CAJ | 학술논문

为了克服光在弱湍流大气条件传输时，光强闪烁造成的突发错误，理论分析了基于开关键控、脉冲位置调制、差分脉冲位置调制和数字脉冲间隔调制方式的自由空间光通信系统性能。首先推导了无线光通信未编码系统在各调制方式下的平均误比特率公式；在此基础上，将低密度奇偶校验码和置信传播算法应用到无线光通信系统中，研究了相应系统模型下的译码，并在大气湍流信道中进行了理论分析和实验仿真验证。结果表明，脉冲位置调制可获得最好的误比特率性能；采用低密度奇偶校验的大气弱湍流光通信系统比未编码的通信系统性能好，并且可以有效地增加信噪比增益，能够提高系统的抗干扰能力，在无线光通信系统中将有一定的应用前景。
위료극복광재약단류대기조건전수시，광강섬삭조성적돌발착오，이론분석료기우개관건공、맥충위치조제、차분맥충위치조제화수자맥충간격조제방식적자유공간광통신계통성능。수선추도료무선광통신미편마계통재각조제방식하적평균오비특솔공식；재차기출상，장저밀도기우교험마화치신전파산법응용도무선광통신계통중，연구료상응계통모형하적역마，병재대기단류신도중진행료이론분석화실험방진험증。결과표명，맥충위치조제가획득최호적오비특솔성능；채용저밀도기우교험적대기약단류광통신계통비미편마적통신계통성능호，병차가이유효지증가신조비증익，능구제고계통적항간우능력，재무선광통신계통중장유일정적응용전경。
In order to overcome the burst error caused by light intensity scintillation under the weak turbulence atmosphere , free space optical ( FSO ) system model was analyzed based on on-off keying ( OOK ) , pulse position modulation (PPM), differential pulse position modulation (DPPM) and digital pulse interval modulation (DPIM).The bit error rate ( BER) calculating formula of uncoded system was derived under all above the modulation methods .On this basis, low density parity check ( LDPC) codes and belief propagation ( BP) algorithm were applied to the optical wireless communication system , the decoding algorithm was analyzed according to the system model , and simulation was carried out in the atmospheric turbulence channel .The results show that , PPM has the best bit error rate performance , and LDPC coded weak atmospheric turbulent optical system has better BER performance than the uncoded system .LDPC codes can augment the code gain efficiently and to improve the jamming-rejection capability , and it is suited for optical wireless communication .