合作式通訊之適應性混合式自動重傳機制

An Adaptive HARQ Scheme for Cooperative Communication

徐志強(Chih-Chiang Hsu)

指導教授 ： 林信標

國立臺北科技大學/電資學院/電腦與通訊研究所/碩士(2010年)

https://doi.org/10.6841/NTUT.2010.00064

摘要

手持式消費性電子產品(如Smartphone、Notebook等)的普及，伴隨著行動商務與豐富的多媒體娛樂需求日益增加，使得在無線通訊上傳輸速率與傳輸品質變的非常重要。因此如何隨時保持最高的傳輸速率與品質是一個重要的課題。錯誤控制是一種能解決上述議題的機制，錯誤更正碼及自動重傳請求是兩種在無線通訊中被廣泛應用的錯誤控制機制。混合自動重傳請求機制結合上述兩種機制以提升系統的吞吐量。而另一種能提升系統的效能的技術為合作式通訊，其是使用中繼站來輔助傳輸，藉由空間分集的方式提高系統的吞吐量。
本論文分別探討混合式自動重傳請求機制應用於合作通訊系統的吞吐量，並分析彼此優缺點與使用時機。本論文再根據所提出的以一種萊斯通道 參數來代表通道品質指標，並利用此 參數的大小對混合式自動重傳請求機制進行適應性的切換，使得傳輸時可以在能接受的錯誤率範圍內達到最高的資料吞吐量。
此外，為了降低手持裝置的功率消耗，本論文提出一種修正型Type-III HARQ，藉由通道環境品質來決定Type-III HARQ是否將收到的封包直接解碼並當解碼錯誤時合併之前封包再重新解碼還是不先解碼先合併再解碼，以降低Type-III HARQ的運算複雜度。從模擬圖可以顯示出修正型Type-III HARQ在低SNR與K值的時候，能提供比Type-II HARQ高的吞吐量。因此，根據減少運算複雜度(減少解碼次數)這個優點來看，Type-III HARQ可減少手持裝置的功率消耗。

關鍵字

混合式自動重傳請求機制 ； 合作通訊

並列摘要

The recent rapid growth in consumer electronic products, e.g. smart phone, notebook, has led to the great deal of demands for mobile commerce and multimedia entertainment. Also, transmit rate and quality become more and more importance. Hence, in order to achieve such demands, maximum transmit rate and reliable quality are very importance issue. For solving above problem, error control is the most adopted scheme. There are two basic error control schemes, namely Automatic Repeat Request (ARQ) and Forward Error Correction (FEC), applying in wireless communication, extensively. For achieving higher throughput, HARQ scheme combines FEC and ARQ technologies. The other solution to enhance performance is cooperative communication, which increases system throughput utilizing spatial diversity by cooperating with relay station.
The throughput for HARQ schemes applying in cooperative communication system are investigated in this paper. Then, we analyze their advantage and disadvantage, and compute the suitable using time by switching each other. Further, for representing the Channel Quality Indicator (CQI), this paper proposes one kind of K factor based on Rician fading. Then, according to this K factor, we can adaptive switch these HARQ schemes. The computer simulation confirms that these scheme can achieve maximum throughput under suitable error rate.
In addition, to lower power of handhold devises, this paper proposes an improved Type-III HARQ. For reducing the complexity of Type-III HARQ, under given CQI, there are two technologies can be chosen. One is decoding the package directly, but when the result of the decoded package is error, the retransmitted package would be combined with pre-package, then decoding again. The other is directly combined with pre-package and then decoding. Then, the simulation results show that at lower SNR and K factor, this improved Type-III HARQ can provide higher throughput than Type-II HARQ. Then, according to this advantage of reducing complexity, i.e.it lower decoding times, Type-III HARQ can lower power of handhold devises.

並列關鍵字

HARQ ； Cooperative Communication

參考文獻

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