無線通訊系統的發展快速
,
通訊網路的發展促使我們生活周遭有許多設備需要用到無線通
訊
,
漸漸的在有限的頻寬下已經沒辦法滿足我們的需求
,
迎向第五代行動通訊變得更為迫切
,
其目標不外乎就是更高容量 、 高速 、 低延遲
,
而在以這些為目標的前提下
,
我們首要解決的
困難是如何再有限的頻寬以及日益聚增的行動設備下
,
如何提升頻譜使用效率
。
而非正交多
址系統 (non-orthogonal multiple accesss, NOMA) 為熱門的技術之一
,
其技術在頻譜的使
用效率上勝於 4G LTE-A 所使用的正交分頻多工 (orthogonal frequency-division multiple
access, OFDMA)
,
因為使用了疊加編碼 (superposition coding) 將用戶的訊號疊加起來傳
送
,
因此可以再同一個頻帶上傳輸多個訊號
,
並且利用不同的功率來區分這些訊號
,
而接收
端可採用連續干擾消除 (successive interference cancellation, SIC) 法來消除用戶間的訊號干
擾問題
。
此篇論文將以此技術為基準
,
來探討下行鍊路中
,
基地台將同時服務單一天線的多
個使用者
,
基地台使用高頻毫米波頻 (millimeter wave, mmWave) 段傳送訊號
,
由於毫米波
訊號通道衰減嚴重
,
因此訊號的發射與接收角度 (angle of arrival, AOA) 對於通訊係數的影
響很大
,
基地台將用戶配置在不同的群集內
,
並利用波束賦形來傳送各個群集的訊號
,
由於用
戶端會受到來自不同群集的干擾以及群集內用戶的干擾
,
因此我們採用連續干擾消除來解決群
集內的干擾
,
並利用強制歸零 (zero-forcing, ZF) 法則來設計各群集的波束賦形向量
,
來降低
群集間的干擾
,
而最後我們也針對群集內的用戶來做功率分配
,
確保每個群集內通道較弱的用
戶傳輸率
,
並提升群集總傳輸率
,
而再用戶配對方面我們採用文獻 [1] 中所提出的結果
,
將用
戶通道夾角相近的配對在同一個群集內
,
並對其夾角中心角度的向量經由零空間投影後
,
以此
波束向量傳送訊號
,
最後我們將這個方法與強制歸零和正交分頻多工系統進行比較
,
從模擬結
果可以得出我們所提出的系統再總傳輸速率上能夠優於另外兩個系統
。
關鍵字 : 非正交多址系統 、 強制歸零 、 毫米波 、 發射與接收角度 、 功率分配 、 波束賦形
。

With the rapid development of wireless communication systems, our daily life is gra-
dually surrendered by various mobile devices. Development of wireless communications
lead to insufficiency of spectrum. Toward the trend of the 5th mobile communications, it
is more and more urgent, to develop wireless transmissions with higher capacity 、 speed
and low latency. This thesis aims to enhance spetrum efficiency, increase the number of
connectted devices. Non-orthogonal Multiple Access(NOMA) is a good candidate to deal
with the challenges. The NOMA technology has better spectrum efficiency than Ortho-
gonal Frequency-division multiple access(OFDMA) that adpot in 4G LTE-A system. By
using superposition coding to superimposed the users’ signals with different power, multi-
ple users can access the channel simultaneously and be distinguished over power domain.
The receive adopts Successive Interference Cancellation(SIC) algorithm to eliminate the
inter-user interference. In the thesis, we consider a multi-user cellular systems, where the
base station accesses the millimeter wave(mmWave) band. Due to serious attenuation of
the mmWave channel, the channel coefficients highly depends on angle of arrival(AOA).
We design an algorithm for the base station to cluster the users. The signal correspon-
ding to each cluster is transmitted by a beamforming vector. To eliminate the inter-beam
interference and intra-beam interference, so we adopt SIC to cancel the intra-beam in-
terference, and zero-forcing(ZF) algorithm to design the beamforming vector. Finally,
to ensure the cell-edage user in the cluster, we propose an intra-beam power allocation
to maximize the systems sum rate. The simulation shows that our proposed method
outperform the convention ZF and ZF combined with OFDM scheme.
keywords : NOMA 、 ZF 、 mmWave 、 AOA 、 power allocation 、 beamforming

1 前言 1
2 文獻探討 6
3 系統模型 11
3.1 用戶配置與通道模型 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11
3.2 非正交多址系統 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14
3.2.1 疊加編碼 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14
3.2.2 連續干擾消除 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14
3.3 強制歸零 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15
3.4 傳送與接收訊號 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16
4 波束賦形向量與功率分配 19
4.1 幾何地線法 (Geometry geodesic) . . . . . . . . . . . . . . . . . . . . . . . 19
4.2 正交投影向量 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20
4.3 用戶的配對與演算 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 21
4.4 群集內的功率分配 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 23
5 模擬結果 26
5.1 強制歸零系統 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 26
5.2 加入了正交分頻多工的系統 . . . . . . . . . . . . . . . . . . . . . . . . . . 28
5.3 系統比較 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 29
6 結論 39
參考文獻 40

[1] W.-J. Huang and W.-T. Cheng,”Beam-forming design and power allocation in
NOMA system,” in Institute of communications Engineering NSYSU, 2016.
[2] Buzzi, Stefano, and Carmen D’Andrea. ”Doubly massive mmWave MIMO systems:
Using very large antenna arrays at both transmitter and receiver.” Global Commu-
nications Conference (GLOBECOM), 2016 IEEE. IEEE, 2016.
[3] Buzzi, Stefano, and Carmen D’Andrea. ”On clustered statistical MIMO millimeter
wave channel simulation.” arXiv preprint arXiv:1604.00648 2016.
[4] Pasupathy, Raghu. ”Generating homogeneous poisson processes.” Wiley Encyclope-
dia of Operations Research and Management Science 2010.
[5] Andersen, Jorgen Bach, and Klaus Ingemann Pedersen. ”Angle-of-arrival statistics
for low resolution antennas.” IEEE Transactions on Antennas and Propagation 50.3
2002: 391-395.
[6] Al-Abbasi, Ziad Qais, and Daniel KC So. ”User-pairing based non-orthogonal multi-
ple access (NOMA) system.” Vehicular Technology Conference (VTC Spring), 2016
IEEE 83rd. IEEE, 2016.
[7] Saito, Yuya, et al. ”Non-orthogonal multiple access (NOMA) for cellular future radio
access.” Vehicular Technology Conference (VTC Spring), 2013 IEEE 77th. IEEE,
2013.
[8] Higuchi, Kenichi, and Yoshihisa Kishiyama. ”Non-orthogonal access with random
beamforming and intra-beam SIC for cellular MIMO downlink.” Vehicular Techno-
logy Conference (VTC Fall), 2013 IEEE 78th. IEEE, 2013.
40
[9] Lee, Heunchul, Sungsoo Kim, and Jong-Han Lim. ”Multiuser superposition transmis-
sion (MUST) for LTE-A systems.” Communications (ICC), 2016 IEEE International
Conference on. IEEE, 2016.
[10] Ding, Zhiguo, et al. ”Application of non-orthogonal multiple access in LTE and 5G
networks.” IEEE Communications Magazine 55.2, 2017: 185-191.
[11] Ding, Zhiguo, et al. ”NOMA Meets Finite Resolution Analog Beamforming in Mas-
sive MIMO and Millimeter-Wave Networks.” IEEE Communications Letters 2017.
[12] Sun, Xiaofang, et al. ”Joint beamforming and power allocation design in downlink
non-orthogonal multiple access systems.” Globecom Workshops (GC Wkshps), 2016
IEEE. IEEE, 2016.