You can always hear how fast the 5G network speed is, compared with 4G carries more information and other advantages, but the specific 5G key points are, how to work, but not very clear, so Xiaobian here to explain to you, this vital 3CC technology
█ What is 3CC
3CC,全称叫3 Component Carriers,三载波聚合或三载波单元。 (Component是"组成、部件"的意思,而Carrier是"载波、载体"的意思,3CC直译应该是"三个组成载波"。 ）
As we all know, wireless communication needs to occupy the radio magnetic wave frequency band. The so-called "3CC" means that operators combine their three frequency bands to form a larger frequency band bandwidth, and then achieve higher speeds.
To put it simply, it's like merging three different lanes into one wider lane to increase vehicle capacity.
3CC is a carrier aggregation (CA) technology. When it comes to carrier aggregation, everyone should be familiar with it. As early as the 4G era, carrier aggregation has made a name for itself.
At that time, the peak downlink speed of FDD LTE was only 150M, and TD-LTE was only 100M, which did not meet the hard requirements of the 4G (IMT-ADVanced) standard proposed by ITU-R (downlink rate of more than 1Gbps for fixed or low-speed movement, and more than 100Mbps downlink rate for high-speed movement).
As a result, 3GPP came up with an LTE-Advanced (that is, LTE-A), which achieves a rate of more than 1Gbps through carrier aggregation technology (up to five carriers can be aggregated), and barely won the "title" of 4G.
The traditional LTE, in fact, is not 4G, but 3.9G, or "quasi-4G".
Now, in the 5G era, we have once again resorted to the trick of "carrier aggregation", no longer to "correct the name" (5G NR has met the requirements of the ITU's 5G standard), but to make further breakthroughs in indicators.
The communication frequency bandwidth is the most important factor affecting the rate.
5G is divided into sub-6GHz bands and millimeter wave bands. The millimeter wave frequency band has not been released in China for the time being, and although the 6GHz frequency band (5.925-7.125GHz) will be used for mobile communications in China, there is no sign of using it for the time being.
Therefore, when modulation, coding and other technologies are close to the limit of capabilities, if you want to further improve the connection rate, you can only make full use of the existing frequency band resources (< these frequency bands of 6GHz).
Frequency band distribution map of domestic operators
3CC is based on this premise.
Operators bind their own different frequency bands (including co-built and shared frequency bands) to achieve higher speeds, which can meet the needs of users on the one hand, and is also conducive to brand promotion on the other hand.
Technical highlights of █3CC
When carrier aggregation (CA) was first proposed, it was divided into three categories, namely:
Adjacent CAs in Frequency Bands: Two carriers belong to the same frequency band as specified by 3GPP and are contiguous in the frequency domain.
Non-adjacent CAs in frequency bands: Two carriers belong to the same frequency band as specified by 3GPP, but are discontinuous in the frequency domain.
Non-adjacent CAs outside the frequency band: The two carriers belong to different frequency bands specified by 3GPP.
As shown in the figure below:
Each carrier that participates in carrier aggregation is the aforementioned Component Carrier, which is called a component carrier in the industry.
There are also classifications for component carriers. The component carrier that carries signaling and manages other component carriers is called the primary carrier, also known as the primary cell (Pcell).
Used to expand the bandwidth and increase the rate, the main carrier determines when to add or delete, which is called the secondary carrier, also known as the secondary cell (Scell).
Domestic operators engage in 3CC and have their own different aggregation schemes.
China Mobile, one of the current solutions is 700MHz (30M) + 2.6GHz (100M) + 4.9GHz (100M), a total of 230M bandwidth.
China Mobile still has 60M in the 2.6GHz frequency band, and it will gradually be used for 5G in the future, becoming 2.6GHz (100M + 60M) + 4.9GHz (100M), with a total of 260M bandwidth.
China Telecom and China Unicom mainly use the 2.1GHz (40M) + 3.5GHz (200M, including co-construction and sharing) scheme. In some places, 900MHz 2×11M will be added. In some places, only 3.5GHz 200M was used.
Looking at the news reports on the Internet, many provinces and cities of domestic operators have done 3CC pilots, and most of the speed tests are above 4Gbps. Zhejiang Jiaxing Mobile even has an official report that it has exceeded 5Gbps (3CC+1024QAM), which should be the highest downlink speed test seen so far.
5046.08 Mbps (Image via Qianjiang Evening News)
In terms of uplink speed, combined with SUL (uplink and downlink decoupling, assisted uplink, and super uplink) technology, it is generally possible to measure a maximum of several hundred Mbps or even more than 1 Gbps (Shanghai Unicom, 1.04 Gbps).
It should be noted that the speed test is related to many factors - the number of surrounding terminals, environmental interference, whether Massive MIMO or higher-order modulation is used, will affect the speed test results. Therefore, it is good to take a look at the speed measurement value, and the horizontal comparison PK is of little significance.
Attentive readers should note that the frequency bands used by 3CC are both FDD and TDD. Yes, 3CC has such capabilities and can support "F+T".
3CC can bring significant experience improvement, but it is still inseparable from some technological innovations.
The 3GPP R18 standard is about to be officially frozen, and this is the first version of 5G-A. In R18, there are several technologies related to 3CC, such as FSA and MB-SC.
FSA stands for Flexible Spectrum Access. It can perform intelligent multi-carrier optimization, freely split and flexibly combine all uplink bands, and realize the integration of control channels and unified scheduling of data channels, which can effectively improve resource utilization and uplink experience.
MB-SC is a Multi-Band Serving Cell. It can integrate and reconstruct discontinuous distributed spectrum to form a virtual large bandwidth, which can further improve resource utilization and uplink experience.
These technologies can manage and schedule spectrum resources in different frequency bands, carriers, and time slots in a unified manner, giving full play to the advantages of carrier aggregation.
Application scenarios of █3CC
As we said earlier, the most direct effect of 3CC is to greatly increase the network connection speed, from less than 1Gbps to 3~5Gbps. Even in scenarios with a large number of users, it is easy to achieve a speed of more than 1 Gbps.
The ultra-high bandwidth will further meet the needs of new services such as live video streaming, cloud gaming, glasses-free 3D, AND XR/VR, bringing users a better user experience.
In transportation hubs such as high-speed rail stations, subway stations, and airports, as well as crowded places such as stadiums, tourist attractions, and urban villages, the bandwidth advantage of 3CC will play a role. At present, the 3CC areas built by operators are mainly concentrated in these places, and most of them are realized through micro base stations.
In the field of industrial Internet, 3CC also has great application value. Scenarios such as intelligent manufacturing, AI detection, remote inspection, security monitoring, and remote mining will have a large number of high-speed terminals or high-definition cameras, which require transmission rate and bandwidth, which can also be solved by 3CC.
While upgrading the bandwidth, 3CC still has differentiated QoS assurance capabilities.
In other words, it can intelligently schedule and allocate bandwidth resources according to service level and service quality requirements to ensure that critical services receive priority, continuity, and stable communication in complex network environments. This is extremely important for vertical industry use cases.
In fact, there is another potential hot application scenario for 3CC, which is FWA (Fixed Wireless Access). Through 3CC, CPE can be provided with greater bandwidth, which is convenient for families, tenants, tourists, and small and micro enterprises to quickly obtain broadband access capabilities.
█ Terminals that support 3CC
Not all phones support 3CC.
At present, as long as it is a mobile phone that uses Qualcomm X75 baseband and MediaTek M80 baseband, it can theoretically support 3CC.
Taking M80 as an example, it supports 5G NR (FR1) with 3-carrier aggregation (300MHz) and 5G mmWave (FR2) with 8-carrier aggregation. Generally speaking, the maximum downlink rate is 5 Gbps and the uplink rate is 1 Gbps.
From the perspective of specific phone models, the Honor Magic6 Pro, Xiaomi 14 Pro, vivo X 100 Pro, OPPO Find X7, etc., all support 3CC. Other models, pending further verification. Apple mobile phones, the current models should not be supported.
█Final words
Well, that's it for 3CC. This year, operators will definitely vigorously promote the popularization of 3CC.
With the continuous upgrade of 5G-A and more and more new models of mobile phones entering the market, everyone will gradually feel the ultra-large bandwidth experience brought by 3CC.
Before the arrival of 6G, unless 6GHz and millimeter wave are released, 5Gbps should be the highest network speed we can enjoy. As the old saying goes, fast internet speed is one thing, and having application scenarios is another. It is hoped that the explosive application of 5G/5G-A will appear as soon as possible, so that there will be motivation to promote the continuous evolution of technology.
Resources:
1. "Running out of the new speed of the national commercial network, Jiaxing user experience exceeds 5Gbps!", Zhejiang Online;
2. "3CC Three-Carrier Aggregation, 5G-A Human Connection Technology at Your Fingertips", Huawei China;
3. MediaTek official website;
4. Weibo @海峰看科技;
Source: Fresh Jujube Classroom
Editor: Lan Duoduo
The reprinted content represents the author's views only
It does not represent the position of the Institute of Physics of the Chinese Academy of Sciences
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