This paper aims to improve the TDMA-based Heartbeat-Driven MAC (H-MAC) protocol for WBAN. H-MAC is designed to be used in star-topology WBAN for time synchronization realization by using heartbeat rhythm information, instead of periodic synchronization beacons. H-MAC therefore saves power of WBAN sensor nodes and reduces the negative effects of electromagnetic radiation on human health during the packet delivery process. To embed heartbeat rhythm information into different bio-signals and check the peak values of wave forms can contribute to time synchronization for BSN. As the heart contracts via systole and relaxes via diastole, pulse is the number of times one's heart beats every minute and the number of pulses measured at different body parts is the same. However, blood vessels run over the whole human body and their distances away from the heart greatly vary in the same systole, leading to an imperceptible time difference and the synchronization problem. We propose to include the presently most mature method for time synchronization, Flooding Time Synchronization Protocol (FTSP), to deal with time differences.