Use of Licensed Spectrum
Cellular wireless communications technology has been here for over two decades solving some of the toughest engineering challenges in wireless connectivity and global mobility. It is now a trillion dollar industry that’s connecting billions of people and devices today. Its design and implementation specifications carry extreme detail in the way they are engineered and standardized. So far this sophisticated mobile wireless technology has not been made fully consumable by enterprise IT.
There have been several attempts and small cell based Radio Access Networks (RAN) can today extend the mobile operator macro network connectivity within an enterprise facility on the licensed spectrum. Such implementations would connect the enterprises to the mobile operator’s core in tight coordination with the macro cellular wireless. Migrating dedicated hardware and boards into a single system-on-a-chip (SOC) made it possible for small cell hardware to get ready for the “enterprise ceiling” and it was done to improve capacity for public cellular networks via cell splitting and extending coverage to indoors. Self Organizing Network (SON) features for the RAN were developed for plug & play deployment as an augmentation to the mobile operator network.
The on-premises cellular system in the enterprise, while now possible, does not give enterprise IT the option to make the network resources private when and if necessary, or even have detailed visibility to the usage of the network.
Shared Spectrum with CBRS
In the United States, Citizens Broadband Radio Service (CBRS) spectrum enables enterprises with up to 150MHz channel capacity between 3.55 to 3.7 GHz. Enterprises will be able to use CBRS private to their facilities without the need to rely on licensed spectrum. And LTE/5G cellular wireless has been defined as the technology of choice to be used in this band. Beyond United States, there are similar spectrum usage opportunities becoming available globally.
First tier in the three-tier system is the highest priority for Incumbents such as ship-borne Navy radar that occupy only a small portion of spectrum and limited to a small geographic region. Priority Access License (PAL, to be available late 2020) users are second tier who can purchase access up to 70 MHz from the first 100MHz of the spectrum, at the county level, with a 10 year lease. Private enterprises who are noted as General Authorized Access (GAA) users in the third tier have the right to use the full extent of the 150MHz spectrum when Incumbent and PAL users are not present within their geo-location. Both PAL and GAA radios need to register with SAS.
CBRS Operational Details
Within a CBRS enabled wireless network, Environmental Sensing Capability (ESC) detects federal incumbent activity and informs SAS so that channels can be cleared of lower priority use. Radios in a CBRS enabled network (also known as CBSDs) must be centrally authorized by a SAS against a specific set of frequencies in order to transmit. Here are the operational details:
- Within an enterprise cellular wireless network, when a new radio comes up, it registers with a SAS solution hosted in the cloud.
- Radio provides it's geo-location, transmit power specifications and requests the use of specific list of desired frequency channels.
- SAS informs the radio of the allowed channels after checking the propagation model based on terrain data at that specific geo-location, and the registration status of other GAA, PAL and Incumbent users within its database.
- CBRS enabled radios begin operation only after this authorization. On an ongoing basis (every 24 hours by default) SAS monitors spectrum usage and manages frequency assignments for each GAA user.
CBRS is also ideal for consumption by enterprise IT given its coverage characteristics as it sits in between the 2.4 and 5GHz Wi-Fi bands. 150MHz spectrum within CBRS band can be deployed 10, 20 or 40 MHz channel assignments on wireless radios, each 10MHz offering up to 200Mbps download and 50Mbps upload real-world performance. Radios operating in the CBRS band are permitted to utilize radio power levels of up to 30dBm (indoors) and 47dBm (outdoors) EIRP - opening doors to applications that would require long-range coverage options.
Consumption models for CBRS
First consumption model for the CBRS spectrum within the enterprise boundaries will be the traditional method of enabling Mobile Operator Capacity Augmentation. For instance, Verizon in the United States has publicly stated their intentions to use CBRS for mobile broadband. This approach will help drive adoption of CBRS by consumer devices like smartphones, but will require small cells deployed by mobile operators within the four walls of the enterprise as an alternative to DAS.
Second model is where Celona's solution will operate and it is also usually called Enterprise Cellular. In this model the infrastructure is deployed and managed by enterprise IT or its managed service provider. It integrates with the existing enterprise IT systems and network infrastructure components as an overlay, and enterprises have direct visibility and ownership of the relevant data.
Third and final consumption model is what's known as the Neutral Host RAN. It is viewed as an addition to the Enterprise Cellular model as it enables the CBRS enabled cellular wireless radios to offer connectivity to devices that are roaming in & out of the enterprise boundaries from the mobile operator macro network.
Neutral Host RAN model requires participation by mobile operators and will be made available as an option in 2021.
Using Cellular Wireless on CBRS
Cellular wireless that takes in the enterprise will be complementary to Wi-Fi by delivering much needed coverage to locations where Wi-Fi would not be the most practical. It offers greater coverage patterns, increased reliability (e.g. due to direct control of the endpoint devices by the network) and improved access control implementation (e.g. due to management of SIM cards on the endpoint devices). It is expected that the initial set of use cases for cellular wireless on the CBRS spectrum will be driven by business critical video, communications and IoT applications.
With the advent of new generation of AI and edge compute powered enterprise applications, use of cellular wireless on the CBRS band gains further importance. Large amount of available spectrum combined with advanced cellular wireless technologies enable a network with high capacity and quality.
LTE was designed from the ground-up with low latency requirements in mind with less than 100ms response times. 5G takes this further by opening door to ultra-low latency use cases with less than 10ms latency metrics. 5G extends the 3-nines reliability and availability targets for LTE to 6-nines. In either scenario, cellular wireless ties such stringent network performance metrics to an actual guaranteed service level agreement (SLA). This has so far been done on a per enterprise basis but as the technology becomes available within the four walls of the enterprise via CBRS, the guaranteed SLA metrics need to be defined per application, network segment, etc.
Traditional network slices in cellular wireless need to adapt to the way existing enterprise IT infrastructures are designed and implemented: from access control to device management, from L2/L3 network design to IT operations. This opens the door for a much different set of exceptions from an enterprise wireless where it would be considered out-of-service if it does not meet SLA requirements defined per category.
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