Symbol Error Rate Model for Communication Using Femtosecond Pulses for Space Applications

In some emerging satellite applications, it is of paramount importance to accurately measure the distance between satellites in formations. Range measurement systems based on femtosecond lasers have been suggested as very precise solutions that could be incorporated into satellites. It would be fortuitous to exploit the same laser link for both the distance measurement and communication, thus achieving two functions with considerably reduced payload weight and size compared with that could be achieved if the two tasks were performed separately. In this letter, we propose to modulate the ranging femtosecond pulses to carry communication information. The proposed modulation is in the frequency domain, benefiting from the wideband property of femtosecond pulses. The method hinges on the special characteristics of the femtosecond pulse, which has a very broad frequency spectrum alongside its ultrashort time duration. We analyze the multiple-inverse-pulse-position modulation (MIPPM) method. The main idea of the MIPPM is the ON-OFF modulation of each spectral component, while each modulated symbol includes all spectral components and only few spectral components are in the OFF state at any given time. We analyzed the performance of the proposed system in terms of symbol error rate for a given set of parameters.