室内光无线信道可以看作准静态、具有低通特性的多径信道,并且可见光通信通常是功率受限系统。为了充分利用信道频谱资源及节约能量,提出将Chow、Hughes-Hartogs、Fischer自适应比特-功率加载算法应用于非对称限幅光正交频分复用(ACO-OFDM)系统,介绍了自适应比特功率加载过程,并比较了自适应ACO-OFDM和自适应直流偏置光OFDM(DCO-OFDM)的性能。结果表明,在保证误码率性能时,相比等比特加载方法,自适应算法能节约15%的光功率和30%的电功率,其中Fischer算法最节约功率,而Hughes-Hartogs算法需要的功率最多。在信息速率相同时,自适应ACO-OFDM比DCD-OFDM更节约功率。

The indoor optical wireless channel can be considered as quasi-static multipath channel with inherently low-pass characteristic. Moreover, the visible light communication is usually a power limited system. In order to make full use of the channel spectrum resources and save the energy, the adaptive bit-power loading algorithms of Chow, Hughes-Hartogs and Fischer are applied to the asymmetrically-clipped optical orthogonal frequency division multiplexing (ACO-OFDM) system is proposed. The process of adaptive bit-power loading is introduced, and the performance of the adaptive ACO-OFDM is compared with that of the adaptive direct current optical OFDM (DCO-OFDM). The results show that, compared with the equal bit loading method, the adaptive load algorithm can save about 15% for the optical power and about 30% for the electric power when the performance of bit error rate is guaranteed. Fischer algorithm can save the most optical and electrical power, while Hughes-Hartogs algorithm needs more power. At the same transmit rate, the adaptive ACO-OFDM is more economical than the adaptive DCO-OFDM.