Da acab: a geog aphical-in o ma ion-sys em-
based expe sys em o he design o cable
ne wo ks
In
˜ igo Monede o,
1
Ca los Leo
´ n,
1
Robe Denda
2
and
Joaquı´n Luque
1
(1) Escuela Te
´cnica Supe io de Ingenie ı
´a In o ma
´ ica, Depa amen o de Tecnologı
´a Elec o
´nica, A da Reina Me cedes s=n, 41012 Se illa, Spain
E-mail: [email p o ec ed]
(2) Manage o Technology Se ices, Endesa Ingenie ı´a, Edi icio Expo, Isla de la Ca uja s=n,
41092 Se illa, Spain
E-mail: [email p o ec ed]
Abs ac : Telecommunica ion ne wo ks ha e e ol ed o e ime as a esul o echnological ad ances, and ne wo k
opologies and equipmen ha e become inc easingly complex. Expe sys ems a e being success ully applied o he
managemen o elecommunica ion ne wo ks. Howe e , applying expe sys ems o ne wo k design is ano he
especially beneficial ye s ill no e y common app oach. In his pape we p opose a ule-based expe sys em called
Da acab. Da acab was de eloped a Endi el Endesa in collabo a ion wi h he Elec onic Technology Depa men o
he Uni e si y o Se ille, o he au oma ic design o hyb id fib e coax (HFC) cable ne wo ks. Using da a om
a geog aphical in o ma ion sys em as inpu , i au oma ically gene a es iable HFC ne wo k designs.
Keywo ds: elecommunica ion ne wo ks, expe sys em, HFC ne wo k, GIS
1. In oduc ion
As a esul o he g ea echnological e olu ion
ha has aken place in elecommunica ions, i is
possible o communica e and access in o ma-
ion apidly, ia elephony and communica ion
ne wo ks such as he In e ne . Telecommunica-
ion ne wo ks ha e e ol ed o e ime o sa is y
he demands o di e en communica ion se -
ices, con inuously equi ing g ea e band-
wid h and a be e quali y o se ice. Ne wo k
echnology has inc eased in complexi y, gene -
a ing he need o a be e adminis a ion o
he esou ces o hese sys ems, which has os-
e ed he e olu ion o ne wo k managemen
sys ems.
On he o he hand, esea ch ca ied ou in he
field o a ificial in elligence has led o impo an
ad ances in he ea men , s o age and exploi -
ing o knowledge. These ad ances include he
field o knowledge-based expe sys ems (Bucha-
nan & Duda, 1982; Liebowi z, 1998; Ignizio,
1991; Awad, 1996; McG aw & Ha bison-B iggs,
2002).
Expe sys ems a e being success ully applied
o he ealiza ion o di e se asks (in e p e a-
ion, p edic ion, diagnosis, design, planning,
ins uc ion, con ol e c.) in mul iple fields such
as medicine, geology, chemis y and enginee ing
(Liebowi z, 1998). Expe sys ems may also
be applied o he field o elecommunica ion
ne wo ks, because many o he p e iously
enume a ed asks equi e specialized knowledge
and a e needed o he managemen and ope a-
ion o hese ne wo ks, which can be au oma ed
by an expe sys em.
Among hese asks is he one o ne wo k
design, which in pa icula equi es he knowl-
edge o expe s. This pape desc ibes an expe
sys em called Da acab o he au oma ic design
o cable ne wo ks. The aim o Da acab is o sa e
ime and wo k du ing he ask o designing a
cable ne wo k. The pape fi s gi es an in oduc-
ion o he s a e o he a o expe sys ems
applied o elecommunica ion ne wo ks; sec-
ond, he hyb id fib e coax (HFC) ne wo k
s uc u e o which Da acab has been applied is
p esen ed, and las ly, he s uc u e and design o
Da acab as well as a base case and expe imen al
esul s a e desc ibed.
2. Applica ions o expe sys ems o
elecommunica ion ne wo ks
Figu e 1 schema ically shows he di e en
applica ion domains o expe sys ems ela ed
o elecommunica ion ne wo ks (Liebowi z,
1988; ITU-T, 1991). The e ficiency o he asks
o ope a ion and main enance o cu en ele-
communica ion ne wo ks la gely depends on
he deg ee o coope a ion be ween he manage-
men sys em and he human ope a o s. The
managemen sys em plays a e y impo an
pa , in o ming on possible anomalies and
execu ing he commands o con ol.
The di e en asks in ol ed in his manage-
men and o which comme cial expe sys ems
cu en ly exis a e as ollows.
Failu e managemen . This ask e e s o he
g oup o unc ions ela ed o ne wo k man-
agemen necessa y o he de ec ion, diagno-
sis, eco e y and co ec ion o sho comings
o he elemen s ha o m a elecommunica-
ion ne wo k. Examples include Max and
Op i-Max (an expe adminis a o o ele-
phony line main enance de eloped by
NYNEX) (Rabinowi z e al., 1991), T ouble
Loca o (an in elligen sys em de eloped by
Pacific Bell o loca ing ailu es a he physi-
cal le el o a local elephony ne wo k) (Chen
e al., 1996), ANSWER (an expe sys em
de eloped by AT&T and in cha ge o supe -
ising hei 4ESS swi ches) and Scou (de el-
oped by AT&T o iden i ying pe sis en
ailu es in he ne wo k) (Raman, 1999).
Configu a ion managemen . This unc ion
helps he adminis a o o exe cise con ol
on he configu a ion o he componen s o
he ne wo k. Changes in he configu a ion
a e ca ied ou o elimina e conges ion, o
isola e sho comings o o make changes
equi ed by use s. Examples o expe sys-
ems suppo ing configu a ion managemen
include ECXpe (de ec ion and epa a ion
o ailu es, de eloped by Lucen Technolo-
gies) (Raman, 1999), ACE (an expe sys em
de eloped by AT&T o help in he de ec ion
and diagnosis o ailu es in cables) (Liebo-
wi z, 1988) and NEMESYS (also de eloped
by AT&T o a oiding ne wo k conges ion)
(Raman, 1999).
Accoun ing managemen . This unc ion al-
lows posi ions and cos s o he use o he
esou ces o he ne wo k o be de e mined
and loca ed, e.g. APRI (de eloped by AT&T
o o ecas ing he p obabili y o alling in o
new deb ) (Ezawa & No on, 1996).
P esen a ion managemen . This ask helps
he ne wo k adminis a o s o moni o and
e alua e he benefi s o he sys em. Example
Failu e managemen
Con igu a ion managemen
Ne wo k managemen Accoun ing managemen
P esen a ion managemen
Secu i y managemen
Expe sys ems
applied o
Use in e aces
Final use applica ion
Communica ion sa elli es
Ne wo k design
P o ocol e i ica ion
Rou ing
Figu e 1: Expe sys ems in elecommunica ion
ne wo ks.
expe sys ems o p esen a ion managemen
a e Ne =Ad iso and Ne Command ( o
moni o ing he s a e o he ne wo k in eal
ime) (Raman, 1999).
Secu i y managemen . This unc ion helps
he ne wo k adminis a o s manage he se -
ices ha p o ide p o ec ion in he access o
he communica ion esou ces. Examples o
expe sys ems ela ed o secu i y manage-
men include EXSYS (a se o expe sys ems
de eloped by Pacific Bell which execu es on
an AT&T 3B2=600 compu e o supe ising
he loop main enance ope a ing sys em om
a se e ) (Raman, 1999).
In addi ion, he e exis o he expe sys ems
such as Ne HELP (which p o ides assis ance
o use oubleshoo ing) and ExSim (assis ance
in he p ocess o ou ing a ne wo k) applied
o o he fields (Raman, 1999), enume a ed in
Figu e 1.
The e is an especially in e es ing ye less
in es iga ed field o he applica ion o expe
sys ems o he wo ld o elecommunica ion
ne wo ks: sys ems applied o assis du ing he
asks o ne wo k design. Wi hin he design
p ocess, he use o knowledge-based sys ems is
o pa icula in e es o he opological design
o he ne wo k. Among hese asks a e he
ollowing:
 he choice o he ype o ansmission: ans-
mission by physical suppo (cable, mic o-
s ip, wa e-guided) and=o ansmission by
adio (elec omagne ic wa es).
 he layou o he ne wo k: in adio ne wo ks
i would be necessa y o es ablish he
layou depending on he ype o communica-
ion (bidi ec ional o omni-di ec ional)
and signal p opaga ion and in e e ence
cha ac e is ics. In cable ne wo ks, his ask
comp ises he p ocess o cable layou .
placemen o he ne wo k elemen s: es ablish-
men and localiza ion o he di e en nodes
and necessa y elemen s in o de o ob ain a
sui able signal le el (spli e s, amplifie s
e c.).
The las wo asks in pa icula equi e he wo k
o expe s who apply a ious design ules and
hei empi ical knowledge. Because o he g ea
numbe o limi a ions o he physical media,
hese asks a e pa icula ly complex in cable
ne wo ks.
On he o he hand, due o he e y specific
cha ac e is ics o he design ules o each ne -
wo k, as well as he high complexi y o he
applica ion o he knowledge, he de elopmen
and comme cial use o expe sys ems o cable
ne wo k design is s ill no e y widely ex ended.
Thus, he cu en ly exis ing app oaches mainly
ocus on esea ch (Lo & Ghau i, 1991; Wu &
Lee, 1993; El-Fishawy & Khamis, 2000). In
some cases, he design is only pa ial (Lo &
Ghau i, 1991); o he app oaches (Wu & Lee,
1993; El-Fishawy & Khamis, 2000) a e limi ed
o he design o local ne wo ks. In his pape we
p opose an expe sys em o he comple e de-
sign o a cable ne wo k.
3. The HFC cable ne wo k
A ypical cable ne wo k, which co e s a med-
ium-sized ci y, consis s o an HFC ne wo k ha
is made up o an op ical fib e ne wo k and i s
con inua ion in o a coax ne wo k. Po en ially, a
pa allel elephony ne wo k is deployed (Tun-
mann, 1995; O adia, 2001).
The cable ne wo k s uc u e suppo s cable
ele ision, In e ne access and elephony se -
ices; i is ep esen ed in Figu e 2. The s uc u e
Main nodes
30.000 o 90.000
Fib e P ima y
Ne wo k
Seconda y nodes
2000 homes
Seconda y Ne wo k
ONT
ONT
ONT
Fib e
Op ical Ne wo k
Te mina ion
500 homes
Dis ibu ion Ne wo k
Remo e Telephony
cen e
Figu e 2: The HFC ne wo k o be designed.
o he ne wo k depends on each coun y and
ope a o , bu ypically a fib e op ic ne wo k is
made up o a head-end connec ed o a p ima y
ne wo k, which con ains a numbe o p ima y
nodes, e.g. se icing be ween 30,000 and 90,000
homes each. These main nodes a e connec ed o
a ne wo k o se e al seconda y nodes (second-
a y ne wo ks), each o which ypically se es
a ound 10,000 homes. In gene al, he seconda y
nodes also con ain a emo e elephony cen e
(RTC). The e ia y ne wo ks (dis ibu ion ne -
wo ks) connec o he seconda y node and end
in op ical ne wo k e mina ions (ONTs), which
a e connec ed o a coax ne wo k. This coax
ne wo k finally dis ibu es he signal o he
subsc ibe s.
The elephony ne wo k ypically s a s a each
RTC and has h ee le els. The fi s le el con-
nec s each RTC o an ONT, he second le el
eaches a g oup o homes and, finally, he hi d
le el connec s wi h he subsc ibe s’ homes.
In Figu e 3, a ep esen a ion o a ypical coax
a ea o a cable ne wo k ex ac ed om a geo-
g aphical in o ma ion sys em (GIS) (Heywood
e al., 1999; Ko e, 2001) is shown. In his figu e,
he buildings a e ep esen ed as shaded poly-
gons, he cables as lines, he connec ions as
small ci cles and boxes, and signal amplifie s as
iangles.
In he design o an HFC ne wo k he layou
o he fi s , seconda y and dis ibu ion fib e
ne wo ks a e no mally easy o ca y ou because
he loca ion o hei elemen s depends on he
a ailabili y o adequa e p emises. Thus, he pa
o he ne wo k ha pa icula ly equi es deep
expe knowledge du ing design is he coax ne -
wo k.
When a human designe ca ies ou a coax
ne wo k design he in many cases is only guided
by his expe knowledge and in ui ion, and e y
basic suppo ools. The designe wo ks his
way: wi h he help o specific so wa e which
eads and ep esen s he geog aphical in o ma-
ion om a GIS he begins he layou a he
ONT p og essi ely placing he cables and ele-
men s and ca ying ou he calcula ion o he
signal le el. I a some poin i is no possible o
each he desi ed signal le el on a pa icula
Figu e 3: Design o a zone o he cable ne wo k.
connec ion wi h he layou in p ocess, he de-
signe has o edesign all o a pa o he layou .
Following his commonly used app oach, he
a e age ime o p oducing a finished design o
an ONT zone o a ound 500 connec ions is
a ound 8 hou s.
4. Da acab: an expe sys em o designing a
cable ne wo k
4.1. In oduc ion
Da acab is an expe sys em we designed and
implemen ed based on ules o he au oma ic
design o an HFC elecommunica ion ne wo k
and which wo ks in an in eg a ed manne wi h a
GIS.
The majo ad an age o he p oposed expe
sys em app oach is he g ea educ ion o he
human wo k o ce needed o he design o he
HFC ne wo k. Wi h Da acab, ins ead o doing
he designs himsel , he human expe only has
o e i y he di e en designs gene a ed by
Da acab. Ano he impo an ad an age is i s
adap abili y, being possible o easily modi y he
knowledge base i he design c i e ia change,
and i s high in eg a ion, wo king as add-on
so wa e o he exis ing GIS. Finally, simila o
o he expe sys ems, he de eloped sys em can
be used o ain new s a .
The GIS in o which Da acab is in eg a ed is
GE SmallWo ld (Rigaux e al., 2002), a powe -
ul comme cial GIS wi h special deploymen in
he a eas o dis ibu ion ne wo ks like wa e ,
elec ici y, gas and elecommunica ion ne -
wo ks.
4.2. In e ac ion wi h GIS
Da acab pe o ms he design o he HFC
ne wo k h ough he phases ep esen ed in
Figu e 4.
Phase 1: Da acab p ocesses he geog aphical
in o ma ion co esponding o he zone o be
designed, adding i o i s knowledge base.
The inpu da a o he di e en elemen s o
he zone wi h hei loca ion and all edesign
in o ma ion (i.e. possible access o accom-
moda ions, p e ious channel loca ions, non-
pe mi ed ac¸ ades e c.) is ob ained om he
GIS.
Phase 2: By means o a g aph ep esen a ion
o he GIS elemen s o he zone and he
mechanisms o applica ion o he knowl-
edge, Da acab ca ies ou he necessa y cal-
cula ions o achie e an op imal solu ion o
he cable ne wo k design. P e iously, a da-
abase access is ealized in o de o ob ain
he di e en pa ame e s, such as he deg ee
o a enua ion o he cables o he gain o he
a ailable amplifie s o he di e en com-
me cial ne wo k elemen s ypically ins alled
by he HFC ope a o .
Phase 3: Da acab p ocesses he ob ained
in o ma ion, gene a es he ne wo k design
based on he ule da abase and p o ides he
GIS wi h he geog aphical in o ma ion o
he elemen s belonging o he cable ne wo k.
4.3. Design
Da acab’s a chi ec u e consis s, like mos expe
sys ems, o a knowledge base and an in e ence
engine. The knowledge base consis s o a class
s uc u e and a ule-based sys em which a e
desc ibed u he below. The in e ence engine,
which akes ca e o he fi ing o he ules, is
Da abase
o elemen s
GIS da a
Ci y in o ma ion Redesign da a
Da acab inpu
Da acab
da abase que ies
GIS da a
Ne wo k elemen s
Da acab ou pu
Figu e 4: Da acab’s in e ac ion wi h GIS.

ca ied ou by an expe sys em en i onmen
called ART*En e p ise which is desc ibed in he
coding sec ion. In addi ion, a salience mechan-
ism was de eloped and added o ule in e en-
cing. This mechanism makes i possible o fi e
he ules in he o de ha co esponds o he
p io i y defined o each ule.
We selec ed a knowledge ep esen a ion, ak-
ing in o accoun ha he p oblem was o med
by di e en ne wo k elemen s, and a se o ules
and condi ions necessa y o place hese elemen s
in he layou . These ules, which a e defined in
in e nal design guides and p ocedu es o he
company, we e s udied and defined du ing he
knowledge acquisi ion phase.
The geog aphic elemen s a e ep esen ed by
objec s acco ding o he class diag am o he
applica ion. The necessa y knowledge da a o
ca y ou he design is con ained in he ule-
based sys em. The me hods which execu e he
fi ing o he ules a e enclosed in a class called
dc:algo i hm (ke nel package).
4.3.1. Class diag am The class diag am o
Da acab was designed wi h he help o he
Ra ional Rose ool using UML (E iksson &
Penke , 1997; Booch e al., 1999) and is o med
o se en packages, which a e linked as shown in
Figu e 5. The class diag am includes geog aphi-
cal elemen s (s ee s, buildings e c.), edesign
in o ma ion (i.e. access poin s o buildings),
coax elemen s (wi es, amplifie s e c.), ci il ele-
men s (caske s, channels e c.) as well as he
elemen s co esponding o he elephony and
fib e ne wo ks, in addi ion o supe classes,
which 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.
The e is an impo an package called Base-
Type. This package ep esen s he g oup o
geome ic elemen s which a e inhe i ed by he
di e en elemen s om he map, ci il, adio
equency and ke nel packages. In Figu e 6 he
classes ha o m his package and ha a e
needed o deal wi h he geog aphic p ope ies
o he elemen s a e illus a ed. The class dc:
segmen ep esen s a segmen o geome ic
elemen s. An objec o his class is composed o
wo objec s o he class dc:poin , which ep e-
sen s a geome ic poin and which is cons i u ed
by a pai o coo dina es. The class dc:a ea
which ep esen s he elemen geome ic a ea is
Ci il
Coax
Fib e
BaseType
Ke nel
Map
global
Telephony
Figu e 5: Package diag am.
dc:gis
id : Enum{...}
s a e:Enum{...}
2..*0..*
dc:segmen
poin s : Se (Poin ) 0..*
dc:a ea
3..*
dc:poin
x : Floa
y : Floa
2..*0..*
Is o med by
0..*
3..*
Is o med by
<<o de ed>>
poin Lis : Sequence(Poin )
Figu e 6: BaseType package.
composed o a so ed lis o objec s o he
dc:poin class. Finally, he e is a class called
dc:gis om which all he men ioned classes
de i e.
The coax package has a supe class called
Coax, which con ains h ee classes co espond-
ing o he ype o coax elemen : passi e compo-
nen (i.e. wi es), ac i e componen (amplifie s)
and powe sou ce ( o eed ac i e componen s).
Thus, he ad an ages o inhe i ance a e impo -
an , o example, in classes inhe i ed om
passi e elemen s which ob ain cha ac e is ics
on he one hand om coax elemen s and on he
o he hand om hei geome ic da a. Se ing as
an illus a i e example, he class diag am o he
passi e elemen s is shown in Figu e 7.
Da acab includes a da abase o elemen s. This
da abase con ains all he cha ac e is ic da a om
he ne wo k elemen s o he co esponding ci y
o zone. Thus, o ins ance, i he company
changes a model o amplifie i is no necessa y
o ep og am Da acab bu simply o upda e he
da abase. In his way, Da acab will ins an ia e
one copy o each di e en child class o he
coax diag am and he a ibu es wi h echnical
cha ac e is ics a e filled in acco ding o hei
cons uc o ia da abase accesses.
4.3.2. Algo i hm When he geog aphic in o -
ma ion is ead om he GIS, each elemen o he
zone, like a s ee o a building, is con e ed in o
an objec o he class diag am and a connec ed
g aph is gene a ed. Ini ially we in es iga ed wo
al e na i es o he design o he algo i hm,
based on he no ion o algo i hms o design o
an expansion ee ela ed o a non-di ec ed
g aph (Sedgewick, 1992; Cas illo e al., 1997;
B a ko, 2001). The al e na i es we e as ollows.
The fi s al e na i e was based on he idea o
K uskal’s algo i hm, which selec s he edges
so ed by cos a oiding cycles in
he layou . K uskal’s algo i hm selec s he
lowes cos edge in each o he i e a ions, as
long as i does no gene a e any cycles.
The second al e na i e was based on he
unning o P im’s algo i hm, which s a s
om a poin and selec s se ial edges o
mino cos , building an expansion ee in
his way.
A e s udying and applying hese wo al e na-
i es o ou pa icula p oblem, and designing
p o o ypes based on bo h o hem, we decided o
implemen he fi s al e na i e which begins by
de e mining he layou and hen es ablishes he
si ua ion o he elemen s o adio equency. I i
is no possible o loca e he elemen s in he
selec ed ou e, a sea ch o a di e en ou e is
dc:poin
( om BaseType)
dc:passi e
Cu en Blocke dc:coaxcable
dc:segmen
( om BaseType)
Te minalCha geEqualise Tapdc:spli e
Figu e 7: Coax passi e elemen s.
ca ied ou and an a emp is made o eloca e
he elemen s.
No e ha when a human expe ca ies ou
he design o a ne wo k, he adio equency
elemen s a e placed a he same ime as he
layou is de e mined, which esembles mo e he
second algo i hm. Howe e , his app oach was
disca ded because o i s highe sys em equi e-
men s and because he fi s algo i hm p o ed o
esul in simila ly good design esul s.
The di e ence be ween K uskal’s algo i hm
and ou algo i hm lies in he dynamic cha ac e -
is ics o he la e . 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 is allowed o a y.
We dis inguished wo kinds o edge cos in he
algo i hm.
The s a ic cos o a ce ain edge is defined as
he cos ha does no depend on he p e-
iously selec ed edges o he layou by he
algo i hm, i.e. he cos ha is independen o
he s a e o he layou such as he longi ude
o a ce ain s ee and he necessa y cable o
co e i .
The dynamic cos is defined as he cos which
a same poin depends on he p e iously
selec ed edges o he layou ; i.e. he cos
which is ela ed o he s a e o he layou as,
o example, he cos o a c ossing be ween a
placed cable and ano he cable ( he com-
pany ies o a oid such cases).
These ules use me hods belonging o he
di e en adio equency objec s which a e de-
i ed om he class adio- equency. The e a e
wo especially use ul me hods o signal-le el
calcula ion.
Reg essi e signal-le el calcula ion calcula es
eg essi ely he le el o signal a a ce ain
objec . The e o e, i calcula es he signal
le el belonging o an elemen and all he
elemen s connec ed om i un il he ONT.
P og essi e signal-le el calcula ion calcu-
la es p og essi ely he le el o signal a an
objec . Thus, i calcula es he signal le el
belonging o an elemen and all he elemen s
connec ed om i un il he di e en poin s
o connec ion in which i is in ol ed.
4.3.3. Rule-based sys em The knowledge da a
a e ep esen ed in he o m o i – hen ules o , o
pu i ano he way, o ules made up o p emises
and conclusions o which a salience mechanism
was added in o de o p o ide hem wi h a
p io i y o de . This sys em o easoning has
been chosen ins ead o o he kinds o easoning,
such as easoning based on cases, because he
design o an HFC ne wo k is based on ules
defined by he expe ience o he expe s.
The e a e fi e main g oups o ules in ou
sys em.
Rules o ini ializa ion (R1) a e a g oup o
ules which ca y ou he p ep ocessing o
he in o ma ion o he s ee s om he GIS,
con e ing hese da a in o Da acab in o ma-
ion. In addi ion, hey ca y ou a se ies o
p e iously necessa y calcula ions o he ex-
ecu ion o he algo i hms.
Rules o edge so ing by s a ic cos (R2) a e a
g oup o ules which ca y ou a so ing by
s a ic cos o he di e en s ee s o he zone.
This g oup o ules comp ises he ules o
he di ision o zones, e.g. om 500 homes
in o ou zones o abou 125 homes.
Rules o so ing by dynamic cos and selec-
ion o edges (R3) so by dynamic cos he
di e en s ee s o he zone. In addi ion, his
g oup con ains he necessa y ules o selec
On he o he hand, he p e ious cos s a e
de e mined by a p io i y numbe which was
defined o he fi ing o each o he ules. Thus,
i he fi ing o wo ules a he same poin was
possible, he one wi h he highe p io i y would
be fi ed and he e o e i would ge assigned a
lowe cos .
Once he layou is achie ed, he ne wo k
elemen s a e placed by means o a g oup o ules
which calcula e he signal le els co esponding
o each o he nodes o he layou . These ules
hus de e mine he posi ioning o he amplifica-
ion elemen s based on he calcula ed a enua-
ion, in o de o p o ide he subsc ibe wi h he
igh signal le el.
om he p e ious o de he edges necessa y
o he layou .
Rules o loca ion o elemen s (R4) is a g oup
o ules belonging o he placemen o he
di e en necessa y adio equency elemen s
o he co ec wi ing o he zone. By apply-
ing hese ules, which calcula e he signal
le el a each node, he di e en adio e-
quency elemen s (i.e. amplifie s, close s e c.)
a e loca ed. I i is no possible o loca e he
elemen s, i is necessa y o go back and fi e a
new g oup o ules.
Rules o gene a ion o he ou pu da a o-
wa d he GIS (R5) gene a e he files wi h he
necessa y GIS in o ma ion o he specifica-
ion o he di e en elemen s belonging o
he esul ing layou , as well as hei co e-
sponding pa ame e s.
The o de o fi ing o he abo e-men ioned
g oups o ules is shown in Figu e 8. Fi s ,
Da acab is ini ialized and he GIS da a a e ead
by means o fi ing g oup R1. La e , he o de ing
o he se e al edges is ca ied ou by means o
g oups R2 and R3. The o de ing om dynamic
so ing gene a es a layou . The elemen s a e
placed and he signal calcula ions a e ca ied
ou by means o he g oup R4. I i is possible o
each he desi ed signal le el wi h he gene a ed
layou om he p e ious phase, he design is
conside ed good and he GIS da a a e gene a ed
(R5). O he wise, ano he s a ic o de is o ced
and he e o e ano he layou is designed.
Cu en ly, he o al numbe o ules is 147.
Table 1 shows some examples o ules o each
g oup. The able con ains ou columns wi h
in o ma ion o each o he ules. The fi s
column indica es he phase in which he ule is
fi ed, he second con ains he name o he ule,
he hi d shows i s p io i y, wi h a lowe numbe
meaning a lowe p io i y, and finally in he las
column a b ie desc ip ion o he ule is gi en.
4.3.4. Coding Fo coding hese ules, we ha e
used a ool o expe sys ems called ART*En-
e p ise. F om he p og amming pa adigm
pe spec i e, ART*En e p ise p o ides objec -
o ien ed p og amming, ule-based p og am-
ming, case-based easoning and p ocedu al
p og amming. I s p og amming language is
e y simila o CLIPS (Gia a ano & Riley,
1994), main aining he same s uc u e. In Figu e
9 we can see an example o he coding o a ule in
ou sys em, which p e e s he edges ha ep e-
sen ac¸ ade cables o e edges ep esen ing cables
equi ing ubes. The ule has a p io i y o 700
which is defined in he code a e ‘salience’, in
he p emises zone (be o e ¼>). The ule
chooses be ween wo possible objec s (s ee 1
and s ee 2), which ep esen wo di e en kinds
o edges ( ac¸ ade o ubes), and p e e ably selec s
he one which is o e ac¸ ade.
An ART*En e p ise applica ion gene ally
consis s o h ee laye s: a g aphical use in e -
ace laye , an applica ion model laye and a
da abase mapping laye . We did no implemen
he g aphical use in e ace o Da acab since
his unc ion was ca ied ou by he GIS appli-
ca ion.
ART*En e p ise has file managemen capa-
bili ies ha make i possible o easily ca y ou
he exchange o da a be ween he GIS and
Rules o ini ializa ion
Rules o so ing o edges
by s a ic cos
Rules o so ing by dynamic cos and
selec ion o edges
Rules o loca ion o elemen s
Rules o gene a ion o he ou pu da a
owa d he GIS
Figu e 8: O de o fi ing he g oup o ules.