Research On Channel Allocation Strategy For Leo Satellite In Space Information Newwork

It has a vital role and significance to construct China's independent control of space information network for the construction of military information battlefield, the social and economic development, the improvement of the comprehensive national strength. It also has an irreplaceable function and meaning in dealing with disasters and increasingly serious environmental degradation problems. Low earth orbit (LEO)satellite network as an important part of the access network of space information network, the most important feature is the quickly movement that relatived to the earth's surface, which makes frequent beam handover become an important problem in the system. In LEO satellite network with extremely valuable resources, the issue how to maximize the user's needs, optimizing bandwidth utilization and service quality of the system when handover has occurred, is urgently to be solved by the technology of channel assignment in wireless resource management. This paper takes the LEO access network of the spatial information network as the research object, the channel assignment and handover issues are studied in detail in this application environment, the main research results are as follows:(1) An analytical calculation method for determining the admission region of traffic load in LEO satellite network is proposed, which is based on guaranteed handover (GH) scheme and channel sharing (CS) scheme under quality of service(QoS) constraints. It avoids the computationally intensive iterative process of iterative method. According to the performance characteristic of GH and CS, relational formulas are established between maximum traffic intensity of GH and new call blocking probability constraint, between maximum traffic intensity of the CS and handover failure probability constraint. Then the maximum new call traffic intensity expressions of GH and CS are deduced. The accuracy of the analysis approach have been verified by computer simulations. In changed network environment, the proposed method can be more effective to calculate the admission region of traffic load in LEO satellite network based on GH and the CS scheme.(2) An analytical approach for calculating the admission region of traffic load in LEO satellite network is proposed, which is based on handover queuing (QH) scheme and fixed channel reserved combining queuing handover (FCR-QH) scheme under quality of service (QoS) constraints. It reduces the computationally intensive iterative process of iterative method. Based on the performance analysis of QH scheme and FCR-QH scheme, the relationships between the QoS constraints and the maximum traffic intensity of QH scheme as well as the FCR-QH scheme are established. The maximum traffic intensity of QH scheme and FCR-QH scheme under the conditions of new call blocking probability and handoff failure probability constraints are respectively solved. According to the monotonically increasing relationship between the QoS performance and the traffic intensity, the maximum traffic intensity of QH scheme and FCR-QH scheme are obtained. The accuracy and effectiveness of the analysis has been verified by computer simulations. Besides, the process of maximum traffic analysis is further simplified if QH scheme is analyzed under the constraint condition of the handover failure probability firstly. The optimal number of reserved channels is determined based on the analysis of traffic load admission region of FCR-QH scheme.(3) A channel allocation scheme based on reserved channel prior occupied for multi priority traffic (MRCP) is proposed. It overcomes the fairness problem of threshold setting existing in the current researches, the low channel utility and high call blocking probability problems caused by reserved channels used in delay. In the proposed scheme, threshold setting of available channel on handoff call and new call between different services is relatively independent, which makes the priority between new call for high priority traffic and handoff call for low priority traffic flexible enough to handle. A theoretical analysis model is established for MRCP scheme,the new call blocking probability, the handoff failure probability, the grade of service and the channel utilization for all kinds of services are derived. Simulation results proved the correctness of the theoretical analysis method. At the same time,the system performance is improved, and the system requirements for fairness are satisfied.Moreover, under the single service condition, the proposed scheme can flexibly adjust the number of reserved channels to cope with the gusty change of QoS requirement in LEO satellite network.