4G is the fourth generation of broadband mobile technology for mobile Internet access. Although it is used in many areas, use of 4G on phones is more widespread. Some companies such as Qualcomm, Samsung, MediaTek and Hisilicon manufacture LTE modems for mobile devices. VoLTE was developed using LTE technology. Supports HD voice calls and improves sound quality compared to 2G/3G calls. Although the maximum 4G download speed is specified as 300 Mbps, it varies depending on LTE categories used in this device (CAT).
What is CAT in LTE
When you look at hardware features of devices with 4G support, LTE categories appear. There are 20 different LTE categories, but 7 of them are most commonly used. The speed also increases when you go to higher numbers. Table with some LTE categories and speeds:
|LTE Categories||Maximum Download Speed||Maximum Upload Speed|
|CAT 3||100 Mbps/Seconds||51 Mbps/Seconds|
|CAT 4||150 Mbps/Seconds||51 Mbps/Seconds|
|CAT 6||300 Mbps/Seconds||51 Mbps/Seconds|
|CAT 9||450 Mbps/Seconds||51 Mbps/Seconds|
|CAT 10||450 Mbps/Seconds||102 Mbps/Seconds|
|CAT 12||600 Mbps/Seconds||102 Mbps/Seconds|
|CAT 15||3.9 Gbps/Seconds||1.5 Gbps/Seconds|
Modems in cell phones, like processors, are divided into different categories, depending on their level of development. We can think of it like the performance difference between the Qualcomm Snapdragon 425 processor and the Qualcomm Snapdragon 860 processor. Every SoC have different modems. Snapdragon 860 has Qualcomm X55 modem while Snapdragon 8 Gen 1 has Qualcomm X65 modem. Also, every device have different combos. Combo means how many antennas connected to base station. As you can see in table above, 4G speeds vary depending on the LTE category. If your carrier supports high speeds, you can see promised speeds in the highest LTE category. Of course, these speeds are expected to increase even more with 5G.