Huawei's "dual-band 4T4R+sector splitting" solution Communications World Wide Web News (CWW) In response to the surge in network traffic of operators, insufficient spectrum and site resources, and high cost of new sites, Huawei launched a capacity triple-hop solution to maximize the release of site potential and build a basic experience network through 4T4R. Hotspot areas 4T4R+ sector splitting is used for capacity expansion, and Massive MIMO is used to maximize spectrum efficiency for traffic super hotspots. What is a dual-band 4T4R+ sector splitting solution Huawei's 4T4R+ sector splitting solution uses dual-band integrated 4T4R modules and sector splitting antenna networking. Based on the traditional multi-frequency, multi-antenna, and multi-sector Technologies such as joint scheduling make the collaboration between spectrums and sectors more efficient, and provide users with a higher experience rate, as shown in Figure 1. Huawei's patented split antenna technology effectively reduces interference in coverage overlapping areas, and improves user experience through algorithm optimization. Figure 1 Dual-band 4T4R+ sector split site structure The dual-band 4T4R+sector splitting solution improves spectrum resources, spectrum efficiency, and cell density, and enhances network capacity through a three-pronged approach. As shown in Figure 2, it releases the capacity potential of LTE sites without increasing site sites. Figure 2 Dual-band 4T4R+sector splitting improves network capacity The program has five main values: 1. The split antenna adopts 33° narrow beam, which improves the coverage by 2~3dB; 2. The number of cells is doubled, and the capacity gain is 50% to 70%; 3. No need to add new site; 4. The site renovation cycle is short; 5. One dual-frequency module is equivalent to two single-frequency modules, which saves antenna and electricity costs, and saves overall TCO. Why dual-band 4T4R+sector splitting is needed The "happiness troubles" of the continuous growth of 4G traffic Driven by business development and competition, operators offer services such as unlimited packages. At present, the hotspot areas of some networks are severely congested, and the average DOU reaches 10GB. The industry predicts that the average annual growth rate of network traffic will exceed 50%, and the 4G DOU will reach 20G in 2021. Operators are both "happy" and "troubled". The traditional site solution can no longer meet the demand for capacity growth. The industry generally pays attention to what is the next hop of the LTE capacity solution. 5G technology is applied in advance, and 4T4R doubles the capacity of the cell Looking back at the history of communication development, in the era of 2G and 3G, 1T2R is the basic network configuration for universal coverage of the entire network. In the 4G era, the basic configuration of the network has been upgraded to 2T2R. Now 5G standards and industries have agreed that 4T4R is the starting configuration for 5G. Multi-antenna technology is one of the key technologies of 5G. 4T4R realizes the early application of 5G technology under 4G network, and doubles the uplink and downlink capacity of the cell, which can significantly reduce the pressure on wireless network capacity and prepare for 5G evolution. 4T4R perfectly meets the requirements of 5G evolution for a three-fold increase in spectrum efficiency, and is the basic configuration of 4.5G/5G networks. The continuous evolution of 4G stock spectrum is a key component of 5G user experience The continuous evolution of existing network spectrum is a key component of future 5G user experience. The network competitiveness in the 5G era is not equal to the competitiveness of the new 5G frequency band. The new 5G spectrum (>3GHz) has high frequency bands, poor coverage, and high network construction costs. It must rely on the existing LTE spectrum for the bottom line. 5G terminals support multi-mode and multi-frequency, and the continuous evolution of existing spectrum can provide smooth experience for 5G users. LTE has a lot of spectrum in stock, and can achieve an experience comparable to the new 5G frequency band through technologies such as CA, 4x4 MIMO, and 256QAM. The "4R" terminal industry chain is gradually maturing, and network development has entered the fast lane From the perspective of the industry, 4x4 MIMO has become the basic capability of terminal chips, fully supported by mainstream chips such as Qualcomm, Intel, and HiSilicon. It is expected that in the second half of 2019, the industry will launch 5G commercial mobile phones, and 4 antennas will be the starting configuration for 5G terminals. Up to now, more than 30 commercial terminals have directly supported four antennas. For example, Huawei P20, Mate20 Pro, Apple iPhone XS, Samsung Note 9/S9 and Sony XZ, etc., all support 4x4 MIMO. Therefore, the current industry chain supporting the 4T4R overall solution has gradually matured, as shown in Figure 3. Figure 3 4-receiver terminal (supporting 4x4 MIMO) gradually matures Value and Application Scenarios of 4T4R+ Sector Splitting Solution The gains brought by 4T4R through arrays, diversity, spatial multiplexing, and interference suppression are key technologies for improving 4G network capacity, experience, and 5G-oriented evolution. 4T4R gain principle There are four types of gains in a multi-antenna system: array gain, diversity gain, space multiplexing gain, and interference suppression gain, as shown in Figure 4. Figure 4 Four kinds of gains and their values in multi-antenna system 1. Array gain Array gain can be obtained by using multiple antenna systems. As shown in Figure 5, the array gain can be obtained by combining the signals on antenna 1 and antenna 2. Since the white noise on different antennas is uncorrelated, the noise power remains unchanged after combination, while the signals on different antennas are correlated, and the signal energy is doubled after coherent combination, so the combination can improve the average SNR of the signal, thus providing Array gain. Figure 5 Schematic diagram of array gain 2. Space diversity gain The idea of space diversity is to ensure that the receiving end can receive the data correctly by transmitting the same data on multiple antennas of the receiving and receiving parties in the MIMO system. Diversity gain can be obtained by using a multi-antenna system. The prerequisite for obtaining diversity gain is that multiple spatial signal branches must have certain independence. As shown in Figure 6, two different signals of the same set of data on antenna 1 and antenna 2 experience deep fading at different times, and the receiving end will compare the two signals received at any time and choose the better one. Reduce or remove the effect of deep fading, thereby obtaining diversity gain. Figure 6 Schematic diagram of diversity gain 3. Interference suppression gain When the nTnR system is used, when the spatial interference has a certain color, the color of the interference can be estimated through multiple antennas, and this information can be used to suppress the interference. Interference suppression can be performed at the transmitting end or at the receiving end. When it is performed at the transmitting end, it is to reduce its own interference to neighboring cells. When it is performed at the receiving end, it is to suppress the interference received by itself. 4. Spatial multiplexing gain When the nTnR system is used, when there is a certain degree of independence in channel fading, the spatial channels that interfere with each other are equivalent to multiple sub-channels that are relatively independent of each other through precoding technology, and there is no or little interference between sub-channels. Transmitting multiple data streams increases the gain in transfer rate. Each subchannel corresponds to a capacity, so the limit capacity of the MIMO channel can increase linearly with the number of transmitting and receiving antennas. For a link system, the number of sub-channels depends on the correlation of the channel and the minimum number of antennas among the transmitting antenna and the receiving antenna. Main Application Scenarios of the Dual-Band 4T4R+ Sector Splitting Solution The dual-band 4T4R+sector splitting solution maximizes the capacity potential of LTE sites based on limited site resources and spectrum resources, and can be widely deployed in scenarios of capacity enhancement, experience improvement, and site simplification, as shown in Figure 7. 1. Meet MBB capacity evolution It is estimated that more than 70% of the residential areas in the hot spots of major cities in China will meet the demand for 2 carriers, and the capacity solution design will be in place in one step, which will solve the capacity demand in the next 1-2 years, avoid secondary site visits, and reduce the overall transformation cost. lExperience guaranteed area: In the 1.8GHz single-frequency expansion scenario, the 1.8GHz/2.1GHz dual-frequency 4T4R module is used to replace the existing network 1.8GHz single-frequency 2T2R or 2T4R module, and the capacity is increased from single carrier to 2.4 carriers; l Hotspot areas: Deploy 1.8GHz/2.1GHz dual-band 4T4R modules, and add 4-port or 8-port split antennas according to capacity forecast requirements. One dual-frequency 4T4R module combined with a 4-port antenna can be split into six 2T2R cells, and the capacity is increased to 3.2 carriers; two dual- frequency 4T4R modules combined with an 8-port antenna can be split into six 4T4R cells, and the capacity is increased to 3.8 carriers; lSuper hotspot area: In scenarios where there is still demand for capacity, add pole sites or micro-sites to split cells as needed, and drip irrigation to absorb traffic. Figure 7 Dual-band 4T4R+ sector splitting application scenario 2. Build 4.5G and 5G experience infrastructure network to improve user experience Compared with 2T2R, 4T4R can improve the edge user experience rate by 1.6 times in the terminal scenario where 2R&TM4 is the main stock. In future 4R-based terminal scenarios, 4T4R can improve spectral efficiency by 1.9 times. 4T4R combined with multi-carrier and 256QAM can increase the peak rate to close to Gbit/s, creating an experience basic network. In the future 5G era, under eLTE, 5G mobile phones combined with 4T4R can enable Gbit/s user experience and avoid the large gap in 4G/5G switching experience outside the initial 5G coverage area, as shown in Figure 8. Figure 8 4T4R enables LTE Gbit/s experience 3. Dual-band 4T4R co-construction simplifies antenna reconstruction Huawei's single 4T4R dual-band integrated module supports 1.8GHz 4T4R and 2.1GHz 4T4R at the same time. Compared with the traditional dual-combination mode, the number of RRUs before the transformation is reduced from 4 RRUs to 1 RRU after the transformation, which significantly saves sky space and tower rent and electricity charges, as shown in Figure 9. Figure 9 Dual-band 4T4R simplifies the antenna and saves investment Application of 4T4R+ Sector Splitting Solution More than 100 LTE networks around the world including Germany DT, UK EE, South Korea LGU+, Thailand TRUE, Mexico AM, Australia Vodafone, Malaysia Celcom, and Peru Entel have verified and deployed 4T4R to promote network evolution and enhance 4G competitiveness. In China, the three major operators have written 4R terminals into the terminal white paper, and completed pilot verification in several provinces. The pilot results show that after the deployment of the multi-sector solution, the system capacity of a single cell can be increased by 50% to 70%, and the user experience rate can be increased by more than 60%, achieving both user experience and traffic release. Up to now, 4T4R has completed the effect verification and widely deployed in more than 20 provinces including Beijing, Chongqing, Shaanxi, Jiangsu, Guangxi, Hebei, Sichuan, Hubei and Anhui. In short, "User experience is the only thing that can't be broken", and the pressure of traffic continues to promote the evolution of terminals and networks. With the rapid popularization of 4T4R network deployment and the continuous maturity of the chip and terminal industry chain, the value of 4T4R+ multi-antenna technology will gradually become prominent. Huawei will continue to innovate in technology, quickly respond to market development needs, and help operators build high-quality networks with higher capacity and better experience.
