2Outline Telephone lines Dial-up modems Digital Subscriber Line (DSL) Cable TV networks
3Telephone LinesTraditional telephone lines can carry frequencies between 300 and 3300 HzGiving them a bandwidth of 3000 HzAll this range is used for transmitting voiceA great deal of interference and distortion can be accepted without loss of intelligibility
8Digital Subscriber Line (DSL) Provides higher-speed access to the InternetSupports high-speed digital communication over the existing local loopsThe existing local loops can handle bandwidths up to 1.1 MHz.
9ADSL ADSL – Asymmetric Digital Subscriber Line Downstream bit rate > upstream bit rateDesigned for residential usersUnsuitable for businessesADSL operates on existing local loopsLocal loops can handle up to 1.1 MHz of bandwidthThe distance limit is ~18,000 feetThe system uses a data rate based on the condition of the local loop line
12Bandwidth Division 4Khz Allocation and modulation of each channel are determined adaptively
13Bandwidth Division Voice – Channel 0 Idle – Channels 1-5 Upstream – Channels 6-3024 data channels, 1 control channel1.44 Mbps (max) upstream bit rateActual bit rate: 64 Kbps to 1 MbpsDownstream – Channels224 data channels, 1 control channel13.4 Mbps (max) downstream bit rateActual bit rate: 500 Kbps to 8 Mbps