Mobile satellite communication is concerned with internetworking of heterogeneous network which provides global coverage and reliable broadband communication. The demand for higher rate and reliable broadband communication with less consumption of power is drastically increasing. The existing work was to control the power by allocating power to the transmitters with the support of Mixed Integer Linear Programming (MILP) and achieving maximum data. This method failed to allocate power for any new Tx-Rx pair getting into the network. Hence Sum-Rate Power Control (SRPC) method is introduced. This proposing work helps to control the power with Quality of Service (QoS) constraints to achieve optimum power level in cross layer based Mobile Satellite Communication network. It allocates the power for Tx-Rx pairs present in the network and also for new Tx-Rx pairs coming to the network by applying Analytical Power Control Algorithm (APCA) and Distributed Power Control Algorithm (DPCA) in case of two Tx-Rx pairs and more than two Tx-Rx pairs respectively. This will result in achieving the optimum power level with QoS constraints.