Are one of those users who after upgrading their device to Ice Cream Sandwich ICS 4.0.4, are stuck with lost signal whenever your device screen goes to sleep? Perhaps it looks like a bug resulting from some messed up code with ICS 4.0.4. It is listed as a known issue and many users are reporting this issue.
With ICS 4.0.2, none of the users have reported any issue like this. It’s happening with different versions of 4.0.4 from the stock version of the Google page or other custom ROMS based on it.
This issue is listed as bug as Issue 28133 now for Samsung Galaxy Nexus at Google Code.
When the phone enters standby, and nothing is using much CPU in the background, cellular signal is lost until phone is brought out of standby.
Solution / Fix to lost Signal with Screen Sleep
Lost Signal issue at the moment (Till someone from Google fixes it officially) can be fixed by raising the minimum CPU speed of your device from 350mhz to 700mhz. Raising the minimum CPU speed of your device is not possible unless you root your device (Samsung Galaxy Nexus here).Even after rooting it, you will need a App called SetCPU to do this trick with the CPU. In short, the steps are as follows:
1. Root your Samsung Galaxy Nexus. ( If you are not sure how to Root it, Just Google it or check the Forums at XDA Developers.)
2. Install SetCPU from Google Play Store. (Keep in mind, for SetCPU to work your device must be rooted).
3. Run SetCPU, raise the minimum CPU speed from 350mhz to 700mhz. Then select “Set on Boot”.
This must fix the signal issue for you without downgrading to Ice Cream Sandwich 4.0.2.