Superior Upstream Weblog Sequence Introduction
Within the Superior Upstream weblog collection we are going to discover how cable operators have historically managed upstream bandwidth capability planning, how market dynamics and technical innovation are driving adjustments, and the place issues are seemingly headed within the coming years. On this entry we are going to focus on the “Extra Bits/Hz” method – or the best way to get the utmost throughput out of the upstream spectrum accessible as we speak by utilizing OFDMA.
What’s OFDMA?
Orthogonal frequency division a number of entry (OFDMA) was launched as a part of the DOCSIS 3.1 specification, however its adoption has lagged its downstream companion OFDM significantly. On the time of the three.1 launch, all eyes have been on the downstream as operators struggled to maintain up with the rise on OTT video companies like Netflix. Enter the pandemic and the ensuing videoconference-driven upstream demand spike and all of a sudden OFDMA deployment plans have been accelerated, particularly for operators with sizeable DOCSIS 3.1 CPE deployments. Operators have been wanting to reap the benefits of the elevated spectral effectivity supplied by OFDMA in addition to the flexibility to make use of noisy spectrum beforehand unusable with SC-QAM.
How To Get a Free 6.4MHz 64QAM Provider
It’s value noting that whereas OFDMA can work in soiled spectrum, clear crops will move significantly extra packets. Only a 4dB enhance in SNR for a 30MHz OFDMA service can internet ~50Mbps enhance – it’s like getting greater than a 6.4MHz SC-QAM carriers value of capability out of the identical spectrum without spending a dime! Plant integrity issues greater than ever with OFDMA, tight crops can flip dB’s into dollar Bills!
Extra Bits/Hz Introduction
Of the three principal choices that operators have to extend upstream capability, the Extra Bits/Hz choice looks as if the simplest route. Simply make a couple of tweaks on the HFC community edges to allow OFDMA and immediately acquire upstream throughput with out ever touching the surface plant – proper? That is at the very least partially true – all DOCSIS CPE needs to be able to supporting OFDMA with possibly only a FW push to allow. CCAP’s could require a brand new card or two and/or licenses however nonetheless little one’s play in comparison with heavy outdoors plant work required for the opposite choices. However the true challenges are available in whenever you take a look at what it takes to keep up and troubleshoot networks working OFDMA.
OFDMA Challenges
- CCAP/CPE compatibility – CCAP’s should have acceptable HW/FW to help OFDMA, and solely DOCSIS 3.1 CPE with OFDMA-ready FW can profit from this technique. The excellent news is that you just don’t must be 100% deployed with 3.1 CPE to learn, your DOCSIS 3.0 CPE will proceed to work superb with SC-QAM’s even after they frequency share with OFDMA as a result of TDMA nature of upstream transmissions. Some operators will selectively deploy 3.1 CPE to their heaviest customers to assist maximize spectrum utilization.
- Reverse Sweep – Conventional sweep methods have positioned sweep pulses each 6.4MHz between upstream carriers however with up-to-96 MHz huge OFDMA carriers that is now not doable. How this problem is addressed rely upon the sweep use case.
- For troubleshooting crucial outages, operators will sweep proper by OFDMA carriers utilizing conventional sweep processes. There may be potential for minor service disruptions doing this, however the advantage of clearing an outage rapidly outweighs this danger.
- To be used circumstances the place service disruptions usually are not permissible like routine amplifier alignment and stability, an improved choice is now accessible which makes use of shorter sweep pulses to reduce possibilities of service disruption whereas retaining the responsiveness of conventional sweep.
- Sweepless return sweep is 100% non-intrusive and can be utilized on subject meters to offer the best decision view of upstream response, and has the added bonus of not requiring any hub-based gear or administration of sweep plans. The first downsides to return sweepless sweep are that it’s not as responsive as conventional sweep variants, solely sweeps occupied spectrum, and requires DOCSIS companies to be operational.
<Sweep Choices Picture?>
- Ingress Detection and Troubleshooting – the Low Density Parity Examine (LDPC) error correction included in OFDMA is kind of strong towards ingress, however operators nonetheless want instruments to detect when ingress is happening and discover and repair it within the subject. Extensive OFDMA carriers complicate this course of by negating using guard bands between carriers to see ingress. Heatmap evaluation in each return path monitoring purposes and subject meters has confirmed efficient by early adopters at offering visibility of ingress together with bursty impulse noise underneath these huge, seemingly always-on carriers.
What’s Subsequent For OFDMA?
Regardless of these challenges, turning on OFDMA is probably going a no brainer for a lot of operators. It’s the least intrusive choice by itself and is very synergistic with the opposite choices
- Required to leverage spectrum above 85MHz for prime cut up
- Elevated SNR from DAA’s digital optical hyperlink permits increased OFDMA modulation orders
For areas with important DOCSIS 3.1 CPE deployments OFDMA is already turning into ubiquitous, for lagging areas it’s one more driver for CPE modernization. Operational advantages delivered by OFDMA will proceed to enhance as 3.1-specfic PNM capabilities acquire adoption, and spectral effectivity will proceed to enhance as synthetic intelligence (AI) and machine studying (ML) ideas evolve to additional optimize profile administration. OFDMA is already serving to us get Extra Bits/Hz as we speak, however we’ve solely scratched the floor of what it might probably ship sooner or later.
Need to study extra? Hearken to the Broadband Lounge Podcast Sequence or go to the VIAVI Superior Upstream Web page for extra info.
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