UE overheating for EN-DC

Nice explanation on what some of you may find: UE overheating for EN-DC:

It happens when EN-DC UE is close to NSA site and loose coverage, whereas 5G site is working well.

UE internal temperature is high (exceeeds 42 degrees).


Note: UE enters overheating mode and it is a kind of protection.

UE internal overheating can cause:

  • Melt the central processing unit (CPU)
  • Shorte devices’s life span
  • Drain / damage battery

When UE become overheated?

  • UE is in a high transmission rate
  • Playing graphically intensive games
  • Use UE under Sunlight or hot weather

Different actions to protect overheating


  • Temporarily suspend all services - except phone and contacts. As a result, eNB send release requirement to gNB with the reason “user-Inactivity”.

  • UE trigger fake A2 event, to force gNB to send release request.

  • UE address the overheating by sending a UEAssistanceInformation message that contains IEs “reducedMaxCCs”, then eNB release SgNB to reduce the peak data rate.


3GPP R2-1808414, UE overheating for EN-DC

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Looking at how many post here in forum (Search results for '"overheating"' - telecomHall Forum) we can see this topic (“overheating”) seems to be one of the biggest challenge for 5G devices, specially with mmWave…

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My sincere opinion is that 5G is still new tech. As chipset vendors and cellphone makers get more experience crafting devices, overall experience will be better