Since the beginning of the cellphone era, the signal bars are visual representatives of the signal strength. Or we can say that just by looking at the signal bars we can tell whether the cellular reception is good or poor. The dip in signal bars outright tells us that cellular reception is not good and vice versa.
There are many factors which impact the cellular reception which includes the build of the phone, the location and the number of bands included by the service provider. Android parses the signal strength value (in dBm units) and represents it accurately in the form of signal bars. Android P, on the other hand, is going to stir things a little bit.
Android P’s new setting will allow the carriers to define custom signal strength for the signal bars that appear on the phone. Though the reason behind this change is not clear right now nor is there any official statement from any concerned source. But if things turn out the way they are appearing then the carriers can alter the signal values according to their choice and trick the users into thinking that they are getting a better signal reception than other competitors. This feature was spotted by developers at XDA Forums in the recent Android Source Code Commit.
It will be a tough job for those who always keep staring at signal bars to determine the signal strength to know how the signal reception actually is. Well, there are many ways to determine the strength of signal reception without looking at those bars, and one such includes third-party apps which measure the signal strength the same way you measure your internet speed. The picture will be more clear once Android P is rolled out to the masses.