Commercial deployment of 5G has become a very real future. How LTE networks will develop, networks that have served us for almost a decade, is a hot topic in the communications industry. At the All Business Connected @ LTE Summit of the Global Mobile Broadband Forum 2018, some 150 operator delegates gathered together to discuss, and to try to reach a general consensus on, issues of common concern in the industry. They all agreed, “In the upcoming 10 years, LTE networks will still be a cash cow for operators. LTE network capabilities will continue to improve, driven by traffic growth and all-business innovations. LTE will become an all-business foundation network in the 5G era.”
I. LTE Users and Traffic Continue to Increase, Stimulating LTE Network Capability Enhancement.
Over ten years of rapid development, LTE has overtaken 2G and 3G as the most popular wireless communications technology. 715 LTE networks have been deployed for commercial use, serving 78% of the global population, with 3.2 billion users. In the next ten years, LTE will maintain strong growth.
- The 2G and 3G networks will gradually be phased out, with nearly 2 billion 2G and 3G users migrated to the LTE networks. GSMA Intelligence estimated that the number of LTE users will increase by 2.3 billion by 2025. The number of LTE IoT users will also increase by 2 billion by 2025, as 900 million 2G and 3G IoT users will be migrated to LTE.
- Network traffic continues to grow rapidly. According to Analysis Mason, the global average handset data traffic per user per month (DOU) has reached 2.7 GB, and this figure will increase over the next few years at a compound annual growth rate (CAGR) of 50%. Despite the advent of 5G commercial use, LTE will still be the main bearer for this ever-growing traffic. It is predicted that by 2021, 5G will carry only 1.5% of the total traffic, and about 80% of the traffic will be provided by LTE networks.
- With the rollout of new services such as ultra-HD video, virtual reality (VR), and mobile gaming, users have higher experience requirements. Currently, the user experienced data rate of major operators around the world has reached 20 Mbps. In the not too distant future, a data rate of 50 Mbps anytime anywhere with zero wait time will become a basic requirement.
- LTE serves huge number of users and provides most of the traffic and services. It is still the main revenue source for operators. Strategy Analytics forecast shows that by 2022, LTE will contribute to 80% of operators’ mobile communication revenue. Based on these facts, LTE will continue to be the main focus of operators’ investment in the future. LTE coverage and capacity will be further improved, making it a foundation network carrying a full range of services in the 5G era.
II. LTE Enters a New Stage of Connecting the Old and New. The Target Network in the 5G Era Is LTE Evolution + NR.
What will the relationship between LTE and 2G, 3G, and 5G be in the future? What will the target network be like in the 5G era? Veni Shone, President of Huawei LTE Product Line, said, “In the past, the evolution of mobile communications technologies was a process of replacing old-generation technologies with new ones. After 3G emerged, 2G standards stopped evolving. This is quite different in the 5G era, where LTE will have to evolve in line with 5G NR over a long period of time in terms of standards, industries, and ecosystems. The target network in the 5G era is LTE Evolution + NR.” The advent of 5G has unveiled a new chapter for LTE evolution. LTE will gradually incorporate 2G and 3G and become an all-business foundation network in the 5G era. LTE will also continue to enhance its capabilities and collaborate with NR in the 5G era.
1. LTE Will Replace 2G and 3G as the Foundation Network in the 5G Era.
Currently, 2G, 3G, and LTE networks coexist. Their operating expense (OPEX) accounts for more than 60% of the total cost operation (TCO) for operators. After 5G is put into commercial use, if all of the four types of networks are deployed for a single operator, the OPEX will be even higher. To improve operational efficiency, 2G and 3G networks will be gradually shut down with the voice, data, and IoT services being migrated to LTE networks, which feature better spectral efficiency. Network simplification is the way of future. Dozens of operators, such as AT&T in the US, Vodafone in Australia, and TELUS/Bell in Canada, have shut down their 2G networks. Most other operators have released network shutdown plans. The years from 2020 to 2025 will witness large-scale shutdown of 2G and 3G networks. In the 5G era, LTE will replace the 2G and 3G networks as the foundation network. The ultimate target network will be LTE Evolution + NR.
2. LTE Will Co-Exist with NR, and Continue to Evolve in Parallel with NR.
In June 2018, 3GPP Release 15, the first version of 5G NR standards, was frozen, marking a milestone in the communications history. In Release 15, LTE air interface is comprehensively enhanced, capable of supporting E-UTRA-NR Dual Connectivity (EN-DC) and LTE connection to 5G Next Generation Core (NGC). This allows LTE to evolve together with NR, both of which will be integral parts of the 5G era.
LTE will evolve in the following aspects: 1. More spectrum resources will be aggregated to provide a higher throughput. 2. Downlink 1024QAM, uplink 256QAM, and Massive MIMO in TM9 will be supported to achieve higher spectral efficiency. 3. Short transmission time interval (short TTI) will be introduced to reduce the latency. 4. The bearer capabilities of NB-IoT and eMTC will be further enhanced to substitute 2G or 3G IoT. 5. LTE will be deeply integrated with the NR architecture to serve as the anchor for NR and support EN-DC and connection to 5G NGC.
The continuous evolution of LTE helps operators reuse investments in LTE to quickly enable 5G services. In addition, the potential of LTE networks will be fully unleashed to cope with the increasing traffic demands.
III. Zero Fallback, Zero Wait, and Zero Copper Are LTE Network Construction Strategies for the New Era. How do we construct LTE networks in this new phase? Mr. Shone provided a brief answer: zero fallback with expanded coverage, zero wait time for better experience, and zero copper for home broadband (HBB) services.
Zero fallback refers to expansion of the foundation LTE network coverage so that it is the same as that of 2G and 3G networks. With expanded coverage, LTE data, VoLTE, and IoT services will always be provided by the LTE network. Users will no longer fall back to 2G or 3G networks. The enhanced coverage also lays a foundation for 2G and 3G users to be migrated to LTE networks.
Currently, LTE coverage is not as good as that of 2G networks. Insufficient coverage causes LTE users to fall back to the 2G or 3G networks, resulting in significant user experience changes. It also leads to congestion on the 2G and 3G networks and makes it difficult to release spectrum used by 2G and 3G. To achieve zero fallback, operators can refarm low frequency bands, fill coverage holes, and take other measures to ensure wider coverage in rural areas and deeper coverage in urban areas. In this way, the 2G and 3G spectrum resources can be released for constructing a simplified target network, an LTE + NR network.
Zero wait means that mainstream services, such as HD video and web browsing, can be accessed without any perceivable delay, providing 5G-like user experience. Zero wait time ensures optimal LTE user experience and makes new services (such as VR and cloud gaming) possible. In addition, user experience will not deteriorate after 5G users leave the coverage area and fall back to the LTE network.
To realize zero wait time, the LTE network capacity needs to be further improved to avoid user experience deterioration caused by network congestion. The target data rate for experience-based LTE networks should be increased to 50 Mbps to narrow the gap with the 5G NR, which aims to provide 100 Mbps. “Zero fallback with 50 Mbps” will become the standard for constructing experience-based LTE networks in the next phase.
Zero copper means the replacement of low-speed copper lines with LTE wireless to the x (WTTx) for existing HBB services and the rapid WTTx deployment for new HBB services. In Europe, Latin America, and other places, the copper-line-based HBB data rate is low, and reconstruction required to increase data rates is difficult. This has become a major factor affecting the Internet access experience of HBB users. In addition, 66.3% of the households around the world still have no access to the Internet due to the lack of ICT infrastructure in certain countries and regions, especially in developing and underdeveloped countries. WTTx is easy to install and can be deployed rapidly. WTTx data rates can be easily increased for a smooth upgrade to 5G. It has become the first choice for last mile HBB access. WTTx is viewed as the main national broadband technology and is granted the same policy support as fixed broadband (FBB) in countries such as France, Greece, Australia, New Zealand, Malaysia, Myanmar, Sri Lanka, Mongolia.
WTTx services are growing fast in regions outside China. They have been deployed in 230 networks worldwide, serving 75 million people. Ovum predicted that the number of HBB users would reach 350 million by 2020. IV. Huawei Launched SuperBAND, Smart Massive MIMO, 4T6S, and 8T8R Evo Solutions to Continuously Enhance the Foundation Network. LTE, the foundation network in the 5G era, faces pressure from the growth in MBB traffic and from 2G and 3G user migration. To help operators cope with the challenges of providing enough capacity, Huawei launched four advanced solutions at the All Business Connected @ LTE Summit of the Global Mobile Broadband Forum 2018: SuperBAND, Smart Massive MIMO, 4T6S, and 8T8R Evo. These four solutions are built on traditional multi-band, multi-antenna, and multi-sector capacity expansion solutions. They use artificial intelligence (AI), sector splitting, joint scheduling of sectors, and additional technologies to enable efficient collaboration between bands, beams, and sectors. User experienced data rate is therefore, significantly improved.
The SuperBAND design was inspired by 5G large-bandwidth technology. 5G supports continuous bandwidth of more than 100 MHz and provides ultra-high peak data rates. As more and more 2G and 3G spectrum is refarmed, LTE networks will be deployed on a large number of bands. The SuperBAND solution uses 5G large-bandwidth and AI technologies to intelligently coordinate the scheduling between frequency bands and neighboring cells. This allows the full use of spectrum resources and provides a user experience similar to 5G. According to test results, eight-carrier-based SuperBAND technology can provide a peak rate of 3 Gbps, improving user experience by up to 50% and spectral efficiency by 5–8%.
Smart Massive MIMO uses AI technology for adaptive network optimization in different coverage and user distribution scenarios, greatly improving the efficiency and user experience. In addition, antenna information sensor units (AISUs) are used to provide the most reliable engineering parameters for network planning and optimization. This reduces the workload of subsequent site adjustment and O&M, and lays a solid foundation for the long-term evolution towards smart networks.
The 4T6S solution uses high-power dual-band 4T4R integrated RRUs and ultra-wideband multi-beam antennas to implement multi-band sector splitting on the 1.8–2.6 GHz band. It can achieve 1.7~2.0 fold capacity gains over 2T3S, In terms of software, the solution uses inter-sector coordinated scheduling technology. Which reduces the interface and improve the user experience between 2 split sectors. With the 8T8R Evo solution, high-power 8T8R TDD RRUs and Huawei’s innovative software-defined multi-sector technology extend traditional three-sector 8T8R to six- and 12-sector 8T8R. The network capacity is 2.0–2.2 times higher than that of traditional TDD 4T4R networks, significantly reducing the single-bit cost of the LTE network.
The preceding four solutions leverage existing spectrum and site resources of operators to further explore LTE network potential and assist operators in building a foundation network in the 5G era. Conclusion: Focus on 5G-Oriented Evolution, Expand and Enhance the Foundation Network to Prepare for the Future.
According to GSMA Intelligence, by 2025, the total number of LTE users will be four times that of 5G users. For operators in many parts of the world, LTE is and will be the foundation for the next 10 years at least. The maturing 5G industry has pushed operators to put 5G construction high on the agenda. However, 5G construction is not merely the construction of NR networks. The target network structure in the future should be considered from a higher perspective. A solid foundation can help operators thrive in the competitions in the coming 5G era. – Globe News Wire