Gigabit technologies such as 5G and Wi-Fi 7 feed the desire for limitless connectivity, creating opportunities for operators to explore lightweight convergence architectures.
The gigabit era — Wi-Fi 7, high speed fiber and 5G — is here. Individually, each technology is an incredible engineering achievement, and the access bottleneck seems to be largely solved.
From a customer perspective, however, the all too frequent edge cases reveal work is still needed. A glitch moving from good coverage to a weaker location, for example, is pronounced and becomes a poor customer experience. Solving this is a major opportunity for operators — and a win for users.
A lightweight convergence architecture can solve this problem. It reduces barriers such as cost and complexity and delivers coverage benefits. The mandate is to select the solution that provides performance and experience that operators can apply in a relatively lightweight manner.
In this article, I make the case for 5G and fiber providers to exploit the Wi-Fi ecosystem to meet mobile customers' service experience expectations. New network architectures and advanced devices combine to catalyze network convergence, and non-terrestrial networks (NTNs) are also part of this.
Fine-tuning the user experience
Choosing the best single access technology was once easier. But capabilities once split clearly by mobility coverage, security and cost requirements are now blurring with new standards such as Wi-Fi 7. The figure below illustrates the characteristics of Wi-Fi 7 and 5G.
Single access scenarios will be vital in some circumstances. For instance, they can guarantee performance and provide strict security and access policies where user privacy concerns prevent the transition to another potentially untrusted network.
5G vs. Wi-Fi 7
Wi-Fi 7 delivers QoS, lower latency and indoor ubiquity. As device and chipset vendors furnish the market with new devices and innovations, fixed line operators are launching new Wi-Fi 7 services for their fiber offerings, emphasizing higher speeds, better multi-device connectivity and reliable experience.
Latency and throughput improvements with multi-link operation in Wi-Fi 7 allow clients to use multiple frequency channels (switching packet-by-packet as required) to deliver less than 5ms delay and maximum performance. In addition, improvements to QoS management in Wi-Fi 7 mean devices no longer contend for a single channel. They can request channel pre-allocation priority for specific application packets (e.g., gaming, VoIP, VR, etc.). Earlier Wi-Fi generations suffered network performance degradation as concurrent users increased.
5G is the choice for medium to large-scale deployments across bigger coverage areas, typically outdoors, due to robust mobility and requiring fewer cells to meet coverage demands. Permitting 5G roaming can offer a lightweight single access experience to extend coverage with a multi-network SIM (roaming agreements), which selects the strongest signal network. Dual SIM solutions are another option, though they typically require additional management, policies and device support.
The best of both worlds
Fixed-mobile convergence (FMC) can offer operators advantages. The transformation to a single (combined network infrastructure) allows simplified management, tighter load balancing, single security and device policies, etc. Implementation, however, can be expensive and complicated (especially for a brownfield), and operators typically retain mobile and fixed networks.
Some forms of convergence require the latest devices to support new technology or protocols. This may challenge adoption timescales as users keep expensive devices longer. Full FMC may also be a costly network upgrade for operators, especially when many users want the coverage at no extra cost.
There are several options for convergence in telco access networks, varying from basic network-to-network transition to full convergence:
Best connection (device-driven): Most applications have some buffering, so the transition from Wi-Fi to mobile and vice versa is not always noticeable (exceptions being live real-time applications such as video calling). Wi-Fi AI roaming techniques (targeted to improve roaming sensitivity and network selection) also help with this transition. While much of the new tech to aid this smoother transition is within the chipsets for the new devices, existing handsets can cope.
Hybrid convergence: Hybrid solutions often focus on private networks and the enterprise sector. Implementation approaches range from software-defined networking (SDN) controllers (directing packet flows) to hybrid access gateways (HAGs). SDN approaches usually control policy and access via dedicated identity services. HAG solutions split traffic into TCP sub-flows (often multipath TCP, or MPTCP) to aggregate and steer traffic across access networks. Both require additional network and CPE/user devices such as hybrid network/residential gateways, AAA servers and native or app device support depending on the solution and vendor (e.g., Cisco, Nokia, HPE, Tessares, etc.). Hybrid solutions often target private networks to extend coverage and bridge mobile and fixed domains.
Network-driven (standards-based): 3GPP Release 15 introduced untrusted Wi-Fi access convergence within its initial 5G standard (an evolution of the 4G evolved packet data gateway). Later releases (Release 16 onward) added trusted Wi-Fi and wireline access, particularly the access traffic steering, switching and splitting (ATSSS) function for 5G. At a high level, the ATSSS uses rules to determine the best network selection, network aggregation (across both access types) or seamless handover. The solution typically requires additional network function support, such as trusted or untrusted access gateways, ATSSS, user plane function (UPF) updates and MPTCP-capable devices, slowing vendor and operator progress. Vendors are not currently seeing huge traction for ATSSS solutions, but DT, MediaTek and Mavenir showcased an ATSSS PoC (3GPP Release 16) in February 2024.
Lightweight standardized approaches: Cutting costs to achieve standards-based network convergence motivated recent 3GPP Release 19 ATSSS Lite study items written by Ericsson in TR.23.700-54 (S2-2306691). The solution requires no additional network functions such as a trusted non-3GPP gateway function (TNGF)/non-3GPP interworking function (N3IWF) and a standalone ATSSS. Instead, the UPF supports some ATSSS functionality, like traffic aggregation. The lightweight architecture significantly reduces deployment capex.
Extended roaming: OpenRoaming creates a cloud federation of access networks and centralized security and policy mechanisms. Wi-Fi and private 5G networks within the agreed federation can roam onto each other's access networks after identity providers (e.g., device manufacturers, CSPs, etc.) authenticate and authorize users. Users can roam uninterrupted if access is available within their location — OpenRoaming does not have large-scale coverage yet, and high speed connectivity is not guaranteed.
NTN extensions: Satellite technology is increasingly an option for coverage extensions, especially in remote areas. Operator partnerships with satellite companies are growing for direct-to-cell technology and Internet of Things (IoT). Demand for standardization is also growing, with 3GPP commencing study items from Release 15 to define the full integration of satellite and mobile ecosystems. 5G and NTN integration is currently immature but likely to rise in prominence with 5G Advanced and add further geographic reach to FMC. NTN may be a cost-effective extension where fiber is scarce or very costly to lay.
Gigabit technologies such as 5G and Wi-Fi 7 introduce reliable connections and higher experiences, driving the desire for limitless coverage. Single network access solutions or a blend of Wi-Fi and other technologies can bridge the gaps and provide operator service opportunities.
In the long term, wireless access technologies must synergize and deliver continuous, reliable coverage. Operators want standardized solutions, but additional network functions, integration costs and an extended ROI are daunting.
Device-driven or open roaming network selection approaches will likely lead to non-critical use cases that are less sensitive to delay in the short term. Lightweight standardized approaches are an attractive stepping stone between performance and complexity and perhaps represent a new drive toward more cost-conscious solutions. Taking advantage of the rapidly growing Wi-Fi ecosystem and capabilities will enable operators to create new offerings and meet customers' always-connected expectations.
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