The Basic Basics
A lot of the most basic information is covered in this post, but we pulled out some common questions here.
Q: What is a “private network”?
A: In this context, a private network is a radio network based on cellular technology, but operated for private use instead of as a service to the general public. It means having your own LTE, 5G, or even GSM/GPRS network, operating independently of mobile network operators (AT&T, Verizon, Vodafone, Orange, Telefonica, T-Mobile, etc.). Devices in this network may be smartphones or embedded modem modules for IoT applications. These devices have the same kind of service in the private network that they would in the public networks that you are familiar with.
Q: Why would I want a private network?
A: Private networks are particularly good for covering large numbers of users and data devices spread over a large area. The specific advantages of private networks over other approaches are covered in this post. Typical uses are in agriculture, port and airport facilities, oil and gas fields, mines, and large factories.
Q: What is CBRS?
A: CBRS is a class of private network operation offered in the US. CBRS allows private parties to operate LTE or 5G networks without licenses, or with licenses that can be acquired relatively easily and at low cost.
Q: What is LSA?
A: LSA (Licensed Shared Access) is a class of licensed private network operation in the EU that is similar in principle to CBRS. LSA is currently in the planning stages, but is expected to be available in late 2021 or early 2022 in Europe.
Cost and Dimensionsing
Q: What is the typical cost of a private network?
A: Working with Legba, the minimum private network costs about US$22k to set up and supports about 600 users or data devices over an area of up to 1 square mile (2.5 km-sq) in open land.
Q: What is the range for a LTE/5G basestation?
A: The range of a radio basestation varies a lot depending on how it is installed and where it is used. Private networks tend to be at frequencies above 2 GHz, which results in shorter ranges than you would see for larger commercial networks. In open land, from a mast, the range may be up to 2 miles (3 km). Indoors, it may be less than 100 yards (100 m). As part of your network planning, Legba will make a coverage analysis and basestation installation plan specific to your needs and insuring good coverage over your site.
Q: How many subscribers can a single basestation support?
A: The basestation will typically allow up to 100 simultaneous connections, which in normal cases is sufficient capacity for 600 users.
Q: What is the data rate for a private network?
A: A CBRS basestation can provide about 22 Mb/s download and 11 Mb/s upload, even under conservative conditions, near the cell edge. (Basestation vendors may quote much higher numbers, but those numbers are under ideal conditions, and not a basis for network planning.) Data rates for other types of private LTE/5G networks (other than CBRS) may be higher.
Q: What kind of specialized knowledge or training is required to install and operate the private network?
A: None. Legba plans and manages the network for you so that you can focus on your own operations.
Q: What are the steps of a private network project?
A: See this blog post.
Q: Do I need a license?
A: It depends on where you are. In some areas in the US, you may not need a license for CBRS operation. In more crowded areas, a license may be recommended for reliable CBRS operation. In other countries, you will probably need a license, but that license may not be difficult or expensive to get. For more information, see this post.
Q: Will Legba help me get a license?
A: Yes, if you are a CBRS customer.
Q: What is the difference between CBRS and LTE? (US)
A: Usually, CBRS is LTE, in a specific configuration that the FCC has approved for unlicensed or shared-spectrum operation in the US. (We say “usually”, because CBRS can also be used for 5G.)
Q: What is the difference between LSA and LTE? (EU)
A: Usually, LSA is LTE, in a specific configuration that the EU has approved for shared-spectrum operation. (We say “usually”, because LSA can also be used for 5G.)
Q: Should I use LTE or 5G?
A: For most private network use cases, there is no particular advantage to using 5G, so we recommend the more mature LTE technology.
Q: Does the private LTE network support VoLTE?
A: The network itself supports VoLTE, but the handsets may not cooperate. Handset vendors usually restrict VoLTE so that it will not work on private networks. For voice service, you will need an over-the-top application. (We will write a blog post on this in the future.)
Q: Does the private LTE network support push-to-talk (PTT)?
A: Yes, but with over-the-top applications. Native support for MC-PTT (mission critical push to talk) is very expensive, but there are some reasonably-price over-the-top solutions.
Q: Can the private network support LTE-M?
A: Yes. LTE-M can also co-exist with standard LTE in the same network.
Q: What are the advantages of LTE or 5G over WiFi?
A: See this blog post.
Q: What are the advantages of a true private network over a special extension of a public network?
A: See this blog post.
Q: Will I be able to use my own phone?
A: Maybe. Your phone will need to support the band that your network uses (band 48 for CBRS, band 40 for LSA). And if you want to continue using your phone in other places, you will need a dual-SIM phone, since your private network will require its own SIM.
Q: How do I get SIMs?
A: Legba will source them for you as part of the project. (You can even get custom graphics.)
Q: Can I run 900 MHz GSM/GPRS in 900 MHz LMR spectrum?
A: Possibly. It depends on the details of the license. Please contact us using the form at the end of this page. (Despite its age, GSM/GPRS is an excellent technology for basic voice service, SMS, and low-rate data.)
Security and Reliability
Q: Can I limit all of my data to my local site, without any cloud services?
Q: Can I run a redundant network for high reliability?
Q: How secure is LTE or 5G?
A: Cellular technologies are much more secure than WiFi or LMR, with independent mutual authentication and ciphering for each device.