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In this chapter, the state of the art of in vivo wireless channel characterization has been presented. Various studies described in the literature are dedicated to the in vivo communication channel, and they consider different parameters in studying various anatomical regions. Furthermore, the location-dependent characteristics of in vivo wireless communication at 915 MHz are analyzed in detail via numerical and experimental investigations. A complete model for the in vivo channel is not available and remains an open research problem. However, considering the expected future growth of implanted technologies and their potential use for the detection and diagnosis of various health-related issues in the human body, the channel modeling studies should be further extended to develop better and more efficient communications systems for future in vivo systems., Comment: 25 pages, 17 figures, 7 tables, URL of the final version: https://digital-library.theiet.org/content/books/10.1049/pbte065e_ch7 . arXiv admin note: substantial text overlap with arXiv:1902.06860

In vivo wireless body area networks (WBANs) and their associated technologies are shaping the future of healthcare by providing continuous health monitoring and noninvasive surgical capabilities, in addition to remote diagnostic and treatment of diseases. To fully exploit the potential of such devices, it is necessary to characterize the communication channel which will help to build reliable and high-performance communication systems. This paper presents an in vivo wireless communication channel characterization for male torso both numerically and experimentally (on a human cadaver) considering various organs at 915 MHz and 2.4 GHz. A statistical path loss (PL) model is introduced, and the anatomical region-specific parameters are provided. It is found that the mean PL in dB scale exhibits a linear decaying characteristic rather than an exponential decaying profile inside the body, and the power decay rate is approximately twice at 2.4 GHz as compared to 915 MHz. Moreover, the variance of shadowing increases significantly as the in vivo antenna is placed deeper inside the body since the main scatterers are present in the vicinity of the antenna. Multipath propagation characteristics are also investigated to facilitate proper waveform designs in the future wireless healthcare systems, and a root-mean-square (RMS) delay spread of 2.76 ns is observed at 5 cm depth. Results show that the in vivo channel exhibit different characteristics than the classical communication channels, and location dependency is very critical for accurate, reliable, and energy-efficient link budget calculations., Comment: 9 pages, 12 figures, 6 tables; accepted version (The URL for the final version: http://ieeexplore.ieee.org/stamp/stamp.jsp?tp=&arnumber=7593228&isnumber=8023990 )