考慮分槽式及實體層網路編碼之交織多重接取

Access Request of IDMA using Slotted ALOHA and PLNC

葉怡賢(I-Hsien Yeh)

指導教授 ： 林茂昭

國立臺灣大學/電機資訊學院/電信工程學研究所/碩士(2015年)

https://doi.org/10.6342/NTU.2015.11304

摘要

交織多重接取系統是一種處理多重接取的技術，透過每個用戶使用不同的交織器資源去傳送資料。實體層網路編碼原應用於雙向中繼設備網路，它可以有效的提升整體系統的吞吐率。
在本論文中，我們結合了交織多重接取系統與實體層網路編碼技術，來處理隨機接取中碰撞的問題。我們會分別介紹交織多重接取系統與實體層網路編碼。在交織多重接取系統中，我們會分析實數及複數通道的情況，再介紹實體層網路編碼應用於二相位偏移調變以及四相位偏移調變。在交織多重接取系統用戶進行隨機接取請求時，可能會發生不同用戶同時選擇同樣的交織器(interleaver)資源，在此篇論文中我們稱之為碰撞。在原本的交織多重接取系統下，碰撞發生時，除碰撞的封包解不回來外，非碰撞封包需要增加展頻碼的長度，等同於降低碼率才有機會解回。我們透過加入實體層網路編碼的概念，去解決上述的問題並提高效能，不僅維持原本的碼率，並解回非碰撞的封包，且碰撞的封包資訊也有機會解回。最後我們延伸至通道估計，以利此系統的實際應用。

關鍵字

交織多重接取 ； 實體層網路編碼 ； 隨機接取 ； 通道編碼

並列摘要

Interleave Division Multiple Access (IDMA) is a type of multiple access communication techniques. In IDMA system, user specific interleavers are employed to separate from on user to another. It has been shown that IDMA can provide high spectral efficiency. Physical Layer Network Coding (PLNC) is originally used in a physical-layer network coded two-way relay system. It can help increase transmission throughput. In this thesis, we will combine IDMA and PLNC techniques to deal with the collision problems on random access request stage. We thoroughly introduce IDMA system and PLNC system separately. In respect of IDMA, we will discuss about real channel and complex channel scenarios. Secondly, we analyse and implement PLNC with different modulations including BPSK and QPSK modulations. We consider that the above two techniques will help in respect of access request in IDMA slotted Aloha.
When the users in IDMA system choose the same interleaver, we call this situation as collision in this thesis. In collision situation, the packets of original IDMA users who access to the same interleaver will be discarded and obey exponential back off algorithm for retransmission. Originally, IDMA receiver may not decode the non-collision packets correctly without increasing spreading length. In order to enhance the successful rate in collision situation of multiple access system's, we perform PLNC techniques to decode the collision packets. It can not only maintain the data rate but also, with high probability, decode the collision packets. Finally, we extend the IDMA principle in resect of channel estimation in IDMA systems.

並列關鍵字

Interleave division multiple Access ； physical layer network coding ； random access ； channel estimation

參考文獻

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