Let’s talk about 3CC, which is very popular this year
Latest update time：2024-03-24
Reads：
The day before yesterday, I posted an article (
link
) about 5G-A in the Greater Bay Area, in which 3CC was mentioned many times.
After the article was published, many friends left me messages asking for details about 3CC. Today, I will write another article specifically talking about this technology.
█What
is 3CC
3CC, the full name is 3
Component Carriers, three carrier aggregation or three carrier unit. (
Component means "component, component", and Carrier means "carrier, carrier". The literal translation of 3CC should be "three component carriers".
)
As we all know, wireless communication requires occupying radio electromagnetic wave frequency bands. The so-called "3CC" means that the operator merges its three frequency bands to form a larger frequency band bandwidth, thereby achieving higher speeds.
Simply put, it's like merging three different lanes into one wider lane to increase vehicle capacity.
3CC belongs to carrier aggregation
(CA, Carrier Aggregation)
technology. Speaking of carrier aggregation, everyone should be familiar with it. As early as the 4G era, carrier aggregation has become famous.
At that time, the peak downlink speed of FDD LTE was only 150M, and that of TD-LTE was only 100M. Neither of them met the rigid requirements of the 4G (IMT-ADVanced) standard proposed by ITU-R (
downlink rate above 1Gbps for fixed or low-speed mobile; high-speed mobile) , the downlink rate is above 100Mbps
).
As a result, 3GPP came up with LTE-Advanced (also known as LTE-A
), which achieved a rate of over 1Gbps through carrier aggregation technology (up to five carriers can be aggregated), and barely got the "title" of 4G.
Traditional LTE is not actually 4G, but 3.9G, or "quasi-4G
"
.
Now that we have entered the 5G era, we have once again resorted to "carrier aggregation", not to "justify the name" (5G NR already meets the ITU's 5G standard requirements), but to make further breakthroughs in indicators.
Communication frequency bandwidth is the most important factor affecting the speed.
5G is divided into Sub-6GHz frequency band and millimeter wave frequency band. The millimeter wave frequency band has not been released in China for the time being. Although the 6GHz frequency band (5.925-7.125GHz) will be used for mobile communications in China, there is no sign of its use for the time being.
Therefore, when modulation, coding and other technologies are close to the limit of their capabilities, if you want to further increase the connection rate, you can only make full use of existing frequency band resources (these frequency bands <6GHz).
Domestic operator frequency band distribution map
3CC emerged based on this premise.
Operators bind their different frequency bands (including co-construction 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.
█
Technical highlights of 3CC
When Carrier Aggregation (CA) was first proposed, it was divided into three categories:
Adjacent CA within the frequency band: The two carriers belong to the same frequency band specified by 3GPP and are continuous in the frequency domain.
Non-adjacent CA within the frequency band: The two carriers belong to the same frequency band specified by 3GPP, but are discontinuous in the frequency domain.
Non-adjacent CA outside the frequency band: the two carriers belong to different frequency bands specified by 3GPP.
As shown below:
Each carrier participating in carrier aggregation is the Component Carrier mentioned earlier, which is called
component carrier
in the industry
.
Component carriers are also classified.
The component carrier that carries signaling transmission and manages other component carriers is called the main carrier, also called Pcell (Primary cell).
It is used to expand bandwidth and increase speed. The main carrier decides when to add or delete it. It is called
secondary carrier, also called Scell (Secondary Cell)
.
Domestic operators engage in 3CC and have different aggregation solutions.
One of the solutions currently adopted by China Mobile is 700MHz (30M) + 2.6GHz (100M) + 4.9GHz (100M), with a total bandwidth of 230M.
China Mobile still has 60M in the 2.6GHz frequency band, which will gradually be used for 5G in the future, becoming 2.6GHz (100M+60M) + 4.9GHz (100M), with a total bandwidth of 260M.
China Telecom and China Unicom mainly use the 2.1GHz (40M) + 3.5GHz (200M, including co-construction and sharing) solution. In some places, 900MHz 2×11M will be added. In some places, only 200M of 3.5GHz is used.
Looking at online news reports, domestic operators in many provinces and cities have conducted 3CC pilots, and most of the speed tests are above 4Gbps. Zhejiang Jiaxing Mobile even has official reports that it exceeds 5Gbps (3CC+1024QAM), which should be the highest downlink speed we have seen so far.
5046.08 Mbps (picture from Qianjiang Evening News)
As for the uplink rate, combined with SUL (uplink and downlink decoupling, auxiliary uplink, super uplink) technology, it is generally possible to measure hundreds of Mbps or even more than 1Gbps (Shanghai Unicom, 1.04Gbps).
It should be noted that speed measurement is related to many factors - the number of surrounding terminals, environmental interference, and whether Massive MIMO or high-order modulation is used, will all affect the speed measurement results. Therefore, just look at the speed measurement value, and horizontal comparison of PK is of little significance.
Careful readers should have noticed that the frequency bands used by 3CC include both FDD frequency bands and TDD frequency bands. 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 will be officially frozen soon. This is the first version of 5G-A. In R18, there are several technologies related to 3CC, such as FSA and MB-SC.
FSA is Flexible Spectrum
Access
. It can perform intelligent multi-carrier optimization, freely split and flexibly combine the entire uplink frequency band, and achieve unified control channel and unified scheduling of data channels, which can effectively increase resource utilization and improve the uplink experience.
MB-SC is Multi-Band Serving Cell. It can integrate and reconstruct discontinuous scattered spectrum to form a virtual large bandwidth, which can further improve resource utilization and improve uplink experience.
These technologies provide unified management and scheduling of spectrum resources in different frequency bands, carriers, and time slots, giving full play to the advantages of carrier aggregation.
█
Application scenarios of 3CC
As we said before, the most direct effect of 3CC is to greatly increase the network connection rate, from less than 1Gbps now to 3~5Gbps. Even considering scenarios with a large number of users, it is easy to achieve an experience speed of more than 1Gbps.
The ultra-large bandwidth will further meet the needs of new services such as live video streaming, cloud gaming, naked-eye 3D, XR/VR, etc., and provide users with a better user experience.
In transportation hubs such as high-speed rail stations, subway stations, and airports, as well as in crowded places such as stadiums, tourist attractions, and urban villages, the bandwidth advantage of 3CC will come into play. At present, the 3CC areas built by operators are mainly concentrated in these places, and most of them are implemented through micro base stations.
In the field of industrial Internet, 3CC also has great application value. In scenarios such as smart manufacturing, AI detection, remote inspection, security monitoring, and remote mining, there will be a large number of high-speed terminals or high-definition cameras, which have requirements for transmission rate and bandwidth, which can also be solved through 3CC.
While upgrading bandwidth, 3CC still has the ability to guarantee differentiated QoS.
In other words, it
can intelligently schedule and allocate bandwidth resources based on business levels and service quality requirements to ensure that key services receive priority, continuous and stable communication guarantees in complex network environments. This is extremely important for vertical industry application scenarios.
3CC actually has another potentially popular application scenario, which is FWA (Fixed Wireless Access). Through 3CC, larger bandwidth can be provided to CPE, making it easier for families, tenants, tourists, and small and micro enterprises to quickly obtain broadband access capabilities.
█Support
3CC terminals
Not all mobile phones support 3CC.
Currently, any mobile phone that uses Qualcomm X75 baseband and MediaTek M80 baseband can theoretically support 3CC.
Taking M80 as an example, it supports 3-carrier aggregation (300MHz) 5G NR (FR1) and 8-carrier aggregation 5G mmWave (FR2). Generally speaking, the maximum downlink rate is 5Gbps and the uplink rate is 1Gbps.
Judging from the specific mobile phone models,
Honor Magic6 Pro, Xiaomi 14 Pro, vivo X 100 Pro, OPPO Find X7, etc. all support 3CC. Other models are pending further verification. Apple mobile phones, current models should not support it.
█Final
words
Okay, the above is an introduction to 3CC. This year, operators will definitely vigorously promote the popularization of 3CC.
As 5G-A continues to be upgraded and more and more new mobile phone models enter the market, everyone will gradually feel the ultra-large bandwidth experience brought by 3CC.
Before the arrival of 6G, unless 6GHz and millimeter waves are liberalized,
5G
bps
should
be the highest network speed we can
enjoy
.
As the old saying goes, fast Internet speed is one thing, but having application scenarios is another. It is hoped that popular applications of 5G/5G-A will appear as soon as possible, so that there will be motivation to promote the continuous evolution of technology.
References:
1. “
Jiaxing’s user experience exceeds 5Gbps, the new speed of the national commercial network!
”, Zhejiang Online;
2. “3CC three-carrier aggregation, 5G-A human connection technology at your fingertips”, Huawei China;
3. MediaTek official website;
4. Weibo @Haifengkan Technology;
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