Research On Timeliness-Sensitive Transmission Techniques For Space-Air-Ground-Sea Integrated Network

As a combination of the new generation of wireless communication technology and the cutting-edge fields of space and ocean sciences,the development trends of space-airground-sea integrated network(SAGSIN)can be summarized as the broadband satellites with high capacity,the networking of satellites in different orbits,the diversified application scenarios and the heterogeneous integration of satellite-terrestrial network.SAGSIN is characterized by vast scale,dramatic dynamics and heterogeneous resources.This poses significant challenges to real-time perception,processing,dissemination,and application of information.Moreover,with the rise of mission-critical applications such as precise remote control and perception,battlefield-awareness real-time command decisions,the demand for timeliness even effectiveness of information is rapidly increasing.Efficient transmission of information is the basis and important guarantee for the successful implementation of mission-critical services in the SAGSIN.However,under the constraints of the characteristics of SASGIN,the applicability of the traditional transmission technology is insufficient.It is difficult to ensure the continuous and timely information delivery under communication links characterized by vast scale and dramatic dynamics,and it is also difficult to provide accurate support for mission-critical services with different requirements and characteristics.Therefore,this poses an urgent need to carry out innovative research on the time-efficient transmission technology for the SAGSIN.Focusing on the timeliness requirement of information transmission and application in SAGSIN,the dissertation aims to improve the applicability of transmission technologies under the constraints of the SAGSIN characteristics.Based on the link characteristic,node capability,task and scenario characteristics of the network,the dissertation carries out novel research on the transmission theory and technology for the SAGSIN.The core technical requirement is to improve gain ability,adaptability and practical ability of the transmission technology.Therefore,the dissertation mainly focuses on reveal the intrinsic essence that constrains the timeliness of information,design high-efficiency transmission strategies for vast scale and dramatic dynamics aerospace links,and propose a joint task scheduling and resource management scheme for the marine Internet of Things scenarios.Thus,the timeliness and efficiency of transmission technology in the SAGSIN can be guaranteed.Specific research on the following aspects.(1)This thesis proposes a general model of the state update system for typical timesensitive services,and clarifies the characteristics of the aerospace links and its impact on timeliness of information delivery.Aiming at the requirement of multi-user information transmission in time-varying channels,a waiting and batching scheme is designed with the goal of improving efficiency.(2)This thesis proposes an Incremental Redundancy Hybrid Automatic Repeat reQuest(IR-HARQ)mechanism for the vast scale links in aerospace communication.According to the limitations and applicability of HARQ,a standard IR-HARQ transmission scheme is designed based on the analyses of the design principles.Aiming at further reduce the impact of retransmission,an advanced Fast IR-HARQ scheme with channel estimation mechanism is designed with the goal of improving transmission efficiency.This work makes the HARQ mechanism suitable for the vast scale aerospace links,and improves the adaptability of the transmission technologies in the SAGSIN.(3)This thesis proposes a two-layer coding strategy for the time-varying links in the SAGSIN.The packet-layer erasure-correction codes are introduced to share the decoding pressure of the error-correction codes within each packet in the physical-layer.To achieve boosted timeliness in aerospace communication,the joint redundancy allocation was studied based on the two-layer coding strategy,and the reliable transmission required for the service was achieved through the cross-layer optimization.This work provides a new high-reliability layered coding scheme for time-varying links,and supports the precise matching of coding schemes to services in aerospace communications.(4)This thesis proposes a joint task scheduling and resource allocation scheme for the marine Internet of Things scenario.To improve the timeliness of mission-critical applications,hybrid low earth orbit and geosynchronous earth orbit(hybrid GEO-LEO)satellite architecture are involved to make full use of the capabilities of nodes at different altitudes.This work provides a new information delivery solution for the marine communication,and improve the timeliness of information transmission and application in the typical scenarios in the SAGSIN.