Integration of Spatial Modulation Scheme With Code Division Multiple Access for VIVO Based Frequency Selective Nano Sensor Networks

Abstract

Due to their suitability for human-body based communications, in-VIVO nano sensor networks are envisioned to use the promising Terahertz signals in order to ensure the forthcoming high-rate communication needs of the modern medicine. However, the propagation losses at these frequency bands are quite significant and dependent on the operation frequency as well as on the physiological characteristics, thus impeding the use of Terahertz rates to their utmost benefit. Using numerous emitting elements is likely to improve the quality of the received signal, but gives rise to multi-channel interference (MCI) emanating from multi-antenna signaling reception, which necessitates a relatively complex signal processing to mitigate it. When multiple physiological signals are of interest, detecting them necessitates to mitigate multiple-access interference (MAI). In this perspective, orthogonal frequency division multiplexing (OFDM) allows to combat the channel frequency selectivity, whereas code division multiple access (CDMA) scheme cancels MAI. In this paper, we propose to embed the novel spatial modulation technique with CDMA architecture in an OFDM framework to ensure a viable communication in in-VIVO frequency selective Nano channels. The immunity of our proposed solution to such an interference is confirmed, since less than −2 dB in SNR level is required to support 5 users simultaneously communicating with a BER which is inferior to <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">${10}^{-{3}}$ </tex-math></inline-formula> when the operating frequency is equal to 1THz. This hybrid scheme is shown to efficiently combat the MCI while enabling a safe retrieval of the useful signal at the very-high data rate communications.