1, replace the current environment, some areas may have weak signals due to network coverage problems.
2, 4G network Internet access, if there is a call, the mobile phone will be cut back to 2G\/3G network, the process of cutting back may appear weak signal problems.
3, cut the card, the SIM card is damaged or dirty may also lead to this situation, you can also try to replace an original small card, see if it improves.
4, if you need to compare the signal strength of different brands of mobile phones in extreme environments, open to check the signal strength: set --> About mobile phones --> Status information --> SIM card status; Because the signal icon on the status bar of different manufacturers is different.
5, if the above operations are ineffective, it is recommended that you back up the mobile phone data update system.
What specific performance, bad signal involves more things. Card carrier phone antenna, you can try to open Settings - carrier network - select your card -APN access point - select the Internet option, and then reset the network in the top right corner.