Introducing Private LTE in Band 48 (CBRS) 3.x GHz
Band 48 CBRS is a great technology for the wireless communications industry specifically within the USA. This technology is available today, just when data growth is inevitably exploding through the new trend of technologies and data-hungry applications.
The concept of having a private LTE as easy as a WiFi network and free of charge will likely change the market for LTE & cellular systems generally. We will shift from having a couple of nation-wide networks to a massive collection of small-scale LTE networks.
Explaining Private LTE (Band 48 CBRS)
The Band 48 CBRS (Citizens Broadband Radio Service) is often referred to as the private LTE. It is the frequency band of 3.5GHz, operating in the LTE spectrum in the United States.
LTE was designed to work across a wide range of frequency bands (450 MHz up to 3.8GHz) referred to as E-UTRA. 4G LTE technology is capable of supporting two modes of communication, FDD (Frequency Division Duplex) and TDD (Time Division Duplex).
Key Benefits of Band 48 CBRS:
- Improved Security. Network connections use dedicated radio equipment. Band 48 CBRS keeps data local.
- Enhanced Mobility & Range. Unlike WiFi, CBRS technology allows high-speed mobility, seamless handovers, and longer signal ranges.
- Capacity. Band 48 has enough capacity to allow high capacity applications and a large number of devices at the same time.
- Optimized Services. Applications can be customized and improved regarding the specific industry, for services such as QoS, bandwidth, latency, etc.
- Interoperability. Devices are capable of communicating with each, from all manufacturers
- New Wireless Devices. New wireless technology, such as AGV helmets, security cameras, agricultural sensors, and others.
Behind Band 48: How It All Started
Introduced by the FCC, the CBRS defined new ways to use the 3.5 GHz band in the U.S., and share its spectrum. The CBRS band consists of a total 150MHz within the 3500 MHz spectrum band that stretches between the 3550-3700MHz (or 3.55-3.7GHz).
The 150MHz were taken from the two LTE bands, the 42 (ranging from 3550 to 3660 MHz) and 43 (ranging from 3660 to 3700 MHz). The CBRS with a band total of 150MHz has been allocated and made available, as the name implies, to “citizens” with lower power resources.
The entire spectrum for bands 42 and 43 now belongs to CBRS, which is also referred to as Band 48. This frequency band is perfect for services that require ultra-high resources, and it could be a roadmap to 4.9G and 5G technologies deployment.
The CBRS Framework
The CBRS spectrum sharing rules were defined to support wireless access to the general public, but also to protect incumbent users from interference. These rules are crucial, because band 42, and 43 are already being used by the US Military and Navy.
The CBRS framework is organized into three tiers that follow a hierarchical order. This model helps to create new opportunities regarding the use and distribution of wireless access.
- Tier 1
- Tier 2
- Tier 3
The first tier is where Incumbent systems are placed. These are systems such as Navy RADARs, US Military, Satellite Stations, etc. This tier has priority on the entire 150MHz (over the lower tiers), but it does not always use the entire band at every location.
The second tier is where priority access devices are placed, this tier is referred to as the Priority Access License or (PAL). This tier offers a non-renewable 3-year license paid to the FCC, to use a 10MHz channel within the 3500-3650MHz portion of the entire band, in a limited geographical area. The license of PAL gives priority over the Tier 3.
And finally, the lowest tier (tier 3) is referred to as the General Authorized Access (GAA). The GAA is a dynamic allocation of 100MHz channels within the entire band (3500-3700 MHz). The idea is that GAA allocates dynamically, so that it does not interfere with the Incumbents or PAL. In other words, the GAA users use the available spectrum that is not occupied by higher tiers. From the 150 MHz, 80-100MHz are available for the GAA or “Private LTE”— WiFi-like authorized devices.
Tier 2 provides a licensed and “reliable service”, but Tier 3 works as an open spectrum without a license, very similar to WiFi.
Uses of LTE Band 48
Band 48 CBRS will likely be used in private and geographically restricted LTE deployments, which is much better than WiFi.
Mobile broadband internet providers (PALs) can use Band 48 to deploy Public LTE Networks and extend and improve their service. To do this, they’ll need to install LTE hardware for Band 48, such as indoor, outdoor antennas, and wireless gateway. Other PALs will likely use private LTE on industrial IoT applications.
Companies can also use an LTE Base Station hardware with Carrier Aggregation with other LTE bands to improve the overall capacity. In this deployment, another band is considered the main one, and band 48 is used to support wider transmission bandwidth.
One of the most popular new use cases of Band 48 will be the use of Private LTE or LTE-U (unlicensed). Any organization, enterprise, or individual, can operate in Band 48 under GAA unlicensed rules. This free LTE license to deploy anywhere operates much like a home Wi-Fi network.
Private LTE Band 48 CBRS Use Cases
- Wireless Sensor Networks and IoT.
- Remote control and sensing.
- Security remote-controlled cameras.
- Industrial and Agricultural Equipment
- Customized Smartphone Apps
To set up CBRS private LTE you’ll need three basic elements:
- The Base Station (BS) or Wireless Gateway.
- The EPC (Evolved Packet Core).
- CBRS devices or CPE (Customer Premise Equipment).
CBRS 4G Base Station (BS)
An LTE BS for Band 48 usually comes with Carrier Aggregation and multiple advanced features. In order to use the Band 48 CBRS, a device requesting service must be authorized by a Spectrum Allocation System (SAS), which may come embedded in the BS, or can be used as a Cloud service.
The SAS works with a database to store license and access information. It has the important task of analyzing the RF spectrum and channels to avoid any interference with the Incumbents or PAL. With this approach, the traditional channel interference issues are gone. If there is an available RF spectrum, the SAS will make it available for the end-user.
An example Base Station is the CableFree 4G Base station which is available in both Macro and Small Cell versions.
EPC (Evolved Packet Core)
The EPC is the main controller of an LTE network. This is the most complex and resource-consumption equipment in the LTE and it is usually operated in the NOCs of enterprise or ISPs. Today, EPCs are usually deployed on premises, but we will start seeing hybrid and cloud deployments of EPC cores.
Private and small LTE networks deploying Band 48 CBRS will have the option for simplified versions of the EPC, deployed on the cloud in a Data Center as a Service (DCaaS).
The private LTE-EPC is in charge of:
- Keeping the user database.
- Enforcing policies.
- Allocating IP addresses.
- Managing mobility and tracking.
- Giving a gateway to the PDN (Public Data Networks).
CBRS devices or CPE (Customer Premise Equipment)
This device provides radio connectivity to the LTE Base Station and must support LTE Band 48. This is the user equipment that gives an interface to the end-user. A CPE can be anything from an indoor, outdoor antennas, to a MiFi (My WiFi or WiFi hotspot). With the rise of IoT, we will start seeing sensors with CBRS base 48 support.
Summary
Shared spectrum model of Private LTE CBRS Band 48 has many advantages: comes with improved security, higher reliability, mobility, etc. Exciting aspects of CBRS technology is that it can be the route to 5G and its adoption to IoT applications.
CBRS Band 48 can be used as localised or private LTE which surpasses 1000x, existing WiFi technology. It is better in terms of security, speed, quality, & performance.
We are already seeing WISPs and other enterprises buy PAL licenses and use this technology to improve its existing LTE network or for industrial IoT applications in agriculture, oil rigs, factories, mining, etc. What is most exciting is that we might also start seeing the use of this technology in households.
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