摘要
针对可见光通信中不均匀限幅光正交频分复用(ACO-OFDM)系统发光二极管(LED)非线性限幅失真严重的问题,提出了一种降低LED非线性限幅失真的最优功率分配方法。基于原信号直接叠加非线性限幅失真成分的限幅处理模型,分析了ACO-OFDM系统中的LED非线性限幅失真;利用有效信噪比来衡量限幅失真,将限幅失真转化为有效信噪比分析;基于有效信噪比最优的原则给出了光功率约束下降低限幅失真的最优偏置信号和ACO-OFDM信号功率分配。仿真结果表明,当信道的信噪比较低时,信道噪声起主导作用;当信道的信噪比较高时,限幅失真起主导作用。在光功率约束下若不考虑偏置信号的影响而直接取其值为LED最小输出功率限制,则系统误码率(BER)在信道信噪比大于40dB的情况下也始终大于10-2,而采用最优功率分配时可以保证系统具有较好的误码率性能,当光功率约束为200mW和250mW时,分别需要24dB和27dB的信道信噪比即可使得系统的误码率低于10-3。
To handle the significant light emitting diode （LED） nonlinearity clipping distortion problem in asymmetrically clipped optical orthogonal frequency division multiplexing （ACO-OFDM） based visible light communication systems, an optimal power allocation method for reducing the clipping distortion is proposed. The LED nonlinear clipping distortion of the system is analyzed based on the clipping process model that original signal directly addes nonlinear clipping distortion components. The effective signal to noise ratio （SNR） is defined to measure the clipping distortion, and the clipping distortion analysis is converted into SNR analysis. Finally, the optimal bias signal and ACO-OFDM signal power allocation under optical power constraints based on the principle of effective SNR optimum are proposed. Simulation results show that the channel noise dominants at low channel SNR value while clipping distortion dominates at high channel SNR value. Bit error rate （BER） is greater than 10 2 even the channel SNR value beyond 40 dB if the bias power is selected as the minimum output power limit value of LED without considering, while optimal power allocation can effectively reduce the LED nonlinear clipping distortion to improve the BER performance. Channel SNR values of 24 dB and 27 dB are enough to insure that BER is below 10-3 under the optical power constraints of 200 mW and 250 mW, respectively.
出处
《光学学报》
EI
CAS
CSCD
北大核心
2014年第7期46-53,共8页
Acta Optica Sinica
基金
国家863计划(2013AA013603)
东南大学移动通信国家重点实验室开放基金(2013D09)
关键词
光通信
可见光通信
不均匀限幅光正交频分复用
限幅失真
功率分配
optical communications
visible light communication
asymmetrically clipped optical orthogonalfrequency division multiplexing
clipping distortion
power allocation
