In this paper, the cognitive multi-beam satellite system, i.e., two satellite networks coexist through underlay spectrum sharing, is studied, and the power and spectrum allocation method is employed for interference control and throughput maximization. Specifically, the multi-beam satellite with flexible payload reuses the authorized spectrum of the primary satellite, adjusting its transmission band as well as power for each beam to limit its interference on the primary satellite below the prescribed threshold and maximize its own achievable rate. This power and spectrum allocation problem is formulated as a mixed nonconvex programming. For effective solving, we first introduce the concept of signal to leakage plus noise ratio (SLNR) to decouple multiple transmit power variables in the both objective and constraint, and then propose a heuristic algorithm to assign spectrum sub-bands. After that, a stepwise plus slice-wise algorithm is proposed to implement the discrete power allocation. Finally, simulation results show that adopting cognitive technology can improve spectrum efficiency of the satellite communication.
To solve the satellite repeater’s flexible and wide-band frequency conversion problem, two novel microwave photonic repeater schemes of generating four and eight different output RF frequencies from one input RF carrier are proposed by adjusting the dual-parallel Mach-Zehnder Modulator’s(DPMZM) electrical configurations. Both schemes can realize simultaneous inter- and intra-band frequency conversion in one single structure and need only one onboard frequency-fixed microwave source. In the first scheme, one C-band RF signal’s 6 GHz carrier can be successfully converted to 2GHz, 4GHz, 16GHz and 22GHz, while the other scheme demonstrates the frequency conversion from 16GHz to eight different frequencies(6GHz, 26GHz, 22GHz, 42GHz, 4GHz, 36GHz, 12GHz and 52GHz).