Florin Baboescu: 5G Networks – The Role of Wi-Fi and Unlicensed Technologies

As the Co-Chair of the 5G project group, I believe the new 5G System (5GS) gives an opportunity for operators to extend their services, and as a result to expand their business opportunities through better integration of Wi-Fi access.

Today’s paradigm is: “no license, no cellular service”. Users cannot access 3G/4G services unless they are under the coverage of licensed spectrum provided by their home operator or its roaming partners. Imagine yourself in a hotel room with great Wi-Fi, but poor cellular coverage. Although connectivity may be available through the hotel Wi-Fi, you may not be able to access any of the 3G/4G services that you have subscribed to. The new 5G System (5GS) allows seamless integration of Wi-Fi access on par with any other Radio Access technology (e.g. LTE, 5G-NR, etc.). Users will have the benefit of switching seamlessly between licensed spectrum (e.g. LTE, 5G-NR) and unlicensed spectrum (e.g. Wi-Fi), or be able to use both simultaneously.

Take for example the hospitality market, in which Wi-Fi quality has become a deciding factor in guests’ perception of the superiority of a hotel. Wi-Fi has transitioned from an amenity to a service that guests demand. If the user is in a hotel room with a good Wi-Fi connection but no cellular coverage, his/her handset is useless for making cellular calls or for receiving SMS messages.

However, upgrading the indoor cellular infrastructure of the hospitality industry takes time and a lot of investment. The next generation of Wi-Fi, 802.11ax, allows a simple and high performance upgrade to the network, allowing users to automatically authenticate to carrier-Wi-Fi networks using Next Generation Hotspot/802.1X. Furthermore the Wi-Fi infrastructure of the hotel may be shared with cellular operators allowing their subscribers to access cellular 5G services while under the Wi-Fi coverage of the hotel.

The next question is, “Is Wi-Fi capable of providing the same type of quality of service as 5G cellular?” The answer is that, in most cases, today’s existing Wi-Fi technologies can provide better access then their cellular counterpart technologies, and this will be further improved by new Wi-Fi standards such as 802.11ax. New devices based on 802.11ax are expected in the market in 2018.

To summarize, for operators, Wi-Fi is the solution with the best price/performance ratio. It can provide similar features as 5G-NR is envisaged to provide. It can be seamlessly integrated into the new 5G System, allowing operators to cost-effectively densify environments such as shopping malls, transit hubs, stadiums and enterprises. We believe that the role of Wi-Fi as an integral part of 5G is driven by the possibility of reusing existing Wi-Fi infrastructure, as well as the possibility of gradual upgrade toward new Wi-Fi technologies operating in various spectrum bands including sub-6GHz, additional emerging microwave bands, as well as mmWave.

An exhaustive comparison of the benefits of Wi-Fi vs 5G-NR is currently difficult considering that the design of 5G-NR has not even started for the bands mentioned above. Therefore, I will refer further to the comparison presented in our whitepaper with regard to the requirements set for 5G-NR. These requirements, detailed in IMT-2020, are based around spectrum utilization, achievable data rates and many other characteristics of radio communications being improved for the user over the capabilities of previous technology generations as indicated in the figure below:

This figure clearly illustrates that 802.11 based systems can outperform the IMT-2020 requirements related to area traffic capacity and latency, whereas network efficiency values are above those associated with IMT-Advanced, although they do not meet the target requirements for IMT-2020.

At a high level, it is clear that the evolution of Wi-Fi technology is having a major impact on the definition of 5G. We can see that many use cases from ITU-2020 can be fulfilled when Wi-Fi is used as an access radio to the 5G Core. Furthermore the use of Wi-Fi in the 5G System provides operators with a low cost deployment of the 5G System, while it also allows incremental updates with new Wi-Fi technologies, whenever they see fit. We also see that the 5G System seems to align with Wi-Fi in its adoption of several key characteristics including broadening of identity concepts in 5G with the likely specification of asymmetric keying and EAP-TLS and shared infrastructure propositions for supporting wireless service to all indoor users, in a multi-operator deployment.