Radio frequency spectrum is a limited resource. Currently the implementation of satellite communication systems in the C-band and Ku-band frequency is already very crowded. Satellite communication system with service coverage using a single beam in C-band and Ku-band frequency - with the bandwidth of each band is around 800 MHz and 750 MHz, respectively - provide limited throughput services. On the other hand, the trend is we need the communication with high data rate. To increase the capacity of satellite services can be done by implementing a Ka-band High Throughput Satellite (HTS) communication system using the concept of multi spot-beams and frequency re-use in Ka-band. Ka-band frequency has a high enough bandwidth, which is about 3.5 GHz. Ka-band HTS system will have double throughput (capacity) corresponding to the number of spot-beams and the amount of repetition frequency which is distributed in multi spot-beams. If the parameters of Ka-band HTS system is implemented in a uniform system, it will produce a total throughput of HTS services with not optimum condition.
To obtain the optimum Ka-band HTS system, we need to apply the modeling of multi spot-beams and frequency re-use by correlating and adjusting the parameters Ka-band HTS systems in heterogeneous and proportional to the condition of Indonesia's geographical areas which are unique and specific. In this paper, heterogeneous modeling is a variation of the selection of bandwidth per frequency channel and variation in pattern of repetition of used Ka-band frequency that is distributed proportionally to each spot-beam. Proportional modeling is an adjustment mechanism for placement of spot-beams in accordance with a position and the size of land area of each region in Indonesia, as well as adapted to the services demand (data rate) and distribution of the Indonesian population.
Ka-band HTS system modeling with heterogeneous and proportional to the condition and position of Indonesia geographical area, would generate a high throughput and optimum Ka-band HTS systems in Indonesia. This research proposed a concept of accomodative throughput to be implemented in Ka-band HTS system in Indonesia. The accomodative throughput means there were many possibilities to allocate the bandwidth in each spot-beam with various number of bandwidth while still maintain the colour pattern allocation of those spot-beams, in order to have the flexibility for the HTS system to accomodate the growth or dynamic traffic demand in the future after the HTS system had been launched.