- 學位論文
WiMAX 下鏈通道估測之效能比較
The performance comparison of WiMAX downlink channel estimation
摘要
移動式網路將是未來網路發展的趨勢，然而行動通訊中，傳輸信號會因通道之影響而有振幅及相位之改變，因此一般接收機會藉通道估測來降低位元錯誤率。 有鑑於此，本論文希望比較若干通道估測之技術，以之評估彼此之相對優劣。通道估測分類比較方式將分為兩類 : 1. 一維通道估測 2. 二維通道估。這二類通道估測會使用各種車速以及訊雜比來比較其位元錯誤率。論文中所使用的資料傳輸規格為WiMAX IEEE 802.16e，移動通道模型為國際電信聯盟無線電通信組(ITU-R)的Vehicular - high antenna channel A及Vehicular - high antenna channel B，雜訊為AWGN。 實驗結果是頻域MMSE是效果最佳的通道估測。而在通道ITUR-3GVA，二維線性內插通估測法優於二維sinc內插通道估測法。在通道ITUR-3GVB，二維sinc內插通道估測法的效果比二維線性內插通估測法好。
並列摘要
Mobile network is the current trend of network development. In wireless communications, the transmission signals are altered due to the influence of the wireless channel and noise. To reduce the effect of the wireless channel the receiver needs to perform channel estimation to reduce the bit error rate. In view of this, we compare several channel estimation methods and present the experimental results in the thesis. Both one-dimensional channel estimation and two-dimensional channel estimation are used in comparison. The results are the performances of bit error rate and mean-square-error for various speeds and SNR(Signal-Noise-Ratio). The wireless communications system used in this thesis is IEEE 802.16e . The mobile channel model is Vehicular - high antenna channel A and Vehicular - high antenna channel B in ITUR 3G channel models, and the noise is additive white gaussian noise (AWGN). The experimental results show that the best channel-estimation method is the frequency domain MMSE. In ITUR-3GVA channel, 2D linear channel estimation is better than 2D sinc channel estimation. However, in ITUR-3GVB channel, 2D sinc channel estimation is better than 2D linear channel estimation. For different speeds, no method can constantly close to that of the ideal channel estimation.