Tishreen University Journal for Studies and Scientific Research- Engineering Sciences Series Vol. (28) No (2) 2006 DMT VDSL

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1 Tishreen University Journal. Eng. Sciences Series 2006 (2) (28) 2006 (2) (28) _ Tishreen University Journal for Studies and Scientific Research- Engineering Sciences Series Vol. (28) No (2) 2006 DMT VDSL * ** *** (2006/12/ / 4 / 12 ) ( Discrete Multitone) DMT CAP (Carrier less Amplitude &Phase Modulation).(Very High speed digital subscriber line) VDSL DMT..VDSL DMT DMT simulation ( DMT ) FMT (Filtered Multitone Modulation). FMT :. DMT (Discrete Multitone). CAP (Carrierless Amplitude & phase Modulation). - VDSL (Very High Speed digital subscriber line ). DMT FMT(Filtered Multitone Modulation). _ _ _. _ _ _ _ **. _ _ _ _ *** * 5

2 VDSL DMT 2006 (2) (28) _ Tishreen University Journal for Studies and Scientific Research- Engineering Sciences Series Vol. (28) No (2) 2006 DMT Modulation is the Best Option for Digital Subscriber Line VDSL (Received 12 / 4 / Accepted 14/12/2006) ABSTRACT Dr. Shahada al Mwssa * Dr. Moieen Yonees ** Wael hassan sakr *** This paper explains reasons for choosing DMT modulation versus CAP modulation as a better option for a very high speed digital subscriber line VDSL. It also illustrates the role of DMT modulation in increasing data bit-rate by increasing data bandwidth in order to make the internet a universally accessible "information superhighway" and support the more demanding web-based applications, being potential sources of revenue. This paper also studies the essence of both modulations and the strengths, weaknesses of each; it includes an analysis of line conditions and other practical matters which explain why DMT is a better option for VDSL system setting. Finally, this paper also includes a simulation of transmitted DMT signal over digital subscriber line with and without filter, and an implementation of FMT (Filtered Multi Tone modulation) system for FMT transmitter and receiver. Key words: DMT: (Discrete Multitone) CAP : (Carrierless Amplitude & Phase Modulation) VDSL: (Very High Speed Digital Subscriber Line) FMT: (Filtered Multitone Modulation) * Professor, Department of Communication Engineering, Faculty of Electrical Engineering, Damascus University, Syria. ** Associate Professor, Department of Communication Engineering, Faculty of Mechanical and Electrical Engineering, Tishreen University, Lattakia, Syria. *** Postgraduate Student, Department of Communication Engineering, Faculty of Mechanical and Electrical Engineering, Tishreen University, Lattakia, Syria. 6

3 Tishreen University Journal. Eng. Sciences Series 2006 (2) (28) :. ( ).. POTS. 56Kb / s 4KHz.1MHz.DSL : -1 xdsl POTS. DSL. video on demand DSL (interactive TV). Cable TV (CATV) 1995 (WWW) :. 7

4 VDSL DMT LAN to LAN. ATM VDSL VDSL. [5] : ADSL. *. *. * IC : VDSL. (SCM) Single carrier modulation -. (MCM) Multi carrier modulation - (QAM).(CAP) (DMT). : :CAP 1-2 (Quadrature Amplitude Modulation) QAM CAP. PAM QAM. QAM CAP [ 1].CAP (2) (1). b b,... 1, 2 b n & a a,... 1, 2 a n. 8

5 Tishreen University Journal. Eng. Sciences Series 2006 (2) (28) a n (1). b n a n D / A b n.cap (1) a n A / D b n.cap (2) (Hilbert pair) h`(t), h(t) (λ 2 ) h`(t), h(t). ( λ 2) ( h`(t)* h(t) = 0 ) h`(t), h(t).(2).(1) 9

6 VDSL DMT ( ). a b n, n ( ) h`(t) h(t).. g`(t), g(t) CAP.CAP [ 2]:CAP xdsl. *.AT&T * *.DMT *. *.( ) * [ 2]:CAP downstream *.DMT *. * - N DMT :DMT DMT.(FFT) (IFFT) [ 1].DMT (3) (4) 1 محول تسلسلي تفرعي لمعطيات الدخل مرمز DMT 2 N IFFT D/A. DMT (3) 0

7 Tishreen University Journal. Eng. Sciences Series 2006 (2) (28) 1 A/D FFT 2 N محول تفرعي تسلسلي لمعطيات الدخل فاك ترميز DMT.DMT (4) N..(DMT) (QAM) N N DMT (IFFT). D/A DMT (SNR)...DMT (5) (4,5). DMT.. 1

8 VDSL DMT [ 2]: DMT ( ) ANSI DMT *. Upstream *. Downstream. *. *.CAP *. * DMT *. CAP [ 2].DMT ( ) DMT *. CAP.CAP AT&T *. DMT * : (SNR). (SNR) / DMT. DMT.. : CAP DMT QAM/CAP DMT. : 2

9 Tishreen University Journal. Eng. Sciences Series 2006 (2) (28) : *. DMT. CAP/QAM. DMT CAP/QAM *.. [3] [4] :VDSL DMT 1-3.VDSL DMT.Optimizing to each line : -1 : :. :.. AM : RF DMT 15 1 QAM... DMT ( ) SCM.QAM. DMT SCM..Operation on difficult channels : -2 CAP QAM. (bridged tap) DMT.( ) SNR. ( ) SNR. SNR 3

10 VDSL DMT DMT QAM /CAP. DMT..Resilience to Ingress : -3 VDSL CAP/QAM. AM RF.. RF. RF RF.( ) RF DMT...Ingress suppression : -4 VDSL CAP/QAM... DMT...Immunity to impulse noise: -5 DMT..250µs DMT 5µs FFT.( ) FFT. DMT. CAP/QAM DMT DMT. DMT. Forword Error (FEC).Corection CAP/QAM CAP/QAM. 4

11 Tishreen University Journal. Eng. Sciences Series 2006 (2) (28) (FEC)..Adaptability to changing condition : -6 CAP/QAM DMT.. CAP/QAM DMT (6db)...Support of required data rates : -7 CAP/QAM ( coarse granularity ) CAP/QAM DMT CAP/QAM. DMT... DMT.Power consumption: -8 DMT CAP/QAM... VDSL. VDSL DMT / (DSP).. VDSL (1watt) VDSL.2.5W 1.8W QAM CAP.Interoperability with ADSL :ADSL -9 VDSL DMT DMT VDSL. ADSL VDSL.ADSL Khz ADSL DMT VDSL (Asymmetric Digital Subscriber Line ).. 5

12 VDSL DMT ADSL.VDSL.meets the(peak to average) PAR demands :PAR -10. PAR PAR.PAR DMT.. PAR DMT CAP/QAM.12dB CAP/QAM 15 db PAR DMT.PAR DSP DMT/VDSL DMT PAR.3dB PAR.. (CAP/QAM) VDSL : DMT (MCM) (FFT) (MCM)... (ISI). (MCM).( ) (QAM). OFDM DMT :OFDM DMT 1-4 [6]:(1) 6

13 Tishreen University Journal. Eng. Sciences Series 2006 (2) (28). * k 2N N-1 DMT. Χ( t). th K th I QAM K X J j OFDM.sinc (f) h(n). (6).FTT OFDM DMT.OFDM DMT (6) T.. (QAM).. 7

14 VDSL DMT Sinc( f ) (FDM) ADSL (7).Downstream Upstream ADSL..(8). ADSL (7). ADSL (8) 8

15 Tishreen University Journal. Eng. Sciences Series 2006 (2) (28) (MCM) :(FMT) :(FMT) 2-4 FMT (9) (2N) (Up sampling) FFT.(2N) (9) X 1 k ( n ) = X h J j ( n 2 kn ) 2 N K = [6]:(2) FMT 2 N 1 j = 0 (2) For j = 1,.2N-1 : X K J X 0 k 2 N j = X K J * For j = 0,N. * h i ( n) FIR [6]: h( n) 2 Π nj 1 j 2 N h j ( n ) = h ( n ) e 2 N (3) 9

16 VDSL DMT 2γN. FIR h( n) (3). γ n h i * i` ( n) h ( n 2Nk) [6]. (4) = δ δi i i` (4) For 0 i, i 2N-1 and k =0, - 1, 0, 1.Kronecker - δ i (4) sinc (1) DMT DMT. [6].(5) otherwise H jπ ft ( e ) = { T f T For 2 2 (5). (5).γ = 14 FMT (10).Blackman.Blackman γ = 14 FMT (10) [6] :FMT 3-4 0

17 Tishreen University Journal. Eng. Sciences Series 2006 (2) (28) FIR 2N (9).γ N 1 FMT.(11). 2γN h i (m) FIR IFFT DMT. 2γN h(n) h i (m) ( m ) = h ( 2 mn i ) h i + (6) k X 0 h 0 ( m ) k X 1 k X 2N 1 2N IFFT h 1 ( m) h ( 2 N 1 m ) P/S X(n).FFT FMT (11).FMT (12) ISI. ICI.(12) :.(FDM). DMT. k X 1 ' h * 0 ( m ) EQ 1 Y(n) S/p * ( h 1 m) 2N FFT EQ 2 k X ' 2 k X ' N * h2 N 1 ( m ) EQ N.FFT FMT (12) 1

18 VDSL DMT : -5 DSL DMT/CAP -1 1 MHz. ATM DSL -2. IC DMT CAP DMT -3 ADSL VDSL.xDSL VDSL.. MCM FMT -4. FMT. γ DMT.γ. : [1]- NEXTEP Broadband White paper, - "xdsl Modulation Techniques, methods of achieving spectrum-efficient modulation for high quality transmissions". Modulation Techniques,May [2]- GORDON, J.reesor Zarling semiconductor "10 reasons to choos DMT fo VDSL design". May 14, [3]- ILHAVY, P. "filtered multitone modulation", ing.pavel ILHAVY, Ph.D.Brno University of technology faculty of electrical engineering and Communication, Czech Republic file://a:\filtered multitone modulation.htm December 3, [4]- NEAL, J. "VDSL very high speed digital subscriber lines", march [5]- JOHNS, D. "other modulation techniques CAP, QAM, DMT ", University of Toronto, [6] Telecom Glossary, Links, Papers "Introduction to the Public Switched Telephone Network And To xdsl", Publicus@maway.com.. Dec [7] ITU-D, study groups 2, "Report on DSL technologies"

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