| Summary: | 碩士 === 國立東華大學 === 資訊工程學系 === 89 === Cellular Communication has become the fastest growing segment of the communications industry over the past decade. The introduction of 3G broadband properties has contributed to the increase in cellular data communications. Multimedia applications are expected to become widespread on 3G systems. In future, Code Division Multiple Access (CDMA) systems with the ability of high transmission rate in multimedia traffics and privacy properties will be the best choose for transmission heterogeneous traffics.
In 3G systems, to support a diverse mix of traffic with diverse QoS requirements, we need a perfect mechanism to schedule traffic resources to avoid system congestion or miss the QoS requirements. To provide high QoS in cellular data communications, we will propose a problem-solving mechanism from the transmitter-end.
In this thesis, we proposed a novel architecture, Feedback WFQ (F-WFQ) to provide QoS guarantee. Three functional modules are developed: a scheduling module, network module and feedback module, respectively. Two elements are contained in the scheduling module, an adjustment element and WFQ element. The adjustment element compensates for the penalty derived from the interferences and location-dependent errors using the equivalent throughput concept and estimation theory. The WFQ element contains the Call Admission Control (CAC) and the queuing system, which will decide accept or reject a call. The CAC function will try to reduce the dropping rate of non real-time traffic under high system load.
Our scheduling module and network module are placed in the feedback module, which graceful performance in scheduling, system integration and high flexibility will be obtained. Numerical results show that more accuracy and graceful curves in controlling the transmission delay for real-time traffics will be obtained under our strategy. The dropping rate is reduced for non real-time traffics as well. Short-term fairness and throughput are guaranteed in error free environment by using WFQ scheme. Once the link errors occur, the compensation mechanism will reduce the transmission delay in the tolerant to 5% variation with QoS requirement. For the non real-time traffics, we will maintain the minimum bandwidth utilization to reduce the dropping rate. By strengthening the transmitter-end, 3G systems will maintain high utilization, low delay experienced by the users and generate a fair schedule for a diverse mix of traffic with diverse QoS requirements in a limited radio spectrum. A high quality, high sharing, and high fairness 3G cellular data service environment is thereby constructed.
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