The next generation of the DOCSIS standard, Full Duplex DOCSIS 3.1, came one step closer to fruition last month when CableLabs released the key MAC layer specification for the standard, The Register reported. This “expands the existing DOCSIS media access control layer with messages specific to setting up full duplex communications between the cable modem and the upstream cable modem termination system (CMTS),” The Register reporter Richard Chirgwin wrote.
The point of that, and indeed the Full Duplex standard as a whole, is to make it possible for MSOs to deliver symmetric 10 Gbps using hybrid fibre-coax (HFC) networks. While that future enabler of even more bandwidth is a ways off yet, in the the meantime there are plenty of benefits cable MSOs can glean from the DOCSIS 3.1 standard as it now stands. These lesser-known features mostly aren’t about bandwidth per se, but rather helping MSOs improve network efficiency.
For example, DOCSIS 3.1 improves radio frequency (RF) and network efficiency:
- Through the use of OFDM/OFDMA. This not only allows simultaneous low-data-rate transmission from several users (more bandwidth from the same channel), but also makes more efficient use of existing 6MHz channels (roughly 25 percent increase), eliminates guard bands, allows isolation of high SNR carriers, and enables differing modulations within sub carriers—operators no longer have to use adjacent channels and when there are interference issues the problem channel can be ‘dropped’ without interrupting service!
- By supporting 4-6k QAM. This makes it possible to convey two digital bit streams, or two analog message streams, simultaneously—which means a lot more bandwidth within each channel, and therefore better network efficiency.
- Increasing usable upstream spectrum, from 5-200MHz, compared with 5-85 for DOCSIS 3.0. That’s a lot more upstream spectrum to work with! This is a better use of existing node split methodologies, and enables symmetric gigabit services trough resource block assignments.
- Increasing usable downstream spectrum, which now includes 1.2-1.7GHz.
- Improving error correction, allowing gains in modulation order in the same signal-to-noise-ratio (SNR) environment.
- Being backwards compatible with legacy DOCSIS physical layer infrastructure. This makes migrating to the new standard a much easier path for network operators and customers. There’s no need, for example, to allocate separate spectrum for legacy and new DOCSIS equipment.
- Extending the use case to phase out legacy analog channels. For MSOs that have been hanging on to legacy analog carrier, this is great news; analog is very inefficient compared with digital.
The long and short of all this is: DOCSIS 3.1 allows cable MSOs to get a lot of additional network efficiency out of their cable plant. Better use of existing resources, and more usable spectrum, means operators can offer more enhanced, on-demand business services to generate new revenue streams.
Of course, as they roll out these new services, MSOs must be able to understand how the network is performing, and how customers are experiencing their use of the services. Stricter service level agreements (SLAs) associated with higher-bandwidth, enterprise services mean the stakes are higher than ever. Using a service assurance solution like Accedian’s SkyLIGHT gives these operators the visibility they need to know they’re delivering the quality of service (QoS) and quality of experience (QoE) their customers contracted, and and to confidently deploy and manage new, advanced services.