What’s Coming with DOCSIS 3.1 and What You Need to Know Today
DOCSIS 3.1 is coming and there are some important things that you need to be aware of so you’re prepared for what’s to come in the future. The purchasing decisions you make today are one example, from buying a new CMTS to the CPE you order.
ZCorum’s VP of Technology, Scott Helms, covered what’s coming with standard and how it will impact your operation in this DOCSIS 3.1 webinar. He discussed the type of hardware you should be buying today to be compatible in the future, how channel space will be changing and RF considerations to start thinking about.
Questions & Answers from the Webinar
About 162 mbps. We get about 12 bits per symbol (basically per Hz) with QAM 4096 as compared to 8 bits per symbol with QAM 256. This is not dramatically more than we could get with 4 bonded channels in D 3.0, about 152 mbps, but we can do it in less spectrum since we only need 2 guard bands rather than 5.
They can certainly use both, but are not required to use both at the same time as long as we’re talking about in the same direction, i.e. upstream or downstream. It’s possible that manufacturers will include this, but I haven’t seen any announcements related to doing this.
Many changes are in process right now. Some of the biggest include dealing with the fact that each sub-carrier will have its own MER/SNR measurements. That means rather than tracking 32 or fewer downstream SNR measurements in D 3.0 and earlier, we could be tracking hundreds or even thousands of MER values for each individual modem.
In the residential market, at least speeds will continue to be an “up to” scenario. We can do 2 GBps with a single 192 MHz OFDM downstream, but that channel will be shared for the foreseeable future among many (your over subscription rates will depend on your business plan and customers) end customers. The reality is that almost all bandwidth is over subscribed at some point, since very few customers are willing to pay for or use a guaranteed gigabit or greater. For those customers, I’d recommend running a direct fiber connection, since most PON solutions have a component of shared (TDM) resources.
About 162 mbps, we get about 12 bits per symbol (basically per Hz) with QAM 4096 as compared to 8 bits per symbol with QAM 256. This not dramatically more than we could get with 4 bonded channels in D 3.0, about 152 mbps, but we can do it in less spectrum since we only need 2 guard bands rather than 5.
You need at least one 96 MHz OFDMA upstream to do 1 gigabit in the upstream, this means the going past 85 MHz to 204 MHz is where you want to set your sights. Most of the large MSOs I’ve spoken with plan on keeping D 3.0 upstreams for the time being, while working on moving to a mid-split.
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