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http://tdr.lib.ntu.edu.tw/jspui/handle/123456789/70636
Title: | 適用於傳送在獨立的衰弱通道之多重接取 Multiple Access for Transmissions Over Independent Fading Channels |
Authors: | Bei-Hao Chang 張倍豪 |
Advisor: | 林茂昭(Mao-Chao Lin) |
Keyword: | 多重進接,分碼多重進接,多載波直接序列分碼多重進接,衰落通道,極化碼,通道容量, Multiple access,CDMA,MC-DS-CDMA,Fading channel,Polar code,Capacity, |
Publication Year : | 2018 |
Degree: | 碩士 |
Abstract: | 多重接取技術對於多個使用者在相同頻帶上傳送資料是很重要的技術。為了使接收端可以將每一個使用者訊號區分出來,每一個使用者必須給予一個獨特的特簽。在本篇論文將探討使用多階檢測(Multi-Level DeTection,或稱 MLDT)技術。在多個使用者傳送訊號,經過各自的衰落通道,利用不同的通道增益來區分使用者。本論文考慮Rayleigh衰落通道。我們推導出具close-form未編碼MLDT錯誤率的分析。針對Coded MLDT系統,我們考慮低密度奇偶檢查碼(LDPC)以及極化碼(Polar Code) 。我們也推導出雙使用者的通道容量的分析。並且以Raptor coded MLDT的模擬結果與雙使用者的通道容量做比較。為了對抗多重路徑干擾,MLDT也可以與多載波直接序列分碼多重進接(MC-DS-CDMA)結合,結合後使用者可使用相同的序列來傳送訊號,因此最大使用者數量可提升為原本的倍數,在此系統下我們也作了Coded的模擬。最後我們發現使用MLDT技術在使用者數提高後會犧牲掉些許錯誤率,但在某些情境下錯誤率的劣化是很小的,這是個顯著的優點。 Multiple access techniques are essential for multiple users to share the same bandwidth. For receivers to separate out the message of the desired user, a unique signature for each user is needed. In this thesis, we study a technique called Multi-Level DeTection(MLDT) for multiple access over independent fading channels. Rayleigh fading channels are considered here. For MLDT, each user employs its channel gain which is likely to be unique to distinguish users. We provide a close-form BER analysis for the uncoded MLDT. For coded cases, both LDPC coded MLDT and polar coded MLDT are considered. We also provide capacity analysis for the two-user coded MLDT. Raptor coded MLDT are simulated to compare with the capacity. To combat the multipath fading channels, MLDT can be applied to the MC-DS-CDMA system. As a summary, we found that using MLDT technique cost some BER performance degradation when number of users increase, but in some scenario the degradation only slight, this is significant advantage. |
URI: | http://tdr.lib.ntu.edu.tw/jspui/handle/123456789/70636 |
DOI: | 10.6342/NTU201802804 |
Fulltext Rights: | 有償授權 |
Appears in Collections: | 電信工程學研究所 |
Files in This Item:
File | Size | Format | |
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ntu-107-1.pdf Restricted Access | 1.47 MB | Adobe PDF |
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