Research On Crosstalk-constraint Routing And Wavelength Assignment Algorithm For All-optical Networks

All optical networks (AON), with many advantages (e.g., higher data transmissionrate, huge data throughput, low bit error rate), well satisfy the ever-increasing datatraffic requirement and will become most promising next generation communicationnetwork. However, due to the lack of electric regeneration (e.g.,optical-electrical-optical (OEO) conversion) at intermediate switches, AON is exposedto high-powered optical crosstalk (i.e., high-powered optical signal caused by devicefault or injected by malicious users, can result in crosstalk impairment betweenlightpaths). High-powered optical crosstalk, due to its propagation characteristic, canseriously threat the network transmission security. This thesis concentrates on routingand wavelength assignment (RWA) algorithms aimed at limiting or preventinghigh-powered optical crosstalk.First of all, the background and significance about this thesis are introduced.Meanwhile, the condition and harmfulness of high-powered optical crosstalkimpairment including in-band crosstalk, out-of-band crosstalk and amplifier gaincompetition in AONs are elaborated. In addition, the present research situation ofprevention and recovery processing mechanism for high-powered optical crosstalk athome and abroad is introduced.Secondly, this thesis defines concept of impairment risk coefficient to assess thedamage of high-powered optical crosstalk to optical switches in AONs. Subsequently,this thesis modifies some existing RWA algorithm by incorporating high-poweredoptical crosstalk and then proposes a RWA algorithm (i.e., IRC_RWA algorithm) forreducing such impairment. Namely, the IRC_RWA algorithm will appropriately reducehighest hops for physical paths and assign lightpath demands the route and wavelengthwhich can minimize the highest impairment risk coefficient in AONs. This thesisspecifically elaborates the condition, steps and pseudocode, and meanwhile analyzes theperformance of IRC_RWA algorithm for reducing the high-powered optical crosstalk bymeans of simulation.Thirdly, based on the previous simulation for propagation ability of high-powered optical crosstalk in AONs, this thesis proposes and analyzes three types of propagationscenarios of high-powered optical crosstalk in which both the primary and backup pathscan be disrupted when a high-powered malicious signal is jammed into AONs.Subsequently, this thesis modifies some existing path protection algorithm byincorporating three types of impairment propagation scenarios, and then proposes aRWA algorithm (i.e., DPPPC algorithm) aimed at preventing such crosstalk. Namely,the DPPPC algorithm will reassign wavelength to the primary path and correspondingbackup path which may simultaneously suffer from high-powered optical crosstalk. Thesimulation results show that the proposed algorithm can effectively preventhigh-powered optical crosstalk by means of protection path and extra wavelengths, etc.Finally, this thesis summarizes the research contents and discusses the future work.The contribution and innovation of this thesis mainly consists of two aspects. Thefirst one is the proposed routing and wavelength assignment algorithm, which canreduce maximum damage of high-powered optical crosstalk to optical switches inAONs and also improve the network’s performance for restraining such crosstalkimpairment. The second one is the proposed dedicated-path protection algorithms,which can efficiently prevent high-powered optical crosstalk by means of the threeproposed impairment propagation scenario and protection path.This work was supported by National Natural Science Foundation of China (No.61071101).