Asymmetric Digital Subscriber Line (ADSL)

Asymmetric Digital Subscriber Line(ADSL)

Table of Contents • Introduction • Advantages • Drawbacks • Conclusion

Introduction • High speed data link. • Pure network connection. • Coming with different schemes: CAP, QAM, and DMT. • Using special modems called endpoints

Server CORE Network ADSL Existing Copper ADSL 1.5 to 9 Mbps Internet 16 to 640 kbps ADSL Connection

Advantages • Connectivity – always connected • Ease of use • Reliability • Security • Speed

Echo Cancellation FDM Upstream Downstream Upstream Downstream POTS POTS Frequency 1 Mhz Frequency 1 Mhz Create Multiple Channel

Nyquist’s Theorem • Maximum data rate = 2H log2V bits/sec H = low-pass filter of bandwidth V = signal discrete levels

Drawbacks • Availability • Signal leaking • Cost of installation and equipment • Not standardization

Telephone line Voice (only) Splitter Voice + ADSL ADSL (only) ADSL modem Phone Phone Fig. 1 ADSL Problem

Telephone line Voice (+ ADSL leakage) Splitter Voice + ADSL ADSL (only) ADSL Filter ADSL modem Phone Phone Fig. 2 ADSL Problem

Conclusion • ADSL is a high speed access to internet. • ADSL has advantages but it also has limitations. • ADSL needs to extend the access distance. • ADSL might improve the speed. • ADSL needs to be standardized.

Asymmetric Digital Subscriber Line (ADSL)

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