PARTNER FEATURE: If we compare 5G communications to a highway, spectrum would equate to the most valuable land resource for global operators during construction. The underlying resource includes sub-3 GHz spectrum(below 3 GHz), mid-bands (such as 3.5 GHz), and high bands (such as microwave).Sub-3 GHz bands offer good propagation performance and are widely used for wide and in-depth coverage, as well as for voice, IoT, and other basic services. Hailed as high-value spectrum, they are fundamental to 2G, 3G, and 4G mobile communications.
As the global mobile infrastructure proceeds with 5G transformation, operators are wasting no time evolving low bands like 700, 800, and 900 MHz and mid-bands like 1.8, 2.1, and 2.6 GHz into 5G.Despite ensuring wider coverage, sub-3 GHz does not provide enough continuous bandwidth, with operators barely afforded the 100 MHz continuous spectrum on these bands required to support 5G’s high bandwidth. As such, the industry now faces a common challenge regarding on the maximizing of sub-3 GHz band value to ensure optimal coverage, capacity, and experience.
At the Global Mobile Broadband Forum (MBBF 2021) Sub-3GHz Evolution Forum held earlier this month, Kevin Zhang, Chief Marketing Officer (CMO) of Huawei’s Infrastructure Business Department, proposed ultra-broadband and multi-antenna solutions designed to address the challenges of sub-3 GHz and accelerate 5G development.
But why is sub-3 GHz so crucial? And why do we start with ultra-wideband and multi-antenna?
Well-Resourced Sub-3 GHz Is Fundamental to 5G
“Sub-3 GHz is the most valuable band for operators,” said Kevin Zhang at the forum. “It plays a leading role in providing voice, data, and IoT services.”“Sub-3 GHz is used on 2G, 3G, 4G, and most 5G networks. Providing abundant resources, it is the key to ensuring continuous evolution and building the 5G foundation networks that provide best-in-class experience.”
In my opinion, we are now at a critical juncture of the 4G-to-5G evolution. Kevin Zhang’s remarks reflect how important sub-3 GHz is for incumbent technologies and services, and it will play a vital role in coping with growing LTE traffic while ensuring smooth evolution to 5G.
176 5G commercial networks are now providing services to nearly 500 million users globally. Given the differences in spectrum assets and varying degrees of 5G progress, sub-3 GHz has different implications for operators.
For operators without C-bands, sub-3 GHz enables them to quickly achieve 5G NR coverage. For example, an operator in the Netherlands used 700 MHz to achieve rapid 5G deployment, even though it does not have access to C-band spectrum.For operators who have launched 5G on C-Band, sub-3 GHz NR improves collaboration with C-Band and ensures better coverage and experience. China Telecom and China Unicom use their respective spectrum strength to implement Super Uplink, while China Mobile and China Broadcasting Network (CBN) have jointly deployed 5G on 700 MHz to improve both the width and depth of 5G coverage nationwide.
A German operator also added sub-3 GHz 5G on top of its C-Band networks, enabling an extra of 15×2 MHz of usable bandwidth on the 2.1 GHz band to extend 5G coverage to 50% of the country’s population. It is also developing 700 MHz 5G to implement multi-band 3D networking.
According to Kevin Zhang, some of the first 5G operators have already embarked on sub-3 GHz evolution to 5G, primarily on the 700 or 2100 MHz bands.
For operators in the emerging markets, such as those in Asia, Africa, and Latin America regions where 2G and 3G still dominate, sub-3 GHz will enable them to improve both LTE coverage and capacity, accelerating their transition to 4G while laying the foundation for further evolution to 5G.
3 Challenges: Sub-3 GHz Growth Requires New Breakthroughs
While both the early-launching and emerging 5G markets utilize sub-3 GHz to provide a better mobile experience, it is clear that many problems still remain.Kevin Zhang believes that these challenges are common to all operators and also provide them with many opportunities. The primary sub-3 GHz challenges involve the following:
First, sub-3 GHz bands have a huge number of user bases due to their strong coverage. This means that operators must use limited sites in order to provide the highest possible capacity required to cope with the explosive growth of data traffic, especially in densely populated urban areas.
Second, sub-3 GHz involves multiple bands, from 700, 800, and 900 MHz to 1.8 and 2.1 GHz. If each band uses one RF module, network complexity will increase, pushing up costs for construction, operations, and site energy use.
Finally, sub-3 GHz 5G must offer a substantially improved experience compared to that already delivered by 4G in order to build business success, highlighting the importance of maximizing sub-3 GHz spectral efficiency during evolution.So, how do we overcome these challenges? Kevin Zhang explained that Huawei carefully analyzed these challenges and formulated the following three goals: multifold downlink improvement on sub-3 GHz; 50% less energy usage by sub-3 GHz networks; and simplified deployment with 30% less complexity.
Two Directions: Helping Operators Accelerate the Upgrade of Both 4G and 5G
Goals lead the way moving forward. From my perspective, the three goals purposed by Kevin Zhang boil down to the following: premium experience; green, low-carbon development; and simplified architecture. These should be at the core of sub-3 GHz construction in the 5G era. However, as the old saying goes, it is easier said than done. So, how can we help operators achieve these goals?Kevin Zhang shared how Huawei intends to contribute. “Huawei will continue working with operators to focus on ultra-wideband and multi-antenna technologies.” ultra-wideband here refers to support for multiple bands in a single box to reduce site footprints and simplify construction, while also saving energy. Multi-antenna enables low-band antennas to expand from 2T to 4T and mid-band antennas from 4T to 8T and MIMO (32T) in order to boost capacity and coverage.
From my point of view, fragmentation is a major sub-3 GHz challenge, and this is where the ultra-wideband modules come in. Sub-3 GHz has more bands and is deployed on more radio access standards, further complicating construction and increasing OPEX. The solution to this issue also lies in ultra-wideband modules. Last but not least, ultra-wideband modules facilitate dynamic power sharing between different bands, which is required for slashing the power consumption of network devices.
Multi-antenna technology further adds three extra major advantages to sub-3 GHz deployment. It enables operators to improve spectral efficiency and reduce per-bit costs in their bid to cope with soaring MBB traffic. Given that 5G is a beam-centric technology, multi-antenna deployment will enable sub-3 GHz to smoothly adapt to future releases of 5G specifications. Moreover, with multi-antenna, operators will be able to maximize the potential of beamforming to considerably improve 5G user experience, particularly when dynamic spectrum sharing (DSS) is used on 5G networks.
Huawei boasts a wealth of accumulated knowledge and experience in the ultra-wideband and multi-antenna domains, and offers a wide range of leading solutions.
For example, Huawei has launched the industry’s only 4T4R RRU product to support three bands in a highly compact form factor. The supported bands can be 700 + 800 + 900 MHz or 1.8 + 2.1 + 2.6/1.4 GHz. Dynamic power sharing is supported among the three bands for all radio access standards, enabling operators to reduce power consumption by 30%. Use of the multi-carrier joint scheduling algorithm can further improve user experience KPIs by 30%.In line with growing trends for spectrum modernization, Huawei has also launched a high-power ultra-wideband 8T8R RRU. It is the only product of its kind in the ICT industry capable of supporting both 1.8 and 2.1 GHz bands in a single box. When working with 8T8R-native antennas that are based on Huawei’s Hertz platform, this product will allow operators to significantly improve both coverage and capacity.
It is also worth noting that Huawei’s Hertz antenna platform incorporates a number of innovative technologies related to feeding systems, array architecture, and energy efficiency designed to help operators evolve sub-3 GHz to NR.Huawei has also launched the FDD BladeAAU, an all-new multi-antenna product that integrates FDD Massive MIMO and sub-3 GHz full-band antennas into a single box, thereby facilitating smooth sub-3 GHz site deployment. As a dual-pole solution similar to MetaAAU, FDD BladeAAU provides operators with an ideal option to explore full-band simplified deployment that equals the 2T2R coverage of 900 MHz and brings Gigabit experience to all users regardless of when and where they are using mobile services.
Two Directions to Unleash the Potential of Sub-3 GHz
One big takeaway from Kevin Zhang’s speech is that sub-3 GHz is quickly emerging as the key to upgrading 4G and 5G networks.
The challenges facing the sub-3 GHz evolution include: improving its spectral efficiency to meet capacity and experience requirements; maximizing investment utilization; and reducing energy consumption. Huawei has purposed the aforementioned three goals to overcome these challenges.
Huawei’s solutions for operators to achieve the goals of smooth sub-3 GHz evolution to 5G are twofold: ultra-wideband and multi-antenna.
As Kevin Zhang concluded, the ongoing COVID-19 pandemic will not impact our collaboration and innovation. I believe that Huawei’s two directions for sub-3 GHz evolution will lead the industry to a bright future.Subscribe to our daily newsletterBackPrevious ArticleMWC21 Los Angeles: Day 1 highlightsNext ArticleSong Shijie of ZTE: Building all-fiber world to accelerate development of home video