Research On FSO/RF Hybrid Link Optimization Method Based On Markov Model

Free Space Optical(FSO)communication is also known as wireless Optical communication.Compared with traditional microwave wireless communication system,FSO has the advantages of high spectral permission-free,transmission rate and easy deployment,However,meteorological conditions and atmospheric turbulence effect seriously restrict the all-weather availability index of FSO communication system.Radio Frequency(RF)link and FSO link are combined with complementary advantages,hybrid FSO/RF communication heterogeneous networking has become a hot research issue at present.In this paper,aiming at the efficient and reliable transmission problem of hybrid FSO/RF communication,based on Markov finite state machine model,the cooperative retransmission and optimization design method of FSO/RF dual link using ARQ protocol scheme is studied.Convex optimization method is used to analyze the average packet error rate,average retransmission times and throughput of hybrid FSO/RF link with soft switching transmission scheme.The specific work is as follows:(1)According to the Gamma-Gamma distribution model and Nakagami-m distribution model of FSO/RF link,the effects of different parameter conditions on the performance of hybrid communication system are studied.The packet error rates of FSO/RF link using phase shift keying(PSK)modulation and ARQ protocol are calculated respectively analytic expressions for packet error rate,average retransmission times and throughput.(2)The convex optimization method was used to calculate the data retransmission cooperation proportionality coefficient when the system throughput was optimal.Under different atmospheric turbulence intensity and fading factors,the performance indexes of ARQ protocol of hybrid FSO/RF link were calculated and analyzed.(3)Aiming at the modeling and analysis problem of hybrid FSO/RF link using ARQ protocol,a steady-state solution for further optimization of hybrid system performance was proposed based on Markov state model of each channel and state transition probability matrix of ARQ protocol.