研究生: |
李威信 Wei-hsin Lee |
---|---|
論文名稱: |
非二位元低密度同位檢測編碼的空時區塊碼與正交分頻多工系統中之功率分配 Power allocation for non-binary LDPC coded STBC-OFDM systems |
指導教授: |
賴坤財
Kuen-Tsair Lay |
口試委員: |
方文賢
Wen-Hsien Fang 邱榮輝 Jung-Hui Chiu |
學位類別: |
碩士 Master |
系所名稱: |
電資學院 - 電子工程系 Department of Electronic and Computer Engineering |
論文出版年: | 2008 |
畢業學年度: | 96 |
語文別: | 中文 |
論文頁數: | 62 |
中文關鍵詞: | 空時區塊碼 、功率分配 、無線傳輸 、低密度同位檢測碼 、正交分頻多工 |
外文關鍵詞: | wireless transmission, low-density parity-check code, power allocation, space-time block code, orthogonal Frequency-Division Multiplexing |
相關次數: | 點閱:480 下載:1 |
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通道編碼已成為現今無線通訊中的一大熱門議題。在雜訊嚴重與頻寬有限的無線衰減通道中傳輸,通道編碼是無線傳輸系統中必要的技術。通道編碼有渦輪碼、迴旋碼、漢明碼、低密度同位檢測碼,其中低密度同位檢測碼已被證明擁有非常好的效能。因此,在本論文中將採用此通道編碼的技術。
在我們的研究中,我們發現使用非二位元低密度同位檢測碼在有限域上,比二位元式有更好的效能,但是其計算複雜度太高,因此使用快速傅立葉轉換降低複雜度。而且,多根天線傳送與接收能提升在無線傳輸上有更好的效能與增益,所以在本篇論文中使用空時區塊碼提供空間與時間的多樣性和容量,並且利用正交分頻多工系統來消除符號間干擾。低密度同位檢測碼與正交分頻多工系統的結合,必須搭配功率分配使每一個子通道等訊雜比,這將是本論文的最主要的議題。並使用子載波選擇,幫助我們把資料傳輸速率與錯誤率的效能做最佳的取捨。另外,我們衍生出一種方式,當確定了欲達到的錯誤率,將可以決定子載波保留的個數。
Channel coding is one of the most popular topics of today’s wireless communications. It is an essential technique when the channel is noisy and fading. There are many kinds of channel coding, such as turbo code, convolutional code, Hamming code and LDPC code. LDPC (low-density parity-check) code has been shown to have excellent performance. It is the channel coding technique that we adopt in this thesis.
In our research, we find that the performance of non-binary LDPC over GF(q) outperforms that of binary LDPC. However, non-binary LDPC has higher computation complexity. To solve this problem, we use FFT transform to reduce the complexity. It is pointed out that use of multiple antenna raises performance and gain for transmitting and receiving in wireless transmission. Therefore, we use space-time block code to provide diversity and capacity in this thesis. We also use OFDM to eliminate ISI. In combining OFDM and LDPC codes, power allocation to make each subcarriers have the same SNR(signal-to-noise ratio) is necessary and is the main topic of this thesis. Sub-carrier selection helps us to strike a balance between data transmission rate and BER(bit error rate) performance. In addition, we derive a scheme to determine the number of subcarriers to be retained when the acceptable BER is specified.
[1] T. Richardson and R. Urbanke. “The capacity of low-density parity check codes under message-passing decoding”. IEEE Transactions on Information Theory, Page(s):599 - 618 Feb 2001
[2]M. C. Davey and D. J. C MacKay, “Low Density Parity Check Codes over GF(q)” IEEE Communications Letters, vol. 2, pp. 165-167, June 1998
[3]B. Sklar, Digital Communications Fundamentals and Applications. 2nd ed.,Prentice-Hall,2001.
[4]R.Gallager, “Low Density Parity Check Codes.” IEEE Transaction on Information Theory, vol.8 pp. 21-28, Jan. 1962
[5] S.M. Alamouti (October 1998). "A simple transmit diversity technique for wireless communications". IEEE Journal on Selected Areas in Communications 16 (8): 1451–1458.
[6] R. Prasad, OFDM for Wireless Communications Systems. John Wiley, 2004
[7] J. G. Proakis, Digital Communication. 4th ed., McGraw-Hill, 2001.