Currently most home users access Internet by dial-up telephone modems at speeds up to 33.6Kbps. The newest access methods available now are by 56Kbps telephone modem and ISDN modem at speeds of 64 Kbps or 128 Kbps. However, these speeds can not satisfy the Internet surfer's need. ADSL modem and cable modem are two leading contenders for providing high speed residential Internet access over the existing infrastructures before the full deployment of FTTH networks. They can transmit up to SMbps (ADSL modem) and up to 36Mbps (cable modem) in the downstream direction and offer low speed upstream transmission simultaneously. Up to date, the standardization of the modems has not fully completed. Large-scale field trials are going underway in the world, and widely applications are expected at the end of this century.
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