Mobile networks already rely on fixed wireline infrastructure. Legacy 3G and 4G LTE networks transport data traffic between antennas and data centres via wired networks. Whenever mobile users connect their devices via Wi-Fi, the traffic is carried via broadband networks, whether DSL, fibre or cable.
There is good reason to believe that the role fixed networks play in mobile delivery will only grow in importance with 5G, offering cablecos a valuable stake in next-generation wireless services. For one, 5G will make use of higher frequency spectrum brands than currently used by mobile. The higher the radio frequency, the shorter the propagation range, creating the need to adopt small cell network architecture - more radio access nodes deployed at a higher density at a local level. While high-frequency, small-cell architecture won’t be the only model used in 5G network infrastructure, it will play an important role. And the increase in access points will create demand for more fixed backhaul to connect them all. In more general terms, the anticipated increase in mobile use cases and subsequently the number of connections that 5G brings about will lead to a dramatic rise in data traffic volumes, which again creates new demands on the backhaul.
One of those use cases, fixed wireless access (FWA), is sometimes talked about as the replacement for wireline broadband. The idea is that the extra speed and capacity offered by 5G will eventually lead to mobile becoming the primary means that people use to connect to the internet, whether they be at home, at work or on the move.
Even if that did come about, fixed-wire links like cable would still have an important role to play in delivering the backhaul required to support such a massive increase in cellular traffic. Far beyond the potential for mere fixed wireless access, fixed wireless convergence is about blending the best of all available transport technologies, wired and wireless, to deliver the best possible services to end users.
To meet these requirements and take a stake in 5G backhaul, cablecos will have to upgrade their networks. With gigabit-plus speeds a baseline expectation for 5G, DOCSIS 3.1 will be a prerequisite in any cable backbone. Similarly, given the expected high demand for 5G connectivity from IoT and enterprise markets, cablecos will have to look to Full Duplex to guarantee the upstream speeds that business use cases will require to upload data to cloud and other systems quickly and efficiently. One innovation which could be of particular interest is software-configurable Frequency-Division Duplex (Soft FDD), which promises to deliver symmetrical 10G speeds over coaxial wiring.
Another aspect of the DOCSIS 3.1 specifications of particular interest to 5G development is low latency. Reliable, real-time data transmissions are a central component of proposed 5G use cases such as HD video streaming, gaming and autonomous vehicle control systems. But minimising latency in mobile backhaul is also an important hurdle to overcome in coordinated multipoint (CoMP) technology, which minimises the risk of signal interference in densified networks by coordinating transmissions in real time. Reliability is also the focus of Profile Management Application, a DOCSIS 3.1 toolset
which minimizes transmission errors while also delivering capacity gains of between 15% and 40% per channel.
DAA approaches such as Remote PHY can support 5G’s goals of higher speeds, higher bandwidth and lower latency by pushing the interface between the cable backhaul and the RAN out to the access nodes. This kind of decentralised edge technology depends on virtualisation, and particularly on having a virtualised converged cable access platform (CCAP). The Open Network Foundation (ONF) has been instrumental in developing virtualised access solutions for the network edge, including CORD (Central Office Re-architected as a Datacenter) and its latest project SEBA (Software Enabled Broadband Access). By building a CCAP using cloud and Network Functions Virtualization (NFV) techniques, cable operators can get benefits such as automated provisioning, orchestration and analytics tools in their cable backhaul. These are highly desirable for managing the multi-access configurations involved in 5G.
