Cross Layer Scheduling in WiMAX QOS for Disaster Management

How a base station assigns free resource slots to BE service class is depending on the available channel bandwidth after all the other classes have been served. Generally, it is known that the performance of BE is always the worst and provides the lowest level of quality compared to all other classes. However, if somewhat unexpected natural disaster strikes or an environmental catastrophe occurs, when the major communication infrastructure has been destroyed, it is possible that the only available Quality of Service (QoS) service is BE. Under this condition, users or, particularly, a rescue team will not have any other options but to use the only available service class for any types of applications including voice communications or even video communications. Based on that scenario, we have performed simulations using OPNET modeler simulation tool to evaluate the rtPS and BE performance with particular focus on video conferencing/streaming and also data transfer applications. Simulation results show that in certain situations, a user with BE QoS could provide better throughput compared to a user with rtPS. In addition, we also propose a cross layer scheduling mechanism by assigning the video conferencing/streaming application to BE service class and file transfer application to the rtPS service class.  The results obtained indicate that for certain combinations of users and QoS, BE service class demonstrates a higher throughput than rtPS. This scenario can be practically applied by a rescue team in any disaster management operations apart from normal teleconference service

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