Base Station Placement in WLANs - Multiobjective Optimization Methodology: A Jumping Gene Approach - page 179

Without cable fault :. In. wired. LANs,. moisture. can. cause. erosion. of.
metallic. conductors. and. then. breakage. of. cables.. However,. this.
problem.does.not.occur.in.WLANs..As.a.result,.WLANs.help.reduce.
network.failures.and.avoid.the.costs.of.cable.replacement.

In.WLANs,.the.nodes.send.and.receive.data.through.one.of.three.wire-
less.transmission.media:.infrared,.radio.frequency.(RF),.and.microwaves.
[7,13].. Although. infrared-based. WLANs. and. microwave-based. WLANs.
have. their. own. advantages. in. terms. of. cost. or. throughput,. RF-based.
WLANs. are. still. more. practical. and. the. most. popular. choice. for. indoor.
use. as. the. RF. can. propagate. through. solid. obstacles. such. as. walls. and.
floors.[9].
There.are.two.modes.of.operation.for.WLANs:.infrastructure.mode.and.ad.
hoc. mode. [8,10].. In. the. infrastructure. mode,. stations. in. the. same. cell. com-
municate.with.each.other.via.an.access.point.that.is.used.to.transmit,.receive,.
and.buffer.the.data.between.the.WLAN.and.the.wired.network.infrastruc-
ture..Stations.from.different.cells.can.also.talk.with.each.other.through.vari-
ous.access.points..Therefore,.the.access.points.act.like.the.base.stations.in.a.
mobile.cellular.system.
When. operating. in. ad. hoc. mode,. each. station. can. directly. communicate.
with. others. through. the. access. points. (i.e.,. peer-to-peer. communication. is.
adopted),.but.within.the.same.valid.transmission.ranges.
This.chapter.provides.information.to.facilitate.the.installation.of.a.WLAN.
in. an. integrated. circuit. (IC). factory.. In. this. study,. an. infrastructure-based.
WLAN.was.considered.for.establishment.in.the.factory;.therefore,.the.loca-
tions. of. its. access. points. (base. stations). had. to. be. correctly. determined. to.
provide.adequate.quality.radio.coverage.for.terminals.
Since.there.is.a.trade-off.between.the.signal.quality.of.terminals.and.the.
number.of.allowable.base.stations,.this.placement.problem.is.better.formu-
lated.as.a.multiobjective.optimization.problem.

8.2 PathLossModel
To. evaluate. the. total. path. loss. and. satisfy. coverage. performance,. the.
log-distance. path. loss. model. is. employed. [15-19].. The. average. total. path.
loss. is. expressed. as. a. function. of. distance. with. respect. to. the. path. loss.
exponent n :

n

∝

.

d
d

PL d ( ) (8.1)

.

0