次世代無線通訊系統(LTE-A)中，傳收發端會配置多根天線(Multiple Input Multiple Output, MIMO)或是使用載波聚合(Carrier Aggregation, CA)來提高資料的傳送速度，這兩種技術的共通點就是多根天線，然而在多天線的系統中會降低系統效能的原因有可能是使用者的使用行為或是天線設計問題等等，若此現象發生我們稱之為天線間的接收功率不匹配(Received Power Imbalance, RPI)，若對此現象置之不理則會造成系統的效能以非線性的速度降低，因此本論文分別在CA系統以及MIMO OFDM系統中使用疊代演算法來降低RPI對系統的影響。根據本論文的模擬結果可以發現使用疊代演算法的接收器能有效降低RPI效應。

For next generation wireless communication like Long Term Evolution-Advanced (LTE-A), in order to increase data rate the transmitter and receiver may equip multiple antennas or the system aggregates many component carriers to approach high data rate. Multiple antennas is a common characteristic between CA and MIMO system, however the received power imbalance (RPI) may cause by design flaw, operator’s negligence etc. If the system does not consider RPI effect, the system will be degradation non-linearly. Consequently in this thesis we will use iterative algorithm to mitigate RPI effect in CA system and MIMO OFDM system respectively. Based on simulation result we can find the iterative receiver can alleviate RPI effect greatly.

List of Figures	V
List of Tables	VI
Chapter 1 Introduction	1
1.1	Study Motivation	1
1.2	Organization	2
Chapter2 The Decoder and Encoder of LDPC Code	3
2.1	Introduction of LDPC	3
2.2	The Sum-Product Algorithm	4
2.3	Based on QC LDPC Codes for Fast Encoding	7
Chapter3 Mitigate RPI Effect in CA System	11
3.1	Introduction	11
3.2	Using LDPC and AMC to Mitigate RPI Effect in CA System	12
3.3	Simulation Result	13
3.4	Conclusion	14
Chapter4 Using Iterative Algorithm to Mitigate RPI Effect in MIMO OFDM System	16
4.1	Introduction	16
4.2	MIMO OFDM Transmitter and Turbo Iterative Receiver	17
4.3	Simulation Result	22
4.4	Conclusion	33
Chapter5 Future Work	34
Reference	35

List of Figures
Figure 2. 1 CN Nodes Update Procedure	4
Figure 2. 2 VN Nodes Update Procedure	5
Figure 2. 3 jth VN collect all information	5
Figure 3. 1 Contiguous Type Carrier Aggregation	11
Figure 3. 2 Non-contiguous Type Carrier Aggregation	11
Figure 3. 3 A Carrier Aggregation Communication System with Received Power Imbalance (RPI)	13
Figure 3. 4 System Performance Comparisons	14
Figure 4. 1 A MIMO OFDM Transmitter and Turbo Iterative Receiver Structure	17
Figure 4. 2 The Receiver Suffers from RPI Effect	23
Figure 4. 3 RPI=0dB, MIMO OFDM Demodulation and LDPC Decoder	24
Figure 4. 4 RPI=-1dB, MIMO OFDM Demodulation and LDPC Decoder	25
Figure 4. 5 RPI=-2dB, MIMO OFDM Demodulation and LDPC Decoder	25
Figure 4. 6 RPI=-3dB, MIMO OFDM Demodulation and LDPC Decoder	25
Figure 4. 7 RPI=-4dB, MIMO OFDM Demodulation and LDPC Decoder	26
Figure 4. 8 RPI=-5dB, MIMO OFDM Demodulation and LDPC Decoder	26
Figure 4. 9 RPI=-6dB, MIMO OFDM Demodulation and LDPC Decoder	26
Figure 4. 10 RPI=-7dB, MIMO OFDM Demodulation and LDPC Decoder	27
Figure 4. 11 RPI=-8dB, MIMO OFDM Demodulation and LDPC Decoder	27
Figure 4. 12 RPI=-9dB, MIMO OFDM Demodulation and LDPC Decoder	27
Figure 4. 13 RPI=-10dB, MIMO OFDM Demodulation and LDPC Decoder	28
Figure 4. 14 RPI=0dB, MIMO OFDM Demodulation and CC216 Decoder	28
Figure 4. 15 RPI=-1dB, MIMO OFDM Demodulation and CC216 Decoder	28
Figure 4. 16 RPI=-2dB, MIMO OFDM Demodulation and CC216 Decoder	29
Figure 4. 17 RPI=-3dB, MIMO OFDM Demodulation and CC216 Decoder	29
Figure 4. 18 RPI=-4dB, MIMO OFDM Demodulation and CC216 Decoder	29
Figure 4. 19 RPI=-5dB, MIMO OFDM Demodulation and CC216 Decoder	30
Figure 4. 20 RPI v.s. EbN0 at BER-3 using CC216 decoder	32
Figure 4. 21 RPI v.s. EbN0 at BER-3 using LDPC decoder	32

List of Tables 
Table 4. 1 Channel Coder	23
Table 4. 2 LTE-OFDM and CP Parameter	24
Table 4. 3 LTE-Multipath Parameter	24
Table 4. 4 Simulation Results Comparison between LDPC and CC216	30

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