AN
EXPERT SYSTEM APPROACH FOR
THE
DESIGN
OF
CABLE NETWORKS
IBigo Monede o Ca los Leon Robe Denda
School
o
Compu e
School
o
Compu e
Endi el
Endesa:
Science and
Enginee ing
Science
and
Enginee ing R&D Depamnen
Elec onic Technology
Elec onic
Technology
Wo ld
T ade
Cen e
lsla
de
la
Cmja
s/n
41012
Se ille(Spain) 41012 Se ille
(Spain)
41092Se ille(Spain)
Dep;uimen
Depa men
A da,
Reina
Me cedes
sin
A da,
Reina
Me cedes sin
Abs ac
-
The aim o his pape is o show he u ili y
o
expe
sys ems in he ask o designing cable ne wo ks. A Endi el
Endesa' we a e cu en ly de eloping a p ojec called Da acab in
collabo a ion wi h he Elec onic Technology Depa men o he
Uni e si y o Se ille. Da acab is an expe sys em o au oma ic
ou ing and posi ioning o he elemen s o bo h he ci il design
and he cabling o a cable elecommunica ion ne wo k. I uses
as inpu da a om a GIS (Geog aphic In o ma ion Sys em) and
ob ains
an
op imal design by applying a speci ic design ules
da abase. Da acah's ep esen a ion o he geog aphic
in o ma ion is en i ely based
on
g aphs. Among he
ad an ages o he p oposed expe sys em app oach is he
possibili y o add new ules o o modi y p esen ules easily i
design c i e ia change.
I.
INTRODUCTION
A.
Expe
Sys ems
An expe sys em is a compu e p og am, which uses non-
nume ical domain-speci ic knowledge in o de
o
sol e
p oblems wi h a compe ence le el compa able wi h ha o a
human expe who is able o e icien ly sol e domain-
speci ic p oblems. Rule-based p og amming is one o he
mos commonly used echniques o de eloping expe
sys ems
[I].
In his p og amming pa adigm, ules a e used o
ep esen heu is ics,
o
" ules o humb, which speci y
a
se
o ac ions o he pe o med o a gi en si ua ion.
Expe sys ems ha e been success ully applied on
elecommunica ion ne wo ks
[2][3][4]
and, in gene al, o he
sea ch
o
op imal solu ions o p oblems o g aphs
[5].
Since
a cable ne wo k's opology can he s udied as a connec
g aph, i makes i pe ec ly sui able o applying such an
expe sys em app oach.
E.
Cable ne wo ks
Cu en cable ne wo ks a e ypically implemen ed as HFC
(Hyb id Fib e Coax) ne wo ks, whe e ansmission media a e
op ical ib es and coaxial cables, and po en ially
a
pa allel
elephony ne wo k.
I
All in ellec ual p ope y igh s o he p esen ed Sys em a e
hold by Endi el Endesa. Fo u he in o ma ion, please
con ac any one o he au ho s.
0-7803-7474-6102/517.00
02002
IEEE
Samuel Muiioz
JosC
Manuel Elena Joaquin Luque
Endi el
Endesa:
School
o
Compu e
School
o
Compu e
R&D
Depamnen
Science
and
Enginee ing Science
and Enginee ing
Wo ld
T ade
Cen e
Elec onic
Technology
Elec onic
Technology
Isla
de
la
Cmja
sin
41092Se ille(Spain)
41012
Se ille
(Spain) 41012 Se ille(Spain)
Depamnen
Depamn-Z"
A da,
Reina
Me cedes
sin
A da, Reina Me cedes
dn
The cable ne wo k s uc u e o he designed suppo s Cable
ele ision, In e ne access and elephony se ices. The ibe
op ic ne wo k is s uc u ed by a head-end connec ed o a
p ima y ne wo k, which con ains a numbe o main nodes
se icing be ween
30.000
o
90.000
homes each. These main
nodes a e connec ed o a ne wo k o se e al seconda y nodes
(seconda y ne wo ks), each o which se es a ound
10.000
homes. In gene al, he seconda y nodes also con ain
a
RTC
(Remo e Telephony Cen e ). The e ia y ne wo ks
(dis ibu ion ne wo k) connec o he seconda y node and
se ice abou
2.000
homes. E e y e ia y ne wo k ends in
ONTs (Op ical Ne wo k Te mina ion), which a e connec ed
o a Coax Ne wo k. This Coax Ne wo k inally dis ibu es
he signal o subsc ibe s.
The Telephony Ne wo k ypically s a s a each RTC and has
h ee le els. The i s le el connec s each RTC o a ONT, he
second le el eaches each package o homes, and inally, he
hi d le el connec s he subsc ibe s' homes.
C. Da acab
Da acab is an expe sys em based on ules
o
au oma ic
ou ing o a HFC elecommunica ion ne wo k as well as i s
co esponding ci il design. Da acab will be applied o
a ious cable communica ion ne wo ks wi h an a e age o
mo e han
200.000
use s each.
Some o he ad an ages o he p oposed expe sys em
app oach a e he possibili y o adding new ules and o
modi y p esen ules easily i he design c i e ion changes.
Design ules can be s died in
a
di ahase in o de o imp o e
accessibili y; inally he de eloped sys em can he used o
ain new s a .
11.
DESIGNING DATACAB EXPERT SYSTEM
A.
Knowledge acquisi ion
The i s s ep in building an expe sys em is he knowledge
acquisi ion. I in ol es elici ing, analyzing, and in e p e ing
he knowledge abou he cu en ne wo k design. Se e al
echniques
o
ex ac ing expe knowledge ha e been
desc ibed in he li e a u e
[6].
We selec ed an app oach o
s uc u ed in e iews wi h he human ope a o s as he main
acquisi ion echnique. A s uc u ed in e iew is a
con e sa ion be ween he expe s and he knowledge
1899
enginee s. The di e ence be ween a s uc u ed in e iew and
a no mal mee ing is ha he knowledge enginee mus decide
on he ques ions and objec i es o discuss be o e he mee ing.
A specialized echnician was commended o ca ying ou
he expe wo k. Along
5
sessions om
1
o
2
hou s
we e
necessa y o build ou i s knowledge base. A ailable
demons a ions abou
HFC
sys em we e addi ionally used.
B. Knowledge Rep esen a ion
Once knowledge had been acqui ed, he nex s ep was i s
ep esen a ion. A class diag am and a ule-based sys em had
o be buil o i . The geog aphic elemen s wi h hei loca ion
and e-design in o ma ion (i.e., possible accc:ss o
accommoda ions, p e ious channel loca ions, non-pe mi ed
aqades
...)
a e s o ed in he
GIS
applica ion.
Class diae am
The class diag am o Da acab was designed wi h he help
o
he Ra ional Rose ool using an
UML
app oach
[7][S]
and
is
composed o
7
packages, which a e linked in he way shown
in ig.
1.
I includes he geog aphical elemen s ((s ee s,
buildings...), e-design in o ma ion (buildings accesses..
.),
coax elemen s (wi es, ampli ie s
...)
and ci il elemen s
(caske s, channels
...)
in addi ion o supe classes o all he
p e iously men ioned elemen s (poin -class, coax-class...).
These supe classes we e c ea ed o gene alize some common
p ope ies o
ou
objec s such as dis ances in linea elemen s
and signal losses in elemen s o he coax ne wo k.
Fig.
1. Package diag am
The
Ke nel
package is made up by he knowledge classes,
e.g., he algo i hm-class. All o Da acab's classes a e de i ed
om one supe class called
Cis
om he
BaseType
package
(see ig.
2).
This class emb aces he main shapes. o he
geog aphical elemen s: poin , segmen and a ea. On he o he
hand, in he
Map
package a e he classes ela ed
o
ci y
elemen s: buildings, blocks, s ee s, oads, pa ks and
:io
o h.
Fig.
2.
BaseTpe package
The
Coax
]package has a supe class called
Coax,
which
con ains h ee classes co esponding o he ype
o
coax
elemen : pa,isi e componen (i.e., wi es), ac i e componen
(ampli ie s) and powe sou ce ( o eed ac i e componen s).
The di e en passi e componen classes o he coax design
a e shown in ig.
3.
In his example ( ig.
3),
he ad an ages o
he inhe i ance can he seen: inhe i ed classes om
Passi e
ge he cha ac e is ics om coax elemen s and hei
geome ic d:i a.
Fig.
3.
Coax passi e elemen s
Finally, he design o he ci il componen classes is made up
by a main class called
Ci il.
Simila ly o he o he
supe classej,
Ci il
has wo child classes depending on hei
cha ac e is ics, dis inguishing segmen s and poin s. The i s
class inhe i s om
Segmen
whe eas he second one om
Poin .
Da acab will ins an ia e one copy o each di e en child class
o he coax diag am and ci il diag am and he a ibu es wi h
echnical cha ac e is ics a e illed in acco ding o hei
cons uc o ia da abase accesses.
Da acab's da abase con ains all he cha ac e is ic da a o he
ne wo k elimen s as well as hei subg oups used o he
co esponding ci y
o
zone. The adminis a o only has o
change he da abase o upda ing Da acab.
1900
Rules-based s s em
Ou knowledge base
is
a
ules-based sys em: he knowledge
is
ep esen ed in he o m o IF
...
THEN ypes ules (p emises
and conclusions), ac s and assump ions abou he p oblem.
This easoning sys em was chosen o e o he s (e.g., case-
based easoning) due o he ac ha he al e na i es in he
cable ne wo k design a e subjec o ules.
So,
when an
expe ca ies ou he design, he guides himsel by p io i y
ules and expe ience, wi h he main pu pose o eaching
e e y subsc ibe homes o u u e subsc ibe homes. Some
ules in ou ing phases a e shown
in
able
I
and he code o
an example one
in
able
XI.
Cu en ly, ou sys em con ains
abou
80
ules.
be
P io ih,w
SESS-OI max
SESS-02 mid
SESS-03 min
111. DATACAB EXECUTION PROCESS
A. Phases
Da acab achie es he ou ing
o
he HFC ne wo k h ough
di e en phases. The di e en phases o Da acab's execu ion
a e shown
in
ig.
4.
Fo coding o hese phases we used a
powe ul ool o expe sys ems called A 'En e p ise.
The i s and he las p ocess o he execu ion diag am (GIS
In e p e e ) a e ela i ely simple due o he ease o he
GIS
ool o expo da a o a desi ed o ma . As a esul , he
in e p e e module gene a es a ile wi h he
GIS
in o ma ion
acili a ing he con e sion p ocess.
The a ibu es o he geog aphical elemen s a e speci ied in
ou class diag am and he objec s c ea ed in he second s ep
a e ins ances o hese classes.
I
GIS
In o ma ion
Cable o e apade
is
be e han cable
ia ubes.
Cable ia ubes unde asphal is be e
han unde pa emen .
The highe he sa ings in cable he
TABLE
I
SOME
RULES FROM
DATACAB
SEDC-02 mid Cable p e e ed i i does no c oss
a enue o Main S ee .
I
be e .
Dynamic (dependen o p e iously selec ed edges)
be
SEDC-01
I
max
I
No
cycles in he g aph
o
ou cable
I
I
I
edges he be e
I
TABLE
II
CODE
OF
SESS-OI
RULE
le ine- ule SESS-01
(decla e (salience
900))
(objec ?algo i hm (ins ance-o algo i hm500-1)
(phase s a ic-cos )
(CS ?node-lis )
(RS
?non-node-lis ))
(ins ance-o dcs ee ))
(ins ance-o dc:non- aqade))
(objec ?s ee 1
(objec ?s ee 2
( es (no (equal ?s ee 1 ?s ee 2)))
( es (no (membe $ ?s ee 1 ?node-lis )))
( es (no (membe $ ?s ee 1 ?non-node-lis )))
( es (supe imposed ?s ee 1 ?s ee 2))
(add-amihu e- alue ?algo i hm CS 7s ee l))
=>
Da acab
In o ma ion
C ea ion
o abjec
Coax
and
Ci il
Solu ion
.(
GIS Solu ion
Fig.
4.
Execu ion diag am o Da acab
E.
Rou ing algo i hm
The
Ke neI
package (see ig.
1)
has embedded he
Ke nel
supe class and
Algo i hm
class. These classes, which make
up he knowledge base, ake ca e o i ing he ules in e e y
phase o he algo i hm'. Besides, he esul s a e s o ed
in
he
class
Algo i hm.
The ke nel algo i hm, cu en ly unde de elopmen , will he
made up o phases each one
o
which will i e
a
g oup o
ules. The i s design idea o he algo i hm consis s o i s
pe o ming he cable ne wo k ou ing, and hen loca ing hee
coax and ci il elemen s.
In
he case ha i u ns ou o be
1901
impossible o place he elemen s wi hin one single cable
ne wo k ou ing,
i
will be ca ied ou du ing a second
ou ing.
The i s s age o he sea ch algo i hm will be based
on
he
K uskal’s algo i hm [9], which
is
a his o ical minimum
expansion ee sea ch algo i hm. These algo i hms ha e a
connec ed g aph as inpu and gene a e a ee co e ing he
whole g aph wi h he lowes possible cos .
In
pa icula ,
K uskal’s algo i hm selec s he lowes cos edge in each one
o he i e a ions, as
long
as his does no gene a e any cycles.
The di e ence be ween K uskal’s algo i hm and ou
algo i hm is in he dynamic cha ac e is ic o he la e one.
While he edge cos in K uskal’s algo i hm does no depend
on
he p e iously selec ed edges, in
ou
algo i hm . he cos
will he allowed o a y. The di e en phases o he algo i hm
o Da acab a e shown in ig.
5.
places-
coax-elemen s
esal s-edges-
by-s a ic-cos
phases
o
he ne wo k ou ing ha e been implemen ed. We
a e cu en ly de eloping he s age o he p ojec ha will
allow
us
o place he coax and ci il elemen s acco ding o he
es ablished ules and signal le el calcula ions.
Besides, we a e p epa ing a es me hod ( alida ion p ocess).
Once inalized hese phases, an expe will e i y he co ec
ne wo k dasigns ca ied ou by Da acab ( e i ica ion
p ocess).
calls
GIS
In e p e e
Fig.
6.
Example o ou ing ob ained o a cable ne wo k
V.
REFERENCES
[I]
E.M. A ad. “Building Expe Sys ems”. Wes Publishing
Company, 1996.
[2] C. Le6n, M. Mejias,
J.
Luque y
F.
Gonzalo. “Expe
sys em o he in eg a ed managemen o
a
powe u ili y’s
communicai:ion sys em”.
IEEE
T ansac ions
on
Powe
Deli e y,
ol. 14,
no
4,
pp, 1208-1212, Oc . 1999.
[3] Jay Liehowi z ed:
“The handbook
o
Applied Expe
Sys ems”.
CRC P ess, 1998.
[4]
I.
Vlahu. as e al. “Expe Ne : An In elligen Mul iagen
Sys em o WAN Managemen ”. IEEE In elligen Sys ems,
ol.
17,
n”4, pp. 62-12,2002.
[5]
E. Cas illo,
J.
Gu ie ez, A1i.S Hadi. “Sis emas Expe os y
Modelos da Redes P obahilis icas”. Monog a ias de la
Academia EspaRola de Ingenie ia, Mad id, 1998.
[6] K.L. McG aw and
K.
Ha hison-B iggs. “Knowledge
acquisi ion: P inciples and guidelines”. P en ice-Hall,
Englewood Cli s, N.J.
[7]
G.
Booch,
J.
Rumbaugh and I. Jacobson. “UML. El
Lenguaje Uni icado de Modelado”, Addison Wesley, 1999.
[8] W. Boggs, M. Boggs. “Mas e ing UML wi h Ra ional
Rose”,
Sybex Inc,
1999.
[9]
R.
Sedgewick “Algo i mos
en
C++”.
Addison Wesley
Ibe oamenca, 1995.
1902