5G is Coming to the iPhone12, What is it?Follow article
With the release of iphone12 on October 14, 2020, we seem to be closer to 5G. What is 5G? Why do we need 5G? With the development of society, we can foresee that the future network will face: 1000 times the data capacity growth, 10 to 100 times the wireless device connection, 10 to 100 times data transfer rate, 10 times the long battery life demand, and many more. Frankly speaking, 4G networks cannot meet these needs. At this time, the emergence of 5G came into being.
However, 5G is not a revolution. 5G is the continuation of 4G. I believe that 5G will not change much in the core network part. The key technologies of 5G are concentrated in the wireless part. Although 5G will eventually adopt which technology in marketing, there is no final conclusion. With the advent of the 5G era, we must understand the existing 5G key technologies.
Here are 8 key breakthroughs of 5G technology:
1) Non-Orthogonal Multiple Access(NOMA)
We know that 3G adopts Direct Sequence Code Division Multiple Access (Direct Sequence CDMA, DS-CDMA) technology, and the mobile phone receiver uses Rake receivers. Due to its non-orthogonal characteristics, fast transmission power control (TPC) must be used. To solve the near-far problem between the mobile phone and the cell. The 4G network uses Orthogonal Frequency Division Multiple Access (OFDM) technology. OFDM can not only overcome the problem of multipath interference, but also cooperate with MIMO technology to greatly increase the data rate. Because of multi-user orthogonality, there is no far-near problem between the mobile phone and the cell, and fast power control is abandoned, and the AMC (Adaptive Modulation and Coding) method is adopted to realize link adaptation. What NOMA to achieve is to regain the principle of non-orthogonal multi-user multiplexing in the 3G era and integrate it into the current 4G OFDM technology.
From 2G, 3G to 4G, multi-user multiplexing technology is nothing more than making a fuss in the time domain, frequency domain, and code domain. On the basis of OFDM, NOMA adds a dimension-power domain. The purpose of adding it is to use the different path loss of each user to achieve multi-user multiplexing. That is, realizing the multiplexing of multiple users in the power domain. It is necessary to install an SIC (Successive Interference Cancellation) at the receiving end, with channel coding (such as Turbo code or low-density parity-check code LDPC, etc.) , it is easy to distinguish the signals of different users at the receiving end.
NOMA can use the difference of different path losses to superimpose the multiplexed signals, thereby increasing the signal gain. It enables all mobile devices in the same cell coverage area to obtain the maximum accessible bandwidth, and can solve the network challenges caused by large-scale connections. Another advantage of NOMA is that there is no need to know the CSI (Channel State Information) of each channel, which is expected to achieve better performance in high-speed mobile devices and to build better mobile node backhaul links.
2) Filter Bank based Multicarrier (FBMC)
In the OFDM system, each sub-carrier is orthogonal to each other in the time domain, and their frequency spectrum overlaps each other, so it has a higher spectrum utilization. OFDM technology is generally used in data transmission in wireless systems. In OFDM systems, due to the multipath effect of the wireless channel, interference occurs between symbols. In order to eliminate inter-symbol interference (ISl), a guard interval is inserted between symbols. The general method of inserting it is to set zeros between symbols, that is, to stay for a period of time after sending the first symbol (no information is sent), and then send the second symbol. Based on this method, although the inter-symbol interference is reduced or eliminated, the orthogonality between the sub-carriers is destroyed, resulting in the inter-sub-carrier interference (ICI). Therefore, this method cannot be used in OFDM systems. To eliminate both ISI and ICI, the guard interval is usually served by CP (Cycle Prefix). CP is a system loss and does not transmit valid data, because it lowers spectrum efficiency. FBMC uses a set of non-overlapping band-limited sub-carriers to achieve multi-carrier transmission. In addition, FMC has very little inter-carrier interference caused by frequency offset, does not require CP, which greatly improves frequency efficiency.
Recommended Reading: Filtering Technique Basics in Electronics
3) Millimetre Waves (mmWaves)
What is a millimetre wave? The frequency range is 30GHz to 300GHz, and the wavelength range is 10 to 1 mm. Due to a sufficient amount of available bandwidth and high antenna gain, millimetre wave technology can support ultra-high-speed transmission rates. And the beam is narrow, flexible and controllable, help to connect a large number of devices.
4) 3D /Massive MIMO
MIMO technology has been widely used in WIFI, LTE, etc. In theory, the more antennas, the higher the spectrum efficiency and transmission reliability. So massive MIMO technology can be realized by some inexpensive and low-power antenna components, which provides a broad prospect for realizing mobile communication in high-frequency bands. For example, it can double the wireless spectrum efficiency, to enhance network coverage and system capacity, which help operators make maximum use of the existing site and spectrum resources. Let's take a 20 square centimetre antenna physical plane as an example. If these antennas are arranged in a grid with a half-wavelength interval, and if the working frequency band is 3.5GHz, 16 antennas can be deployed.
5) Cognitive Radio Spectrum Sensing Techniques
The biggest feature of cognitive radio technology is the ability to dynamically select wireless channels. Under the premise of no interference, the mobile phone selects and uses the available wireless spectrum by constantly sensing the frequency.
6) Ultra-wideband Spectrum
The channel capacity is proportional to the bandwidth and SNR. In order to meet the Gpbs-level data rate of the 5G network, a larger bandwidth is required. The higher the frequency, the larger the bandwidth and the higher the channel capacity. Therefore, high-frequency continuous bandwidth has become an inevitable choice for 5G. Thanks to some technologies that effectively improve spectrum efficiency (such as massive MIMO). In addition, even if relatively simple modulation techniques (such as QPSK) are used, it is possible to achieve a transmission rate of 10Gpbs on an ultra-bandwidth of 1Ghz.
7) Ultra-dense Hetnets
HetNet refers to the deployment of access points such as microcells, picocells, and femtocells in the macrocellular network layer to meet data capacity growth requirements. In the 5G era, more things can be connected to the network, and the density of HetNet will increase greatly.
8) Multi-technology Carrier Aggregation (MCA)
The existing 3GPP R12 has already mentioned this technical standard. The future network is a converged network. Carrier aggregation (CA) technology must not only realize the aggregation between carriers in LTE but also expand to the integration with 3G, WIFI and other networks. Together with HetNet, MCA technology will eventually achieve a seamless connection between everything.