Because these RF signal wavelengths travel through the air, people often underestimate their significance. What’s more, the reality is that since there are no physical differences between an unlicensed frequency and a licensed frequency, it’s easy to make some potentially costly assumptions when it comes to cellular networks.
Spectrum is a very valuable yet limited resource. Hence, we have to share the available spectrum for different kinds of services that are essential to our society, such as microwave, marine radio, aircraft communications, TV (good old VHF and UHF), GPS, infrared, Wi-Fi, satellite comm, AM radio and cell phones. In order to enable a fair sharing of this non-renewable resource to allow different communication systems to coexist, governments have established spectrum licenses. Once a channel license is purchased, only the owner of the license can legally operate a communication system using that channel.
In the U.S., communications service providers (CSPs) such as Verizon, AT&T, T-Mobile and a few others own the licenses for terrestrial mobile communication spectrum. Enterprise companies either used publicly available “free” spectrum to build wireless networks (e.g., Wi-Fi) or they simply purchased wireless services from CSPs, who would, in turn, deliver these services using networks that operate on their licensed spectrum assets.
Recent changes in government regulatory policy and the clearing of large bands in the radio spectrum have now enabled private enterprises to acquire spectrum more easily for their own purposes. For example, in the USA, there is bandwidth in the 3.55 to 3.70 GHz range known as Citizens Band Radio Service (CBRS) that has been converted for shared access. This means the same channels will be shared between an incumbent government entity (such as the Navy), a Priority Access License (PAL) license owner or in a non-licensed fashion General Availability Access (GAA). This has enabled enterprises to build private dedicated wireless network services that typically support both 4G LTE and 5G communications.
There are a few compelling reasons to use unlicensed spectrum to support a broad range of digital transformation use cases. These include:
- no dependency on a telecommunications provider
- no recurring costs for connectivity
- lower initial capital costs
Yet, there are tradeoffs to be aware of:
- Network reliability. Unlicensed spectrum is a shared asset and bandwidth cannot be guaranteed, meaning it is difficult to enable higher service level commitments for mission-critical applications. Unlicensed spectrum cannot be dynamically allocated to priority applications. An application with low-latency, high-bandwidth needs must compete for bandwidth with applications that have completely different latency/bandwidth requirements.
- A cellular system built on unlicensed spectrum can operate well in an environment with fewer devices and fewer systems coexisting in an area. However, when systems and devices start to compete for the available spectrum, the availability and performance degrades quickly.
- In the U.S., CBRS spectrum may be co-opted by higher-priority authorities, such as the U.S. Navy
- Unlicensed spectrum could be risky in environments that have high-availability mission-critical services dependent on the private cellular network.
Another factor is something enterprises often realize only after deployment: Cellular networks are more complicated to design, operate and optimize than Wi-Fi networks. To achieve desired (not to mention optimal) performance, these systems much be engineered with a careful assessment of where radios and antennae are deployed. Very few companies have the in-house expertise to diagnose, troubleshoot and resolve cellular issues as they arise.
Businesses may find that a balance between licensed and unlicensed spectrum best fits their needs, when it’s aligned with geographies, company locations and application requirements. For example, we expect that in many environments, Wi-Fi and/or unlicensed cellular will coexist with licensed cellular, optimally serving their respective applications and requirements.
To put a fine point on it, we encourage customers in the market for private cellular services to carefully weigh their options and understand the short- and long-term implications of each option.
