The key technologies in 5G
As the next generation of cellular network, 5G network is based on 5G NR (New Radio) unified air interface (unified airinterface), designed to meet the expanding global connection demand in the next decade.
Qualcomm believes that in order to realize the construction of 5G NR, there are three types of key technologies that are indispensable
1. Optimized OFDM-based waveforms and multiple access (Orthogonal Frequency Division Multiplexing, Orthogonal Frequency Division Multiplexing) Multiplexing)
One of the most important decisions in the 5G NR design process is to adopt OFDM-based waveforms and multiple access technology, because OFDM technology is Today's widely adopted 4G LTE and Wi-Fi systems are well-suited for 5G requirements due to their scalability to high-bandwidth applications, high spectral efficiency, and low data complexity. The OFDM family of technologies enables enhancements such as enhanced frequency localization through windowing or filtering, more efficient multiplexing between different users and services, and creation of single-carrier OFDM waveforms for energy-efficient uplink transmission.
2. Flexible frame design (A flexible framework)
To realize the large-scale service of 5G, it is far from enough to only have OFDM-based optimized waveform and multiple access technology. While designing 5G NR, we are also designing a flexible 5G network architecture to further improve the efficiency of 5G service multiplexing. This flexibility is reflected not only in the frequency domain, but also in the time domain. The framework of 5G NR can fully meet the different services and application scenarios of 5G.
Scalable Transmission Time Interval (TTI) Compared with the current 4G LTE network, 5G NR will reduce the delay by an order of magnitude. In order to support services with "long delay requirements", the flexible framework design of 5G NR can expand TTI up or down (that is, use longer or shorter TTI), depending on specific needs. In addition, 5G NR also supports multiplexing at the same frequency with different TTIs.
Self-contained integrated subframe (Self-contained integrated subframe) is another key technology, which is of great significance for reducing latency, forward compatibility and a series of other 5G features.By including data transmission (transmission) and acknowledgment (acknowledgment) in a subframe, the delay can be significantly reduced.
3. Advanced new wireless technologies (Advanced wireless technologies).
While 5G is evolving, LTE itself is still evolving (such as the recently realized Gigabit 4G+), 5G will inevitably use advanced technologies currently used in 4G LTE, such as carrier aggregation, MIMO technology, and non-shared spectrum utilization, and so on; it can be said that 5G is largely based on 4G.
MIMO (Multiple-Input Multiple-Output) technology is an important innovative research project in the field of wireless communication at present.
By intelligently using multiple antennas (device side or base station side), transmitting or receiving more signal space streams, the channel can be significantly improved. Capacity; and through intelligent beamforming, the energy of the radio frequency is concentrated in one direction, which can improve the coverage of the signal. These two advantages are enough to make it one of the core technologies of 5G NR, so we have been working hard to promote the evolution of MIMO technology, such as improving from 4G 2x2 antenna to the current 5G 4x4 MIMO antenna. But more antennas also mean taking up more space. It is obviously unrealistic to accommodate more antennas in a device with limited space. Therefore, more MIMO can only be superimposed on the base station. From the current theory, 5G NR can use up to 256 antennas at the base station, and through the two-dimensional arrangement of antennas, 3D beamforming can be realized, thereby improving channel capacity and coverage.
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