Three-Stage Stepwise Detection Algorithm for Zero-Padded Dual-Mode Optical OFDM Index Modulation

doi:10.3788/AOS240599

IR > 计算机与通信学院

	Three-Stage Stepwise Detection Algorithm for Zero-Padded Dual-Mode Optical OFDM Index Modulation
其他题名	零填充双模光正交频分复用索引调制的三级分步检测算法
	Wang Huiqin1 ; Zhou Weiyu 1; Tang Qihan 1; Wang Zhen1 ; Wu Pengfei 2; Peng Qingbin1 ; Zhang Yue 1
	2024-06
发表期刊	ACTA OPTICA SINICA
ISSN	0253-2239
卷号	44 期号:11
摘要	Objective Optical orthogonal frequency division multiplexing index modulation (OOFDM-IM) is a novel multicarrier technique that achieves higher transmission rates by additionally adding mode order indexing via loading two different modes of constellation symbols on the active subcarriers and retaining the silent subcarriers. At the same time, the presence of silent subcarriers improves the bit error rate (BER) performance of the system. However, the presence of silent subcarriers also brings a waste of spectrum resources. Therefore, in this paper, a zero-padded dual-mode optical orthogonal frequency division multiplexing index modulation (ZDM-OOFDM-IM) is proposed to improve the transmission rate. Meanwhile, in order to solve the problem of excessive system detection complexity, a three-level stepwise detection algorithm based on K-mean clustering algorithm (KMC++) is proposed by combining the greedy (GD) algorithm, loglikelihood ratio (LLR) algorithm, and KMC++ algorithm. Methods In the ZDM-OOFDM-IM system, the active subcarrier was selected by the subcarrier index, and the constellation symbols of two different modes were mapped by the symbol information. Then, the modulation symbols were loaded on the active subcarriers according to the order index to complete signal modulation. After orthogonal frequency division multiplexing (OFDM) data block merging, inverse fast Fourier transform, non-zero clipping, and other processing, the light source sent it out. The optical signal transmitted through the atmospheric turbulence channel was received by the detector and could be restored to the original signal after processing by fast Fourier transform, subcarrier recovery, and maximum likelihood (ML) detection. According to the subcarrier index, constellation pattern order, and different characteristics of constellation symbols in the ZDM-OOFDM-IM system, GD, LLR, and KMC++ algorithms were used to detect the proposed detection algorithm, so as to reduce the complexity of the receiver signal detection. Finally, the feasibility of the system and the proposed algorithm were verified by the Monte Carlo method and experimental equipment. Results and Discussions In this paper, the ZDM-OOFDM-IM system and its low-complexity novel detection algorithm are proposed, and its feasibility is verified through simulation and experimental devices. In addition, the influence of the key parameters of the system on the BER is analyzed. The results show that the ZDM-OOFDM-IM system can effectively improve the transmission rate, which gradually approaches the dual-mode OOFDM-IM with the increase in the subcarrier block length and the number of active subcarriers (Fig. 2). Moreover, at all modulation orders of 4, the signal-to-noise ratio (SNR) of the proposed system is improved by about 4.02 dB compared to DM-OOFDM-IM at BER of 3.8x10(-3) (Fig. 4). In addition, when the subcarrier block length is fixed, increasing the number of active subcarriers can significantly increase the transmission rate but inevitably results in BER loss. When the number of active subcarriers is constant, an increase in subcarrier block length leads to an improvement in BER performance. For example, compared to the (4,2,1,2,4) system, the transmission rate of one frame of the (4, 3, 1, 2, 4) and (4, 3, 2, 2, 4) systems is improved by 64 bit/s and 128 bit/ s, respectively, while their SNRs are lost by 2.17 dB and 2.26 dB at BER of 3.8x10(-3), respectively. Compared with the (4,2,1,2,4), (4,3,1,2,4), and (4,3,2,2,4) systems at BER of 3.8x10(-3), the SNRs of the (8,2,1,2,4), (8,3,1,2,4), and (8,3,2,2,4) systems are improved by 4.53 dB, 3.72 dB, and 2.50 dB, respectively (Fig. 5). The proposed algorithm achieves a BER that approximates the ML detection and eliminates the plateau effectof the conventional KMC algorithm (Fig. 6). Under the proposed algorithm, it is concluded that the increase in the modulation order leads to a significant increase in the transmission rate although it brings a smaller BER loss. For example, when ML detection is employed at BER of 3.8x10(-3), the SNRs of the (4, 2, 1, 2, 2) and (4, 2, 1, 4, 4) systems lose 3.41 dB and 5.56 dB, respectively, compared to the (4, 2, 1, 2, 2) system, whereas the transmission rates of their one-frame signals are enhanced by 64 bit/s and 128 bit/s, respectively (Fig. 7). Moreover, in the experimental setup, the system BER and the performance of the proposed algorithm also achieve results consistent with the simulation (Fig. 9 and Fig. 10). Finally, the computational complexity of the proposed algorithm is given and compared with several classical decoding algorithms to demonstrate its computational complexity advantage (Fig. 11). Conclusions In order to solve the problem of unsatisfactory transmission rate and BER performance in the traditional wireless OOFDM-IM system, a ZDM-OOFDM-IM system is designed in this paper, which effectively enhances the transmission rate. Compared with the OOFDM-IM system, its transmission rate is increased by 96 bit/s for one frame of information when the number of subcarriers is 16, and the number of active subcarriers is 8. Meanwhile, in order to solve the problems of excessive ML decoding complexity and poor BER performance of other traditional detection algorithms, a three-stage stepwise detection algorithm is proposed by combining the GD, LLR, and KMC++ algorithms, which obtains a complexity close to that of linear decoding algorithms under the premise of guaranteeing the BER performance. Finally, the system successfully realizes wireless optical communication transmission with a BER of lower than 3.8 x 10(-3) through the constructed indoor transmission experimental device, which verifies the feasibility of the system and the proposed algorithm.
关键词	optical communication index modulation stepwise detection K-means clustering experimental verification
DOI	10.3788/AOS240599
收录类别	ESCI ; EI
语种	中文
WOS研究方向	Optics
WOS类目	Optics
WOS记录号	WOS:001249316300002
出版者	CHINESE LASER PRESS
EI入藏号	20242616424794
EI主题词	Bit error rate
EI分类号	443.1 Atmospheric Properties ; 631.1 Fluid Flow, General ; 716.1 Information Theory and Signal Processing ; 717.1 Optical Communication Systems ; 721.1 Computer Theory, Includes Formal Logic, Automata Theory, Switching Theory, Programming Theory ; 723.1 Computer Programming ; 744.8 Laser Beam Interactions ; 903.1 Information Sources and Analysis ; 921.3 Mathematical Transformations ; 922.1 Probability Theory ; 922.2 Mathematical Statistics
原始文献类型	Article
引用统计	无
文献类型	期刊论文
条目标识符	https://ir.lut.edu.cn/handle/2XXMBERH/170858
专题	计算机与通信学院外国语学院
通讯作者	Wang Huiqin
作者单位	1.Lanzhou Univ Technol, Sch Comp & Commun, Lanzhou 730050, Gansu, Peoples R China; 2.Xian Univ Technol, Sch Automat & Informat Engn, Xian 710048, Shaanxi, Peoples R China
第一作者单位	兰州理工大学
通讯作者单位	兰州理工大学
第一作者的第一单位	兰州理工大学
推荐引用方式 GB/T 7714	Wang Huiqin,Zhou Weiyu,Tang Qihan,et al. Three-Stage Stepwise Detection Algorithm for Zero-Padded Dual-Mode Optical OFDM Index Modulation[J]. ACTA OPTICA SINICA,2024,44(11).
APA	Wang Huiqin.,Zhou Weiyu.,Tang Qihan.,Wang Zhen.,Wu Pengfei.,...&Zhang Yue.(2024).Three-Stage Stepwise Detection Algorithm for Zero-Padded Dual-Mode Optical OFDM Index Modulation.ACTA OPTICA SINICA,44(11).
MLA	Wang Huiqin,et al."Three-Stage Stepwise Detection Algorithm for Zero-Padded Dual-Mode Optical OFDM Index Modulation".ACTA OPTICA SINICA 44.11(2024).