Shinichi Nomoto

Frequency and time slot assignment algorithms for FDMA/TDMA non-GEO MSS with multiple gateway Earth stations

FDMA/TDMA non-GEO MSS (mobile satellite services) systems generally require a pre-planned pool of radio resources, i.e., frequency and time slot plan (FTSP), for each gateway Earth station (GES) prior to the real-time channel allocation by the multiple GESs sharing the resources harmoniously. The time-variant nature of those systems implies that a dynamic FTSP planning method is crucial to the operation to cope with time-variant traffic demand and inter-beam interference condition. This paper proposes and compares two resource assignment algorithms (spread type algorithm and concentrated-type algorithm). Numerical evaluation demonstrates that the spread type algorithm is very effective and promising in the FTSP generation for such systems.

Traffic load optimization for multiple satellites system under power limit constraints

In satellite communications systems, the total satellite transmitting power (in short, satellite power) is one of the important radio resources, as well as spectrum resources, because of the limited capability of onboard electric generators. Therefore, for attaining optimum satellite radio resource utilization, it is not enough to just consider the spectrum resources but also to take account of the satellite power. This paper proposes algorithms using the linear programming for optimally distributing the traffic demand to multiple satellites in a system. The algorithms are applicable to any kind of satellite system with multiple satellites (GEO, MEO, LEO or combination of any) to increase the system capacity in terms of the total amount of traffic accommodated by the system. Numerical examples demonstrate that the proposed algorithms contribute to maximizing the system capacity.

DOA estimation by using small size array based on spatial FFT

In this paper, simple DOA (Direction of Arrival) estimation method based on spatial FFT will be proposed. The accuracy of the estimation and the duration which is required for the estimation will be examined. At last, it is shown that the proposed DOA estimation method has sufficient performance to supply estimated DOA for HA (Howells Applebaum) adaptive array as a reference for the adaptive control of the directivity of the array antenna.