Although it is still being defined, 5G is becoming a priority for telecom operators and it comes with the promise of unseen services and a broad range of new use cases and business models ranging from enabling autonomous vehicles to smart agriculture and factories. 5G is expected to push the digitization of the economy further due to its ability to handle large volumes of data with low latency in real time.
Importantly, these new 5G environments such as factories, cities, automotive, energy, and eHealth are typically served by private networks, frequently based on Wi-Fi technology, so it is natural to envisage the role of Wi-Fi in the evolution towards 5G.
The purpose of this article is to present the findings of the recently published white paper by the Wireless Broadband Alliance, “The Role of Wi-Fi and Unlicensed Technologies in 5G Networks.” The paper provides an outlook on the possible role that unlicensed technologies can play in 5G and an overview of the work that is still needed to make that role a reality.
5G market requirements
In addition to supporting the evolution of the current consumer-centric business models, next-generation networks will expand to enable operators to support vertical industries with new vertical revenue streams, and contribute to the mobilization of industries and processes beyond the MNO-centric traditional model.
In general, the potential use cases for 5G networks include 4 main categories:
Enhanced Mobile BroadBand (eMBB)
Massive Internet Of Things (MIOT)
Critical Communications (CriC)
Enhanced Vehicle-to-X communications (eV2X)
Several industry bodies are currently defining and working on 5G-related topics, including ITU, 3GPP, NGMN, 5GPPP, Small Cells Forum, IEEE, IETF and Broadband Forum. The 3GPP specifications are expected to formally appear as a part of 3GPP releases R15 and R16.
Each body is working on proposed improvements to different aspects of the network which will impact the role of Wi-Fi and unlicensed technologies in next-generation wireless networks. Those include:
Identity and authentication: promote a generic authentication framework that leverages the Extensible Authentication Protocol (EAP) that enables support of multiple authentication methods as in 802.11 networks
Spectrum aggregation: The first 3GPP 5G NR specification will make use of both sub-6 GHz and mmWave spectrum bands, enabling 5G devices to connect to sub-6GHz and mmWave-based accesses simultaneously.
Network slicing: Although primarily focusing on partitioning the core network, slicing concepts can include the RAN, enabling partitioning of radio resources between different usage scenarios as functions evolve from dedicated hardware towards generic software functions.
Integrated keying hierarchy: The 5G core network is defining a common keying hierarchy that is intended to encompass all 3GPP and non-3GPP access networks. This can be contrasted to traditional approaches to Wi-Fi integration that have defined independent approaches to keying.
Virtualized access: 5G New Radio gNB (the new base station) is characterized by the definition of a new internal RAN split for supporting a decomposition between the gNB central unit and gNB distributed unit.
Multi-access edge computing: MEC provides an IT service environment and cloud-computing capabilities at the edge of the mobile network, within the RAN and near mobile subscribers. The aim is to reduce latency, ensure highly efficient network operation and service delivery, and offer an improved user experience.
Role of unlicensed in 5G
The multitude of use cases requires a variety of radio technologies. In dense environments, unlicensed technologies coupled with core networks can increase the access network capacity and benefit users’ wireless experience.
The role of Wi-Fi as an integral part of advanced wireless networks is driven by new technologies such as 802.11ax and the spectrum bands combination derived efficiencies of technologies such 802.11ad, sub-6Ghz and mmWave.
Unlicensed technologies such as LAA and LWA are expected to complement licensed technologies to provide increased capacity for small cells in a variety of locations such as indoor for enterprises and public venues, and outdoor for network hotspots and events.
A roadmap for the WBA
The WBA vision is not to focus on the definition of 5G but rather on the use cases being discussed and how Wi-Fi and other unlicensed technologies can play a key role in enabling those in a 5G framework.
The capabilities of 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, and they do not meet the target requirements for IMT-2020.
The WBA proposes to work on some of the following areas where Wi-Fi is falling short of 5G expectations. Those include:
Wi-Fi related evolution – Address Wi-Fi provisioning gaps, Wi-Fi performance instrumentation to enable enhanced aggregation solutions
Roaming framework – WRIX enhancements for 5G roaming of new non-SIM based identifiers
New use cases and projects – 802.11 in vehicular environments and rail environments and integrated keying hierarchy
5G testing and interoperability – Testing the 5G unlicensed wireless building blocks aided by a convergent approach with the cellular world and interworking
WBA members are kicking off new 5G streams to address the above-mentioned areas as well as WRIX enhancements for 5G roaming.
The industry is certain that 5G will be a combination of licensed and unlicensed technologies and Wi-Fi is the leading unlicensed technology under the 5G umbrella. The convergence and coexistence of those technologies will require a great deal of work between the various standard bodies including the WBA.
The WBA’s IoT analysis has also highlighted the need for some IoT use cases to be supported over connectivity networks with enhanced service assurance and reliability. It has been concluded that there is an opportunity for WBA to describe best practice aspects of Wi-Fi system configurations necessary to address the support of time-critical communications, service reliability and service outage avoidance.
