In this paper, we propose a method to ensure larger number of channels than the current Satellite Digital Multimedia Broadcasting (S-DMB). For Backwards Compatibility (BC) for legacy subscribers, we apply Hierarchical Eight Phase Shift Keying (H-8PSK) modulation and Low Density Parity Check (LDPC) code. Using the newly proposed method, we simulate the performance deterioration of the existing stream and the performance of the new stream according to code rates of LDPC and deviation angle. As the result, we present the optimal deviation angle, which produces the least performance deterioration of the existing system and the best performance of the new system, drawing satisfiable improvement in transmission rate.