5G FWA: Solution to Last Mile Deployment

In October 2018, Verizon began to launch its 5G Home service in parts of four cities in the United States. Although this launch was based on proprietary rather than fully standardized 5G technologies, it marked a new milestone for global 5G commercialization.

5G has three application scenarios: eMBB, mMTC and URLLC. Fixed wireless access (FWA) is a special application of eMBB and also one of the earliest commercial use cases in the 5G era. 5G-based FWA (5G FWA) provides three-dimensional coverage and fiber-like experience, satisfying multiple needs of operators.   

Three-Dimensional Coverage  

The last mile access is a complicated process that involves a long period of engineering practice, difficult secondary construction, and high maintenance costs as well as high complaints caused by the destruction of property and decoration. All these result in a deployment problem in the last mile.

However, FWA using electromagnetic waves instead of cables as the medium for signal transmission avoids the problems of traditional deployment including digging trenches and cabling (Fig. 1). The traditional wired access solution provides one-dimensional coverage, that is, signal transmission is provided where there are cables. FWA offers two-dimensional coverage, that is, when a site is established, users in the site-centered coverage area can enjoy high-speed access service. 5G-based FWA can even provide three-dimensional coverage, that is, users in the high-rise buildings covered by the site can enjoy high-speed data access service.

FWA is the only option in many scenarios such as rural areas or the areas where fibers cannot reach the home. In developing countries, only 20% of households have access to fixed broadband networks. FWA is a better choice of broadband connection for the remaining 80% of households.

Fiber-Like Experience

The reason why 5G FWA can address the growing needs for broadband data access is mainly due to the improvements and breakthroughs that have been made on key 5G technologies including new radio (NR) interface, massive MIMO, as well as network slicing and QoS guarantee. 5G FWA provides users with fiber-like experience.

New Radio Interface

The overall design of 5G NR protocol layer is based on LTE and has been enhanced and optimized. At the physical layer, NR reduces air interface overhead by optimizing the reference signal design and enables flexible bandwidth configuration by using more flexible waveform and frame structure. The new channel coding and modulation scheme allows the 5G physical layer to have more flexibility and better performance for adapting to different application scenarios.

Massive MIMO

There will be a significant increase in the number of 5G base station antennas and ports, which will enable a large-scale antenna array with hundreds of antennas and dozens of antenna ports. Depending on the accurate and mature channel estimation algorithm and multi-user MIMO (MU-MIMO) scheduling mechanism, Massive MIMO supports spatial multiplexing transmission of multiple users, which leads to several-fold increase in 5G spectrum efficiency and is beneficial to enhance user experience in user-intensive high-capacity scenarios.

Network Slicing and QoS Guarantee  

Network slicing is an important enabling technology for 5G networks. Provided that key indicators such as spectral efficiency, system capacity and network quality are not affected, wireless network slicing places emphasis on the utilization efficiency of air interface time-frequency resources and uses a combination of flexible frame structure and QoS differentiation to achieve intelligent scheduling of radio resources. Moreover, differentiated network slicing comes true through flexible re-configuration of radio network parameters.

The current test made by ZTE shows that 5G offers a user experience rate of 1 Gbps (100 times that of 4G) and a peak data rate of 20 Gbps (20 times that of 4G). This implies that making full use of every bit of spectral resource available in a 5G network improves the data speed, capacity, latency, reliability, efficiency and coverage to a new level, so that the need for last mile access can be completely satisfied.

Choice of Bands

Which frequency bands should be used for a 5G FWA network? Verizon uses 28 GHz and 39 GHz bands to deliver 5G Home services, but views from the industry are not exactly the same. In fact, the 5G FWA solution has no specific requirement for frequency bands. The frequency bands used by FWA need to be strongly related to band strategies, user and business development, and existing network conditions of operators.

The transmission distance of sub-6 GHz (below 6 GHz) primarily depends on path loss and indoor penetration loss. As sub-6 GHz meets the needs of both coverage and capacity, it can reach an ideal compromise between peak rate and coverage. Therefore, sub-6 GHz is more suitable for suburban or rural areas where MBB services are needed.

Millimeter wave (mmWave) spectrum above 6 GHz provides ultra large bandwidth, larger capacity and higher speeds. But in addition to path loss and indoor penetration loss, mmWave is also affected by trees, radio-wave scattering and rain attenuation. Despite the lack of continuous coverage, mmWave is a better option for short-distance FWA (below 200 meters).

At present, fourteen countries and regions in the world have made 5G plans on the sub-6 GHz bands, while six countries and regions have planned 5G on the bands above 6 GHz. To meet the requirements of different countries and regions, ZTE has released a full range of new-generation 5G base stations operating on sub-1G, sub-6G and mmWave to fully support commercial deployments of FWA around the world.

Satisfying Multiple Needs

5G FWA provides mobile operators with the opportunities to expand into the home and enterprise broadband market without the need to build a fixed-line network. Introducing hybrid service products into the home and enterprise market in the form of FWA bundled eMBB services, and binding home broadband to voice and video services are the most effective solution to attract users and increase the monthly average revenue per user (ARPU). In this way, users can cut costs, and operators can enhance user stickiness, increase network revenue and gain more market share.

FWA allows traditional fixed-line operators to rapidly deploy wireless broadband networks based on their existing transmission networks, so that they can quickly attract users and occupy the market. Utilizing the 5G network, FWA services can be launched to enable broadband access for households, enterprises and individuals in different scenarios. With the existing transmission resources, FWA and FTTx can complement each other.

FWA can help emerging operators quickly enter the regional market for its small investment, rapid deployment and short return on investment, laying a sound foundation for their future network expansion.

Summary

FWA has become one of dominant broadband access solutions for last mile access and has also been considered one of the earliest mature use cases in the 5G era. ZTE has successfully deployed wireless broadband services based on TDD networks in many countries and has accumulated rich deployment experience. Incorporating its successful experience into the increasingly mature 5G system, ZTE can respond quickly to the needs of fixed wireless broadband and offer tailor-made products and solutions.

[Keywords] 5G FWA, solution to last mile deployment, fiber-like experience, three-dimensional coverage