Internet speed

[pdq1]

Why is the Upload speed usually a fraction of the download speed.

[pdq1]

My recent check:Download 2.2 Mb/s and Upload was 0.45Mb/s

[sunny-dave]

From Wikipedia :

Overview

ADSL differs from the less common symmetric digital subscriber line (SDSL) in that bandwidth (and bit rate) is greater toward the customer premises (known as downstream) than the reverse (known as upstream). This is why it is called asymmetric. Providers usually market ADSL as a service for consumers to provide Internet access in a relatively passive mode: able to use the higher speed direction for the download from the Internet but not needing to run servers that would require high speed in the other direction.

There are both technical and marketing reasons why ADSL is in many places the most common type offered to home users. On the technical side, there is likely to be more crosstalk from other circuits at the DSLAM end (where the wires from many local loops are close to each other) than at the customer premises. Thus the upload signal is weakest at the noisiest part of the local loop, while the download signal is strongest at the noisiest part of the local loop. It therefore makes technical sense to have the DSLAM transmit at a higher bit rate than does the modem on the customer end. Since the typical home user in fact does prefer a higher download speed, the telephone companies chose to make a virtue out of necessity, hence ADSL. On the marketing side, limiting upload speeds limits the attractiveness of this service to business customers, often causing them to purchase higher cost leased line services instead. In this fashion, it segments the digital communications market between business and home users.

[Old_Geezer]

You rarely want to upload, and download all the time you're on the Net, so my suspicion is that it pays to bias your resources towards the greatest demand, for greatest efficiency.

[methyl]

In domestic internet connections most commonly you type something short (which is downloaded) and the much larger reply comes back (which is uploaded). This the upload proportion of the line speed needs to be the greater proportion of the line speed.

[MarkRae]

Methyl, it's precisely the other way round...

[deggers316]

youve got more upload than me with plusnet
upload 00.37 Mb/s
download 19.00 Mb/s
a vast difference

[kalavani]

ya correct upload speed usually fraction of download speed. I tested my speed at http://www.scanmyspeed.com
My download speed ==1.2mbps
upload speed ====0.7mbps

There isn't some secret conspiracy to rob customers of upload speed, this is simply how the xDSL and Docsis standards were developed. Despite what people think, this was done to solve technical/engineering problems and wasn't done for purely marketing reasons.

In the context of ADSL/ADSL2+, the lowest part of the frequency band is allocated for upstream, with the vast majority of the 1.1/2.2mhz spectrum kept for downstream. When the standard was developed, loop lengths were often several kilometers, so the bands had to be split this way, or most customers wouldn't train at all (or would have almost no downstream rate, from the reduced bitloading in the downstream band).

Having the lowest frequency band reserved for upstream also minimized problems with far-end crosstalk from other pairs affecting your upstream rate. This topic is a very, very complex problem with VDSL2 (ie: short loops puke fext onto longer loops and will clobber the upstream bands), and is why telco's are studying vdsl2 upstream power back off in detail.

With the Docsis standards, its a slightly different problem but only the 5 - 42mhz frequency range is allocated for upstream (due to noise and other factors, like existing analog/digital-qam channel allocation). With Docsis2 and QAM64 modulation, that usually results in ~30mbps upload for the entire node, which is why most cable co's are cheap on upstream rates. Docsis3 adds channel bonding of course, but that requires new CMTS line cards, modems, and possibly a re-shuffling of existing spectrum.