ENHANCEDBASE-TO-USERSATELLITE GAIN VARIATION REDUCTION ALGORITHMFOR MUOS

Based on Universal Mobile Telecommunications System (UMTS) Wideband Code Division Multiple Access (WCDMA) technology, the Mobile User Objective System (MUOS) provides a wide range of wireless telecommunications services to the war fighter over geosynchronous satellites. As MUOS is a multiple beam system, it is ofparamount importance for the User Entry (UE) to select the best beam, which in turn requires accurate transmit powerfrom the satellite. To minimize the satellite path gain uncertaintyfrom the base station to the UE, the Enhanced Gain Variation Reduction (EGVR) algorithm is proposed. Implemented on the basis of the measurements of the received signal code power (RSCP) ofthe pilot channel from the UEand the measurements ofthe received signal code power at the terrestrial base station, the EGVR process generates the transmission power estimate and integrates it into the overall gain adjust system to keep the transmission power levels as desired. Thefeatures ofthe algorithm include the weighted gain adjusts generated from the estimation error, appropriate timers to control the measurementflow, and differential measurements to eliminate the common errors between satellite beams. The preliminary study shows that the EGVR can reduce the power uncertaintyfrom 2.4 dB to 0.4 dB, in addition to reducing any differential errors encountered. With the blending ofthe telemetryfeedback into the algorithm, it can make the transmitpower uncertainty even smaller.