5G FWA Systems

- Overview

5G Fixed Wireless Access provides standardized 3GPP architectures and common mobile components to deliver ultra-high-speed broadband services to residential subscribers and commercial business customers. 5G FWA features New Radio (NR) in the millimeter wavelength (mmWave). This makes 5G FWA Internet a competitive alternative to fixed-line DSL, Cable, and fiber across all markets. As a result, both urban and rural areas will receive the bandwidth required to support high definition streaming services and high speed Internet access. One major benefit of 5G Fixed Wireless Networks is that it can provide a level of service bandwidth capacity comparable to fiber optics. These narrow mmWave beams enable a higher density of users without causing interference. 

As with any technological advance, FWA brings new design hurdles and technology decisions. Let’s dig into five things to consider when designing FWA systems:

• The choice of frequency spectrum: millimeter wave (mmWave) or sub-6 GHz
• Achieving higher data rates with antenna arrays
• All-digital or hybrid beamforming
• Power amplifier (PA) technology choices: silicon germanium (SiGe) or gallium nitride (GaN)
• Choosing components from today’s RF front-end (RFFE) product portfolios

- The Choice of Frequency Spectrum

The first decision is whether to use mmWave or sub-6 GHz frequencies for FWA. It's critical to look into both mmWave and Sub-6GHz spectrum options to decide which option will best fit your application needs. In short, mmWave spectrum allows for large bandwidth, which paves the way for potentially faster speeds. Sub-6 GHz spectrum, meanwhile, has limited bandwidth and therefore its speeds could potentially be slower than possible with mmWave spectrum. 

Efficient use of frequency range (sub-6 GHz or mmWave) is critical to scaling deployments. The choice for any situation will depend on balancing the goals of speed and coverage.

• mmWave supports component carriers up to 400 MHz wide and enables gigabit data rates. The challenge is path loss due to obstacles like vegetation, buildings and interference. However, don’t assume FWA is useful only in clear line-of-sight settings between the base station and the home. FWA can actually perform very well in both urban and suburban settings. It’s true that vegetation and interference are challenging, but these can be overcome with antenna arrays that provide high gain.
• Sub-6 GHz. This lower-frequency spectrum helps overcome the problems caused by obstructions, but at a cost. Only 100 MHz of contiguous spectrum is available, so data rates are lower.

- Achieving Higher Data Rates with Antenna Arrays

An FWA system will also need to employ active antenna systems (AAS) and massive MIMO (multiple input/multiple output) to deliver gigabit service. 

• Active Antenna Systems (AAS): AAS provides many directional antenna beams. These beams are redirected in less than a single microsecond. This enables beamforming that leads to reduced path loss due to higher frequencies. 
• Massive MIMO: Massive MIMO uses anywhere from a few to thousands of antennas. This allows for simultaneous transmission of either single or many data streams between each other. The benefits to Massive MIMO include: Improved capacity, Reliability, High data rates, low latency, Less inter-cell interference, Better coverage.

- PA Technology Decisions (SiGe vs. GaN)

The technology that will work best for FWA front end all depends on multiple functions of beamforming gain including Effective Isotropic Radiated Power (EIRP), Antenna gain, and Noise Figure (NF). These are all functions of the array size. This will help you choose between a SiGe or GaN front end to achieve your specific electronic design needs.

In wireless infrastructure applications, equipment must last for at least 10 years. So reliability is imperative. For FWA, GaN is a better choice than SiGe for reliability, cost, lower power dissipation, and array size.

- Hybrid or All-Digital Beamforming

Both hybrid and all-digital approaches have advantages and disadvantages. In many ways, the hybrid approach seems to be more beneficial and doable in today's world. However, new products in the near future could could make the all-digital approach equally as beneficial.

- Choosing from the Latest RF Technology Innovations

It's important to select product solutions that are actively being used in real-world applications. There are many companies out there who can provide and support development of sub-6GHz mmWave FWA infrastructure.

Across the RF industry, examples of products for FWA include: 

• Sub-6 GHz products: Dual-channel switch/LNA modules and integrated Doherty PA modules
• cmWave/mmWave: Integrated transmit and receive modules

Additionally, in the 5G infrastructure space, several things are a must:

• Integration
• Meeting passive cooling requirements at high temperatures