群播可以有效率的傳送同一份訊息給多個接收者並且減少系統資源的使用效率。而在群播系統中，為了確保群播群組裡面的接收者全部可以完全接受到資料，傳送端會根據群播群組裡面接收者中通道狀況最差的接收者去決定我們的傳輸資料速率。群播運用的好處像是現今的多媒體以及資料服務廣泛的運用在３Ｇ無線資料網路。而現在的問題在於如何分組接收者，來達到我們資料總傳輸量的最大化。而最大的群組尺寸能讓總傳輸量達到最大，這是在一個連續型傳送資料速率的情況之下討論的結論，可是在實際系統中，我們通道資料傳送速率是離散型的，而我們也經由此論文發現到，使用離散型和連續型的傳送資料速率會有截然不同的結論。所以在此論文將探討在離散型資料傳送速率下，如何決定群組尺寸，來使我們的總傳輸量達到最大。經由我們定理分析，我們證明了我們最佳的群組尺寸會隨著我們基地台的傳送功率變大而隨之變大，而且我們將會找到的最佳群組尺寸，可以使我們的總傳輸量達到最大。而我們最後也經由模擬證明我們的分析。

Multicast is an efficient transmission scheme for the same content to multiple receivers while minimizing networks resource usage. In multicast systems, the transmitter adapts its data rate to the worst channel among all users in the multicast group, so as to guarantee service quality to each user. Applications that can benefit from multicast, such as multimedia streaming and data services, are now being deployed over 3G wireless data networks. A natural question that arises is how to group users in order to maximize the total throughput of multicast systems. In convention, the maximum group size can maximize the system throughput. However, this conclusion is based on one condition of continuous-rate assignment. In practical systems, the assigned data rate on each subchannel must be discrete. Therefore, in this thesis, how to group users or determine the group size under considering discrete-rate assignment is studied. Through theoretical analysis, we prove that the optimal size in a multicast group increases with the increasing transmission power from the base station. Moreover, by the proposed optimal group size, the achieved throughput in multicast systems is maximized. Our analysis is validated through simulations.

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