寬頻分碼多工系統之速率調整機制及功率控制之最佳化設計

Abstract

3G的通訊時代即將來臨，其中最為吸引人之處為提供多種傳輸速率的服務，隨著多種傳輸速率可供選擇，如何配合傳輸功率，選擇最適當傳輸速率變成眾人最有興趣的問題之一。如果能夠針對這個問題，得到出色的解決方法，則可以預見在傳輸量，系統容量，都有顯著的提升。 這篇論文就是要設計整合傳輸功率控制和傳輸速率的演算法，針對設計的演算法，尋求適當的參數，以期得到最佳的傳輸表現，並且解決功率控制中target Eb/No設定的問題，使整套演算法更為完整，得以在真實系統中呈現其傑出的表現。 論文的第一部份，我們假設已知通道特性，針對通道特性選取最適當的target Eb/No給傳輸功率控制機制。再參考3GPP的粗略指導方針提出了Constrained Power Based Rate Adaptation algorithm，其特色在於同時考慮傳輸功率控制，傳輸速率控制，並且可以非常有效的使用傳輸功率。 第二部份則是在不知通道特性的情況下，為滿足需要的FER，而設計了Turbo code iteration based dynamic target Eb/No setting algorithm。以較少量的傳輸功率，便能得到相同的FER，此特性令人印象深刻。 第三部份則是把第二部份的演算法做了些改變，使得Constrained Power Based Rate Adaptation algorithm即使在未知通道特性的情況下，亦能只需花費少量的時間即找出適當的target Eb/No。如此一來，Constrained Power Based Rate Adaptation algorithm將可以在實際系統中展現其突出性能。

Abstract Third generation systems are designed for multirate communication, it’s the most charming part of third generation. How to combine power control and choosing the suitable data rate is one of the most popular issues. If we can find an excellent solution for this problem, we believe we will have an obvious promoting in throughputs and system capacity. Design power control and rate control algorithm jointly is the main point of this work. Searching the suitable parameters that need for our algorithm to improve the performance. And we discuss how to set the target Eb/No in power control mechanism to complete the whole algorithm. Then we can apply this algorithm in real system and see its impressive performance in real worlds. At the beginning of this paper, we assume the suitable target Eb/No for certain channel is known. And we refer the guidelines in 3GPP to design “Constrained Power Based Rate Adaptation algorithm”. This algorithm considers power and rate control jointly, and using transmission power very efficiently. In the second part of this paper, we proposed “FER estimation based dynamic target Eb/No setting algorithm” to satisfy required FER when the channel is unknown. The impressive point of this algorithm is using less power to satisfy required FER. At the last part, we modify “FER estimation based dynamic target Eb/No setting algorithm” then we can use a short time to find suitable target Eb/No for “Constrained Power Based Rate Adaptation algorithm” even the characteristic of the channel is unknown. Therefore, “Constrained Power Based Rate Adaptation algorithm” can show it’s excellent performance in real system.