Why are upload speeds slower than download speeds?

Answer 1

Upload speeds are generally slower than download speeds because of the fact that most internet connected equipment is asymmetric. Asymmetric means that any one packet of data can either go in, or out, but not both ways at the same time.

Since most internet users are receiving more data than sending, the internet connected equipment has shifted the higher majority of the signals to go toward downloading.

If an internet provider allows your connection to be 5Mb download and 1Mb upload, this same connection is capable of handling 3Mb upload and 3 Mb download. But this would then slow down the most important part of the internet, the receiving and downloading of requested data.

Answer 2

in UPLOADING the analog signal must be sampled at the switching station.In this direction,quantization noise is introduced into the signal ,which reduces the SNR ratio and limits the rate to 33.6.

BUT...there is no sampling in DOWNLOADING .the signal is not affected by quantization noise and no subject to the Shanon capacity limitation.The maximum data rate in uploading direction is still 33.6,but the data rate in the dowloading direction is now 56kbps.

Answer 3

That's because most ISPs (Internet Service Providers) offers ADSL (Asymmetric Digital Subscriber Line) technology to their customers. You can find out more about ADSL here: http://en.wikipedia.org/wiki/Asymmetric_digital_subscriber_line

This comes as default because most of the time, whether you are just simply browsing through the internet or playing games, you are 80% retrieving (or downloading) the data from the remote server (where the website is hosted). Oftentimes, you only upload a tiny bit volume (e.g. text, image, etc.) in comparison to download.

If you wish the two to be equal (e.g. if you run a server), you can switch to SDSL or SHDSL and their cousins. [ http://en.wikipedia.org/wiki/Symmetric_digital_subscriber_line ]

Here's a tip to remember them: If "Asymmetric DSL" is one-way flow, then "Symmetric DSL" is both-way flow (equal). (Hence: the letter "A" in Asymmetric.)