A precise estimation and compensation of SFO (Sampling Frequency Offset) is an important issue in OFDM (Orthogonal Frequency Division Multiplexing) system, because sampling frequency mismatch between the transmitter and the receiver dramatically degrades the system performance due to the loss of orthogonality between the subcarriers. However, the conventional method causes serious performance degradation of SFO estimation in low SNR (Signal to Noise Ratio) or large Doppler frequency environment. Therefore, in this paper, we propose two SFO estimation methods which can achieve stable operation in low SNR and large Doppler frequency environment. The proposals for SFO estimation / compensation are mainly specialized on DVB (Digital Video Broadcasting) system, and we verified that the proposed method has good performance and stable operation through extensive simulation.

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In this paper, we propose group Manchester code (GM) modulation scheme for medical in-body wireless body area network (WBAN) systems. In IEEE, the WBAN system is assigned as 802.15. Task Group 6 (TG6), and the related standardization is being progressed. Recently, in this Group, group pulse position modulation (GPPM), which can obtain data rate increase by grouping pulse position modulation (PPM) symbols, is proposed as a new modulation scheme for low-power operation of WBAN system. However, the conventional method suffers from BER performance degradation due to the absence of gray coding and its demodulation characteristics. Therefore, in this paper, we propose a modified GM scheme which groups Manchester code instead of PPM. In the proposed GM scheme, a low-complexity maximum likelihood (ML) demodulation method is employed in order to maximize the BER performances. Also, log likelihood ratio (LLR) decision method is proposed to employ the Turbo code as forward error correction (FEC). Finally, we verified that the proposed method has a good performance and is an appropriate scheme for in-body WBAN system through extensive performance evaluation.

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