Multi-beam GEO satellite concept for the mobile user objective system

The mobile user objective system (MUOS), the next-generation ultra-high frequency (UHF) military satellite communications system, will face several technical challenges, including accommodating users operating low-power hand-held terminals. The U.S. Navy (PNW-146) tasked The Johns Hopkins University Applied Physics Laboratory to develop a geo-synchronous (GEO) satellite concept for MUOS that will have the flexibility to provide various types of new narrow-band communications services as well as be able to function with legacy terminals. The satellite concept consists of four GEO satellites that will use several advanced communications techniques to accommodate the new requirements. In particular, the satellites will benefit from technical advances in satellite subsystems such as efficient solar cells and batteries, lightweight structures, and attitude control mechanisms and sensors. Advances in payload technology such as large antennas and signal processing will also have a significant impact, and advanced modulation and source coding techniques will maximize spectrum use. This paper describes the spacecraft design (excluding the communications payload), telemetry tracking and control operations, the ground segment including gateway architecture and mobile terminal design, legacy terminal issues, and the frequency spectrum environment.