By Doris He | 15 September 2022 | 0 Comments
What Is 5G RedCap?
As the 3GPP R17 release continues to progress, a new term is becoming popular, and that is 5G RedCap.
What exactly is RedCap and why was it introduced? What is the difference between it and the current 5G?
See the in-depth explanation in this article.
Part I. What is 5G RedCap?
5G RedCap, the full name is Reduced Capability. It is a new technology standard that 3GPP is studying in the 5G R17 phase.
The name RedCap may seem strange to you. In fact, its previous name is 5G NR light (5G NR lite).
To put it bluntly, RedCap is a lightweight 5G.
Part II. Why is there a 5G RedCap?
As we all know, 5G is divided into three major application scenarios, which are eMBB (enhanced mobile broadband), uRLLC (low latency and high-reliability communication), and mMTC (massive IoT communication).
1.eMBB is the upgrade of MBB (Mobile Broadband) in the 4G era, mainly focusing on network speed, bandwidth capacity, spectrum efficiency, and other indicators. The 5G mobile communication we are currently using belongs to the eMBB scenario.
2. As for uRLLC and mMTC, the uRLLC focuses on reliability and latency, while the mMTC focuses on the number of connections and energy consumption. Both are mainly serving the industry Internet, including industrial manufacturing, automotive networking, and other vertical industry fields.
As 5G continues to be commercially available, it has been discovered that the above three application scenarios still do not fully meet demand, and there are "blind spots" that are not covered.
At this stage, the application of 5G in various industries is entering a climbing period. Seemingly hot but in fact a lot of resistance.
One of the biggest resistance is the high cost of 5G terminal chips and modules.
5G terminal chips and modules are incredibly complex in design, with high R&D thresholds and huge investment costs. Their prices, too, have remained high.
In the long run, how can 5G be developed?
Moreover, people also found that most of the industry application scenarios do not have high requirements for the rate and other indicators. 5G's existing capabilities have exceeded the needs of the system.
So the industry asked, "Is it possible to re-do the balance between cost and performance, sacrificing a few metrics, lowering some requirements, and then, lowering the cost?
Thus, 5G RedCap (5G NR light) was born.
In terms of technical characteristics, RedCap is in between eMBB (Ultra Broadband) and LPWA (Low Power Wide Area Network, NB-IoT, etc.).
5G RedCap is mainly targeted at applications where bandwidth, power consumption, and cost requirements are based between eMBB and LPWA. Its bandwidth and communication bit rate is lower than eMBB but much higher than LPWA, and its power consumption and cost are higher than LPWA but much lower than eMBB.
The power consumption and cost are higher than LPWA but much lower than eMBB.
In fact, from the perspective of current practical applications, RedCap is not a technology that is in very urgent demand.
RedCap corresponds more to medium speed or medium speed. Currently, LTE Cat1 and Cat4 already cover this part of the demand.
Part III. How does RedCap achieve low cost?
First, RedCap's spectrum bandwidth is much smaller. In the Sub-6GHz band, RedCap has a bandwidth of 20MHz, less than the 100MHz of traditional 5G.
Second, RedCap reduces the number of transceiver antennas and reduces the number of MIMO layers. For the Sub-6GHz band, the RedCap terminal can be reduced to 1 or 2 receive links, with the corresponding reduction in downlink MIMO to 1 or 2 receive layers. This reduces the capability requirements for the terminal's RF transceiver and baseband processing module.
Third, RedCap uses 64QAM, a simpler modulation method, which also means significantly lower RF and baseband requirements.
Fourth, RedCap uses half-duplex FDD (HD-FDD), which allows it to transmit and receive on different frequencies at different times, eliminating the need for duplexers. This not only saves cost, but also provides better integration capabilities (duplexers are generally larger), reduces the device's footprint, and facilitates equipment miniaturization.
Fifth, RedCap introduces power-saving tools, such as enhanced discontinuous reception (eDRX) and longer sleep mode, allowing the terminal to reduce power consumption and achieve higher endurance.
Based on these changes, RedCap is predicted to have about 70% cost reduction on the baseband and RF side compared to 5G public network terminals. There are even claims that the overall cost of RedCap could be reduced by a factor of 2-5 or even 7-8.
Part IV. What does 5G RedCap lose?
Speed: As terminal bandwidth decreases, MIMO reception is simplified, and the maximum modulation order decreases, RedCap's peak speed will also decrease significantly. According to the UE peak rate calculation method given in 3GPP TS36.306, the theoretical peak rate of RedCap is around 80-90Mbps.
Coverage capability: Because of the shrinking antenna design and the size limitation of the wearable terminal, the coverage capability is slightly shrunk.
Transmission delay: HD-FDD cannot transmit and receive at the same time, so the transmission delay will increase. However, for the application scenario of RedCap, these problems do not have much impact.
It is worth mentioning that, considering the application scenario and cost, 3GPP proposes that RedCap can only work in one band at a time and does not need to support carrier aggregation or dual connection.
Price: According to forecasts, RedCap's module price will be in the range of $15-30, much lower than the current 5G modules, but higher than NB-IoT modules.
Part V. Typical Business Scenarios for RedCap
According to the 3GPP R17 standard, RedCap supports three major service scenarios: wearable devices, industrial sensors, and video surveillance.
1. Wearable devices, taking smartwatches as an example.
At present, the mainstream smartwatches on the market only support 4G, not 5G, because the 5G chip is too costly and generates too much heat, and the high speed of eMBB is a bit redundant for the screen size of the watch.
With RedCap, it can fully meet the video calling needs of smartwatches, with not only sufficient downlink bandwidth but also much higher uplink bandwidth than LTE Cat1.
In addition, RedCap can meet the needs of smartwatches in terms of size and power consumption.
When will RedCap be commercially available?
RedCap was first introduced as an R17 Study Item at the 3GPP RAN #84 meeting in June 2019.
In March 2021, 3GPP officially approved the NR RedCap UE standardization project. It is planned that when 3GPP R17 is frozen, the RedCap standardization will be completed.
As a rule of thumb, it takes at least 1-2 years to achieve initial industrialization after standardization. Therefore, we expect to see early commercialization of RedCap by mid-2023.
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