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.

In this paper, a new fine timing synchronization method of orthogonal frequency division multiplexing (OFDM) system is presented to solve the performance degradation from the diagonally allocated pilot structure. For systems based on diagonal pilots, by using the conventional timing estimation method which is proposed by Hsieh and Wei, the estimation performance can be degraded due to the relatively large pilot distance in the frequency selective fading channel. Therefore, we propose a new fine timing synchronization method, which is based on symbol accumulation with phase interpolation, and that can reduce the effect of frequency selectivity and frequency offset. By mathematical analysis and simulation, we verified that the proposed method can achieve better performance than conventional method in large frequency selective fading environment.