04/08/2021 | News release | Distributed by Public on 04/08/2021 04:09
The demand for high-speed data service bandwidth has continued to grow in recent years, accelerated in many unexpected ways by the COVID pandemic. Much of this new demand is the result of unprecedented shifts in working and schooling from home, coupled with the augmentation of several existing trends. Anticipating this new growth trajectory is the subject of cable operators' current broadband network planning.
The specific drivers of tomorrow's bandwidth growth are difficult to predict, but we see the following trends playing a large role in industry strategies for years to come:
These demands of the future will undoubtedly move operators towards the ultimate adoption of many 10G-oriented technologies as they plan for their next-generation networks.
Note: Within this article, any technology that provides a bandwidth service level agreement that is greater than 1 Gbps and less than 10 Gbps is viewed as a 10G-oriented technology. All of these technologies may be utilized on the 'road to 10G.'
HFC augmentation paths
Although the HFC network has existed for many years, cable operators are only beginning to recognize its full capabilities. Many of its latent potential will be ripe for exploit over the next five to ten years, as operators phase in upgrades to their HFC plants.
While each operator will utilize a slightly different path, most will follow the progression described below. It's important to note that some may opt to change the order and skip or delay certain steps, but the resulting path will still be a logical one to follow.
Step 1 - Node segmentation and node splitting: For most operators that require a quick and simple augmentation of their effective per-subscriber bandwidth capacity, the node segmentation (for segmentable nodes) or the node split (for non-segmentable nodes) is the obvious path. Both approaches effectively increase the depth of fiber-moving the HFC plant down the directionally-correct path towards an ultimate PON solution in the deeper future. The only potential challenge with these approaches is that they tend to be more costly on a per-subscriber basis as the number of subscribers per node becomes smaller.
Step 2 - DOCSIS 3.1 OFDM and OFDM enablement: This step involves merely enabling more spectrum using the DOCSIS 3.1 OFDM (downstream) and OFDMA (upstream) capabilities that were deployed over the past five years. Transitioning from SC-QAM downstreams with ~6 bps/Hz spectral efficiencies to OFDM downstreams with ~8 bps/Hz spectral efficiencies or higher results in a 33% increase in bandwidth capacity for those transitioned channels. Transitioning from SC-QAM upstreams with ~4 bps/Hz spectral efficiencies to OFDMA upstreams with ~8 bps/Hz spectral efficiencies or higher results in a 100% increase in bandwidth capacity for those transitioned channels.
Step 3 - DOCSIS 3.1 mid-split or high-split enablement with 1.2 GHz downstreams: This step requires operators to make changes to active equipment within their HFC plant. The enablement of mid-split operation with the upstream operating to 85 MHz or high-split operation with the upstream operating to 204 MHz will provide increased upstream bandwidth capacity when compared to the 42 MHz or 65 MHz splits of the past. In particular, 85 MHz splits will likely support ~500 Mbps upstream service level agreements (or higher), and 204 MHz splits will likely support ~1.2 Gbps upstream service level agreements (or higher). However, this requires changes to filters within the already-deployed amplifiers and nodes. In areas where downstream congestion is expected to be problematic, operators can enable 1.2 GHz downstreams while also enabling the mid-split or high-split operation.
Step 4 - Low latency DOCSIS enablement: This is a relatively new option in the field of DOCSIS capabilities for the HFC network. It is the array of tools used to ensure low-latency transport for latency-sensitive services on the HFC plant. For many operators, this step will help ensure that gamers will continue to experience good service even if congestion occurs and will likely result in the activation of this feature in upcoming CMTSs and CMs.
Step 5 - DOCSIS 4.0 ultra high-split enablement: This is a futuristic move to DOCSIS 4.0 ultra high-split operation, which permits the operator to run the upstream spectrum to 300 or 396 or 492 or 684 MHz. This transition can permit up to ~5 Gbps of upstream bandwidth capacity, however it may require more extensive changes to the actives (amplifiers and nodes) within the HFC plant.
Step 6 - DOCSIS 4.0 full duplex (FDX) DOCSIS enablement: This is also a futuristic move to DOCSIS 4.0 with the enablement of FDX operation, which permits running the downtream spectrum and the upstream spectrum on top of one another in a selectable region within the FDX band (between 108 and 684 MHz). This transition can permit the downstream to support up to 10 Gbps while the upstream supports ~5 Gbps. However, it may also require more extensive changes to the actives (amplifiers and nodes) within the HFC plant.
Step 7 - DOCSIS 4.0 extended spectrum DOCSIS (ESD) enablement: This step is an alternative to the previous one with a move to DOCSIS 4.0 with the enablement of ESD operation, which permits running the downtream spectrum above the upstream spectrum, but the downstream spectrum is permitted to operate up to 1794 MHz. This transition can also permit the downstream to support up to 10 Gbps while the upstream supports ~5 Gbps. However, it may also require more extensive changes to the actives (amplifiers and nodes) and passives (taps) within the HFC plant.
Reclaiming bandwidth from video
An important complement to the above steps is the implementation of strategies to reduce the RF bandwidth that is assigned to traditional digital TV delivery. In today's networks, 50-70% of the precious downstream bandwidth is used for video delivery. As operators move to smaller service group sizes, and consumers move from traditional to streaming services, this is an increasingly inefficient allocation of capacity. There are four options that operators can pursue for the recovery of some or all of this bandwidth within the context of traditional linear and on-demand service offerings:
Conclusions
From the lists above, it should be clear that operators will have many technologies and many options from which to pick as they migrate forward towards 10G operation in the future. Each operator will choose its own unique path, but all will be utilizing some form of these technologies in the coming decade. Regardless, it is important to define and execute a bandwidth reclamation strategy for video and to plan the overall evolution of the network in a holistic manner.