Demodulation performance for MUOS user-to-base downlink receiver

In the DOD mobile-user objective system (MUOS), the U2B downlink feeds data representing 32 digitized WCDMA beam-carriers from the spacecraft to ground. To meet system requirements this link must be highly available. Link format and coding design have been performed to support these needs. Ground hardware development is well underway, and demodulation performance data is now available that provides confirmation of many aspects of the design. This paper presents the rationale for the predicted demodulation performance as well as the measured performance. Degradation due to transmitter phase noise has been a particular concern; therefore, this paper also includes predictions of expected degradation due to phase noise as well as measured BER performance with phase noise intentionally imparted onto the downlink test signal input to the U2B receiver.