Top Five Questions About 5G RedCap

5G New Radio (NR) continues to evolve, fulfilling its promise for faster and more reliable communications. 5G NR aims to give rise to the Internet of Things (IoT), autonomous driving, wireless broadband, interruption-free video, and the fourth industrial revolution, among other applications. The latest standard release of the 5G specification introduces many exciting new features. 5G RedCap, short for reduced capability, is one of them. It intends to fill the gap for medium throughput and latency use cases with low cost and power consumption requirements. In doing so, 5G will enable many new IoT applications.

This article answers some of the most frequent questions surrounding 5G RedCap and provides more insight into the vision for 5G.

1. What is 5G RedCap?

RedCap is a feature in the third standard release (Release 17) of the 5G NR specification from the 3rd Generation Partnership Project (3GPP), the global industry organization that develops the technical specifications for mobile communication systems. 

RedCap is a variation of 5G technology. It supports wireless devices with reduced capabilities, meaning simpler, lower-cost, and more power-efficient devices than conventional 5G devices like smartphones. These devices do not require the full capabilities and performance enabled by the 5G NR standard.

The first 5G RedCap chipsets will be available in 2023 and 2024, and commercial RedCap devices will follow suit. Industries and consumers are expected to adopt 5G-connected wearables for health monitoring and other applications, low-cost wireless sensors for industrial data collection and asset-tracking, and surveillance devices for use in smart cities, factories, and other applications.

2. Who will use 5G RedCap and what are the use cases?

5G NR use cases include:

• enhanced mobile broadband (eMBB), which refers to the target 5G peak and average data rates, capacity, and coverage as compared to traditional mobile broadband
• massive machine-type communications (mMTC) to support 5G IoT use cases with billions of connected devices and sensors
• ultra-reliable and low-latency communications (URLLC) for applications requiring fail-safe, real-time communications
• time-sensitive networks (TSN) 

mMTC, URLLC, and TSN enable IoT connectivity, but they only cover use cases with high-bandwidth and low-latency requirements such as manufacturing robots and drones. They are not suitable for simpler and lower-cost IoT devices like sensors and actuators that send small packets of information continuously and require a long battery life. 

5G RedCap is meant to address these applications. Release 17 specifies three RedCap use cases – industrial wireless sensors, health wearables, and surveillance devices – but more are expected to emerge as many IoT applications have lower capacity and latency requirements than those served by the other 5G use cases. 

Each RedCap use case has its own requirements for maximum data rate, end-to-end latency, and service availability. Industrial wireless sensors currently have a maximum data rate of 2 Mbps, an end-to-end latency requirement of less than 100 ms, and require 99.99% service availability. Health wearables have a higher maximum data rate of 25 Mbps, but no end-to-end latency or service availability requirements. Finally, surveillance devices have a maximum data rate of 150 Mbps for the downlink and 50 Mbps for the uplink, an end-to-end latency requirement of less than 500 ms, and service availability can vary between 99% and 99.9%.

IoT device makers serving these applications who want to provide a higher level of service quality to their customers on a global scale will be the primary users and early adopters of 5G RedCap. 

3. What are the key advantages of 5G RedCap?

5G RedCap devices use fewer antennas and support lower bandwidths than other 5G terminals. Fewer antennas and the resulting lower number of multiple-input multiple-output (MIMO) layers reduce costs for the device. Lower bandwidths also help cut costs by reducing power amplifier (PA) costs. 

You can further reduce the cost of your 5G RedCap device by using half-duplex frequency division duplex (HD-FDD) transmission. This mode of operation prevents the device from transmitting and receiving data on different frequencies at the same time, so there is no need to isolate the transmit path from the receive path in the device, enabling you to replace expensive duplexers with switches. 

Fewer antennas, lower bandwidths, and different modes of operation also help reduce power consumption. RedCap devices also do not have to monitor the same number of blind decoding (BD) and control channel element (CCE) limits in the physical downlink control channel (PDCCH), reducing power consumption further. The devices also use the system frame number (SFN) technique to increase extended discontinuous reception (eDRX) cycles when disconnecting from the network or going into idle state, helping to increase battery life.

RedCap devices can also transmit data without connecting to the network and have less stringent radio resource management (RRM) requirements than other 5G devices, helping the device save energy.

4. What are the key disadvantages of 5G RedCap devices?

For starters, trade-off is a more appropriate term for the situation, but because these devices have fewer antennas and support lower bandwidths, they have fewer capabilities than their 5G counterparts. Hence, the name. 5G RedCap devices only support 2x2 MIMO for the downlink and single-input single-output (SISO) for the uplink, and bandwidths of 20 MHz for frequencies below 6 GHz and 100 MHz for millimeter-wave (mmWave) frequencies.

These reduced capabilities have additional implications for the device and network operation. Low bandwidths require changes in bandwidth part (BWP) configurations for both the downlink and the uplink. There are also new information elements (IE) so that the bandwidth can adapt dynamically to the device’s actions. 

5G RedCap devices also use a different random-access channel (RACH) procedure to access the network, and the network can specify a BWP for RedCap devices or reduce the size of the BWP to attach to the network, which means that you will need to check the compatibility of your device with the new signaling parameters and procedures to ensure connectivity. 

If you have opted to implement the HD-FDD transmission mode to reduce the cost of your device further, remember that it will not be able to transmit and receive data at the same time. 5G RedCap devices also do not detect scheduling information for the downlink and the uplink in the same set of symbols so, for example, they will not be able to monitor messages in the downlink while in uplink mode or send information in the uplink while monitoring the downlink.

5. What are the other technologies for IoT connectivity besides 5G RedCap?

First, there are non-cellular IoT technologies like Bluetooth and Wi-Fi. However, cellular IoT (cIoT) technologies deliver much better quality of service by using regulated spectrum and the support of mobile network operators. Adherence to 3GPP standards and certification organizations also means global compatibility for your device. 

cIoT technologies emerged in 3GPP Release 13 and include extended coverage GSM (EC-GSM-IoT) based on 2G, Long Term Evolution (LTE) for machine-type communications (LTE-M), and Narrowband IoT (NB-IoT). 5G RedCap is the latest technology development in cIoT. It is of interest if your device's use cases serve low-to-medium data-rate applications.

LTE is a major player in the cIoT space. LTE-M is suitable for use cases using data rates under 1 Mbps that require extended coverage and low power consumption, but it is limited geographically. Release 13 specifies a maximum coupling loss range of less than 11 km at 144 dB, a spectrum bandwidth of 1.4 MHz in the 700 to 900 MHz bands, voice service, and battery life greater than 10 years. 

NB-IoT is another option for lower data rates (under 100 kbps). It has a slightly better coupling loss range than LTE-M, lower spectrum bandwidth (200 kHz), and does not support voice service. The technology has been serving use cases requiring very low data rates, extended coverage, and/or ultra-low power consumption. NB-IoT cannot handle mobile use cases though, and network availability is limited to specific geographies.

Amid all this, technology development is another aspect to keep in mind. You will be hard-pressed to find a device development test solution that supports all cIoT technologies, never mind one designed for it.

The good news? Solutions designed for cIoT testing do exist. 

Here at Keysight, for instance, we are leveraging the proven architecture of the UXM 5G wireless test platform to provide a streamlined test solution for cIoT technologies including 5G RedCap that spans all test domains – protocol, RF, and functional/performance. 

We play an active role in 3GPP and collaborate with industry leaders to provide the technology and insights you need to ensure design conformance to the latest standards developments.The promise of 5G is unfolding. We get closer to the 5G vision every day. Join us on this exciting journey. We have only had a glimpse of what cellular technology can do for IoT.

Click here to learn more about 5G RedCap

About the Author

Jessy Cavazos is a well-known industry analyst, having worked as the Industry Director for Frost & Sullivan’s Test & Measurement practice for more than 15 years. In addition to authoring market studies highlighting key opportunities and disruptive trends in test and measurement, she has written numerous articles on topics pertaining to 5G, Private Networks, and 6G. She is also the author of 5G & Beyond for Dummies®. Currently, Jessy serves as the 5G Solutions Manager at Keysight Technologies. Jessy holds a degree in international business from the Institut de Formation Internationale in Rouen, France.