Research On The Characteristics Of Space-based Wavelength-routed Optical Satellite Constellation Networks

Driven by the rapid development of terrestrial communication networks, networkingbetween satellites becomes the future development of satellite communications. Opticalintersatellite links technique could establish the high-speed and convenient informationaccess between satellites with the laser as an information carrier. It is an application exten-sion for free space optical communications in the field of satellite communications, and ithas also been considered as an importance research branch in the field of modern satellitecommunications with high capacity demand. Since the optical ISL terminals clearly out-perform their microwave counterparts in terms of required dc power consumption, massand size, they are more suitable for the developments of networking in satellite communi-cations. Space-based Wavelength-routed Optical satellite Networks (WROSN for short)make use of optcial intersatellite links (ISLs) as the data carrier between satellites in theconstellation, date transfer between different regions covered by different satellites canbe achieved through these ISLs, which leads to a global space-based networking. Opti-cal networking employing wavelength division multiplexing (WDM) architectures withwavelength routing on top of physical ISL topologies of constellation networks couldcreate an optical transport network (OTN) as global service backbone. The OTN couldnot only reduce the mass, size and dc power consumption of satellite, but also satisfyextremely the users proliferating traffic demand by efficiently usage of optical amplifiedbandwidth onboard. In addition, wavelength routing guarantees to simplify the routingdecisions of the intermediate nodes and minimize its processing delays, resulting in re-ducing transfer delays and delay jitter of long distance data traffic. Therefore, the WROSNis the future development of satellite communication networks.With reference to the published paper, previous works have been rarely devoted tothe research of the WROSN. Only a few papers describe the concept of the WROSN andsingly analyze its wavelength requirements, of which the results has limit applications.Based on the practicalities, we have focused the our theoretical research and sim-ulation analysis on the performance of WROSN. It provides the preliminary theoreticalelements for the new techniques applied in the broadband satellite constellation networks.First of all, the dissertation have provided with the state-of-art of current research on this issue, including that of optical satellite communications and broadband satellite constella-tion networks. Then based on the actual cases, we have described the model of WROSN,and analyzed the time-variant characteristics of physical ISL topologies and their rela-tionship with constellation parameters. With this understanding, we have carried on thefurther research works. The primary contents of the dissertation and its innovations arelists as follows.(1) Doppler characterization for the WROSN and its in?uence on the communi-cation performances of the networks are systematically analyzed. When the ISLs havebeen established between communicating satellites with high-speed relative movement,it is inevitable that the received signals are in?uenced by the Doppler Effect. Definedby the ability of laser ISL terminals, optical ISLs in the WROSN are of diversity. In thepaper, theoretical expression of the Doppler wavelength shift for the optical ISLs in theWROSN has been derived as a function of constellation parameters. And the Dopplercharacterizations for different ISLs have been analyzed with it. In order to describe theDoppler characterizations of intermittent ISLs which is of time discontinuity, estimationsof Doppler wavelength shift and visibility duration for intermittent ISLs have also beendeveloped. Results derived from the expressions have validated the approximations wellfor the intermittent ISLs. In order to characterize the impact of Doppler Effect on theWROSN, study on degradation of the BER caused by Doppler wavelength shift is alsodone based on the typical constellation parameters.(2) Linear in-band crosstalk in the routing node of the WROSN is analyzed, andcrosstalk characteristics and its in?uencing factors for the WROSN with single-hop andmulti-hop ISLs are analyzed, furthermore, the crosstalk margin of routing nodes for multi-hop ISLs is also given under different BER. In-band crosstalk is generated among ISL sig-nals with the same nominal wavelength from different input ISLs in wavelength routingnodes of the WROSN. It would restrict the transmission distance of WDM ISL signals be-tween satellites and be the key impairment for the WDM networks. In terms of crosstalkamong WDM signals from different input ISLs in wavelength routing units, theoreticalmodel for the linear in-band crosstalk in the routing node of the WROSN has been estab-lished. Then, crosstalk in?uences on the WROSN with single-hop ISL and multi-hop ISLconnectivity have been analyzed, the minimum requirements for the crosstalk level of therouting node is given for different multi-hop ISLs. (3) In view of temporal and spatial characteristics of WROSN, wavelength require-ments and related issues are analyzed in detail for the WROSN. Wavelength requirementin the WROSN is a direct re?ection of financial cost and operational feasibility of net-work design. According to time- and space-dependent network physical ISL topologies,we have demonstrated the best routes search method for source-destination satellite con-nection requests. Physical ISL topologies of the WROSN have been randomly generatedin order to satisfy their network connectivity, and a statistical analysis of wavelength re-quirements for the generated topologies has been carried out. To illuminate the advantageof the WROSN with arbitrarily connected ISL topologies, we have also compared theresults with that of the regular ISL topologies.(4) Statistical analysis of celestial background noise is done for the constellations.Celestial background is the inevitable noise source for the optical ISLs. We have given theexpression for the celestial background noise power received by the ISL terminals basedon the spectral irradiance function of the stars. Then, combining with SAO catalog, wehave analyzed the celestial background noise in detail for the optical ISLs with differentwavelength band, for different wavelength allocation of WDM ISLs and for the typicaloptical ISLs in the WROSN.The works of this dissertation provides a preliminary theoretical model and designconsignment for the design of the WROSN. They will promote the development of WDMtechniques for optical intersatellite communication systems. The dissertation will lay theelementary research foundations for the development of the WROSN in our country.