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Sub-spectrum suppressed transmission based on DSD (Direct Spectrum Suppression) is a technology that can increase frequency utilization efficiency of single carrier satellite communication systems. In order to suppress ISI (Inter Symbol Interference) caused by the sub-spectrum suppression, proposed ASR (Autologous Spectrum Regeneration) can equalize distorted waveform iteratively. In this paper we optimize ASR processing in two points of view; computational complexity and combination of MCS. First, distribution of iteration for turbo decoding, that is necessary per ASR iteration, is optimized to reduce computational complexity. Second, we evaluate various combinations of adaptive suppression and MCS (Modulation and Coding Scheme) to maximize frequency utilization efficiency. Based on computer simulation, we show those performances and clarify their optimization settings. [ABSTRACT FROM PUBLISHER]

Superposed multicarrier transmission scheme is known to improve frequency utilization efficiency where several systems share spectrum without any spectrum spreading techniques. In superposed multicarrier transmission scheme forward error correction (FEC) coding is applied over subcarriers so that the effects of interference caused by superposition is mitigated by interleaving effects. When the interference power is large, the effects of FEC become smaller particularly owing to the mis-setting of initial log likelihood ratio (LLR). To solve this problem, FEC metric masking is proposed where initial LLRs for superposed subcarriers are replaced by neutral value in the receiver followed by decoding. This technique is effective, however, it needs the information about superposed frequency band. In this paper we propose a scheme to detect superposed band by using FEC metric masking. In the proposed scheme, the subcarriers where FEC metric masking is applied are changed and packet error rate (PER) is measured. When the FEC metric masking is applied to the superposed subcarriers, PER is minimized. Based on the change of PER, we can detect the superposed band. We evaluate the proposed scheme by computer simulation and show that it can detect the superposed band with high probability. [ABSTRACT FROM PUBLISHER]