| Along with the fast growth of science and technology,people have made deeper researches on space communication technology.Stimulated by massive communication data and diverse user services,high-power orbit carrier technology and large capacity satellite technology in the field of space technology continue to improve,and new technologies such as artificial intelligence also begin to integrate into all aspects of the satellite industry.Satellite optical communication technology uses laser as carrier and atmosphere as transmission medium,which inherits the advantages of microwave communication,as well as combines the advantages of radio communication and optical fiber communication.It not only has high transmission rate,large transmission capacity,strong ability of anti-electromagnetic interference and security,but also can establish laser communication without radio license.In terms of hardware configuration,the transmitting and receiving antennas that meet the needs of laser communication are small in size and more portable for satellite.The optical satellite network for high-speed and large-capacity communication is formed by Inter satellite links(ISLs)based on laser communication technology,meeting the higher requirements of satellite communication capacity and transmission rate due to the exponential increase of data transmission in recent years.As an important component system of military and commercial space network in the future,space laser communication has important research and application significances.With the increasing demand for multi types of services and high quality of users,more and more traffic exists in the satellite optical network.In the meantime,the complexity of space environment and the inherent vulnerability of wireless communication also bring great challenges to the satellite network with high-quality transmission performance.So,in this paper,the characteristics of laser link based on wavelength division multiplexing(WDM)and the high dynamic change of topology are fully considered to develop research on the routing algorithm and resource management on-board in satellite dynamic optical network.In order to support different kinds of services,improve the stability and reliability of high-capacity and high-speed network communication,as well as deal with the uneven network traffic and service congestion problems caused by high transmission rate and large capacity of satellite optical network,we focus on the routing and wavelength assignment(RWA)technology,and the routing optimization strategy based on security objective and heavy traffic load.Besides,the efficient allocation method of on-board resources is studied to solve the contradiction between growing traffic requirements and limited on-board resources.As result of the above research,the secure and high-quality transmission of communication is realized,and the maximum utilization of limited resources is improved.The main contributions and innovation of this paper are as follows:1.A RWA algorithm based on bee colony optimizationThis paper proposes a bee colony algorithm optimization based on link cost for RWA(BCO-LCRWA)in satellite dynamic optical networks.The cost model of ISLs is established with metrics of delay and wavelengths utilization,with constraints of Doppler wavelength drift,transmission delay,wavelength consistency and continuity.Specifically,the fitness function of bee colony exploited in the proposed algorithm takes communication hops and wavelength resources utilization into account to implement reasonable routing and effective utilization of wavelengths.The results show that the proposed algorithm overcomes the shortcomings of long delay and high bit error rate(BER)in satellite optical network,meets the requirements of real-time traffic transmission,eliminates the detrimental effect of Doppler shift on communication performance,and ensures the efficient utilization of wavelength resources at low blocking rate.2.A load balancing algorithm based on secure routing strategyFocused on the security problems caused by the openness of space environment,this paper proposes a secure routing strategy based on multi-layer satellite.After the procedures of satellite cluster division,link report generation and trusted routing calculation,the trust evaluation is constructed by information of network delay,packet loss rate and available bandwidth.And then a path with higher trust value is routed by the senior satellite manager to achieve reliable data transmission and to improve system security.Furthermore,aiming at widely used single-layer satellite structures,a load balancing algorithm based on security strategy is proposed to solve unbalanced traffic load caused by the diversity of global traffic distribution and routing unsecurity in satellite optical network.Compared with the traditional heuristic algorithm,the proposed schemes have better applicability,lower blocking rate and more secure communication performance.3.Congestion control algorithm based on traffic diversionIn this paper,a satellite congestion control algorithm based on traffic diversion is proposed to solve the congestion problem caused by the limited processing capacity of satellites and unbalanced distribution of global traffic.The artificial bee colony(ABC)mechanism is appiled to solve the congestion control optimization model with multiple constraints Aiming at the predictable traffic accumulation resulting in network congestion,a link cost modification based on traffic distribution,which disperses the traffic in heavy load area in advance through the modified path cost,is proposed to obtain the global optimal routing result.While for sudden congestion,a congestion control indicator based on wavelength utilization is designed to avoid the network paralysis caused by local congestion to the maximum extent considering the simultaneity of wavelength assignment and routing.In view of cascading congestion caused by the congestion node,the congestion region is set to avoid further deterioration of the performance.The above scheme solves the congestion problem of satellite optical network comprehensively,which can achieve high communication success rate and low transmission delay,as well as the rational management of wavelength resources on the basis of congestion avoidance.4.A dynamic bandwidth allocation algorithm for multi-QoS guaranteeBased on the bandwidth allocation problem of broadband satellite communication system,this paper proposes a dynamic bandwidth allocation algorithm for different quality of service(QoS)guarantee to solve the contradiction between the limited on-board resources and the growing demand of broadband multimedia services.Firstly,a cross-layer bandwidth allocation model is constructed,which considers the information of application layer,media access control(MAC)layer and physical layer.Then,we establish the utility function with modifying factor based on cross-layer information to allocate bandwidth resources by optimized bee colony algorithm.The algorithm we proposed fully considers and analyzes the modulation order,coding efficiency,transmission rate and QoS priority of different types of users.Finally,the research results show that the proposed algorithm not only meets the QoS requirements of multiple users,but also achieves efficient bandwidth allocation and high-speed service transmission on the basis of considering the physical layer transmission environment. |
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