1. Infocom Systems Infokommunikációs rendszerek 10. előadás ADSL
Takács György
Infocom

2. 2004
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3. 2006. november maximális letöltési sebesség (kbit/s)
maximális feltöltési sebesség (kbit/s)
Havidíj hűségnyilatkozattal (Ft)
ADSL Optimum
512 96
4900
ADSL Prémium
1024
128
7900
ADSL Maximum
2048
192
9900   
                                                                            
Infocom

4. maximális letöltési sebesség (kbit/s)
2008. november
maximális letöltési sebesség (kbit/s)
maximális feltöltési sebesség (kbit/s)
Havidíj hűségnyilatkozattal (Ft)
DSL CLASSICHappy
2 Mbit/sec
192 kbit/sec
3 990 Ft
DSL CLASSIC MEDIUM
8 Mbit/sec
480 kbit/sec
6 890 Ft
DSL CLASSIC EXTRA
25 Mbit/sec
4 Mbit/sec
9 890 Ft   
                                                                            
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5. 2012. November NetMániaS 10 (1) 0,5 (0,2) 3990 NetMániaM 20 (10)
maximális
(garantált) letöltési sebesség
(Mbit/s)
Maximális
(garantált) feltöltési sebesség (Mbit/s)
Havidíj 2 év hűségnyilatkozattal (Ft)
NetMániaS
10 (1)
0,5 (0,2)
3990
NetMániaM
20 (10)
1 (0,5)
4690
NetMániaL
30 (20)
1 (1)
5490
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6. 2015. November
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7. 2016 november
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8. What is ADSL(VDSL, XDSL,G.fast) ?
Asymmetric Digital Subscriber line,
A modem technology,
Convert existing twisted-pair telephone lines into access paths for multimedia and high speed data communication,
Can transmit to 30 Mbps downstream (VDSL 100 Mbps G.fast up to 1 Gbps!) ,
Can transmit up to 30 Mbps upstream,
Transform the existing PSTN network to a powerful system capable of bringing multimedia, full motion video to the subscriber’s home.
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9. ADSL system components
PSTN
Network
low pass filter
low pass filter
user
twisted
pair cable
IP Network
bandpass filter
bandpass filter
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10. ADSL system components
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11. ADSL in the complete system (Application Service Provider, Internet Service Provider, ACCESS Network Provider, Customer/User
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12. ADSL components at the subscriber
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13. ADSL components at Central Office
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14. Maximum speed capabilities
DSL Technology Options
Family
ITU
Name
Ratified
Maximum speed capabilities
ADSL
G992.1
G.dmt
1999
7 Mbps down 800 kbps up
ADSL2
G992.3
G.dmt.bis
2002
8 Mbps down 1 Mbps up
ADSL2plus
G992.5
2003
24 Mbps down 1 Mbps up
ADSL2-RE
Reach Extended
SHDSL
G991.2
G.SHDSL
5.6 Mbps up/down
VDSL
G993.1
Very-high-data-rate-DSL
2004
55 Mbps down 15 Mbps up
VDSL2-12MHz long reach
G993.2
Very-high-data-rate-DSL 2
2005
55 Mbps down 30 Mbps up
VDSL2-30MHz short reach
100 Mbps up/down
G.fast
G9700 G9701
2014
1000 Mbps (Aggregated) <100m
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15. Twisted pair to the building, Fibre to the Cabinet
(FTTCab), Fibre to the Building (FTTB)
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16. What is the future of the ADSL?
Will play a crucial role over the next ten years for telephone companies and other service providers
New broadband cabling will take decades to reach all prospective subscribers.
EU regulation document on local loop unbundling because no competitive technology!
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17. dividing the spectrum to 256 subfrequencies
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18.        adaptive SNR discovery
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19. The technology being used is DMT which divides the frequency range to 256 sub-frequencies from 64Khz to 1.1Mhz Each sub-ferqency is an independent channel and has it own stream of signals . The ADSL protocol defines a basic stream of data which is known to both endpoints in advanced and enables them to find the specific SNR for each  sub-frequency , and uses this information to split the data over the sub-frequencies
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20. Infocom

21. VDSL frequency plan and profiles
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22. Infocom

23. Infocom

24. Limiting factors: Cable attenuation Reflexion Crosstalk (NEXT, FEXT)
Noises, interferences
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25. key requirements (1)
Test loops – makeup and topology (to ensure adequate penetration).
Cross talk or steady state noise margin (to allow for interactions from other DSL in a multi-pair cable).
Data rates (both line and payload).
Impulsive or transient noise margin (to allow for noise spikes e.g. ringing).
Transmitter power spectral density limits (to ensure spectral compatibility and minimise unwanted RF emissions).
Return loss (to ensure good line matching and signal power transfer).
Line interface balance (to prevent EMC problems).
Infocom

26. key requirements (2)
Framing and data scrambling (to prevent cyclo-stationary effects e.g. line spectra).
Latency (to minimise delay e.g. for voice traffic).
Jitter and wander (to minimise data loss).
Start up protocols (handshaking).
Warm/cold start limits (time taken to synchronise and achieve reliable bit transport – to minimise circuit unavailability).
Line coding (to achieve efficiency in terms of bits/s/Hz)
Duplexing (e.g. time, frequency, echo cancellation).
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27. key requirements (3)
Forward error correction (to self-correct physical layer transmission errors and   not burden higher layer protocols with data re-transmission.)
Embedded operations and maintenance (for the transfer of service related   information e.g. QoS).
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28. Code & Error Correction
One of the most important technology breakthrough that helped the ADSL is the coding . Using a method called consellation encoding and based on Reed Solomon coding decoding the information on the line can be damaged and yet the decoder rebuild the information in a very high reliability.To improve the performance of ADSL system some companies use 16 state 4 dimensional trellis code on top of the consellation encoding. Another useful method to increase the ADSL systems reliability is Forward Error Correction (FEC).
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29. Framing & Scrambling  
As most of the Computer communication networks the ADSL uses a specific framing method . The main frame is called Superframe and it is composed of 68 ADSL data frames , the ATU-C sends a superframe every 17 msec . Each data frame gets his information from two data buffers (interleaved buffer and fast buffer)which are scrambled at a specific sequence , this scrambling method makes the error correction and coding more efficient.
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30. Infocom

31. DSLAM-s near to the PPKE-ITK Campus offered by the Hungarian Telecom (Reference Unbundling Offer)
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32. Beyond VDSL2 – G.fast
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33. Fibre to a distribution point -- FTTdp
Service rate performance targets:
Mbit/s for FTTB
500 Mbit/s at 100m
200 Mbit/s at 200m
150 Mbit/s at 250m
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34. Infocom

35. Coexistence and migration from VDSL2 to G.fast
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36. Optional control of downstream/upstream
Duplexing method: TDD (time division duplex) easily vary DS/US asymmetry ratio
Optional control of downstream/upstream
asymmetry ratio from 90/10 to 10/90
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37. Modulation: discrete multi-tone (DMT)
2048 sub-carriers for 106 MHz,
4096 sub-carriers for 212 MHz
Sub-carrier spacing kHz
Bit loading of ≤12 bits/sub-carrier
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38. Standardization
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39. What can we learn from XDSL story?
No ultimate technology!!
Frequency division multiplexing, time division multiplexing, modulation, error control, flow control, scrambling, signal processing, adaptation, STM-ATM, trellis coding, in-service performance monitoring and surveillance, initialization, handshaking, channel analysis, are mixed in XDSL
More room for further development….
Infocom