Adaptive radio resource allocation to support unicast/multicast transmission schemes

Abstract

Wireless communications have become one of key technologies in modern society. Many users demand wireless services equivalent to high-speed wireline services provided at home. In order to fulfill this demand, future wireless communication systems will require to guarantee quality of service (QoS) requirement, system capacity enhancement, and efficient spectrum utilization. Since radio resources for wireless communications are very limited, various wireless transmission schemes to guarantee various QoS requirements should share the limited radio resources. In order to enhance the spectrum efficiency, radio resources should be allocated dynamically according to varying transmission characteristics and users` channel states. Future mobile communication systems are also expected to improve the system performance and spectrum utilization efficiency through a new cognitive radio technology. In this dissertation, we first consider a wireless communication system supporting both multicast and unicast services. We provide a mathematical analysis framework for evaluating unicast and multicast transmission schemes. The unicast transmission scheme makes full use of channel variation of each user, while the multicast transmission scheme utilizes multicasting within a communication range. Our analysis shows that cell radius and the number of users in a cell affect the performance of the unicast and multicast transmission schemes. Delay-tolerant and large-sized packet services are proper for the unicast transmission, while delay-sensitive and small-sized packet services are appropriate for the multicast transmission. We also propose a novel adaptive scheduling scheme for mixed multicast and unicast traffic in cellular systems in order to utilize radio resources more efficiently and compare the system performance of the proposed scheme with that of the conventional scheme. In order to transmit data to a wireless user group more efficiently, the system needs to select a trans...