Digital Subscriber Line (DSL)
Became popular as a way to increase data rates in the local loop.
- Uses full physical capacity of twisted pair (copper) phone lines (up to 1 MHz)
- Instead of using the 0-4000 KHz voice channel
1 MHz capacity split into (FDM):
- a 4 KHz voice channel
- an upstream channel
- a downstream channel
Requires a pair of DSL modems
- One at the customer’s site; one at the CO site
May be divided further (via TDM) to have one or more logical channels