1. Although 5G is not commercially available, it is very popular.
Although it has not been officially commercialized, the current 5G has become very popular. The three major telecom operators in China are actively carrying out the 5G pilot work. China Mobile has also submitted a 5G commercial license application recently. As a person in the communications industry, if you don't understand 5G technology, you are out of date.
2. 5G's main technology
When planning a 5G network, it is important to consider how to improve the coverage distance of the base station, support concurrent access to massive terminals, and maximize system capacity. Like 4G, 5G will also adopt technologies such as large-scale multi-antenna (MIMO: multiple input and multiple outputs) and beamforming to improve spectrum utilization efficiency through multiple dimensions such as time domain, airspace and frequency domain; 5G differentiated application scenarios and requirements, such as high-frequency band communication, access for large-scale terminals, and saving network investment costs, etc., 5G will adopt the above-mentioned downlink decoupling, multi-address access, non-independent networking, and other emerging technology.
3. Up-down decoupling technology
At the same transmitting power, the higher the frequency of an electromagnetic wave, the shorter the transmission distance. Whether in the 3.5GHz or 4.9GHz band, the signal transmission distance of 5G base station is much closer than that of the 4G base station, and because the transmitting power of 5G terminal is much smaller than that of the base station, the 5G upstream coverage will be very limited. Up-down decoupling technology can effectively solve this problem and save the investment of base station construction for Telecom operators.
As shown in the following figure:
The 5G terminal uses 3.5GHz frequency band in downlink and 3.5GHz or 1.8GHz frequency band in upstream according to the distance of the base station. When the terminal is in the 3.5 GHz upstream coverage range, it uses 3.5 GHz to carry the upstream and downstream data; when the terminal is outside the 3.5 GHz upstream coverage range, it interacts with the base station to send the upstream data based on 1.8 GHz.
Up-down decoupling technology can effectively solve the problem of limited upstream coverage in 5G high-frequency band, greatly reduce the number of new 5G base stations, and reduce the investment of telecom operators.
4. Multiple access technology
In order to support concurrent access of massive terminals, improve spectrum utilization efficiency, and minimize the signaling overhead of the system, 5G networks introduce multiple access technologies, similar to CDMA (Code Division Multiple Access) technologies in the 3G era. The modulated data of a plurality of users are transmitted in parallel in the same time domain and frequency domain, and the receiving side demodulates the user data. The current multiple access technologies mainly include PNMA (Power Domain Non-Orthogonal Multiple Access), SCMA (Sparse Codebook Multiple Access), RSMA (Resource Extended Multiple Access), MUSA (Multi-User Sharing) Access technology) and so on.
RSMA is a non-synchronous, non-orthogonal, contention-based multiple access technology that enables multiple terminals to transmit data without network pre-scheduling, thereby reducing the complexity and signaling overhead of device implementation. The SCMA utilizes the codebook to overload the user data through the multi-dimensional constellation modulation and the sparse spread spectrum technology, so that the number of users is more than the number of resources carried, thereby improving the utilization efficiency of the spectrum. Which multiple access technology is specifically selected in the 5G application scenario will be comprehensively evaluated based on the complexity of the terminal receiving processing, the spectrum efficiency improvement, and the system capacity gain.
5G smart city
5. Non-independent networking technology
At the end of 2017, 3GPP officially released the first 5G international standard, which mainly specifies the 5G new air interface standard for non-independent networking. It anchors the control plane to the LTE network, and the user plane is independently carried by the 5G new air interface or with LTE. Co-bearing. In the early stage of 5G development, the application of non-independent networking technology, telecom operators only need to deploy 5G access network and do not need to build a complete end-to-end network to achieve ultra-high-speed Internet access, thus saving a lot of investment.
6. 5G pilot and application
Up to now, many telecom operators at home and abroad are actively investing in 5G testing. NTT DOCOMO mobile communication operators have completed 5G field test based on 3GPP NR (New Radio) standard, using 200MHz bandwidth in a 4.5GHz band, and average throughput. The rate reached 11.29 Gbps, and also verified large-scale multi-user multiple access multiples (Massive MIMO), sub-band filtering based OFDM (f-OFDM), sparse codebook multiple access (SCMA) and polarization code ( Polar Code) and other 5G key technologies.
5G intelligent transportation system
In 2017, the field test of the second phase of 5G has been completed in China. In the continuous wide-area coverage scenario, the single-user peak rate exceeds 1.6 Gbps, and the peak rate of the cell exceeds 10 Gbps (200 MHz bandwidth). In the high and low-frequency hybrid scene, the 3.5GHz and 26GHz high IF hybrid mode are adopted, 3.5GHz is used as the anchor point of the control plane, and 26GHz is used to improve the cell capacity. The test results show that the single user peak under static conditions can exceed 20Gbps, 4 users. The peak throughput of the cell exceeds 65 Gbps.
China Mobile is also actively carrying out 5G test work in China. For example, a certain city has built a 5G test network based on the 15G frequency band (400M bandwidth). After testing, the average throughput of the 5G new air interface can reach 3.34Gb/s and the peak throughput can be achieved. Up to 5.79Gb/s, it can smoothly play multiple HD videos. In the industrial automation test, the robot controlled by the 5G network can accurately select the material with the specified number according to the input command, and the network delay is only 0.75 milliseconds.
5G car network automatic driving
At present, 5G technical standards have been issued, and the complete version of the standard (R16) is scheduled to be completed in 2020. Therefore, 5G is still in the experimental stage at home and abroad, requiring investment from the whole industrial chain of chips, terminals, wireless devices, network operations, etc. to promote the maturity of its technical standards and commercialization.
Autopilot to avoid high-speed congestion
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