Short Messaging Services using TDRSS with low-power Personal Communication Devices

The Tracking and Data Relay Satellite (TDRS) and the TDRS System (TDRSS) form the basis for NASA´s Space Network (SN) originally intended for manned spaceflight communications. While admirably serving this function, the TDRSS can also provide alternate communications for a variety of low-power operational requirements. This includes the use of Short Messaging Services (SMS) with personal-sized devices where small amounts of text can be communicated over beyond line-of-sight distances (BLOS). TDRS´s high-gain Ku-band antennas enable BLOS communication to low-power Personal Communications Devices (PCD). In analyzing these communication links, several factors must be considered and alternatives studied to obtain optimum performance. This paper addresses several such factors including link parameters, link closure, data rates, suitable error correction and coding, antenna constraints, transmit power, and area coverage and their relationship in establishing a high-probability of successful communication. Overall, this paper presents a functional concept including practical considerations using TDRSS for SMS with personal communications devices.