載波聚合正交分頻多工系統下基於參數通道模型之多路徑衰減通道估測

Estimation of Multipath Fading Channels for Carrier Aggregation OFDM Systems Based on Parametric Channel Modeling

鄭舜文(Shun-Wun Cheng)

指導教授 ： 蘇柏青

國立臺灣大學/電機資訊學院/電信工程學研究所/碩士(2012年)

https://doi.org/10.6342/NTU.2012.02482

摘要

為了克服在無線通訊系統中的多路徑衰弱，通道估測扮演了非常重要的腳色。此外，我們經常運用正交分頻多工(OFDM) 系統來減少多路徑衰弱的干擾。近來載波聚合(CA) 是一個直接了當的解決方案來提供使用者更多的傳輸頻寬。因此，本論文探討載波聚合正交分頻多工系統下之引導數據輔助(pilot-aided) 通道估測。我們提出了一種在載波聚合正交分頻多工系統下基於參數通道模型之引導數據輔助通道估測。我們的方法是基於參數通道估測器。具體一點來說，首先運用最小描述長度(MDL) 準則來判斷路徑數目。接著藉由旋轉不變性之信號參數估測技術(ESPRIT) 來估測多路徑時間延遲。有了多路徑時間延遲的資訊後，最小均方誤差(MMSE) 估測器被用來估測多路徑增益。在上述的過程中，我們運用不同傳輸頻帶之間的合作以及路徑數目低估的補償來提升通道估測的效能與減少運算複雜度。最後，當適當的非時變通道模型被選擇時，模擬結果顯示了我們提出的方法優於前人所提出的方法。

關鍵字

載波聚合 ； 數據輔助通道估測 ； 參數化通道模型

並列摘要

In order to overcome the multipath fading, channel estimation plays a very important role on the wireless communication systems. Besides, we usually apply orthogonal frequency division multiplexing (OFDM) systems in wireless transmissions because of its advantage in lessening the effect of the multipath fading. Carrier aggregation (CA) is recently a direct solution for providing users with wider transmission bandwidth. Thus, pilot-aided channel estimation for CA OFDM systems is considered
in this thesis. We proposed a pilot-aided channel estimation based on parametric channel modeling for CA OFDM systems. Our approach is based on the parametric channel estimator. Specifically, we first use the minimum description length (MDL) criterion to determine the number of paths in the channel. Then, we exploit the estimation of signal parameters by rotational invariance techniques (ESPRIT) to estimate the multipath time delays. With information of the multipath time delays, a minimum mean-square-error (MMSE) estimator is used to estimate the multipath gains.
In the above-mentioned process, we combine it with the cooperation between different transmission bands and the compensation of path underestimation for improving the
channel estimation performance and reducing the computational complexity. Finally, simulation results show that the proposed method outperforms previously reported
methods when the channel model is properly chosen and is time-invariant.

並列關鍵字

Carrier aggregation ； Pilot-aided channel estimation ； Parametric channel modeling

參考文獻

[1] B. Yang, K. B. Letaief, R. S. Cheng, and Z. Cao, “Channel estimation for OFDM

transmission in multipath fading channels based on parametric channel modeling,”

IEEE Transactions on Communications, vol. 49, no. 3, pp. 467–479, 2001.

[2] H. Sari, G. Karam, and I. Jeanclaude, “Transmission techniques for digital terrestrial

100–109, 1995.