高速调制光通信中的码型和编码应用研究  

Pattern and Coding Applications in High Speed Modulation Optical Communications

作　　者：张德玲 盛于邦 谢炎飞 姜章海 孙莉萍[1,2] 付永安 ZHANG De-ling;SHNEG Yu-bang;XIE Yan-fei;JIANG Zhang-hai;SUN Li-ping;FU Yong-an(Wuhan Research Institute of Posts and Telecommunications, Wuhan Hubei 430074, China;Accelink Technology Co., Ltd., Wuhan Hubei 430074, China)

机构地区：[1]武汉邮电科学研究院,湖北武汉430074 [2]武汉光迅科技股份有限公司,湖北武汉430074

出　　处：《通信技术》2019年第10期2331-2335,共5页Communications Technology

基　　金：国家重点研发计划“面向数据中心应用的宽带光收发集成器件及模块”(No.2018YFB220090)~~

摘　　要：在高速率光通信中,NRZ码型的ISI(Inter—Symbol Interference)会劣化到均衡器无法恢复的程度。PAM4调制在保证容量的情况下速率降低一半,大大减小了通信通道对码型的损耗。但是,PAM4调制的信噪比相比NRZ劣化9.5dB左右,所以PAM4信号更易受信号反射和串扰等影响而导致误码率大大增加,需要寻找一种新的编码来减小外界噪声引起的误码。格雷码作为一种错误最小化的编码方式,在400G光通信中得到了广泛应用。由于格雷码相邻的两个码之间只有一位不同,因而用于模数转换时,当模拟量发生微小变化而可能引起数字量发生变化时,格雷码仅改变一位。相比于改变两位和多位的编码方式,它减少了出错的可能性,允许电路能以较少的错误在较高的速度下工作。In high-speed optical communication, ISI (inter-symbol interference) of NRZ code type would degrade to the point where the equalizer cannot recover. PAM4 modulation reduces the rate by half when the capacity is guaranteed, which greatly reduces the loss of the communication channel to the pattern. However, the signal-to-noise ratio of PAM4 modulation is about 9.5dB worse than that of NRZ, so PAM4 signal is more susceptible to the influence of signal reflection and crosstalk and the bit error rate is greatly increased. It is necessary to find a new code to reduce the error caused by external noise. Gray code, as an error minimization coding method, has been widely used in 400 G optical communication. Since there is only one bit difference between the two adjacent codes of Gray code, when used for analog-to digital conversion, the Gray code changes only one bit when the analog quantity changes slightly and the digital quantity changes. The Gray code reduces the possibility of errors compared to changing the encoding of two or more bits, allowing the circuit to work at higher speeds with fewer errors.

关 键 词：光通信 信号编码 PAM4 GRAY码 

分 类 号：TN256[电子电信—物理电子学]