There are both technical and business reasons for the gap between upstream and downstream speeds
There are a few technical reasons. There is less upstream frequency available in the upstream. 42 MHz is the standard upstream/downstream split, 85 MHz is a midsplit, 200 MHz is a high split, and the downstream goes up to 1Ghz or even 1.2Ghz. The upstream modulation runs at 64 QAM (~27Mbs) and downstream modulation runs at 256 QAM (~38 Mbps). The upstream is also more sustainable to interference and impairments. So the technology is inherently imbalanced.
From a business prospective it is very difficult to cost justify. Moving the upstream/downstream split and/or upgrading to DOCSIS 3.1 is very expensive. The reality is that the typical customer use very little upstream bandwidth. It isn't uncommon for me to see a node with 24 or 32 downstream channels at 80% usage and 4 upstream channels are at 25% utilization or less. We see a downstream to upstream usage ratio of about 15:1. If you move the US/DS split that means you are taking away from available downstream frequency which means less DS data bandwidth or fewer video channels. It's hard to make a business case to invest in increasing upstream bandwidth when the data says people aren't going to use it.
Newer technology like DOCSIS 3.1, Docsis FDX, Remote PHY and modern plant designs like N+0 or N+1 (which means fewer customers per node) will bring higher upstream bandwidth, but it will be awhile before we see anything close to symmetrical speeds.
Just wanted to mention the info that the biggest or second biggest (depends on how you count, it's a duopoly) cable ISP in Serbia is finishing up the migration to DOCSIS 3.1, and will provide gigabit speeds to cable customers. However, the upload will still be 50 Mbps maximum. Currently the fastest they have is 300/15 Mbps, which is better than what they will offer with DOCSIS 3.1 -- 1000/50 Mbps.
Most of their passive and active equipment in areas which have been fully "digitalized" is 3.1 compliant, they just need to finish the whole city and then they will start marketing the offer. Modems will have to be changed as well as equipment on the customer's side which they haven't done yet, so it will take quite some time.
They "promised" it by the end of 2019. (in 2016.), seems it will be 2025. By that time the Chinese government and Telekom Srbija will have FTTH to every home.
This doesn't surprise me. Most providers that are deploying DOCSIS 3.1 today are only doing OFDM in the downstream and the upstream is still doing ATDMA (same as DOCSIS 3.0). I'm sure there are some but I don't know of anyone doing 3.1 in the upstream yet.
If they did upgrade all their actives then 3.1 upstream is likely in the works. DOCSIS has some pretty amazing diagnostics and troubleshooting - I can look at a modem and say "approximately 71 ft from the modem there is a break in the cable causing an RF impairment" or "These 14 modems in the same neighborhood show the same impairment - there is likely a fault at this specific segment of cable". DOCSIS 3.1 expands on that even more and as more 3.1 CPEs get deployed operators are able to leverage that additional data to get the plant ready for 3.1 upstreams. OFDM frequencies are also not backwards compatible with 3.0 CPEs but a 3.1 CPE can bond both types of channels, so as the ratio of 3.1 CPEs increases that allows operators to shift more frequencies from legacy modulation to newer 3.1 modulation.
>The reality is that the typical customer use very little upstream bandwidth.
I’m not trying to disagree with this especially since you are talking about coax, but the new mmwave WiFi installations at places like Ohio state stadium have shown the opposite. The vast majority of their traffic were photo and video uploads to social media. Consumers want upload; it’s just overshadowed by streaming.
That's interesting, I wouldn't have considered that but it make sense. If I'm at a football game or concert I'm much less likely to be streaming content and much more likely to be sharing content than a user at home.
On an unrelated note - I've been pretty disappointed with the WiFi at The Shoe. The first game I tried to use it I couldn't event join the network, the second time I could join but it wasn't usable. It was early in the season though so they could have still be working out the bugs - I can't even imagine how much goes into supporting a system like that. Trying to get 100k devices on a WiFi network is impressive.
You should take a look at Australia, where we try to shove hundreds of customers onto a single node (Up to 900 per node, up to 250 per segment).
Edit: Although it wouldn't be fair to leave out that it's a EuroDOCSIS 3.0 setup with 16/4 downstream/upstream, with very limited 3.1 being used on a small scale.
IIRC, Australia has limited broadband options, they're expensive and data is expensive relative to other countries. Also, isn't data transiting outside of AU more expensive than intra-national data?
In the US, there's a 1 GbE variant of Comcast "cable modem" service called Xfinity that often has a 1000 GiB "data plan" (varying by state, some states have unlimited data) that imposes a charge per GiB beyond that. Where I use it, the network is all optical with copper from poles to customer. During power outages, it only lasts about a day... and we now have 3-6 day "public safety" outages in the summer.
Yikes! I mostly work with small providers that don't have the same resources as the big guys so I'm dealing with networks that are Node + 7 or more actives (vs the N+0 or N+1 the big guys do now) and anything about about 200 modems is when we start planning for node splits.
Also prior to the NBN (wholesaler) taking over the network, "take rate" (number of homes actually connected to the cable) was ~30%. Changing a network designed around that to 80% is quite a task
I won't call it inherently, or even "technical reason(s)".
Nothing stopped the standard to split the frequency bands for up and downstream in a more way, or even swap the frequencies for each. They're simply configured/designed this way is because of the business reason.
". I should also note that since the cable operators' infrastructure was built around sending the same TV signals to all houses, they basically just run one cable to your neighborhood, and then use passive splitters and dumb amplifiers to split that one cable to all the houses in your neighborhood. So you don't have a dedicated coax cable directly from your house to their headend equipment, so they can't change the frequency split on a house-by-house basis."
There are passive devices out in the field that split the upstream and downstream (such as directional couplers). Passive devices are favored over active devices whenever possible because they are much less likely to fail, are less expensive, and require less maintenance.
There are both technical and business reasons for the gap between upstream and downstream speeds
There are a few technical reasons. There is less upstream frequency available in the upstream. 42 MHz is the standard upstream/downstream split, 85 MHz is a midsplit, 200 MHz is a high split, and the downstream goes up to 1Ghz or even 1.2Ghz. The upstream modulation runs at 64 QAM (~27Mbs) and downstream modulation runs at 256 QAM (~38 Mbps). The upstream is also more sustainable to interference and impairments. So the technology is inherently imbalanced.
From a business prospective it is very difficult to cost justify. Moving the upstream/downstream split and/or upgrading to DOCSIS 3.1 is very expensive. The reality is that the typical customer use very little upstream bandwidth. It isn't uncommon for me to see a node with 24 or 32 downstream channels at 80% usage and 4 upstream channels are at 25% utilization or less. We see a downstream to upstream usage ratio of about 15:1. If you move the US/DS split that means you are taking away from available downstream frequency which means less DS data bandwidth or fewer video channels. It's hard to make a business case to invest in increasing upstream bandwidth when the data says people aren't going to use it.
Newer technology like DOCSIS 3.1, Docsis FDX, Remote PHY and modern plant designs like N+0 or N+1 (which means fewer customers per node) will bring higher upstream bandwidth, but it will be awhile before we see anything close to symmetrical speeds.