Performance Analysis Of The Channel Coding Technology Of Underwater Wireless Optical Communication Systems Based On Water Turbulence

Underwater wireless optical communication(UWOC)is a kind of new underwater wireless communication technology,which was paid great attention by researchers duing to its high bandwidth,high speed and good security.However,oceanic turbulence has severe effect on the performance of UWOC.The application of UWOC is hindered by oceanic turbulence,due to the fact that oceanic turbulence could degrade the average bit error rate(ABER)performance of the system.Therefore,it is meaningful to study how to overcome the negative impact of the oceanic turbulence and improve system performance.In this work,the performance of low density parity check(LDPC)coded UWOC system is investigated in detail over generalized gamma distribution(GGD)fading channels.The main works are shown as follows: 1.The performance of point to point LDPC-coded UWOC system is investigated in detail on the basis of binary phase shift keying(BPSK)and multiple phase shift keying(MPSK)modulation over GGD fading channels.Firstly,the ABER expressions of BPSK and MPSK modulated systems are derived,respectively,with the help of Gauss-Laguerre quadrature rule.And the outage probability expressions are achieved based on cumulative distribution function(CDF)formula.Then,numerical simulations are also provided to confirm the validity of the ABER model we proposed.On this basis,the ABER performances of LDPC UWOC system are studied systematically under different temperature gradient conditions and modulations.The results show that LDPC-coded can improve the ABER performance of UWOC,but the coding gain of LDPC-coded is affected by modulations,channel conditions and the parameters of LDPC-coded.2.The performances of multi-hop LDPC-coded UWOC system are studied under the oceanic turbulence-induced fading modeled by GGD distribution for two different modulations.The analytical ABER expressions of BPSK and MPSK modulated systems are derived over GGD fading channels adopting Gauss-Lagure quadrature rule,respectively.Then the outage probability expressions of present BPSK and MPSK modulated multi-hop UWOC systems are achieved as well,respectively.Numerical simulations are also adopted to verify the correctness of the analytical results of the multi-hop UWOC system.For comparison,the performances of the system without LDPC-coded are investigated as well with the method of numerical simulation.The results show that LDPC-coded can optimize the ABER performance of multi-hop UWOC system.In addition,LDPC-coded still works well,in spite of the increase of node numbers.This work is helpful for the design of LDPC-coded UWOC system.