可见光通信非对称限幅光多载波码分多址系统的设计及性能分析
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摘要
基于码分多址(CDMA)和非对称限幅光(ACO)正交频分复用,提出了非对称限幅光多载波码分多址系统。在视线传播和散射传播信道中,采用正交恢复合并(ORC)、最大比合并(MRC)和等增益合并(EGC)算法,推导了受限幅噪声影响时系统的信噪比,建立了蒙特卡罗误比特率(BER)仿真模型。研究结果表明,通过增大扩频序列长度可以提高BER性能。随着用户数增多,多用户间干扰增大,MRC算法性能变差,ORC算法保持了用户间的正交性,BER性能最好。所提系统的性能比反转多载波CDMA和单极性多载波CDMA系统的更好。
An asymmetrically clipped optical(ACO) multi-carrier(MC) code division multiple access(CDMA) system is proposed based on CDMA and ACO orthogonal frequency division multiplexing. The theoretical expression of signal-to-noise ratio for the system affected by clipping noises is derived with the orthogonality restoring combining(ORC), maximum ratio combining(MRC) and equal gain combining(EGC) algorithms in the sight and sattering propagation channels. The model for Monte Carlo bit-error-ratio(BER) simulation is established. The reasearch results show that the BER performance can be improved with an increase in the length of spreading codes. As the number of users increases, the MRC algorithm deteriorates due to the muli-user disturbance, however the ORC algorithm maintains the orthogonality among different users and demonstrates the best BER performance. The proposed system outperforms the Flip-MC-CDMA and the unipolar multi-carrier CDMA(U-MC-CDMA) systems.
An asymmetrically clipped optical(ACO) multi-carrier(MC) code division multiple access(CDMA) system is proposed based on CDMA and ACO orthogonal frequency division multiplexing. The theoretical expression of signal-to-noise ratio for the system affected by clipping noises is derived with the orthogonality restoring combining(ORC), maximum ratio combining(MRC) and equal gain combining(EGC) algorithms in the sight and sattering propagation channels. The model for Monte Carlo bit-error-ratio(BER) simulation is established. The reasearch results show that the BER performance can be improved with an increase in the length of spreading codes. As the number of users increases, the MRC algorithm deteriorates due to the muli-user disturbance, however the ORC algorithm maintains the orthogonality among different users and demonstrates the best BER performance. The proposed system outperforms the Flip-MC-CDMA and the unipolar multi-carrier CDMA(U-MC-CDMA) systems.
引文
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[26] Jia K J, Hao L, Yu C H. Modeling of multipath channel and performance analysis of MIMO-ACO-OFDM system for indoor visible light communications[J]. Acta Optica Sinica, 2016, 36(7): 0706005. 贾科军, 郝莉, 余彩虹. 室内可见光通信多径信道建模及MIMO-ACO-OFDM系统性能分析[J]. 光学学报, 2016, 36(7): 0706005.
[27] Carruthers J B, Kahn J M. Modeling of nondirected wireless infrared channels[J]. IEEE Transactions on Communications, 1997, 45(10): 1260-1268.
[28] Wilson S, Armstrong J. Transmitter and receiver methods for improving asymmetrically-clipped optical OFDM[J]. IEEE Transactions on Wireless Communications, 2009, 8(9): 4561-4567.
[29] Dimitrov S, Sinanovic S, Haas H. Clipping noise in OFDM-based optical wireless communication systems[J]. IEEE Transactions on Communications, 2012, 60(4): 1072-1081.
[30] Cho K, Yoon D. On the general BER expression of one- and two-dimensional amplitude modulations[J]. IEEE Transactions on Communications, 2002, 50(7): 1074-1080.
[2] Ayyash M, Elgala H, Khreishah A, et al. Coexistence of WiFi and LiFi toward 5G: concepts, opportunities, and challenges[J]. IEEE Communications Magazine, 2016, 54(2): 64-71.
[3] González O, Martín-González J A, Poves E, et al. Adaptive code-division multiple-access system for communications over indoor wireless optical channels based on random optical codes[J]. IET Optoelectronics, 2009, 3(4): 187-196.
[4] Salehi J A. Code division multiple-access techniques in optical fiber networks. I. Fundamental principles[J]. IEEE Transactions on Communications, 1989, 37(8): 824-833.
[5] Salehiomran A, Salehi J A. Spatial heterodyning optical code division multiple access technique for near-field free-space optical communication systems[J]. Journal of Optical Communications and Networking, 2009, 1(5): 498-511.
[6] O’Farrell T, Kiatweerasakul M. Performance of a spread spectrum infrared transmission system under ambient light interference[C]. Ninth IEEE International Symposium on Personal, Indoor and Mobile Radio Communications, 1998: 703-707.
[7] Schenk T C W, Feri L, Yang H M, et al. Optical wireless CDMA employing solid state lighting LEDs[C]. IEEE/LEOS Summer Topical Meeting, 2009: 23-24.
[8] He C, Yang L L, Xiao P, et al. DS-CDMA assisted visible light communications systems[C]. IEEE 20th International Workshop on Computer Aided Modelling and Design of Communication Links and Networks (CAMAD), 2015: 27-32.
[9] Alsaadi F E, Elmirghani J M H. MC-CDMA indoor optical wireless system[C]. IEEE Global Telecommunications Conference, 2007: 2455-2460.
[10] Matsuo R, Matsuo M, Ohtsuki T, et al. Performance analysis of indoor infrared wireless systems using OOK CDMA on diffuse channels[C]. IEEE Pacific Rim Conference on Communications, Computers and Signal Processing, 1999: 30-33.
[11] Matsuo R, Ohtsuki T, Sasase I. Performance analysis of indoor infrared wireless systems using PPM CDMA with linealizer with dead-zone and PPM CDMA with hard-limiter on diffuse channels[C]. IEEE International Conference on Communications, 2001: 2016-2020.
[12] Liu J, Pan Z N, Noonpakdee W, et al. Impact of light reflection on indoor wireless optical CDMA systems[J]. Journal of Optical Communications and Networking, 2012, 4(12): 989-996.
[13] Carruthers J B, Kahn J M. Multiple-subcarrier modulation for nondirected wireless infrared communication[J]. IEEE Journal on Selected Areas in Communications, 1996, 14(3): 538-546.
[14] Armstrong J, Lowery A J. Power efficient optical OFDM[J]. Electronics Letters, 2006, 42(6): 370-372.
[15] Tsonev D, Sinanovic S, Haas H. Novel unipolar orthogonal frequency division multiplexing (U-OFDM) for optical wireless[C]. IEEE 75th Vehicular Technology Conference (VTC Spring), 2012: 6240060.
[16] Fernando N, Hong Y, Viterbo E. Flip-OFDM for unipolar communication systems[J]. IEEE Transactions on Communications, 2012, 60(12): 3726-3733.
[17] Hara S, Prasad R. Overview of multicarrier CDMA[J]. IEEE Communications Magazine, 1997, 35(12): 126-133.
[18] Luan Y Z, Jiang G, Li J D. MC-CDMA for optical wireless communications[J]. Proceedings of SPIE, 2005, 6021: 60210Z.
[19] Alsaadi F E, Elmirghani J M H. Adaptive mobile line strip multibeam MC-CDMA optical wireless system employing imaging detection in a real indoor environment[J]. IEEE Journal on Selected Areas in Communications, 2009, 27(9): 1663-1675.
[20] Alsaadi F E, Elmirghani J M H. Spot diffusing angle diversity MC-CDMA optical wireless system[J]. IET Optoelectronics, 2009, 3(3): 131-141.
[21] Farooqui M Z, Saengudomlert P. Transmit power reduction through subcarrier selection for MC-CDMA-based indoor optical wireless communications with IM/DD[J]. EURASIP Journal on Wireless Communications and Networking, 2013: 138.
[22] Shoreh M H, Fallahpour A, Salehi J A. Design concepts and performance analysis of multicarrier CDMA for indoor visible light communications[J]. Journal of Optical Communications and Networking, 2015, 7(6): 554-562.
[23] Yu Z H, Baxley R J, Zhou G T. Peak-to-average power ratio and illumination-to-communication efficiency considerations in visible light OFDM systems[C]. IEEE International Conference on Acoustics, Speech and Signal Processing, 2013: 5397-5401.
[24] Elgala H, Mesleh R, Haas H. Non-linearity effects and predistortion in optical OFDM wireless transmission using LEDs[J]. International Journal of Ultra Wideband Communications and Systems, 2009, 1(2): 143-150.
[25] Bussgang J J. Crosscorrelation functions of amplitude-distorted Gaussian signals[R]. Cambridge: Research Laboratory for Electronics, Massachusetts Institute of Technology, 1952: 216.
[26] Jia K J, Hao L, Yu C H. Modeling of multipath channel and performance analysis of MIMO-ACO-OFDM system for indoor visible light communications[J]. Acta Optica Sinica, 2016, 36(7): 0706005. 贾科军, 郝莉, 余彩虹. 室内可见光通信多径信道建模及MIMO-ACO-OFDM系统性能分析[J]. 光学学报, 2016, 36(7): 0706005.
[27] Carruthers J B, Kahn J M. Modeling of nondirected wireless infrared channels[J]. IEEE Transactions on Communications, 1997, 45(10): 1260-1268.
[28] Wilson S, Armstrong J. Transmitter and receiver methods for improving asymmetrically-clipped optical OFDM[J]. IEEE Transactions on Wireless Communications, 2009, 8(9): 4561-4567.
[29] Dimitrov S, Sinanovic S, Haas H. Clipping noise in OFDM-based optical wireless communication systems[J]. IEEE Transactions on Communications, 2012, 60(4): 1072-1081.
[30] Cho K, Yoon D. On the general BER expression of one- and two-dimensional amplitude modulations[J]. IEEE Transactions on Communications, 2002, 50(7): 1074-1080.