Data rate enhancement method for body channel frequency selective digital transmission scheme

Human body communication (HBC) is an emerging communication technique for wireless body area networks, which has recently been included in IEEE802.15.6 standard. The HBC transmitter uses the frequency selective digital transmission (FSDT) scheme, where Walsh code are used to spread the information bits. The data rate of this system is limited to 1.3125 Mbps, due to the limited set of spreading codes available for use under the transmission mask of IEEE802.15.6. In this paper, we present a code stacking method that effectively doubles the data rate using the same set of Walsh code. The performance of the proposed amplitude modulated FSDT scheme depends on the effectiveness of the system to reduce the effect of inter-symbol interference (ISI). Two methods for minimizing the effect of ISI are presented in this paper. Comparing to the FSDT scheme, doubling the data rate resulted in signal to noise ratio degradation of 1 dB.