Flexible transmission bandwidth management with effective channel reservation techniques for NGSO MSS networks

This paper describes efficient transmission bandwidth management based on flexible channel assignment and effective grade of service (GOS) control methods for nongeostationary orbit mobile satellite service (NGSO MSS) networks. Our basic approach for the flexible channel assignment is to use linear programming (FLEXCA-LP), and to apply the column generation technique for further reduction of the total bandwidth requirement. These methods efficiently assign channels, taking account of moving spot beam coverage and dynamic traffic load variation for large-scale networks. The GOS is investigated for the channel assignment by FLEXCA-LP to make the GOS of ongoing calls better than that of fresh calls as stipulated in ITU-T Recommendations. We propose a few effective means to improve the results of FLEXCA-LP by reducing the disruption possibility of ongoing calls. One is to add channels utilizing a hysteresis concept. The others are effective use of GOS control techniques for NGSO MSS networks. These techniques are evaluated by a simulation study to identify promising techniques. Under time-variant conditions, we show that a reliable channel assignment plan is generated first by FLEXCA-LP considering the traffic load of fresh calls only and then by GOS control techniques to improve handover failure and call disruption rates