Our present and future depend on moving more bits and fewer people. Broadband access is an essential utility for us to connect with each other and the cloud, from the convenience of our homes.

Ultimately broadband evolution is about delivering a reliable and affordable user experience at gigabit speeds. Despite the marketing, most broadband consumers do not care what access technology is used for their Gigabit on-ramp to the Internet cloud. Copper, fiber, coax, wireless? No single technology can cover all use cases equally well. To connect every home with the digital world we live in requires a multi-access broadband strategy that combines an expanding range of fixed and wireless access technologies.

The blog discusses how wireline access providers can efficiently complement and enhance their existing wireline broadband offer with fixed-wireless access (FWA) to deliver a converged multi-access broadband experience everywhere.

The case for converging fixed and wireless access

Communication service providers (CSPs) have done a remarkable job of extending the life and utility of the existing copper and coaxial access plant to bring the Internet to nearly every home. By pushing fiber ever closer to the home, they were able to speed up data transfer rates from kilobits to megabits per second and do so without breaking the bank.

But the bonanza of mining existing copper and coaxial plant for broadband gold is finally coming to an end. Demand for faster access continues unabated and may even be mandated by public regulations and spurred by national broadband initiatives, but the cost increments of trenching fiber to replace the remaining few hundred meters of copper and coax are very steep. Fiber to the home is typically the preferred and future safe way to go, but deployment can be costly and time consuming, even for new housing projects. Gradually and inevitably, a faster broadband experience may literally become out of reach for more and more consumers.

Fixed-wireless access can address these last-mile broadband wireline coverage issues. LTE/5G radio deployed in the sub 6 GHz frequency bands can rapidly cover large areas with access speeds that meet or exceed copper-based DSL broadband technologies. Small cells operating at mmWave frequencies (24 to 39 GHz) can even deliver fiber-grade Gigabit broadband services. Besides licensed spectrum, many regulators have actively engaged to make shared and unlicensed spectrum available in various frequency bands. For example, the US Federal Communications Commission designated spectrum in the 3.5 GHz band for shared use (the “innovation band” of the Citizen’s Broadband Radio Service or CBRS).

Figure 1. The case for fixed-wireless broadband access

FWA perfectly complements wireline broadband deployments in the last mile (Figure 1). In brownfield it can be used in overlay to address capacity and coverage issues of underserved wireline broadband users. In greenfield, FWA can be an effective tactic to get quick service coverage and revenues and potentially support a phased fiber-to-the-home rollout. So how to easily deploy FWA with minimal investments and risk?

The fixed-wireless broadband edge

A converged fixed-wireless edge plays a crucial role in delivering affordable, high-performance broadband services to every home. However, wireline and wireless access technologies come from very different worlds, so where does fixed-wireless access fit in? Wireline or wireless?

To answer that question, we must compare their service characteristics (Figure 2).

Figure 2. Comparing mobile and home broadband requirements

To complement (or compete with!) wireline broadband, fixed-wireless access gateways must support the same residential applications. There are no roaming requirements because all user devices are tethered to a single, stationary home gateway that serves up to a dozen user devices such as TVs, PCs, tablets and gaming consoles. Home broadband services are always on and must sustain high bandwidth usage for multi-cast IPTV and streaming ultra-high definition broadcast TV, binge-watching Netflix, Zoom video conferencing, and downloading software for PCs and game consoles. Sophisticated quality-of-service (QoS) techniques are needed for the delivery of multiple services over the same bearer. Monthly data usage per home averages several hundreds of Gigabytes that are charged at a monthly flat rate, without usage caps for the highest service tiers.

In contrast, wireless broadband users typically connect a single device (smartphone) with short-lived dynamic user sessions. Although mobile devices can generate significantly more control plane traffic, mobile data volumes are orders of magnitude lower and charged by the Gigabyte. Mobile data rates are comparably high; a Gigabyte of data costs up to $8 in the US and $12 in Canada. One month of broadband usage charged at mobile data rates would easily cost a homeowner the same as a two-year wireline broadband subscription. To avoid these fees, mobile users tend to use private or (free) public Wi-Fi hotspots wherever they can.

As a result of their different usage characteristics, wireless gateways are polar opposites of the wireline gateways (Broadband Network Gateway or BNG) used for residential broadband:

• Wireless gateways are optimized for dynamic, mobile user applications that yield a high revenue per bit. They are typically centralized and virtualized, which allows operators to cost-efficiently pool resources for roaming users and leverage cloud-native compute and storage to support dynamic user sessions with elastic scaling needs. They are not designed nor dimensioned to cost-efficiently support bandwidth-intensive internet or IPTV applications over extended periods of time.
• Wireline BNGs are cost-optimized for delivering always-on Gigabit broadband services to homes and businesses. They are typically purpose-built network appliances that leverage custom routing silicon for granular bandwidth management and hierarchical QoS to ensure that available network resources are fairly and optimally shared among subscribers and user devices. Default residential broadband service features such as Internet access and IPTV multicast replication are far more economical to deploy and scale on BNGs compared to Internet offload (LIPA-SIPTO) and IP multicast replication (eMBMS) on mobile gateways.

In conclusion, the service requirements of fixed-wireless access are very similar to wireline broadband access. Because fixed-wireless access gateways and wireline BNGs share most requirements, there are potentially significant operational cost and performance synergies when leveraging the same edge platform for both.

Converged fixed-wireless broadband delivery

To optimize residential broadband coverage and cost requires a selective deployment of fixed-wireless access in conjunction with wireline access, under a common and shared operational support infrastructure. A high-capacity fiber backhaul network is needed in all cases to aggregate subscriber traffic.  

Broadband providers deploying FWA will chiefly consider using shared, unlicensed or mmWave spectrum because licenses are more affordable. 5G mmWave radio will require an outdoor receiver at each home with a clear line of sight (LoS) to small cells placed in the vicinity. However, since home broadband receivers are stationary there is no need to provide blanket service coverage from multiple angles for roaming users and no need to support user mobility on the FWA gateway.

Figure 3. Converged fixed-wireless and wireline broadband on a multi-access edge

Nokia collaborated with the Broadband Forum, 3GPP and the IETF to create the necessary standards to evolve the wireline BNG to a multi-access broadband gateway supporting fixed-wireless access and fixed-mobile convergence on a 4G/LTE or 5G core. Development of the necessary functional extensions started several years ago, and today Nokia offers a complete, working solution that is unmatched in the market (Figure 3).

To support fixed-wireless access requires a SPGW (Serving Gateway/Packet Data Network Gateway) network function, and a subset of the Mobility Management Entity (MME) and Home Subscriber Service (HSS) functions. The Nokia 7750 Service Routers and SR OS operating system implement all the necessary SPGW user and control plane functionality that is required of a fixed-wireless access gateway, and can perform these in addition of a wireline BNG and optionally Hybrid Access Gateway (HAG). The Nokia Compact Mobility Unit (CMU) appliance can be deployed to support the FWA Mobility Management Entity (MME) and Home Subscriber Service (HSS) functionality.

The Nokia solution also supports BNG disaggregation (see Broadband Forum TR-459), which separates the BNG Control and User Plane with standardized interfaces and protocols that are derived from the 3GPP CUPS standards. In the CUPS deployment model, the SPGW control plane functions are decoupled (from the BNG+SPGW user plane) and performed by the CMU as well. BNG CUPS is not mandatory for converging wireline and fixed-wireless access, but it may help to optimize service delivery cost and performance by giving the flexibility to manage distributed BNG network appliances under a centralized control plane that can scale out in the cloud. Having a single access point for managing all distributed user plane instances simplifies operations and makes it easier to interface to external systems (i.e. PCRF, AAA). Other benefits include independent lifecycle management of control and user plane functions, more flexible and cost-effective redundancy models, and more efficient and dynamic IPv4 address pool management.

As an industry leader in LTE/5G radio and wireline access, with decades of deployment experience with mobile-wireless and fixed-wireline gateways, Nokia brings unique experience and proven capabilities for fixed-wireless broadband convergence. Leveraging wireline BNG platforms for fixed-wireless access grants broadband service providers a very economical solution with excellent scaling properties. They can leverage the same fiber backhaul infrastructure to aggregate both wireline and fixed-wireless access, and efficiently manage all subscribers with the same operational back-end systems they use for wireline broadband services.

Besides fixed-wireless access convergence, the Nokia Multi-access BNG also enables fixed-mobile convergence on a 4G/LTE or 5G core. This will be discussed in a later blog.

To learn more, please refer to:

• Web page: Residential broadband services
• Datasheet: Nokia Broadband Network Gateway

For a deeper dive, please read the white paper “Broadband Network Gateway evolution to 5G through Control and User Plane Separation and fixed-mobile converged broadband interworking”.