1. Asymmetric Digital Subscriber Line (ADSL)

2. Table of Contents
Introduction
Advantages
Drawbacks
Conclusion

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

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

5. Advantages Connectivity – always connected Ease of use Reliability
Security
Speed

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

7. Nyquist’s Theorem Maximum data rate = 2H log2 V bits/sec
H = low-pass filter of bandwidth
V = signal discrete levels

8. Drawbacks Availability Signal leaking
Cost of installation and equipment
Not standardization

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

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

11. 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.