| Summary: | 博士 === 國立成功大學 === 電機工程學系碩博士班 === 91 === Nowadays, in the evolution toward the next-generation mobile system, a wide range of services (such as high quality voice, data, electronic mail, facsimile, video and interactive applications) has imposed itself as an essential demand of the universal communications. To efficiently utilize the radio resource of mobile systems and provide services of high quality for all users, radio resource management has become a noticeably important issue in a service-integrated mobile cellular system. Therefore, we are motivated to investigate and develop resource-allocation strategies for integrated services in mobile cellular systems. The most principal concept of the proposed strategies is to schedule the data transmissions in accordance with the load of voice traffic and to ensure the predefined quality of service (QoS) requirements of all connections.
In this dissertation, we first propose a resource-allocation strategy to integrate packet-switched data traffic into current TDMA-type circuit-switched digital voice system. This integrated system transmits data packets during the silent periods of a conversation with voice activity detection and adapts itself to GSM/GPRS system which uses the idle channels to provide data service. We show that the proposed strategy can increase the bandwidth utilization efficiency and improve throughput/delay performance of the data transmission, while minimize he impacts on current GSM/GPRS system. Then, we study the effect of voice activity on the system performance in a voice-oriented CDMA sys-tem. We present a general analytical methodology to evaluate the capacity gain due to voice activity and the time duration of idle period of multiaccess link. It is demonstrated that a lot of unused capacity and a long enough idle period of multiaccess link can be employed to send the packet-switched data traffic. Last, we investigate the resource-allocation strategy for an integrated voice/data cellular CDMA system. The delay-sensitive voice traffic has a higher priority to use the channel resource, whereas the error-sensitive data traffic has a higher priority to use the power resource. Three power resource allocation schemes are compared: equal power scheme, equal service-reliability scheme, and robust data scheme. By means of the power resource allocation and the admission control, the sys-tem can offer different service reliability (and QoS) to voice and data services. The concept of guard channel is used as interference margin to improve the service reliability. This integrated CDMA sys-tem is analyzed for two cases : 1) system with .xed length data traffic and 2) system with variable length data traffic. Different from the former one, the system with variable length data traffic employs a two-level admission control policy, which consists of a call-admission control and a packet-level admission control, and adopts a dynamic guard-channel scheme to tune the system performance.
|
|---|
