2 research outputs found
An improved resource allocation scheme for WiMAX using channel information
In recent years, tremendous progress has been made in wireless communication systems to provide wireless coverage to end users at different data rates. WiMAX technology provides wireless broadband access over an extended coverage area in both fixed and mobility environments. Most of the existing resource allocation schemes allocate resources based on respective service class of the incoming users’ requests. However, due to variation in channel conditions, user mobility and diverse resource requirements QoS based resource allocation either results in over or under utilization of allocated resources. Therefore, resource allocation is a challenging task in WiMAX. This research proposes an improved resource management mechanism that performs resource allocation by taking into consideration not only the user service class but also the respective channel status. Based on these two parameters, this research aims to achieve improved resource allocation in terms of resource utilization, fairness and network throughput. First, a Channel Based Resource Allocation scheme is introduced where priority in resource allocation is given to users’ requests with relatively higher service classes and better channel status. To maintain fairness in resource allocation process, a Fair Resource Allocation Based Service mechanism is developed where priority is given to users’ requests having less additional resources demand. Finally, to improve throughput of the network, a Channel Based Throughput Improvement approach is proposed which dynamically selects a threshold level of channel gain based on individual channel gain of users. During resource allocation process, users above the threshold level are selected for resource allocation such that priority is given to users with high channel gain. Different simulation scenario results reveal an overall improved resource utilization from 87% to 91% and the throughput improves up to 15% when compared to existing schemes. In conclusion the performance of resource utilization is improved if channel status is considered as an input parameter
A Novel Approach for Implementing Worldwide Interoperability for Microwave Access for Video Surveillance
Video surveillance applications have experienced an increase in demand over the last decade. Surveillance
systems can easily be found in places such as commercial offices, banks and traffic intersections, parks and
recreational areas. Surveillance applications have the potential to be implemented on a WiMAX (Worldwide
Interoperability for Microwave Access) network. Moreover, WiMAX devices have been used widely in the
market and WiMAX-based video surveillance products have also been available. As a radio technology,
WiMAX is a wireless broadband system that offers greater capacity than WiFi networks and wider coverage
than cellular networks.
The acceptance of WiMAX in the market, the availability of WiMAX products and its technology excellence,
contribute to the possibility of implementing it for surveillance application. However, since WiMAX is designed
to accommodate various applications with different quality of service (QoS) requirements, dedicated surveillance
network implementation of WiMAX may not achieve optimum performance, as all Subscriber Stations (SSs)
generate the same QoS requirements.
In the medium access (MAC) layer, this thesis proposes a bandwidth allocation scheme that considers the QoS
uniformity of the traffic sources. The proposed bandwidth allocation scheme comprises a simplified bandwidth
allocation architecture, a packet-aware bandwidth request mechanism and packet-aware scheduling algorithms.
The simplified architecture maximizes resources in the Base Station (BS), deactivates unnecessary services and
minimizes the processing delay. The proposed bandwidth request mechanism reduces bandwidth grant and
transmission delays. The proposed scheduling algorithms prioritize bandwidth granting access to a request that
contains important packet(s). The proposed methods in the MAC layer are designed to be applied to existing
devices in the market, without the necessity to change hardware.
The transport protocol should be able to deliver video with sufficient quality while maintaining low delay
connectivity. The proposed transport layer protocol is therefore designed to improve the existing user datagram
protocol (UDP) performance by retransmitting packet loss selectively to increase the received video quality, and
utilizing MAC support to achieve low delay connectivity.
In order to overcome the limitations of the lower layers, this thesis employs a rateless code instead of transport
layer redundancy in the application layer. Moreover, this thesis proposes post-decoding error concealment
techniques as the last means to overcome packet loss.
To evaluate the performances of the proposed methods, simulations are carried out using NS-2 simulator on
Linux platform. The proposed methods are compared to existing works to measure their effectiveness. To
facilitate the implementation of the transport layer protocols in practical scenarios, UDP packet modification is
applied for each transport layer protocol.Indonesian Directorate General of Higher Education (DGHE/DIKTI