Guest post by Dr. Rizwan Ghaffar (linkedin)

With the 5G deployment spreading rapidly, there is a question of what would be the future of Wi-Fi in the world connected by 5G. In my opinion, Wi-Fi and WWAN (wireless wide area networks) will continue their convergence/competitive journey along the road. They will coexist and play an important role in providing uninterrupted, reliable and better performance for AI, edge, and cloud applications benefiting consumers, mobile workers, and organizations alike. These two RATs (radio access technologies) will generally have their own market segments with little or no overlap. Below a short analysis and comparison is provided for the two technologies discussing some key aspects which are going to play vital role in the future deployments:

Wi-Fi and NR-U

Inherently Wi-Fi and cellular were targeting two different domains where Wi-Fi was focusing on unlicensed bands whereas cellular focus was on the licensed spectrum. However with license-assisted (LAA) and standalone NR-U (NR unlicensed) having been incorporated in 3GPP Release 16, cellular domain is trying to wedge into the unlicensed spectrum.  This is not a new paradigm as 3GPP has been trying to penetrate into unlicensed spectrum for about a decade now. 4G LTE License Assisted Access (LAA) standards was first introduced in 3GPP release 13 followed by enhanced LAA (eLAA), introduced in 3GPP release 14. Standalone operation was also tried as MulteFire Alliance but these efforts did not achieve the commercial success that was envisioned at that time. Now with NR-U, 3GPP is again trying to extend NR capabilities to the unlicensed spectrum.

License-assisted NR-U

First considering the license-assisted NR-U which can also be termed as synchronous operation in the unlicensed spectrum. It will have control plane traffic being transported over the licensed spectrum whereas data plane traffic will be transported over the unlicensed spectrum. This will ensure connectivity and Wi-Fi will not compete with NR-U in this vertical as there is no licensed spectrum access in Wi-Fi.

Standalone NR-U

In unlicensed spectrum, standalone NR-U has been designed to coexist fairly with other unlicensed technologies such as Wi-Fi by employing contention-based listen before talk (LBT) protocols. This is also referred to as asynchronous NR-U operation and it will limit some of the benefits of 5G NR, such as the ability to support ultra-reliable low-latency communication (uRLLC).  NR-U will be the vertical where NR will compete with Wi-Fi. Following are the different aspects of this competition. 

• Cost and density 

Wide proliferation of Wi-Fi, decades of experience of operating in the unlicensed spectrum and the cost of establishing a Wi-Fi network will give an edge to Wi-Fi in this space. NR-U standard and developers will take time to learn optimizations in this new vertical where cost, power consumption and area will be the key factors.

A very important aspect is related to the fact that a master scheduler (base station or gNB) will need to be furnished within each local network to orchestrate the cellular network. The cost of a base station simply makes it next to impossible to consider a wide use of cellular for the unlicensed spectrum, unless there are some other strong reasons as discussed below. Going in the same vein, the licensing for intellectual property related to cellular networks has a very diverse, complicated and expensive bearing on the network operation. This also makes it very complicated for new and smaller players to join and use the technology in their devices, hindering the wider growth for cellular in unlicensed spectrum.

• Mobility

Wi-Fi has been designed for static or semi-static users and the Wi-Fi standard doesn’t provide the infrastructure to track high mobility users (larger Doppler spread). Tracking time domain variations within a frame is not the focus in Wi-Fi designs. NR-U will have an edge over Wi-Fi as NR is designed for high-speed users and users will get the better QoS. This will also unlock new opportunities for the industrial Internet of things (IIoT) and other use cases. Nevertheless, this comes with the question of whether there is really a need for such high mobility devices localized in a given area, probably apart from some very limited and very specific use cases.

• mmWaves 

3GPP Release 16 has considered NR-U standalone mode for all sub-7 GHz mid-band ranges. Release 17 is extending it to high-band frequencies in the 57 to 71 GHz ranges that are opening up around the globe. Wi-Fi is also focusing on this part of the spectrum (60 GHz) in the form of 802.11ay standard which has recently been published. Wi-Fi is not new in this part of the spectrum as the 802.11ad focused on 60 GHz with Multi-Gigabit Wireless Systems about a decade ago. However, that effort couldn’t achieve commercial success. The problems of power consumption in the analog front end (more chains) as well as in the digital portion (higher sampling rate) makes it harder to productize this technology especially for handheld devices. As the cellular community is now focusing more on mmWaves (6G is even looking at TeraHertz), Wi-Fi development will need to focus on this part of the spectrum. However NR will also learn the challenges of operating in this spectrum that Wi-Fi learnt a few years ago. 

• 5G Private Networks

 There are companies that want to have more controlled local networks with higher and guaranteed reliabilities and scalable network capacity. The basic scenarios foreseen for 5G private networks is where the environment is sort of reserved, i.e., no unintended devices are present to facilitate the QoS guarantees. 5G private networks will compete with Enterprise solutions for Wi-Fi in this domain. NR features such as multi-numerology and mini-slots will benefit 5G private networks and they will take some share of Wi-Fi but they will generally have their own specific use cases. Multi-million dollar industries where the cost of these networks is not a primary concern will adopt 5G private networks for their use cases (industrial automation, time sensitive networks etc). New spectrum is also opening (3.8 GHz to 4.2 GHz) in some parts of the world for these private networks. This is a new vertical where 5G will have an edge over Wi-Fi.

In a nutshell, it is foreseen that the two technologies will have their key business areas still intact for many years to come, while both trying to expand the market and use cases resulting in a larger number of overlapping use cases. In addition, I expect that most of the future IoT devices, so-called everything connected, will be primarily equipped with WIFI and its upcoming versions resulting in multi-billion growth of WIFI products.

Author: Dr. Rizwan Ghaffar (linkedin)