Diversity Reception Evaluation for In-Body to On-Body Communication Channel in UWB Low Band

In this paper, a preliminary diversity reception investigation for the in-body to on-body communication channel in UWB low band for wireless capsule endoscope (WCE) application has been carried out through simulation procedure. Spatial diversity antenna, polarization diversity antenna and a combination of both configurations are designed to overcome the shadow fading due to the position variation of the swallowed capsule. Limited to the simulation capability, representative TX antenna positions in the body are designed in terms of symmetry relationship relative to the diversity reception antenna configurations. The values of the diversity gain using classical combination techniques, i.e., selection combining (SC), equal gain combining (EGC), and maximal ratio combining (MRC), have been calculated and compared. Complex correlation coefficient and power imbalance are given to analyze the diversity performance. Different from the multipath fading in the on-body communication channel, a relatively small diversity gain will be expected resulting from the shadow fading in the in-body to on-body UWB communication channel. It is verified that diversity works at its best if fading at the branches is low correlated and the branch signals have a small power difference.