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beermattuk
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Message 11 of 12
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Re: How to increase upload speed

Definitely.  I almost didn't join because of this, and am even considering cancelling it, definitely not staying longer than my 12 month contract unless they change it.

The ratio is ridiculous, what good is having superfast download speeds when your uploads are so weak.  Most people do fairly heavy uploading whether they realise it or not - photos, videos, dropbox, onedrive, other cloud storage solutions, online backups, emails/messaging, etc etc.

The daft thing is there are no physical restrictions.  It's not like the old ADSL days where there were only so many frequencies.  Fiber optical cables are by nature two way, all the restrictions are at the software side.  It's just throttling on the routers/switches/firewalls.

Virgin have this crazy ratio because it looks good on their marketing blurb, but they need to make it optional so people can choose to sacrifice download speed for upload.  Otherwise people will be walking back to BT for better performance.

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griffin
Alessandro Volta
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Message 12 of 12
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Re: How to increase upload speed

You cannot sacrifice download speed for upload speed as they work on different frequencies.

The Downstream works on round 112MHz up to 1GHz whilst the Upstream works between 5MHz and 85 MHz  with the lower frequencies not used due to inherent noise. The Upstream can carry far few channels than the downstream, so more channels can be bonder together to increase speed on the downstream (up to 24 with the Hub 3)..

Due to the upstream residing in the noisier part of the spectrum a lower data modulation needs to be used to allow for the noise.

The 6Hhz wide upstream channels use 16, 32 or 64QAM modulation (4,5,6 bits per symbol)  whilst the 8MHz wide downstream channels use 256 QAM (8 bits per symbol)

Two, take away points, as you see the downstream spectrum is much wider than the upstream spectrum which is unsurprising since Docsis was developed for Cable TV with the downstream still carrying the TV channels, and the Upstream cannot carry as much data as the upstream channels due to narrower channel width and lower modulation.

The other main consideration that Docsis is a shared medium, with a one to many relationship on the downstream and a many to one relationship on the Upstream.

So each Hub on a segment has to share the same upstream port at the CMTS. per upstream channel. This is done by the CMTS allocating each Hub "talk time"  slots. (ATDMA). So even that each Upstream channel can carry 30Mbps it needs to be shared with every other Hub on the local segment.

VM, may be able to increase the upstream a bit if they wanted to, but whether it would be commercially beneficial is another matter. However, VM have been upgrading the number of downstream channels from 2 to 4 which would give more capacity.

Docsis 3.1 is on the horizon which will be a game changer regarding speeds, so we might have to wait until then for significant upload speed.

At the end of the day it is horses for courses, if you want faster upload speeds go with the ISP with the best upload speeds.