With peak download speeds of 20 Gbps and latencies as low as 1 millisecond, there aren’t many fixed or mobile applications that 5G can’t handle. But not every application requires that kind of extreme performance.
Enter RedCap, which strikes a balance between affordability and longevity. Introduced in 3GPP Release 17, the technology provides a reduced capability version of 5G New Radio (NR). It’s a good fit for fitness trackers, medical wearables, smart utility meters, industrial sensors, and other Internet of Things (IoT) devices that need to remain in service for several years.
One reason is because RedCap is designed to maximize battery life with mechanisms such as discontinuous reception (DRX), where the device puts itself to sleep to save power. Depending on the configuration, a DRX cycle can range from about 10 seconds to three hours.
Another reason is because RedCap is a 5G standard, which means devices are using the latest mobile technology, thus providing greater future proofing than legacy 4G LTE. In fact, RedCap sometimes is described as a bridge between 4G and 5G because it supports many of the same use case requirements as LTE Cat 1 through Cat 4, such as sub-100 Mbps throughput.
Like LTE Cat 1-4, 5G RedCap enables use cases that otherwise would be difficult or impossible with the full versions of their respective technologies. One example is a home health device that needs a broadband connection to upload patient data. RedCap eliminates the problem of installation in homes where patients don’t have internet access because this capability can be built into the device. And when the patient or caregiver unboxes the device and powers it on, it can automatically connect to a RedCap network without manual configuration.
Reduced capabilities also mean reduced device complexity and in turn lower bill-of-materials (BOM) costs. That makes RedCap a good fit for price-sensitive IoT applications. And in the case of premium devices, such as high-end smart watches, RedCap’s lower BOM costs can increase profit margins.
Enhanced RedCap (eRedCap) debuted with 3GPP Release 18. It reduces throughput to 10 Mbps on both the downlink and uplink, further reducing BOM costs and power consumption.
Antennas and Other Implementation Considerations
Device OEMs and systems integrators can leverage their LTE product designs and experience when selecting and integrating antennas for RedCap. For example, both technologies require two antennas. Their spectrum allocations also are nearly identical except for the additional frequency bands above 2.7 GHz that only 5G uses.
In fact, one benefit of RedCap is that its reduced complexity compared to 5G means fewer antennas to integrate: two for Redcap and one for eRedCap compared to four with 5G. This is because RedCap supports only one transmit antenna rather than uplink MIMO. RedCap supports downlink MIMO, but it’s mandatory only for FR2 spectrum.
Comparison of the simplest regular 5G device with the simplest and the most advanced RedCap device.
Another antenna consideration is operator rollouts.
Network and device support are slowly growing. For example, in June 2024, AT&T began upgrading its standalone (SA) 5G network to support RedCap, while T-Mobile began selling RedCap devices in October 2024. Both Redcap and eRedCap also can be deployed as private networks, such as in the Citizens Broadband Radio Service (CBRS) band.
As with LTE and 5G, operators have efficiency requirements for RedCap. For LTE/5G lower bands (617-894 MHz) in the U.S., antenna efficeincy should be greater than 32%, greater than 50% for mid and high bands. Operators provide total radiated power (TRP) and total isotropic sensitivity (TIS) figures, such as this example from AT&T. (For more information about TRP and TIS, see “Why Cellular Pre-Certification is Critical.”)
RedCap and eRedCap provide OEMs, systems integrators, and their customers with new options for affordable, power-efficient connectivity and device longevity. But like any brand-new technology, they have a learning curve. Taoglas can provide guidance for successfully implementing RedCap/eRedCap, including selecting the right antenna, integrating it, and passing carrier certification.
To learn more about how to select the right antenna, speak to Taoglas’ Engineering team by clicking on the button below.
