Private Celluar Network
As far as I remember, the first time I saw a Private LTE Network solution was at CTIA show in Sep 2015. I don't recall the name of the company for now but there was a booth presenting a small femto cell sized box which contains an LTE dNB and EPC (core network) in the single box. The person in the booth said the product is good for building my own LTE network with a single box and I can get it connected to the internal with a ethernet port.
At the time I was interested in the box only for technical reason. I wish I could get one of those boxes because I could play with various things on both eNB and core network of LTE and try many experiments. But I couldn't think of strong business drive because I thought there would be many obstacles to build a private network with a cellular technology like LTE. However, recently (as of late 2017) I started seeing more and more solutions for private LTE network and also see some movement to remove some of the obstacles that I thought of.
The first question that struck me when I first saw the eNB+EPC one box was 'in which spectrum (frequency) I can use this box'. Of course the first answer that I could think of was to use ISM band in which we normally use Bluetooth and WiFi. The frequency may work if I configure this box within a very short radius (like only within my house) and replacing the WiFi AP(Access Point) in my house. However, it is too costly to use the solution only to cover a couple of devices in my house and it would easily interfere the WiFi operation in the neigbours. It would sound more reasonable if we use the solution to cover a wider area like a whole campus and office building etc. However, even in this case using the ISM band would be a little bit risky to interfere WiFi in the neighbour.
Luckily recently FCC freed up pretty wide spectrum mainly for this kind of private network purpose. The band is called CBRS. It is likely to see this kind of free spectrum for other regions as well.
Another question that popped up in my mind when I first saw this solution was "OK, it is good to have this kind of small sized / private network solution. However, who would manufacture / supply UEs (devices) for this network ?". If you configure the frequency of the private to one of the licensed frequency, you would easily get a device that can work with your private network, but it is not allowed for you to use the licensed frequency without the permission from the carrier who owns the spectrum. However, if you configure the private network(eNB) to any other arbitrary frequency, it would not be easy to find any device that works with the network.
Why device manufacturere does not produce a device that can work with any arbirary frequency ? It would be mainly because of the cost for compliance / conformance testing for those devices. For each and every frequencies a device claims to support, the manufacturer should complete a huge set of conformance test and it will cost a lot. So, there wouldn't be many device manufacturer who will produce such a small set of devices for the private network.
However, if there is a certain block of a common spectrum like CBRS for Private Network, the size of device market may get large enough for device makers to jump in. This kind of market will be especially appealing for those who is manufacturing IoT devices.
[Note 1] If you are using CBRS band as the frequency range for your private LTE network, you may easily get the UE(e.g, SamSung Galaxy S10) supporting the frequency range (LTE band 48, specified for CBRS)
The answer to this question might be different for different persons, but you would find some of the common advantage that many people can agreed upon from Qualcomm WhitePaper Private LTE Networks that are listed as below (I would suggest you to refer to the original whitepaper if you want to get some detailed description for each of these items).
If you ask me about my personal motivation for adopting the private network, I would say as follows :