The subchannel switched frequency-division multiple-access (SS/FDMA) system improve the routing flexibility of transponder banks in channelized multibeam satellites. This system can efficiently be utilised to construct a VSAT (very small aperture terminal) network and/or a business satellite communications network using small aperture terminals. The authors address the application of the SS/FDMA system to such networks. A proof-of-concept (POC) model of SS/FDMA onboard equipment called the SS/FDMA router is described in terms of its configuration and measured electrical performance. Results of transmission experiments using the POC model as well as computer simulations are presented. In addition, a redundant SS/FDMA router configuration is proposed, and its reliability is calculated for a 15-year satellite mission time. Finally, estimated values of volume, mass, and DC power consumption of the redundant SS/FDMA router are presented.>

A computer-aided approach to the planning of SS/TDMA network operation is proposed. SS/TDMA is a sophisticated satellite communication network based on an onboard switch matrix, whose operation planning is formulated as a large-scale scheduling problem. An overall planning and scheduling model is presented to deal with practical SS/TDMA systems, such as a two-frequency channel network and nondisjoint beam coverage. For systematic planning suitable for a computer-aided approach, the entire scheduling process is divided into several steps, for each of which an efficient mathematical model is proposed. A linear programming model is used for distribution of traffic on a beam-to-beam basis and the generated switching sequence is further refined by a model using the traveling salesman problem. Burst scheduling is carried out by the Bin packing algorithm and scheduling models for practical networks allowing transponder hopping and multidestination bursts. An algorithm called enhanced rescheduling is presented to further improve the scheduling capability of the existing methods. The performance of the proposed methods is demonstrated by simulation results.>

Efficient algorithms that generate a detailed operation plan for satellite-switched time-division multiple access (SS/TDMA) systems are proposed. A burst time plan generation problem is analyzed and two algorithms for burst scheduling are presented. The first method is an algorithm based upon a bin pack problem. The other algorithm schedules new bursts while reassigning already scheduled bursts by a single machine scheduling model. These algorithms are shown to be applicable to practical systems operating with transponder hopping and multidestination bursts. Simulation results for a number of example problems are presented.>

A systematic method of determining carrier frequency assignment is proposed to minimize the cochannel interference in satellite communication systems. For the mathematical treatment of the problem, discrete positioning of carriers is introduced to avoid the nonlinear expression inherent in interference evaluation. The proposed method converts this nonlinear problem into the well-known assignment problem and enables the development of an algorithm based on the branch-and-bound method. Extended models of the proposed method are presented for practical application. To demonstrate the effectiveness of the method, computation results are shown for two typical problems. In both of the examples, cochannel interference is significantly reduced as the result of optimization of frequency assignment.>

The limitation in the effective use of the geostationary orbit is the intersatellite interference problem. A theoretical approach to realize an optimal usage of the orbit is provided in this paper, with particular attention to the constraints of service arcs, existence of spotbeam operating systems and different frequency plannings. The problem is formulated as a nonlinear programming problem and the sequential unconstrained minimization technique is applied to solve it numerically. Example computations are also given and various interference criteria are evaluated in terms of orbit utilization.