Network drop

[jashanlubana]

Hi, I have galaxy s8 and recently moved to public mobile. Why does public mobile prefers 3G over LTE? Every time network drops to 3G from LTE.

[sheytoon]

@szymon247

The eNodeB (LTE radio access node) provides all instructions, and the UE (phone) can only act upon the instructions.

In idle mode, the instructions are contained in SIB6 messaging. This procedure is known as inter RAT reselection. Once the network tells the UE when it should perform reselection, the UE can do so. In idle mode, the eNodeB does not know the status of the UE.

In connected mode, the instructions are sent via RRC_CONN_RECFG messages. The event thresholds are specifically known as A2 and A4. This procedure is known as inter frequency handover. This is controlled by the eNodeB, and UE can only provide A2 and A4 measurement reports. It's the eNodeB that makes all the decisions.

Without this information, the UE would be permanently stuck on the same frequency unless it completely lost signal and dropped the call.

@will13am, you could be right. Send me your work location inn a private message if you like and I can look up additional details for the sites in the area.

[will13am]

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@sheytoon wrote:

@szymon247, sorry but this is not correct.

The network controls everything and will instruct the phone when to switch. The number of bars is not a good way to obtain these measurements. The correct way is to use a measurement known as RSRP.

@jashanlubana, it's unusual to be on 3G for data browsing these days. LTE coverage is very good in most places. Who was your previous provider?

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At the salt mine (what I call the work HQ), I connect to so many towers I can't keep count.  It must be at least 30 depending on which part of the building I am at.  Even at a fixed location, I get handed off from tower to tower like musical chairs.  In the middle of the building, I do get a 3G connection quite often even though there are 700 and 850 Mhz LTE available.  I take this to mean that 850 Mhz on 3G is a lot more widespread than 850 Mhz on LTE or 700 Mhz for that matter. 

[szymon247]

@sheytoonThe network switch relies on the signal strength as received by the phone's modem, which is represented graphically by the signal strength bars, but can also be seen in detail in the advanced network menu on Android. 

The Qualcomm modems in some of the Galaxy phones (including OP's Canadian S8 variant) perform the changes on their own. They disable the LTE radio and probe its signal strength periodically without making themselves available to the tower unless the signal is strong enough relative to the 3G signal. They can balance the network connections much more efficiently than a network could on its own. They can also choose which cell to connect to. While a cell could request a switch based on its own stats, in the end, it's the phone's modem doing the most switching.

[sheytoon]

@szymon247, sorry but this is not correct.

The network controls everything and will instruct the phone when to switch. The number of bars is not a good way to obtain these measurements. The correct way is to use a measurement known as RSRP.

@jashanlubana, it's unusual to be on 3G for data browsing these days. LTE coverage is very good in most places. Who was your previous provider?

[szymon247]

How many bars of signal strength did you get on LTE? If it's at or below 2-3 bars, the S8 will check the strength of 3G, if it's much better, it will switch and stay there until the LTE signal gets stronger, or the 3G signal gets weaker relative to the LTE signal. It's a mix of maintaining service quality and conserving battery life by the Qualcomm modem.

[popping]

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@jashanlubana wrote:

Web browsing 

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As per @MoreYummy mentioned, it may be the signal strength between the 3G and LTE signals.

[jashanlubana]

Web browsing 

[popping]

@jashanlubana

PM switches from LTE to 3G during a voice call.

What you were doing when your S8 swithes to 3G?

[MoreYummy]

It probably due to signal strength in the area you in are, so your phone choose whatever it thinks is the best at that time and location.