Has your LTE connection been letting you down lately? Or stopped working all together? Don’t worry! There are various fixes you can try before blowing up your cell carrier’s customer support line.

Turn airplane mode on and off

Sometimes the most obvious fix is the most reliable one. If your mobile data is giving you trouble, one of the first things you should try is turning airplane mode on and off. You can do this simply by dragging down the notification bar and tapping on the airplane icon, or you can do it through Settings.

Paths can differ slightly depending your Android version and phone manufacturer, but you can usually enable Airplane mode by going to Settings > Wireless & networks > Airplane mode. Turn it on for at least a couple of seconds, then disable it. In a lot of cases your LTE connection issues will be gone.

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2. Each subframe consists of two equally sized slots of 0.5 ms in length (Tslot= 15360 Ts). Each slot in turn consists of a number of OFDM symbols which can be either seven (normal cyclic prefix) or six (extended cyclic prefix). Figure 3 shows the frame structure for LTE in FDD mode (Frame Structure Type 1).

Restart your device

If toggling airplane mode didn’t solve your problem, it’s time for another tried and true step — restarting your device. Simply press and hold the power button of your smartphone and then tap Restart. Wait a couple of seconds and turn it back on. Check your status icon, but also test the speed of your LTE connection by opening some websites or downloading some smaller apps.

Once you’re done, your LTE connection should be back to normal. Check if you’re using the correct SIM slot Certain dual-SIM phones only support LTE in one of the two available SIM slots.

Make sure the right network mode is enabled

What is LTE Advanced?

Depending on your smartphone and carrier, you should have at least three connection types – 2G, 3G, and 4G LTE or just LTE. Usually, your device will try to connect to the fastest option when available, but if you’ve been tinkering with your settings or recently installed an update, that might need to be adjusted manually. Here is how to do it:

• Go to Settings, then tap on Mobile Network.
• Select Network mode. A pop-up list of preferred modes will appear.
• Tap on the auto or LTE option.

Take out and readjust your SIM card

If none of the steps above did the trick, the problem might lie in an ill-positioned SIM card. Eject it and carefully reposition it in its tray. Be careful when inserting it back into your device. Once you’re done, your LTE connection should be back to normal.

Check if you’re using the correct SIM slot

Certain dual-SIM phones only support LTE in one of the two available SIM slots. If you plugged the SIM in the wrong one without realizing, it may prevent LTE from working. Try moving the SIM card to the other slot.

Reset network settings

If you tried all of the above, but nothing changed, it’s time to take a slightly more drastic step. Resetting your network settings. Here is how you can do it:

• Head to Settings, then find either Reset or Backup & reset. Tap on it.
• From the list, tap Network settings reset. Keep in mind that this step will erase all network settings, including saved Wi-Fi networks, paired Bluetooth devices and so on. If you are sure you want to proceed tap Reset Settings.
• You will be asked to enter your PIN if you have one. Do so and confirm resetting your network settings.

Once you’ve done this, wait a couple of minutes — new network settings should be picked up by your phone automatically. If nothing happens, a good old reboot is always an option, but at the end your LTE connection should be back to normal. Factory reset is always an option too, but don’t resort to it if you haven’t tried other steps first.

Contact your cell carrier

If you’ve tried everything else on the list and nothing seemed to fix your problem, it’s time to contact your cell carrier. You can always do so on social media, but sometimes a good old-fashioned call might address your concerns better. Here are the customer support numbers of the major US providers:

• Verizon Wireless: 800-922-0204
• Sprint: 888-211-4727
• AT&T: 611 from an AT&T phone or 800-331-0500
• T-Mobile: 611 from a T-Mobile phone or 1-877-746-0909 from another phone
• U.S. Cellular: 611 from a U.S. Cellular phone or 1-888-944-9400 from another phone

Get your phone checked out for hardware problems

Sometimes a disappearing or inconsistent LTE connection is the fault of hardware. If you’ve recently dropped your device that could have resulted in damage to internal components. Take it to an authorized repair shop to get it checked out. If your device is brand new, on the other hand, but still experiencing consistent connection issues, you might have a faulty unit.

Connection problems can be the result of damaged or faulty hardware.

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Contact the smartphone manufacturer or carrier you bought it from immediately. In most cases you will have to send in your device to get it checked out. Make sure you back it up before handing it in. If faulty, in most cases you should get a replacement unit in a reasonable amount of time.

These are our tips and tricks on fixing your LTE connection. Did we manage to help you solve your issue? Let us know in the comments below.

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LTE Physical Layer 2 radio frames are supported:

1. Type 1: FDD : Frequency Division Duplex
2. Type 2: TDD : Time Division Duplex

For multiple access, LTE uses:

For down link: OFDMA: Orthogonal Frequency Division Multiple Access
For up link: SC-FDMA: Single Carrier Frequency Division Multiple Access

1. Type 1: FDD : Frequency Division Duplex

1. It is valid for both half duplex, and full duplex FDD modes
2. Type 1 radio frame has a duration 10 ms and consists of equally sized 20 slots each of 0.5 ms.
3. A subframe comprises two slots, thus one radio frame has 10 sub‐frames.

There are six time units: frame, half-frame, subframe, slot, symbol, and the basic time unit (Ts):

Time Unit Value
Frame 10 ms
Half-frame 5 ms
Subframe 1 ms
Slot 0.5 ms
Symbol (0.5 ms) / 7 for normal CP, (0.5 ms) / 6 for extended CP

Ts 1/(15000 * 2048) sec » 32.6 ns

A resource block (RB) is the smallest unit of resources that can be allocated to a user. It is 180Khz. That is 12 carriers in the frequency domain and 0.5 ms (or 7 CP) in time domain.

So minimum resource allocation to a user in LTE is 180Khz or 1 slot(0.5ms).

TTI is 1ms.

Below is the pictorial representation of FDD

Here the down link and uplink will be done in 2 different frequencies.

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In full-duplex FDD, uplink and downlink frames are separated by frequency and are transmitted continuously and synchronously.

In half-duplex FDD, UE cannot receive while transmitting.

LTE Bandwidths

LTE standard bandwidths are 1.4, 3, 5, 10, 15, and 20 MHz.

Type 1 Frame Structure

2. Type 2: TDD : Time Division Duplex

1. Half of the subframes are available for downlink, and the other half are available for uplink transmission.
2. In each 10 ms interval, where downlink and uplink transmission are separated in the frequency domain.
3. The uplink and downlink subframes are transmitted on the same frequency and are multiplexed in the time domain.
4. There are seven possible configurations given in the standard.
5. Depending upon the traffic, carrier/operator can choose any of the configurations

Special subframes

Special subframes are used for switching from downlink to uplink and contain three sections: DwPTS, GP, and UpPTS.

DwPTS is Downlink Pilot Time Slot.
UpPTS is Uplink Pilot Time Slot.
GP is guard period between DwPTS and UpPTS.

Note:

1. Subframes 0 and 5 and DwPTS in TDD frames are always allocated to downlink transmissions.
2. Subframe 1 is always configured to be a special subframe.
3. Subframe 6 can also be configured to be a special subframe.

Below is the pictorial representation of TDD

Here the down link and uplink will be done in 2 different time slots.

UPLINK / DOWNLINK SUBFRAME CONFIGURATIONS FOR LTE TDD (TD-LTE)

OFDMA:

Number of OFDM symbols in each slot depends on type of Cyclic Prefix(CP) used.

– For Normal CP – 7 OFDM symbols per slot

– For Extended CP – 6 OFDM symbols per slot

what is Cyclic Prefix? (CP)

The cyclic prefix is a guard interval to protect the OFDM signals from intersymbol interference.

It is the copy of last part of OFDM that is perpended to transmitted symbol and removed at the receiver before demodulation.

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To make OFDM insensitive to time dispersion, CP is inserted.

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List Of Tutorials available in this website:

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