are also conducted to verify the system design. The design is downloaded to the Field Programmable Gate Array (FPGA) for system verification.

WiMax, the Worldwide Interoperability for Microwave Access is a new technology dealing with provision of data over long distance using wireless communication method in many different ways. Based on IEEE 802.16 WiMax is claimed as an alternative broadband rather than cable and DSL. In our thesis study we will findout the phenomenon and factors involved in WiMax handover and their effect on overall quality of service. We also intend to look into the solutions possible for those problems effecting WiMax QoS in handover. Handover is the main theme of wireless technolgy and it makes interoperability between diffrent network technologies and provides mobility. However there are some problems during handover and the problem in our focus will be handover delay. Handover delay if longer than expected makes the communication faulty and introduces errors and packet loss which in turns degrade QoS in WiMax

Wireless broadband networks (such as WiMAX) provide more bandwidth for video streaming applications. However, too many streaming services over WiMAX would lead to congestion in the wireless links. How to relax the traffic on WiMAX links and provide users with a better QoS of streaming services is a worthy studying problem. In this thesis, we propose packet replication and duplication mechanisms for video streaming with the same connection requests to decrease traffic load over WiMAX links. Besides, we propose admission control and low-priority dropping mechanisms for video streaming with different priority levels. We reject low-priority video requests to guarantee QoS for high-priority video streams. If the network is congested, we decrease the bit rate through statistically dropping the low-priority video packets, which consequently improves the quality of high-priority video streams. A subscriber gateway is implemented on Linux platform to demonstrate the above-mentioned three mechanisms. In the implementations, we classified the video priority levels and developed a scheme to drop low-priority packets in a multimedia streaming server. Finally, from the experimental results, we have shown that our mechanisms can decrease the traffic load over WiMAX links and provide users with different levels of service quality in multimedia streaming.

Esta memoria tiene como objetivo general crear esquemas de troubleshooting para tecnologías de acceso, en particular, para la tecnología Ethernet y para WiMAX, que corresponde a una tecnología inalámbrica que está entrando en el mercado como una buena alternativa para los proveedores de servicios. Para complementar el trabajo en WiMAX se estudian distintos tipos de enlaces inalámbricos, en donde las fallas son similares sobre todo en la capa física.

Approved for public release / The proliferation of Fourth Generation (4G) mobile wireless networks has led to an increased demand for position-based services. In many densely populated environments, there is an abundance of base stations by which a mobile station may be passively geographically located (geolocated) using various techniques that require multiple base stations. Areas in which base station density is sparse may not possess the requisite number of base stations to perform such techniques and, therefore, require different methods by which to geolocate mobile stations. In this thesis, we present a passive geolocation scheme that only requires observation of the initial ranging information exchange between a mobile station and a single base station in order to determine a position estimate for the mobile station. The scheme is specifically applied to the Institute of Electrical and Electronics Engineers (IEEE) 802.16 Worldwide Interoperability for Microwave Access (WiMAX) 4G standard. The method is validated through computer simulation and field experimentation in an Alcatel-Lucent IEEE 802.16e-2005 deployed network. The mean geolocation error resulting from simulation and experimentation was 85 meters, which is a degradation of 58 meters compared to a three-base station scenario. / Captain, United States Marine Corps

Error free transmission is one of the main aims in wireless communications. With the increase in multimedia applications, large amount of data is being transmitted over wireless communications. This requires error free transmission more than ever and to achieve error free transmission multiple antennas can be implemented on both stations i.e. base station and user terminal with proper modulation scheme and coding technique. The 4th generation of wireless communications can be attained by Multiple-Input Multiple-Output (MIMO) in combination with Orthogonal Frequency Division Multiplexing (OFDM). MIMO multiplexing (spatial multiplexing) and diversity (space time coding) having OFDM modulation scheme are the main areas of focus in our thesis study. MIMO multiplexing increases a network capacity by splitting a high signal rate into multiple lower rate streams. MIMO allows higher throughput, diversity gain and interference reduction. It also fulfills the requirement by offering high data rate through spatial multiplexing gain and improved link reliability due to antenna diversity gain. Alamouti Space Time Block Code (STBC) scheme is used with orthogonal designs over multiple antennas which showed simulated results are identical to expected theoretical results. With this technique both Bit Error Rate (BER) and maximum diversity gain are achieved by increasing number of antennas on either side. This scheme is efficient in all the applications where system capacity is limited by multipath fading.

3G and WiMAX are two main streams in the existent broadband wireless access technologies. It has been 6 years since the 3G license be released in October, 2001. 3G enters the market much earlier; it not only extends the mobility of 2G, but combines the advantage of sounds, data, and image. But so far, it still can¡¦t inspire customer¡¦s demand. On the other hand, with the power of Intel, the new technology, WiMAX intends to adopt the successful experience of WiFi into the market of broadband wireless access technologies. WiMax can also offer triple-play, even lower cost, and faster transfer. When these two similar technologies both exist in the market, will they be complementary or mutually exclusive? This question will be discussed in the paper. The conclusion is, after comparing 3G with WiMAX, figuring out 6 key factors that would affect the co-competition. 1.the time of technology competition 2. segmentation of services 3. demand of customers 4.market orientation and strategy 5. policy of government 6. building ecological system. Basically speaking, when WiMAX moves toward 3G, the market share is depended on technology maturity, entrance time, using habit of customers, and cost advantage of product.

Fixed Broadband Wireless Access (BWA) for the last mile is a promising technology which can offer high speed voice, video and data service and fill the technology gap between Wireless LANs and wide area networks. This is seen as a challenging competitor to conventional wired last mile access systems like DSL and cable, even in areas where those technologies are already available. More importantly the technology can provide a cost-effective broadband access solution in rural areas beyond the reach of DSL or cable and in developing countries with little or no wired last mile infrastructure. Earlier BWA systems were based on proprietary technologies which made them costly and impossible to interoperate. The IEEE 802.16 set of standards was developed to level the playing field. An industry group the WiMAX Forum, was established to promote interoperability and compliance to this standard. This thesis gives an overview of the IEEE 802.16 WirelessMAN OFDM standard which is the basis for Fixed WiMAX. An in depth description of the medium access control (MAC) layer is provided and functionality of its components explained. We have concentrated our effort on enhancing the performance of Fixed WiMAX for VoIP services, and best effort traffic which includes e-mail, web browsing, peer-to-peer traffic etc. The MAC layer defines four native service classes for differentiated QoS levels from the onset. The unsolicited grant service (UGS) class is designed to support real-time data streams consisting of fixed-size data packets issued at periodic intervals, such as T1/E1 and Voice over IP without silence suppression, while the non-real-time polling service (nrtPS) and best effort (BE) are meant for lower priority traffic. QoS and efficiency are at opposite ends of the scale in most cases, which makes it important to identify the trade-off between these two performance measures of a system. We have analyzed the effect the packetization interval of a UGS based VoIP stream has on system performance. The UGS service class has been modified so that the optimal packetization interval for VoIP can be dynamically selected based on PHY OFDM characteristics. This involves cross layer communication between the PHY, MAC and the Application Layer and selection of packetization intervals which keep the flow within packet loss and latency bounds while increasing efficiency. A low latency retransmission scheme and a new ARQ feedback scheme for UGS have also been introduced. The goal being to guarantee QoS while increasing system efficiency. BE traffic when serviced by contention based access is variable in speed and latency, and low in efficiency. A detailed analysis of the contention based access scheme is done using Markov chains. This leads to optimization of system parameters to increase utilization and reduce overheads, while taking into account TCP as the most common transport layer protocol. nrtPS is considered as a replacement for contention based access. Several enhancements have been proposed to increase efficiency and facilitate better connection management. The effects of proposed changes are validated using analytical models in Matlab and verified using simulations. A simulation model was specifically created for IEEE 802.16 WirelessMAN OFDM in the QualNet simulation package. In essence the aim of this work was, to develop means to support a maximum number of users, with the required level of service, using the limited wireless resource.

Zugl.: Dresden, Techn. Univ., Diss., 2009

Broadband Wireless Access technologies have significant market potential, especially the WiMAX protocol which can deliver data rates of tens of Mbps. Strong demand for high performance WiMAX solutions is forcing designers to seek help from multi-core processors that offer competitive advantages in terms of all performance metrics, such as speed, power and area. Through the provision of a degree of flexibility similar to that of a DSP and performance and power consumption advantages approaching that of an ASIC, coarse-grained dynamically reconfigurable processors are proving to be strong candidates for processing cores used in future high performance multi-core processor systems. This thesis investigates multi-core architectures with a newly emerging dynamically reconfigurable processor – RICA, targeting WiMAX physical layer applications. A novel master-slave multi-core architecture is proposed, using RICA processing cores. A SystemC based simulator, called MRPSIM, is devised to model this multi-core architecture. This simulator provides fast simulation speed and timing accuracy, offers flexible architectural options to configure the multi-core architecture, and enables the analysis and investigation of multi-core architectures. Meanwhile a profiling-driven mapping methodology is developed to partition the WiMAX application into multiple tasks as well as schedule and map these tasks onto the multi-core architecture, aiming to reduce the overall system execution time. Both the MRPSIM simulator and the mapping methodology are seamlessly integrated with the existing RICA tool flow. Based on the proposed master-slave multi-core architecture, a series of diverse homogeneous and heterogeneous multi-core solutions are designed for different fixed WiMAX physical layer profiles. Implemented in ANSI C and executed on the MRPSIM simulator, these multi-core solutions contain different numbers of cores, combine various memory architectures and task partitioning schemes, and deliver high throughputs at relatively low area costs. Meanwhile a design space exploration methodology is developed to search the design space for multi-core systems to find suitable solutions under certain system constraints. Finally, laying a foundation for future multithreading exploration on the proposed multi-core architecture, this thesis investigates the porting of a real-time operating system – Micro C/OS-II to a single RICA processor. A multitasking version of WiMAX is implemented on a single RICA processor with the operating system support.