数字副载波强度调制与光脉冲调制系统误比特率分析

Analysis of bit error rate for digital sub-carrier intensity modulation and optical pulse system

为了分析数字副载波强度调制与光脉冲调制系统的差错性能,本文首先给出了无线光信道通信系统简化模型,在此基础上推导了2种调制方式的信噪比,并分析比较了功率有效性和误比特率。数字副载波强度调制使用二进制移相键控(BPSK),光脉冲调制采用曼彻斯特编码。仿真结果表明,在同等条件下,光脉冲调制系统的功率有效性要优于数字副载波调制系统,误比特率也明显低于数字副载波调制系统。由于光脉冲调制对激光器的线性要求较低,因此在实际应用中一般考虑使用光脉冲系统。但数字副载波调制也有其优势,有利于实现高速数字通信。

Based on the simplified model for wireless optical communication system, the signal noise ratio（SNR） of digital sub-carrier intensity modulation and optical pulse system is given and power effectiveness and error performance are analyzed in order to analyze their error performances. BPSK and Manchester code are adopted for digital sub-carrier intensity modulation and optical pulse system respectively. Simulation shows that the power effectiveness and bit error rate of optical pulse system obviously outperform those of digital sub-carrier intensity modulation system under the same conditions. On the other hand, there is less demand of laser linearity for optical pulse modulation system, which is often adopted in practical application, compared with digital sub-carrier intensity modulation. However, digital subearrier intensity modulation is in favor of high speed communication.