It’s been nearly a year since the Mobile Backhaul vendor and operator team that I lead started working on techniques to improve DOCSIS® technology to provide better backhaul for mobile. One of the team’s main and most pressing issues was to solve the problem of how to provide precision synchronization and timing.
Today, I am happy to announce that we have published the first draft release of the Synchronization Techniques for DOCSIS Technology Specification. This spec is the first under a new category of DOCSIS specs designed for Mobile Applications.
Synchronization service is fundamental to any mobile deployment
You can read all about the technical details in the SCTE white paper that I co-authored last year. Traditionally, macrocell sites use GPS for synchronization. But as small cells are being deployed on a large scale, GPS may not be an economic solution, and may not be feasible in deployment scenarios, such as instances when there isn’t a clear view of the sky outdoors or indoors. This is why the transport and the backhaul networks will need to provide timing services.
The Solution? DOCSIS Time Protocol
With the varying network architectures that our mobile operator members have, how do we approach the solution? Turns out the common denominator is DOCSIS Time Protocol (DTP). One of the most significant challenges DOCSIS technology faces in providing precision timing service is the differences in delay in forward and reverse paths due to network asymmetry. This means standard protocols such as Precision Time Protocol (PTP) cannot be carried over the DOCSIS network directly.
DTP was introduced back in 2012 as part of DOCSIS 3.1 specs, in order to solve the asymmetry issue. In this draft release of the mobile sync spec, the team specified the performance requirements on the DOCSIS equipment when running DTP, in order to meet an end-to-end timing performance budget that the mobile operators require for LTE and LTE-A deployments.
Future Plans
- My team will be working on a second draft release that focuses on a different set of transport network requirements.
- At the same time, we will be setting out to prove the performance capabilities of the DOCSIS equipment by establishing a Mobile Backhaul lab here at CableLabs, turning specs into a reality. We mentioned this in a previous blog in May, and we will be providing more updates later.
I hope the ability to provide reliable and precision timing services will make it easier for the mobile operators to choose DOCSIS backhaul as a high performing and economic solution.
The draft spec is available to CableLabs operator members and NDA vendors only at this time on InfoZone. As an NDA vendor with CableLabs, you get early and exclusive access to:
- Spec information,
- Technical papers and documentation,
- Software code and more
You can find more information here. Don’t have an InfoZone account? Register here.
A big round of applause goes to my colleagues that did a lot of the heavy lifting in the spec work: Yair Neugeboren (ARRIS), John Chapman (Cisco), Peter Meyer (Microsemi), and Alvaro Simon (Vodafone).
