Was there any 4G variant of Snapdragon 865? If not, then how did it launch in India in 2020 as there was no 5G network at that time in India?

Snapdragon 865 is an integrated mobile platform. That is in addition to the RF modulator it contains many other components like processor, camera and audio. To determine what kind of mobile networks it supports you’ll have to look at the modem that is on the platform. Which is in this case “X55 5G modem”

https://www.qualcomm.com/products/snapdragon-x55-5g-modem

And while it says 5G in the title here are the actual specs in the cellular technology section

Cellular Technology: WCDMA (DB-DC-HSDPA, DC-HSUPA), TD-SCDMA, CDMA 1x, EV-DO, GSM/EDGE

LTE Technology: LTE FDD, LTE TDD including CBRS support, LAA, LTE Broadcast

5G Technology: SA, NSA, 5G NR FDD, 5G NR TDD

As you can see, not only does it support 4G LTE but it also supports older technologies like GSM and Edge. This is why Snapdragon 465 mobile platform could launch in India and other countries even when there have been no 5G networks in place.

With that out of the way a natural question would be how can these modems support multiple cellular networks at the same time?

To understand this you’ll have to know a bit about the OSI layer. Cellular technology is divided into multiple layers of communication (7 in total) with each layer handling a particular aspect of the whole system.

A modem like X55 5G ,that we discussed above, is responsible mainly for layer 1 and layer 2.

Layer 1 determines the physical channel of communication. In mobile platforms this channel is wireless. The modem is responsible for producing these wireless signals that can be picked up by the nearest mobile tower.

Layer 2 determines how that channel is accessed and used by the participating members. That is all the other people with the mobile handset who are communicating with the same nearby tower.

These layers are hardware specific and can’t be modified after sales. All the other layers are software. And as such they can be programmed and used on demand according to the situation. In simple words layer 1 and layer 2 can’t be changed. All the other layers are flexible.

The G networks are simply protocol specifications. And as long as the Physical layer is capable of producing specific frequencies on which they operate and the data link layer can provide access to those frequencies any network protocol can be supported. A 4G modem’s physical layer can translate well to 5G because the two protocols use similar frequencies (a few new frequencies have been added to 5G but they are largely the same,which incidentally puts telecom operators in a dilemma, should they keep supporting 4G on the frequencies they have bought or move to 5G or buy more frequencies to support both 4G and 5G? As you can see this is not an easy question to answer for anyone) however since the firmware on such a modem does not understand 5G protocol it won’t actually work.

A simple firmware upgrade should do the trick (as per my understanding,but I’m no expert) but it's unlikely that it would happen. Modem manufacturers have no interest in supporting old hardware because it would disrupt the sales of new ones, so the consumers have to buy a new handset to enjoy a new G network. Up until now this ploy worked because mobile phones were evolving in capability (processing speed, interface,design). But today the advancements are not that significant. A screen that is a little longer perhaps, or foldable maybe. A couple more cameras in front. A bunch more in the back. But these changes are superficial and are failing to impress me. I wonder how long this trick can work?

Akshat Jiwan Sharma

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email:getellobed@gmail.com

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Notes by Akshat Jiwan Sharma

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