With the development of 5G and its deepening integration with the real economy, some practical problems have surfaced. Among them, cost and performance have become the two most prominent problems: first, the contradiction between the high cost of 5G terminal chips and modules to the terminal and the application of 5G in vertical industries; second, the actual demand for many application scenarios is medium speed requirements , the performance requirements are medium, the power consumption requirements are medium, and the requirements are higher than NB-IoT and lower than 5G.

In this case, RedCap became the industry's solution to these problems.

RedCap, the full name of Reduced Capability NR. As the name suggests, this means reducing NR capabilities, that is, functional tailoring of 5G NR.

So, what features have been cut out? It mainly includes bandwidth, antenna capability, minimum downlink MIMO layers, and maximum downlink modulation order.

In addition, in R17, RedCap also introduced half-duplex mode, which can support TDD and FD-FDD modes, which is conducive to the miniaturization of equipment.

After maximizing function tailoring, RedCap can support theoretical peak rates of uplink and downlink in the range of about 20Mbps-100Mbps in the FR1 frequency band.

In order to achieve a higher peak rate, RedCap terminal equipment can also adjust the performance tailoring degree appropriately and choose more advanced functions, such as supporting 2 receiving antennas, 2 downlink MIMO layers, 256QAM, full-duplex FDD, etc. In addition, by introducing an independent initial BWP and a non-cell-defined synchronization signal into the 5G network, RedCap takes full advantage of 5G's large bandwidth advantages and large system capacity and other generational differences, and achieves efficient coexistence with eMBB terminals. Overall, RedCap is close to Cat.4 terminal capability in terms of data rate.

Of course, in addition to tailoring the physical layer functions listed above, RedCap also tailors some higher layer functions, such as reducing the maximum number of DRBs from 16 to 8, reducing the PDCP SN and RLC-AM SN lengths from 18 bits reduced to 12 bits, optional support for ANR function, etc. RedCap has also introduced some power saving means, such as enhanced discontinuous reception (eDRX), using a longer sleep mode, allowing the terminal to reduce power consumption and obtain higher battery life.

With 5G Rel-17 officially frozen, RedCap chips are expected to launch in 2023.

After tailoring, not only the complexity of the RedCap terminal is reduced, but also the cost based on the above solution. The industry predicts that the cost of RedCap modules will be significantly lower than that of eMBB, and the price will probably be less than 200 yuan.

At present, the price of Cat.4 communication modules on the market is between 60-80 yuan. After the large-scale commercial use of RedCap, the price of the module may be comparable to the price of the Cat.4 module.

Since the sword refers to the medium and high-speed Internet of Things application scenario, its opponent is not only Cat.4. In Rel-17, it aims to replace Cat.4, and in the follow-up Rel-18, another version will be defined. At that time, the maximum bandwidth of RedCap will be 5MHz, designed to replace Cat.1.

Also from the perspective of cost, the current price of Cat.1 modules has dropped between 30-40 yuan. With the application of Cat.1 in various vertical industries in the future, the price can still be further dropped to about 20 yuan. At that time, the RedCap communication module that replaces Cat.1 is expected to be around 50 yuan. Whether the handover can be successfully passed depends on the healthy development of the entire industry chain ecology.

In other words, although the cost of RedCap will be greatly reduced compared to high-performance 5G modules, compared with 4G modules, the cost of initial commercial use is still much higher.

It took many years for the cost of 4G modules to drop to this level and the shipments reached more than 100 million. Therefore, the reduction of RedCap costs will also need to go through the test of time and shipments. Since RedCap faces relatively low-value IoT scenarios, its application fields are also highly cost-sensitive, which will limit the development of RedCap industry applications to a certain extent.