The idea of deploying multiple wireless sensors around the human body to enable ubiquitous healthcare by measuring continuously all the physiological data of interest has received considerable attention. Ultra-wideband (UWB) is a promising communication technology for short-range communication scenarios like body-centric wireless network (BCWN) (i.e, in the area of medical healthcare). UWB is characterized by low-power which makes it suitable for human body exposure and extends the life of the system. UWB is a high data rate technology that provides immunity to multipath interference, which facilitates the compatibility of such technology in body-centric applications. High data-rate wireless communications, nearing 1 Gb/s transmission rates, are of greater interest in emerging wireless technologies. The demand for higher data rate is increasing with the passage of time. To achieve higher data rates, greater than 50 Mb/s, multiple transmit and multiple receive antennas (MIMO) is recommended in IEEE 802.11n. To reach the target of 1 Gb/s, more advanced techniques like Ultra-wideband (UWB) technology combined with MIMO is an attractive research area now-a-days [1]. For BCWN, the use of multiple antennas at transmitter and receiver can simply be considered as a tool to further increase the signal to noise/interference ratio and additional diversity against fading. BCWN mainly experience fading due to relative movements of body parts, polarisation mismatch, shadowing, diffraction, and scattering from the body parts and surrounding environments. Multiple antennas can be used to combat fading and multipath effects. There has been an increasing interest in diversity and multiple-input, multiple output (MIMO) techniques for enhanced mobile and wireless communications in recent years. There are some studies presented in the open literature, where the benefits of multiple antenna techniques for body-centric communications in narrow-band systems have been investigated. The aim of this work is to investigate channel characterization (i.e having comprehensive radio channel knowledge and accurate channel model) and improve channel capacity provided by a UWB MIMO antenna system in body centric communication systems. The work will specifically investigate how UWB radio signals are affected by body shadowing and what kind for of improvement can be achieved in terms of channel capacity by using MIMO technology for BCWN. This is done by incorporating two different models on the measured data in an indoor environment (Fig. 1 shows the MIMO antenna position during measurements), and calculating various parameters like Rician factor, average received power, shadowing deviation, polarization loss for each spatial sub-channel. In addition, water filling is used in place of uniform distribution which provides higher capacity even at low SNR.


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