This tutorial shows how to view the signal and data availability.
INSTRUCTIONS & INFO
From the clock screen, swipe down from the top edge of the screen.
While connected to your galaxy device via Bluetooth, the Bluetooth paired icon will be displayed in the moments bar.
When connected to a Wi-Fi network, the Wi-Fi icon will be displayed in the moments bar.
While connected via Mobile data, the Signal Strength icon will display the strength of the network signal. When you are within range of a cellular tower the indicator will show more bars. If you are not in range of a cellular tower, you will have fewer bars/less signal strength.
If 4G is available, the 4G icon will be displayed in the Notifications Bar.