WiMAX Wireless Networks Research Articles

State of the Art on Video Streaming and Applications

The real-time and live video streaming are playing an important role in our daily lives; therefore enhancing the quality of real-time and live video streaming over wired and wireless packet erasure networks which becomes more and more important topic nowadays. The main objective of this tutorial paper is to highlight state of the art on video streaming and the most important methods for enhancing video streaming over wired and wireless packet erasure networks to the computer/communication engineering students and new researchers. Firstly, it presents an overview of layered coding compression techniques (like: H.264/SVC) which lead to better real-time video streaming quality than single layer coding techniques (like: H.264/AVC). Secondly, it highlights how to solve the channel errors and lost packets problems in video streaming via implementing some of Forward Error Correction (FEC) techniques. Furthermore, it presents Backward Error Correction (BEC) techniques for enhancing the video streaming. After that it talks about the implementation of rateless FEC techniques with feedback for solving the real-time and live video streaming issues. Then it presents some recent researches on the Unequal Error (or Loss) Protection (UEP) techniques which are more powerful and achieve better Peak Signal to Noise Rate (PSNR) than the previous Equal Error Protection (EEP) techniques. Also it highlights the adaptive UEP scheme which brings significant improvements in terms of average PSNR over static UEP scheme for same used bandwidth. Furthermore, it talks about the multipath video streaming which leads to better loss characteristics and better load distribution on wireless networks than the single path video streaming. Finally, it presents some recent researches that based on hybrid solution of rateless FEC and advanced BEC techniques for enhancing the real-time and live video streaming quality over 3G, Wi-Fi and WiMAX wireless networks.

Design and Development of an Efficient EBG Structures Based Band Notched UWB Circular Monopole Antenna

Band notched circular monopole antennas for ultra-wide band applications are proposed in this paper. The proposed antennas in this paper can reject worldwide interoperability for microwave access WiMAX band (3.3–3.8 GHz) and wireless local area network WLAN band (5–6 GHz). Antennas utilises mushroom-type electromagnetic band gap (EBG) structures and I-slot embedded edge located via (ELV) EBG structures to achieve band-notched designs. The advantages of band notched designs using EBG structures like notch-frequency tuning, dual-notch antenna designs and stable radiation pattern are also verified. Various antenna designs with slot in EBG structures, variations in placement of EBG structures, number of EBG structures and ELV type EBG structures are simulated. About 30% reduction in size of EBG structures is obtained if conventional mushroom type EBG is replaced by proposed I-slot embedded ELV-EBG structure. Fabricated and measured results are in good agreement with simulated ones.

COUPLING MEASUREMENTS OF AN ANTENNA SYSTEM SUITABLE FOR RELAY-AIDED WIMAX NETWORK

In this paper two novel antennas, suitable for access and backhaul links, are designed, fabricated and tested for a Relay Station in a WiMAX wireless network. A single modifled E-shaped patch antenna is described, presenting 10dB gain over 12.4% bandwidth. This antenna element is used for the design of a 4 £ 4 planar array which provides experimental gain of 21.2dB. The antenna system on the Relay Station operates at 3.4GHz and includes one single antenna element for access link realization and an antenna array for the backhaul link realization. These antennas are installed in two conflguration arrangements and tested in terms of their radiation performances and coupling efiects. The simulated and measured results are quite satisfactory and in good agreement at which the maximum coupling between the access and backhaul antennas is found below i25dB for all tested cases.

Mobile WIMAX Wireless Network Planning Based on Optimization

Mobile WIMAX Wireless Network Planning Based on Optimization

A Host-based Fast Mobility Scheme (HFMS) in 802.16j Mobile RS Mode

As technologies for the high quality multimedia application and 4G WiMAX network prevail, one can easily be under services everywhere through WiMAX wireless network. However, the service disruption time (SDT) caused by handover procedure leads to an unacceptable quality of service (QoS) for mobile users, especially in IEEE 802.16j mobile relay station (MRS) mode. Therefore, we proposed a host-based fast mobility scheme (HFMS) in IEEE 802.16j MRS mode to reduce the SDT and solve the packet loss problem during handover via the cooperation between the MRS's link-layer and mobile station's (MS's) IP layer. In the proposed scheme, the MRS's link-layer will notify the MS's IP layer to perform IP layer handover procedure when the MRS performs link-layer handover. The parallel handover reduces the SDT efficiently. On the other hand, the proposed buffering mechanism can avoid packet loss. As a result, the seamless mobility and satisfactory QoE can be achieved for mobile users in IEEE 802.16j MRS mode.

Priority Based Scheduling in WiMAX System

In this paper, we propose an approach which combines the priority scheduling with the resource allocation over the WiMAX wireless network to increase the throughput and reduce the delay between the base station and subscriber stations. The simulation is conducted by using Network Simulator-2 to compare the performance of the proposed scheme with other scheduling schemes. The results show that our proposed scheme experiences acceptable delay for different serviceflow types as compared with other schemes. Furthermore, the uplink throughput of the proposed scheme is about 1.5 times better than other schemes.

A Service-Oriented Medical Framework for Fast and Adaptive Information Delivery in Mobile Environment

The need for fast treatment of patients in critical conditions motivates the use of mobile devices to provide prompt and consistent communication between hospitals and physicians. We propose a framework that supports ubiquitous access to medical systems using personalized mobile services and integrated medical systems. The proposed service-oriented medical framework provides dynamically composed services that are adapted to contextual variables such as the user's role, the network bandwidth, and resources available at mobile devices while supporting task allocation in distributed servers for massive resource-consuming services. It also manages accurate patient data by integrating local medical systems using medical information standards such as Digital Imaging and Communications in Medicine and Health Level 7. We have demonstrated the effectiveness of our framework by building a prototype of context-based adaptation of computerized tomography image retrieval for acute stroke treatments, which allows images to be viewed on mobile devices with WiMax wireless network. The proposed medical framework reduces hospital delays of patients and facilitates treatments in the absence of medical specialists.

Quality of Service and Max-Min Fair Transmit Beamforming to Multiple Cochannel Multicast Groups

The problem of transmit beamforming to multiple cochannel multicast groups is considered, when the channel state is known at the transmitter and from two viewpoints: minimizing total transmission power while guaranteeing a prescribed minimum signal-to-interference-plus-noise ratio (SINR) at each receiver; and a fair approach maximizing the overall minimum SINR under a total power budget. The core problem is a multicast generalization of the multiuser downlink beamforming problem; the difference is that each transmitted stream is directed to multiple receivers, each with its own channel. Such generalization is relevant and timely, e.g., in the context of the emerging WiMAX and UMTS-LTE wireless networks. The joint problem also contains single-group multicast beamforming as a special case. The latter (and therefore also the former) is NP-hard. This motivates the pursuit of computationally efficient quasi-optimal solutions. It is shown that Lagrangian relaxation coupled with suitable randomization/cochannel multicast power control yield computationally efficient high-quality approximate solutions. For a significant fraction of problem instances, the solutions generated this way are exactly optimal. Extensive numerical results using both simulated and measured wireless channels are presented to corroborate our main findings.