ADSL.VDSL and Multicarrier Modulation.John A.C.Bingham Copyright 2000 John Wiley Sons,Inc. Print ISBN 0-471-29099-8 Electronic ISBN 0-471-20072-7 2 ADSL NETWORK ARCHITECTURE. PROTOCOLS,AND EQUIPMENT A.J.Weissberger P.O.Box 3441,Santa Clara,CA 95055-3441,E-mail:alan @lambdanetworks.com 2.1 ADSL ADVANTAGES AND APPLICATIONS ADSL is attractive to both telcos and users,because it solves two problems simultaneously: 1.It provides a simple,affordable mechanism to get more bandwidth to end users:both residential and small-to medium-size business.This is increasingly important for Internet access,remote access to corporate servers,integrated voice/data access,and transparent LAN interconnec- tion. 2.It enables carriers to offer value-added,high-speed networking services, without massive capital outlays,by“leveraging"the copper loop.Examples include access to frame relay or ATM networks,virtual private networks, video distribution,streaming,or video retrieval services. In North America,the driving applications of ADSL are high-speed Internet access and remote access to corporate LANs.Other applications include video retrieval or streaming,interactive multimedia communications,video on demand,video catalog shopping,and digital telephony:either voice telephony over ATM or voice over IP (VToA and VolP). In Asia and parts of Europe (e.g.,United Kingdom and Germany)video on demand (VoD)and audio playback are much more important than in the United States.Ironically,VoD was the ADSL application driver for North America in 1993 but has since been abandoned by most U.S.telcos.In Asia,however,where there is not as large an installed cable TV customer base,ADSL could be very important for video and audio distribution. 9￾          ! "#$%&&'()*+,*-.*/*(-0123224%&&'(546*7.8*.*+9.*6:;*+<,=#/>? @#6 ￾AB CDEFCDGCHICJKECHDCLLFMNCIMOHE PQRSTUVWWXVYWTZ[W\]\W^W[_Y\UV`abU[XUc][YVbU[TWU\_Z[UWd\eX\]_[fU UTfb_WV`[\bU_gh ijkWeX\ZTa[UVUTfe_[cVll\XaV]_[f[Y^V`TUfW\m[Wf\X[]V`adTaW^W\[`a bU[XUh]\W^X[UTa[`WTV_V`aUfV__nW\f[aTbfnUTo[]bUT`[UUjp^TUTU T`YX[VUT`m_gTfe\XWV`Wl\Xk`W[X`[WVYY[UUcX[f\W[VYY[UUW\Y\Xe\XVW[ U[XZ[XUcT`W[mXVW[aZ\TY[qaVWVVYY[UUcV`aWXV`UeVX[`WSPrT`W[XY\``[Yn WT\`j sjkW[`V]_[UYVXXT[XUW\\ll[XZV_b[nVaa[ac^Tm^nUe[[a`[Wd\XtT`mU[XZTY[Uc dTW^\bWfVUUTZ[YVeTWV_\bW_VgUc]guu_[Z[XVmT`mvvW^[Y\ee[X_\\ejwxVfe_[U T`Y_ba[VYY[UUW\lXVf[X[_Vg\XPpy`[Wd\XtUcZTXWbV_eXTZVW[`[Wd\XtUc ZTa[\aTUWXT]bWT\`cUWX[VfT`mc\XZTa[\X[WXT[ZV_U[XZTY[Uj k`r\XW^Pf[XTYVcW^[aXTZT`mVee_TYVWT\`U\lPQRSVX[^Tm^nUe[[ak`W[X`[W VYY[UUV`aX[f\W[VYY[UUW\Y\Xe\XVW[SPrUjzW^[XVee_TYVWT\`UT`Y_ba[ZTa[\ X[WXT[ZV_\XUWX[VfT`mcT`W[XVYWTZ[fb_WTf[aTVY\ffb`TYVWT\`UcZTa[\ \` a[fV`acZTa[\YVWV_\mU^\eeT`mcV`aaTmTWV_W[_[e^\`gh[TW^[XZ\TY[W[_[e^\`g \Z[XPpy \XZ\TY[\Z[Xk{|}p\PV`a}\k{~j k`PUTVV`aeVXWU\lwbX\e[|[jmjc`TW[a€T`ma\fV`a[XfV`g~ZTa[\\` a[fV`a|}\Q~V`aVbaT\e_Vg]VYtVX[fbY^f\X[Tfe\XWV`WW^V`T`W^[`TW[a RWVW[UjkX\`TYV__gc}\QdVUW^[PQRSVee_TYVWT\`aXTZ[Xl\Xr\XW^Pf[XTYVT` i‚‚ƒ]bW^VUUT`Y[][[`V]V`a\`[a]gf\UWjRjW[_Y\Ujk`PUTVc^\d[Z[Xcd^[X[ W^[X[TU`\WVU_VXm[V`T`UWV__[aYV]_[p}YbUW\f[X]VU[cPQRSY\b_a][Z[Xg Tfe\XWV`Wl\XZTa[\V`aVbaT\aTUWXT]bWT\`j „…†‡ˆ‰…†‡ˆŠ‹ŒŽ‘’Š‘•ŒŽŠ‘•‹j\^`PjjT`m^Vf \egXTm^W™ sššš\^`›T_[gœR\`Uck`Yj {XT`WkRršnžins‚š‚‚nŸ w_[YWX\`TYkRršnžinsššžsnž