“…Few surveys specifically discuss certain layer [46] based on services and functions. 6 layers [30], [40], [87], [94] 5 layers [11], [24], [30], [31], [64], [78], [79], [94] 4 layers [10], [11], [38], [63], [64], [67], [75], [78], [80], [89], [90] 3 layers [20], [31], [32], [44], [62], [68], [78], [86], [88], [100] Specific layer [18], [31], [37], [46], [56], [68], [73], [79], [80] The percentages of the trend for the IoT architecture layers review, according to the layers classification, are shown in Fig. 7.…”