5G Fixed Wireless Access (FWA) and Virtual Fiber

5G Fixed Wireless Access (FWA) is a technology that takes advantage of the latest wireless communication systems to deliver fiber-like gigabit connectivity to last-meter endpoints.  The endpoint can either be a home customer or a 5G tail site, connected to a fiber pop.

Virtual fiber wireless technology may be used for FTTH connectivity and for 5G broadband in a case where a wired/fiber connection is too costly or difficult to deploy.

The main aim is to support the deployment of 5G small cells and WiFi access points in dense urban environments.  Fixed Wireless Access applications can provide gigabit connectivity to houses, apartments and city offices.  Virtual fiber can be used to connect various smart city devices and support the Internet of Things (IoT) and new Smart City applications.

Virtual fiber versus Fiber-to-the-home (FTTH)

Deploying fiber up to the end user’s premises is still the preferred solution for all Operators.  However, the number of WiFi Access points (APs) and 5G small cells to be deployed in the next several years is expected to rise significantly.  Wireless connectivity may, therefore, provide an alternative solution to typical fiber-to-the-home (FTTH) deployments, with the following advantages:

Time-to-market

Wireless technology can be deployed fast.  As soon as the Service Providers define the areas to be covered, the wireless connection can be planned and implemented even on the next day.   

Cost-effectiveness

Wireless connectivity may reduce significantly the capital expenditure (CapEx) and labor costs in cases where the Operators have to dig a fiber connection to every last-mile or even last-meter spot.

Ease of Deployment

It is not always easy to dig for fiber at any point, any street, and any building area.  Wireless equipment on the other hand, may be deployed fast on existing street furniture, such as lamp posts, bus stops, traffic lights, even road signs.

5G FWA Spectrum and Gigabit services

Fixed Wireless Access technology is intended to use the sub-6GHz spectrum and millimeter-wave bands.  Due to the limited available spectrum and data rates at sub-6GHz frequencies, the 3.5GHz band (3.4 – 3.8 GHz) is more suitable for fixed broadband ADSL/VDSL services. 

The 3.5 GHz band is also one of the first 3GPP bands to provide 5G NR access eMBB services. Thus, this band is difficult to be used for FWA in an urban environment but could support FWA services in specific rural areas.

To achieve gigabit connectivity and be able to support FTTH and 5G services the Operators target to use the millimeter-wave region.  FWA addresses two specific areas of the millimeter-wave Spectrum, the 5G NR 3GPP 26/28 GHz and the 60 GHz (57 – 66 GHz) WiGig technology based on the IEEE 802.11ad/ay networking standards.  

In these specific frequency areas, higher amounts of spectrum can support Gigabit speeds and a fiber-like experience.

60 GHz WiGig

WiGig has been developed to support Multi-gigabit wireless speeds at the unlicensed spectrum of 60 GHz frequency band.  WiGig is part of the 802.11 wireless networking standards family, for wireless LAN Wi-Fi network communications.  WiGig takes its name from the Wireless Gigabit Alliance, the extension of the Wi-Fi Alliance, with an aim to expand the Wi-FI technology in the multi-gigabit 60GHz wireless range. 

IEEE 802.11ad and 802.11ay

IEEE 802.11ad was the first standard to be developed and initially specified four channels of 2.16 GHz bandwidth each, in the 60 GHz band. IEEE 802.11ay is an extension of the 802.11ad standard. 

Using advanced mechanisms such as channel bonding and MIMO technology, IEEE802.11ay bonds together four of the 2.16 GHz channels of 802.11ad, to form a maximum bandwidth of 8.64 GHz. Furthermore, 802.11ay uses higher order modulation schemes and MIMO from 4 up to 8 streams.  These mechanisms can provide up to 300Gbps data rates when combined with 8 streams MIMO and a 64QAM modulation scheme.  

5G FWA coverage

3.5 GHz based on the 3GPP 5G NR standard can cover typical distances of up to 1Km, reaching cell capacities of ≥ 3.5 Gbps with the use of a 100 MHz channel.  Based also on the 3GPP 5G NR, 26 GHz spectrum can reach distances of up to 250m with a maximum cell capacity of 6.6 Gbps using an 800MHz channel bandwidth. 

On the other hand, for typical distances of up to 250m, the available 2.16 GHz channel bandwidth of WiGig technology can support capacities of 1.8 Gbps for 802.11ad standard and up to 15 Gbps for 802.11ay, using 4x 2.16 GHz bandwidth.

5G FWA Spectrum characteristics

Based on the above, it is evident that the larger the available channel bandwidth, the higher the capacities that can be achieved.  There is also an apparent trade-off between data rates and distance covered, because of the signal attenuation that occurs in high-frequency bands of the millimeter-wave region.

Frequencies above 10GHz typically suffer from signal attenuation under severe weather phenomena, such as rain, hail, ice, and sleet.  The signal degradation is due to the water vapor and the oxygen absorption effects that attenuates the energy of the transmitted signal.

It is evident that signals at 60 GHz suffer the most, primarily because of the high attenuation due to the Oxygen absorption that peaks at this specific frequency.

Licensing model @ 60 GHz

Wireless links typically have to be declared to the national regulatory authorities, and a specific fee for the spectrum usage has to be paid by the Operators annually.  However, 60 GHz is an unlicensed or a light-licensed band, depending on each country’s specific licensing model. 

60 GHz spectrum is either completely unlicensed, where the frequency is shared among different Operators, or a lightly-licensed model may be adopted, where a declaration to deploy, grants the spectrum. 

5G FWA deployment

Due to the nature of the signal propagation and the larger wavelengths, the Sub-6GHz solutions can cover greater distances and may even penetrate or deflect on certain materials.  These characteristics mean that they may also be used in near or Non-Line-Of-Sight scenarios (nLOS/NLOS). For the millimeter-wave spectrum, both at 26/28 and 60 GHz, LOS solutions seem inevitable. 

Equipment at Sub6 have a larger size and are typically not suitable for street-level deployment.  These units are better to be placed on towers or rooftops.

On the other hand, the form factor at higher freqeuncy bands such as 60 GHz, makes this equipment suitable for street furniture installation.  However, to support the LOS prerequisite, the concentration node of the point-to-multipoint solution at 60 GHz may also be deployed in rooftops and sides of buildings, depending on the area and distances to be covered.

5G FWA planning

Since FWA systems and 5G small cells, will be deployed in a street-level environment, 3D data analysis plays a vital role for FWA and 5G planning. 

The required planning tools should have the ability of high Level Of Detail (LOD) 3D representation of the environment and be able to identify street furniture and different building types and structures. 

3D Level of Detail

There are various LOD levels according to the actual detailed representation of 3D objects.  LOD1 typically provides details of 3D volume and basic building structures.  LOD2 can also deliver specific rooftop details, while LOD3 structural information on street-level, such as benches, bus stops, and lamp posts. Finally, LOD4 provides a 3D representation of a detailed indoor environment.

Building types and tree foliage in a street-level environment

Building types and the material used may vary between different structures and may affect radio penetration, reflection, and diffraction of the signal.  The volume and density of tree foliage are also important since signal penetration, especially in the 60GHz band, may have a problem with dense tree foliage blocking the LOS.

3D map sources and 3D models

3D map sources are usually available by existing aerial and satellite imagery.  For a higher level of detail, Operators may utilize 3D laser scanning imagery using Light Detection And Ranging (LiDAR) techniques.

3D map sources may be expensive to acquire by the Operators, or specialized personnel visits should take place to scan a specific geographical area. 

5G FWA rollout

5G FWA deployments are still at an early stage. 

In the US, Verizon offers 5G FWA in 28 GHz in four cities, Houston, Indianapolis, Los Angeles and Sacramento with fiber-like speeds, branded as 5G Home Service.  AT&T has announced an aggressive 5G FWA rollout target covering 18 states by 2020.

Operators in Europe are currently proceeding with PoC trials to explore the full potentials of this technology.  In the 60 GHz band, the vendors are now on the verge of producing commercially available products based on the IEEE 802.11ad standard and exploring the 802.11ay.

5G FWA regulation

3GPP defines two frequency ranges for 5G NR.  FR1 (450 – 6000 MHz) which covers the sub-6 frequency range and FR2 (24250 – 52600 MHz) which defines the millimeter-wave range (including the 26 & 28 GHz bands).

Standardization procedures for the 60 GHz band are ongoing.  FCC (Federal Communication Commission) in the US has allocated the 54–66 GHz band for use in an unlicensed scheme.  FCC proposed to expand the band up to 71 GHz for unlicensed usage and future wireless deployment.

In Europe, ETSI (European Telecommunications Standards Institute) has requested to relax the regulation in 57-66 GHz and to release this spectrum for Fixed outdoor use within 2019.