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States, but no analysis on interference between the two bands has States, but no investigation on interference involving the two bands has ever been done so far. Band F may be the two.36 GHz medical band newly authorized by the Federal Communication Commission (FCC) in the United states of america. The Industrial Scientific Healthcare (ISM) band usually used in BSNs operates at two.4 GHz. Hence, for the sake of avoiding interference, corresponding solutions which could deal with interference has to be made [110]. UWB communication is believed to possess terrific positive aspects and is promising in WBAN applications. It really is a approach with low-power and higher data price functions. Its substantial bandwidth signals deliver robustness to jamming with low probability of interception. Additionally, UWB is often utilized to monitor essential respiration and heart-rate parameters [111?13]. Additionally, UWB has good penetrating properties that may be applied to imaging in health-related applications [114]. Figure 3. BSN frequency bands.HBC MICS A NB B WMTS C D E FCC F ISM G Low Frequency Band UWB Higher Frequency BandMHzIn 2007, the Sixth Functioning Group of IEEE 802.15 was established to standardize on BSN bands. The team eventually divided the bands into 3 components: UWB, NB, and HBC [115]. MICS, WMTS, FCC, and ISM belong to NB. Furthermore, using the newly proposed IEEE802.11ad typical, researchers try to present novel strategies to allow over-body propagation in between 15 GHz and 40 GHz, and in some cases the unlicensed 60 GHz region [116]. (two) Channel CharacterizationAccurate channel characterization can improve the excellent of applications, which include estimating delay and minimizing path loss. In recent years, a different important BSN physical layer investigation area will be the channel characteristics of different bands. The IEEE802.15.six working group has put forward the fundamental content about channels and their characterization. There are actually 3 typical channel characterization strategies: (a) Measurement-based solutions. Fabio et al., have measured the narrow band transmission channel, and analyzed the channel characteristics such as the typical path spreading obtain, large-scale attenuation, and small-scale attenuation. Results have shown that movement, place, and environmental things may cause path losses. Movements of the human physique will lead to shadows [30]. (b) Simulation-based solutions. Reference [117] makes 3D scene simulation of signal propagation inside the channel by suggests of Finite-Difference Time-Domain (FDTD). It employs a leap frog algorithm to alternately calculate the electric field and magnetic field in the space-domain405 402 23.625 18.958902 87010233.3244.eight 2483.6240 4742.Sensors 2013,and simulate the electromagnetic field alterations by time-domain updating. This simulation model is of good applied value, as outlined by the comparison among simulation outcomes and measured data. (c) Mixture with simulation and actual measurement technique. Reference [118] has provided a path loss model which is usually used to evaluate the energy performance in single-hop and multi-hop networks. The sensor nodes deployed around human physique can measure the sent and received information among distinct components of human body, then import the collected information into a 3D model of human body, and numerically study path losses. Ultimately, the path loss parameters and time-domain channel characteristics may be obtained. 4.1.four. MAC Layer The original goal from the BSN MAC layer was to achieve maximum throughput, minimum delay, and to maximize network lifetime by controlling the key sources of energy waste, i.e., collisions, idle liste.