臺灣博碩士論文加值系統

對於第五代蜂巢式系統通道估計時所面臨的領航訊號汙染問題，在本篇論文當中，我們提出了兩種有效的疊代式通道估計方法。因為領航訊號數目的限制，如果它們在不同的細胞中重複的使用，就會產生領航訊號汙染問題。我們所提出的的兩種疊代式方法是在疊代時分別只使用資料訊號、將領航訊號和資料訊號共用兩種不同方法來做通道估計。由於我們是採取領航訊號和資料訊號疊加的方式傳送訊號，所以在做通道估計時資料訊號也會成為干擾，我們所提出的方法可以讓資料訊號不再只是干擾而是對於通道估計有所幫助。模擬的結果顯示，我們所提出的方法能夠在適當的疊代次數下就到達理想的位元誤碼率。

In this thesis, we propose two kinds of iterative channel estimation method to suppress the pilot contamination phenomenon in 5G cellular mobile radio communication systems. Due to pilot sequence reuse in different cells, the estimated channel would be contaminated by neighboring cells which use the same pilot. To solve the pilot contamination problems caused by pilot sequence reuse, we first use estimated data sequence as a pilot signal to execute iterative channel estimation. Secondly, as the pilot and data sequences are transmitted in a combined manner, our second proposed method utilizes data sequence as an auxiliary pilot signal in addition to utilizing the orthogonal pilot signal when executing channel estimation. Our simulation results show that these methods can achieve the required BER performance within a acceptable number of iterations.

Contents
中文摘要 i
ABSTRACT ii
誌謝 iii
List of Figures vii
List of Tables ix
1 Introduction 1
1.1 Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1
1.2 Massive MIMO . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3
1.2.1 Massive MIMO channel state information . . . . . . . . . . . . . . 4
1.2.2 Pilot contamination . . . . . . . . . . . . . . . . . . . . . . . . . . 4
1.3 Thesis Organization . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5
2 System Architecture 7
2.1 Uplink Transmission Structure . . . . . . . . . . . . . . . . . . . . . . . . . 7
2.2 Proposed 5G Channel Model . . . . . . . . . . . . . . . . . . . . . . . . . . 9
2.3 Generalized Orthogonal Sequence . . . . . . . . . . . . . . . . . . . . . . . 11
2.3.1 Characteristic of Generalized Orthogonal Sequence . . . . . . . . . 12
2.3.2 Generate Binary Generalized Orthogonal Sequences . . . . . . . . . 13
2.4 Gold Sequence . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15
2.4.1 Generate Gold Sequence . . . . . . . . . . . . . . . . . . . . . . . . 15
2.4.2 Characteristic of Gold Sequence . . . . . . . . . . . . . . . . . . . . 16
3 Uplink Channel Estimation and Data Detection 18
3.1 Uplink Communication Scheme . . . . . . . . . . . . . . . . . . . . . . . . 18
3.2 Channel Estimation and Data Detection in Uplink Communication . . . . 20
3.2.1 Uplink with Generalized Orthogonal Sequence . . . . . . . . . . . . 20
3.2.2 Uplink with Gold Sequence . . . . . . . . . . . . . . . . . . . . . . 24
3.3 Impact of Pilot to Data Power Ratio . . . . . . . . . . . . . . . . . . . . . 27
3.3.1 Impact of P2DR with Generalized Orthogonal Sequence . . . . . . 27
3.3.2 Impact of P2DR with Gold Sequence . . . . . . . . . . . . . . . . . 36
4 Pilot Contamination Suppression Scheme 40
4.1 Proposed Pilot Contamination Suppression Scheme . . . . . . . . . . . . . 40
4.1.1 Proposed Data-Based Channel Estimation Scheme . . . . . . . . . 41
4.1.2 Proposed Data-Assisted Channel Estimation Scheme . . . . . . . . 44
4.2 Performance Improving Methods for Proposed Schemes . . . . . . . . . . . 47
4.2.1 Time Advance for cluster . . . . . . . . . . . . . . . . . . . . . . . 47
4.2.2 Channel Threshold . . . . . . . . . . . . . . . . . . . . . . . . . . . 49
5 Simulation Results 52
5.1 Comparison of Different Methods . . . . . . . . . . . . . . . . . . . . . . . 53
5.2 Comparison of Different Window Size . . . . . . . . . . . . . . . . . . . . . 55
5.3 Channel Decision &; Average Power Change . . . . . . . . . . . . . . . . . 57
5.4 Soft Capacity . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 60
6 Conclusion 61
References 62

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